This document discusses methodologies for paralleling emergency generators in low and medium voltage applications. It provides an overview of basic synchronization theory, automatic load sharing techniques, and protective relaying considerations for paralleling generator switchgear. The document outlines typical applications for distributed generation, auto standby, and prime power systems and describes example control solutions for each. It also reviews synchronization, load sharing controls, and common protective relays used in paralleling generator systems.
Circuit breakers are devices designed to automatically open an electrical circuit under abnormal current conditions without being damaged. They can be reset to resume normal operation, unlike fuses which must be replaced. There are different types of circuit breakers including oil, air, SF6, and vacuum. Circuit breakers can sense overcurrent through either thermal or magnetic methods and operate on either a time delay or instantaneous basis. Common circuit breakers used in buildings include miniature circuit breakers and molded case circuit breakers.
Practical handbook-for-relay-protection-engineersSARAVANAN A
The ‘Hand Book’ covers the Code of Practice in Protection Circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, Dos and Donts in execution. Also, principles of various protective relays and schemes including special protection schemes like differential,
restricted, directional and distance relays are explained with sketches. The norms of protection of generators, transformers, lines & Capacitor Banks are also given.
The document appears to be a technical paper on electrical engineering topics related to symmetrical components, transformer energization, and fault analysis. It includes diagrams of symmetrical component representations of faults, discussions of transformer magnetic flux and core saturation during energization, and waveform diagrams of currents and voltages under different fault conditions.
Manual do inversor de frequência danfossClaudio Arkan
Este documento fornece instruções de segurança e instalação para o VLT Micro Drive. Ele alerta sobre os perigos da alta tensão e fornece diretrizes para evitar choques elétricos e partidas acidentais. Também inclui especificações técnicas, como dimensões mecânicas, capacidade de corrente e aterramento.
Static relays use electronic components like semiconductors instead of mechanical parts to detect faults and operate. They have components like rectifiers to convert AC to DC, level detectors to compare values to thresholds, and amplifiers and output devices to trigger trips. The document discusses the components, types, and applications of various static relays like overcurrent, directional, differential, distance and instantaneous relays used in power system protection.
This document discusses procedures for operation and maintenance of electrical equipment. It outlines steps to monitor voltages, check breaker trip circuits, observe battery performance, ensure communication equipment is working, monitor transformer loading and temperatures, check diesel generators, inspect the substation yard, test gas pressures in SF6 breakers, and check additional equipment. Precautions are provided for testing procedures and limits are given for acceptable pole discrepancies when measuring circuit breaker operation times.
The document discusses transformer protection. It describes various failures that can occur in transformers such as winding failures, bushing failures, and tap changer failures. It provides statistics on historical transformer failures. It also discusses different types of protection for transformers including electrical protection methods like differential protection, overcurrent protection, overexcitation protection and thermal protection. Internal short circuits, system short circuits, and abnormal conditions are some of the issues addressed by transformer protection schemes.
Unlock full featured course with 250+ Video Lectures at 20% Discount for "Learn 5 PLC's in a Day" lifetime E-Learning course for 39 USD only: https://www.udemy.com/nfi-plc-online-leaning/?couponCode=slideshare2016
Enroll for Advanced Industrial Automation Training with PLC, HMI and Drive Combo with 300+ Video Lecture for 69.3 USD only: http://online.nfiautomation.org/catalog/1769?couponCode=LEARNING_MADE_EASY
Circuit breakers are devices designed to automatically open an electrical circuit under abnormal current conditions without being damaged. They can be reset to resume normal operation, unlike fuses which must be replaced. There are different types of circuit breakers including oil, air, SF6, and vacuum. Circuit breakers can sense overcurrent through either thermal or magnetic methods and operate on either a time delay or instantaneous basis. Common circuit breakers used in buildings include miniature circuit breakers and molded case circuit breakers.
Practical handbook-for-relay-protection-engineersSARAVANAN A
The ‘Hand Book’ covers the Code of Practice in Protection Circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, Dos and Donts in execution. Also, principles of various protective relays and schemes including special protection schemes like differential,
restricted, directional and distance relays are explained with sketches. The norms of protection of generators, transformers, lines & Capacitor Banks are also given.
The document appears to be a technical paper on electrical engineering topics related to symmetrical components, transformer energization, and fault analysis. It includes diagrams of symmetrical component representations of faults, discussions of transformer magnetic flux and core saturation during energization, and waveform diagrams of currents and voltages under different fault conditions.
Manual do inversor de frequência danfossClaudio Arkan
Este documento fornece instruções de segurança e instalação para o VLT Micro Drive. Ele alerta sobre os perigos da alta tensão e fornece diretrizes para evitar choques elétricos e partidas acidentais. Também inclui especificações técnicas, como dimensões mecânicas, capacidade de corrente e aterramento.
Static relays use electronic components like semiconductors instead of mechanical parts to detect faults and operate. They have components like rectifiers to convert AC to DC, level detectors to compare values to thresholds, and amplifiers and output devices to trigger trips. The document discusses the components, types, and applications of various static relays like overcurrent, directional, differential, distance and instantaneous relays used in power system protection.
This document discusses procedures for operation and maintenance of electrical equipment. It outlines steps to monitor voltages, check breaker trip circuits, observe battery performance, ensure communication equipment is working, monitor transformer loading and temperatures, check diesel generators, inspect the substation yard, test gas pressures in SF6 breakers, and check additional equipment. Precautions are provided for testing procedures and limits are given for acceptable pole discrepancies when measuring circuit breaker operation times.
The document discusses transformer protection. It describes various failures that can occur in transformers such as winding failures, bushing failures, and tap changer failures. It provides statistics on historical transformer failures. It also discusses different types of protection for transformers including electrical protection methods like differential protection, overcurrent protection, overexcitation protection and thermal protection. Internal short circuits, system short circuits, and abnormal conditions are some of the issues addressed by transformer protection schemes.
Unlock full featured course with 250+ Video Lectures at 20% Discount for "Learn 5 PLC's in a Day" lifetime E-Learning course for 39 USD only: https://www.udemy.com/nfi-plc-online-leaning/?couponCode=slideshare2016
Enroll for Advanced Industrial Automation Training with PLC, HMI and Drive Combo with 300+ Video Lecture for 69.3 USD only: http://online.nfiautomation.org/catalog/1769?couponCode=LEARNING_MADE_EASY
Differential protection relays operate by comparing electrical quantities on both sides of a circuit. They provide precise unit protection for equipment. There are several types, including current, voltage, biased, and voltage balance differential relays. Current differential relays compare currents entering and leaving a system, while voltage balance relays use pilot wires and current transformers to compare voltages induced at both ends of a protected feeder. Differential relays have advantages like fast operation for very close internal faults and less incorrect operation during external faults.
- Transmission line faults are mainly transient faults caused by lightning or persistent faults from downed lines.
- Distance protection relies on measuring the impedance between the relay and the fault to determine the fault location and operate selectively.
- Distance relays divide the line into zones and use different impedance thresholds and time delays for each zone to coordinate with protection on adjacent line sections.
Digital transformer protection systemsmichaeljmack
The document discusses Beckwith's digital transformer protection systems. The systems provide:
1) Software that adapts to any transformer winding or CT configuration to provide differential protection for up to 4 windings.
2) A full complement of protective functions including metering, oscillography, and communication capabilities.
3) User-friendly software for configuring, monitoring, and analyzing the protection systems. The software facilitates commissioning and fault diagnosis.
The document discusses various aspects of partial discharge (PD) testing, including definitions, types, and detection methods. It defines PD as localized electrical discharges that only partially bridge insulation between conductors. Four main types are discussed: corona, surface, cavity, and treeing discharges. Detection methods covered include electrical, acoustic, UHF, optical, and chemical (DGA) techniques. The electrical method measures apparent charge, while acoustic localization and UHF detection have advantages of immunity to electromagnetic noise. Optical detection relies on light emission during discharges. A comparison table outlines advantages and disadvantages of each detection method.
Tap changers are devices fitted to power transformers that allow for regulation of the output voltage. Voltage regulation is achieved by altering the number of turns in one winding of the transformer, which changes the transformer ratios. Tap changers offer variable control to keep the supply voltage within limits. They can be on load or off load tap changers. On load tap changers consist of a diverter switch and selector switch to transfer current between taps without interruption.
The document discusses busbar protection, including the need for busbar protection, types of busbar protections like high impedance, medium impedance and low impedance protections. It describes the requirements of busbar protection like short tripping time and stable operation during external faults. The document discusses different busbar arrangements and applications of numerical busbar protection systems like RADSS. It provides examples of busbar protection schemes for different bus configurations. The document also includes excerpts from technical manuals providing recommendations on busbar protection in substations.
Dissolved gas analysis (DGA) of transformer oil detects gases generated within oil-filled transformers that can indicate internal faults. Key gases include hydrogen, methane, ethylene and acetylene, which can identify thermal or electrical issues. DGA interpretation methods like the key gas method or IEC gas ratio method analyze individual and total dissolved combustible gas concentrations to evaluate transformer condition and risk of failure. Regular oil sampling per ASTM standards from the drain point helps assess the internal condition of transformers to support effective maintenance.
Different methods of pwm for inverter controlTushar Pandagre
This document discusses different pulse width modulation (PWM) techniques for inverter control. It describes single pulse modulation, multiple pulse modulation, sinusoidal pulse modulation, and phase displacement control. PWM techniques allow for efficient internal control of the output voltage of an inverter by varying the pulse width. Using multiple pulses or sinusoidal pulses reduces harmonics in the output voltage. Phase displacement control combines the output of multiple inverters with phase shifts between them to control voltage. PWM techniques provide voltage regulation without additional stages but require fast switching devices and complex control circuits.
The document discusses the design of a transfer scheme for a secondary selective substation with two busses that can each be supplied by an incoming line circuit breaker, connected by a normally open bus tie breaker. It outlines the equipment arrangement, existing system loading conditions, and final configuration. Key aspects of designing the transfer scheme are discussed, including conditions for transfer, safety concerns, implementation methods, testing procedures, and maintenance. Logic diagrams of the main breaker and tie breaker are presented, showing how the transfer is initiated and blocked under various conditions.
The document outlines various components of a power system protection system. It discusses the need for protection to maintain reliable power supply and minimize equipment damage. The key elements to be protected include generators, transformers, transmission lines, and busbars. Protection schemes for each element are then described, such as differential protection for generators and transformers, Buchholz relays for transformers, and distance and line differential protection for transmission lines.
On Load Tap Changer (OLTC) is used in "High Power Transformers" to control output voltage, when electric load on transformers get increase the output voltage get decrease due to internal voltage drop inside winding, change in tap is required to maintain output voltage. OLTC is a device which perform tap changing in High Power Transformers during On Load conditions and is powered by a motor.
A contactor is an electrically controlled switch used for switching electrical power circuits similar to a relay but with higher current ratings. It has three main components - contacts that carry the current, an electromagnet or coil that provides the driving force to close the contacts, and an insulating enclosure housing the contacts and coil. Contactors are designed to directly connect to high-current load devices above 15 amps, unlike relays which are lower capacity and can be normally open or closed. Modern contactors use techniques like vacuum or inert gases to extinguish arcs that occur when contacts open or close and can damage the contacts over time if not properly protected.
This document discusses basic protection and relaying schemes used in power systems. It begins by explaining why protection systems are needed to handle severe disturbances that could jeopardize the power system. The key elements of a protection system are then introduced, including protective relays, circuit breakers, and current/voltage transducers. Common protection schemes like overcurrent, directional overcurrent, distance, and differential protection are described at a high level. The advantages of digital relays over electromechanical relays are also briefly mentioned. Overall, the document provides a high-level overview of protection systems and some of the basic schemes used to protect different components in a power grid.
This document provides an overview of transformer protection. It discusses the types of faults that can occur in transformers, including internal faults like winding faults and external faults. It describes Buchholz relays, which detect faults inside the transformer tank by sensing gas and oil movement. Differential protection is also covered, which can detect faults not caught by Buchholz relays. The document outlines considerations for transformer differential protection like current transformer ratings and connections. It provides examples of Merz-Price protection schemes for star-delta and star-star transformers.
Generator and Transformer Protection (PART 1)Dr. Rohit Babu
Part 1. Generator Protection
Protection of generators against stator faults
Rotor faults and abnormal conditions
Restricted earth fault and inter-turn fault protection
Numerical examples
The document discusses automation and tools used for automation including PLCs and SCADA systems. It provides an overview of what PLCs and SCADA are, including their components and programming. PLCs are microprocessor-based devices that interface inputs and outputs to control industrial automation applications. SCADA systems are used for supervisory control and data acquisition in industrial processes allowing remote monitoring and control. Common PLC and SCADA manufacturers and software are also mentioned.
This document provides guidelines for overcurrent protection and coordination settings for industrial equipment such as transformers, buses, feeders, and motors above 600V. It outlines typical recommended pickup and time delay settings as rules of thumb for phase and ground overcurrent relays protecting this equipment. Care must be taken to properly coordinate settings between protective devices to prevent unintended tripping and ensure equipment is protected against damage from faults.
ABB Medium Voltage MV Indoor and Outdoor Current Transformers
ABB POWER PRODUCTSABB CT's - Current Transformers
ABB Medium Voltage MV Indoor Bushing Current Transformers CT's, 3.3kV to 11kV/12kV - ABB TTR
ABB Medium Voltage MV Indoor Bushing Current Transformers CT's, up to 25kV - ABB TTR
ABB Medium Voltage MV Indoor Current Transformers CT's, 3.3kV up to 40.5kV - ABB TPU
ABB Medium Voltage MV Indoor Current Transformers CT's, up to 25kV - ABB TPE
ABB Medium Voltage MV Outdoor Current Transformers CT's - ABB KON-17
ABB Medium Voltage MV Outdoor Current Transformers CT's, 17.5kV 24kV 25kV- ABB TPO6
This document discusses motor protection principles and thermal modeling for motor protection relays. Some key points:
- Motors account for a large portion of electricity usage and failures can be costly. Thermal stress is a major cause of failures.
- A motor protection relay uses a thermal model to monitor the thermal capacity used based on operating conditions like load, ambient temperature, voltage, and current balance. It can trip for overload based on reaching 100% thermal capacity.
- The thermal model considers motor states like running, starting, and overloaded. It uses thermal limit curves, an overload curve, cooling time constants, and a hot to cold stall time ratio in its calculations. Current unbalance is also accounted for through a bias factor.
The document describes an automatic synchronization and load sharing system between two diesel generator sets. When the mains power fails, the master generator set is started and picks up the load once its voltage is healthy. If the load reaches 80% of the first generator's capacity, the second generator is automatically started. Load is then shared between the two generators proportionally to their capacities. The generators continue to run in synchronization until the load drops below 80% of one generator's capacity.
This document discusses providing security against faulty synchronization when connecting two electrical sources. It defines proper closure as having acceptable phase angle difference, slip frequency, voltage difference and magnitude. Faulty synchronization can cause damage through excessive mechanical stress and current flows. Modern automatic synchronizing relays calculate a safe advance time to close based on measured phase angle and slip frequency. Sync check relays supervise synchronization but may introduce delays. Proper synchronization is important for generator connection and tie line applications.
Differential protection relays operate by comparing electrical quantities on both sides of a circuit. They provide precise unit protection for equipment. There are several types, including current, voltage, biased, and voltage balance differential relays. Current differential relays compare currents entering and leaving a system, while voltage balance relays use pilot wires and current transformers to compare voltages induced at both ends of a protected feeder. Differential relays have advantages like fast operation for very close internal faults and less incorrect operation during external faults.
- Transmission line faults are mainly transient faults caused by lightning or persistent faults from downed lines.
- Distance protection relies on measuring the impedance between the relay and the fault to determine the fault location and operate selectively.
- Distance relays divide the line into zones and use different impedance thresholds and time delays for each zone to coordinate with protection on adjacent line sections.
Digital transformer protection systemsmichaeljmack
The document discusses Beckwith's digital transformer protection systems. The systems provide:
1) Software that adapts to any transformer winding or CT configuration to provide differential protection for up to 4 windings.
2) A full complement of protective functions including metering, oscillography, and communication capabilities.
3) User-friendly software for configuring, monitoring, and analyzing the protection systems. The software facilitates commissioning and fault diagnosis.
The document discusses various aspects of partial discharge (PD) testing, including definitions, types, and detection methods. It defines PD as localized electrical discharges that only partially bridge insulation between conductors. Four main types are discussed: corona, surface, cavity, and treeing discharges. Detection methods covered include electrical, acoustic, UHF, optical, and chemical (DGA) techniques. The electrical method measures apparent charge, while acoustic localization and UHF detection have advantages of immunity to electromagnetic noise. Optical detection relies on light emission during discharges. A comparison table outlines advantages and disadvantages of each detection method.
Tap changers are devices fitted to power transformers that allow for regulation of the output voltage. Voltage regulation is achieved by altering the number of turns in one winding of the transformer, which changes the transformer ratios. Tap changers offer variable control to keep the supply voltage within limits. They can be on load or off load tap changers. On load tap changers consist of a diverter switch and selector switch to transfer current between taps without interruption.
The document discusses busbar protection, including the need for busbar protection, types of busbar protections like high impedance, medium impedance and low impedance protections. It describes the requirements of busbar protection like short tripping time and stable operation during external faults. The document discusses different busbar arrangements and applications of numerical busbar protection systems like RADSS. It provides examples of busbar protection schemes for different bus configurations. The document also includes excerpts from technical manuals providing recommendations on busbar protection in substations.
Dissolved gas analysis (DGA) of transformer oil detects gases generated within oil-filled transformers that can indicate internal faults. Key gases include hydrogen, methane, ethylene and acetylene, which can identify thermal or electrical issues. DGA interpretation methods like the key gas method or IEC gas ratio method analyze individual and total dissolved combustible gas concentrations to evaluate transformer condition and risk of failure. Regular oil sampling per ASTM standards from the drain point helps assess the internal condition of transformers to support effective maintenance.
Different methods of pwm for inverter controlTushar Pandagre
This document discusses different pulse width modulation (PWM) techniques for inverter control. It describes single pulse modulation, multiple pulse modulation, sinusoidal pulse modulation, and phase displacement control. PWM techniques allow for efficient internal control of the output voltage of an inverter by varying the pulse width. Using multiple pulses or sinusoidal pulses reduces harmonics in the output voltage. Phase displacement control combines the output of multiple inverters with phase shifts between them to control voltage. PWM techniques provide voltage regulation without additional stages but require fast switching devices and complex control circuits.
The document discusses the design of a transfer scheme for a secondary selective substation with two busses that can each be supplied by an incoming line circuit breaker, connected by a normally open bus tie breaker. It outlines the equipment arrangement, existing system loading conditions, and final configuration. Key aspects of designing the transfer scheme are discussed, including conditions for transfer, safety concerns, implementation methods, testing procedures, and maintenance. Logic diagrams of the main breaker and tie breaker are presented, showing how the transfer is initiated and blocked under various conditions.
The document outlines various components of a power system protection system. It discusses the need for protection to maintain reliable power supply and minimize equipment damage. The key elements to be protected include generators, transformers, transmission lines, and busbars. Protection schemes for each element are then described, such as differential protection for generators and transformers, Buchholz relays for transformers, and distance and line differential protection for transmission lines.
On Load Tap Changer (OLTC) is used in "High Power Transformers" to control output voltage, when electric load on transformers get increase the output voltage get decrease due to internal voltage drop inside winding, change in tap is required to maintain output voltage. OLTC is a device which perform tap changing in High Power Transformers during On Load conditions and is powered by a motor.
A contactor is an electrically controlled switch used for switching electrical power circuits similar to a relay but with higher current ratings. It has three main components - contacts that carry the current, an electromagnet or coil that provides the driving force to close the contacts, and an insulating enclosure housing the contacts and coil. Contactors are designed to directly connect to high-current load devices above 15 amps, unlike relays which are lower capacity and can be normally open or closed. Modern contactors use techniques like vacuum or inert gases to extinguish arcs that occur when contacts open or close and can damage the contacts over time if not properly protected.
This document discusses basic protection and relaying schemes used in power systems. It begins by explaining why protection systems are needed to handle severe disturbances that could jeopardize the power system. The key elements of a protection system are then introduced, including protective relays, circuit breakers, and current/voltage transducers. Common protection schemes like overcurrent, directional overcurrent, distance, and differential protection are described at a high level. The advantages of digital relays over electromechanical relays are also briefly mentioned. Overall, the document provides a high-level overview of protection systems and some of the basic schemes used to protect different components in a power grid.
This document provides an overview of transformer protection. It discusses the types of faults that can occur in transformers, including internal faults like winding faults and external faults. It describes Buchholz relays, which detect faults inside the transformer tank by sensing gas and oil movement. Differential protection is also covered, which can detect faults not caught by Buchholz relays. The document outlines considerations for transformer differential protection like current transformer ratings and connections. It provides examples of Merz-Price protection schemes for star-delta and star-star transformers.
Generator and Transformer Protection (PART 1)Dr. Rohit Babu
Part 1. Generator Protection
Protection of generators against stator faults
Rotor faults and abnormal conditions
Restricted earth fault and inter-turn fault protection
Numerical examples
The document discusses automation and tools used for automation including PLCs and SCADA systems. It provides an overview of what PLCs and SCADA are, including their components and programming. PLCs are microprocessor-based devices that interface inputs and outputs to control industrial automation applications. SCADA systems are used for supervisory control and data acquisition in industrial processes allowing remote monitoring and control. Common PLC and SCADA manufacturers and software are also mentioned.
This document provides guidelines for overcurrent protection and coordination settings for industrial equipment such as transformers, buses, feeders, and motors above 600V. It outlines typical recommended pickup and time delay settings as rules of thumb for phase and ground overcurrent relays protecting this equipment. Care must be taken to properly coordinate settings between protective devices to prevent unintended tripping and ensure equipment is protected against damage from faults.
ABB Medium Voltage MV Indoor and Outdoor Current Transformers
ABB POWER PRODUCTSABB CT's - Current Transformers
ABB Medium Voltage MV Indoor Bushing Current Transformers CT's, 3.3kV to 11kV/12kV - ABB TTR
ABB Medium Voltage MV Indoor Bushing Current Transformers CT's, up to 25kV - ABB TTR
ABB Medium Voltage MV Indoor Current Transformers CT's, 3.3kV up to 40.5kV - ABB TPU
ABB Medium Voltage MV Indoor Current Transformers CT's, up to 25kV - ABB TPE
ABB Medium Voltage MV Outdoor Current Transformers CT's - ABB KON-17
ABB Medium Voltage MV Outdoor Current Transformers CT's, 17.5kV 24kV 25kV- ABB TPO6
This document discusses motor protection principles and thermal modeling for motor protection relays. Some key points:
- Motors account for a large portion of electricity usage and failures can be costly. Thermal stress is a major cause of failures.
- A motor protection relay uses a thermal model to monitor the thermal capacity used based on operating conditions like load, ambient temperature, voltage, and current balance. It can trip for overload based on reaching 100% thermal capacity.
- The thermal model considers motor states like running, starting, and overloaded. It uses thermal limit curves, an overload curve, cooling time constants, and a hot to cold stall time ratio in its calculations. Current unbalance is also accounted for through a bias factor.
The document describes an automatic synchronization and load sharing system between two diesel generator sets. When the mains power fails, the master generator set is started and picks up the load once its voltage is healthy. If the load reaches 80% of the first generator's capacity, the second generator is automatically started. Load is then shared between the two generators proportionally to their capacities. The generators continue to run in synchronization until the load drops below 80% of one generator's capacity.
This document discusses providing security against faulty synchronization when connecting two electrical sources. It defines proper closure as having acceptable phase angle difference, slip frequency, voltage difference and magnitude. Faulty synchronization can cause damage through excessive mechanical stress and current flows. Modern automatic synchronizing relays calculate a safe advance time to close based on measured phase angle and slip frequency. Sync check relays supervise synchronization but may introduce delays. Proper synchronization is important for generator connection and tie line applications.
Load balancing is a technique for distributing work across multiple computers or resources to maximize efficiency and minimize response times. It involves using load balancers to distribute incoming network traffic and workload between servers in a server farm. The document discusses basic and advanced load balancing concepts and techniques, and applications of load balancing for global server load balancing, web caching, and in the Java programming language.
In the presentation all about, the operation of Parallel System of two alternators and in the sense how in power plants, they utilize it in their sensitivity to produce more electricity at one operation and after all how they reduce the per cost of electricity unit. I hope, this presentation helpfull to all the Engineering Students.
This document provides an overview of generator basics, including:
1) Descriptions of synchronous generator types and connections to power systems such as direct connected and unit connected configurations.
2) Explanations of generator excitation and automatic voltage regulator (AVR) control systems.
3) Discussions of generator grounding methods like low impedance, high impedance, and dual grounding; and considerations for multiple generator installations.
4) Details on generator protection devices and multifunction digital relays, appropriate levels of redundancy, and potential VT connection issues.
1) For alternators to operate in parallel, they must be synchronized by having equal line voltage, frequency, phase sequence, phase angle, and waveform.
2) When alternators are synchronized and operating in parallel with no load, a circulating current will flow if their speeds or excitations differ slightly.
3) This circulating current acts to resynchronize the alternators by speeding up the slower one and slowing the faster one through their functioning as motor and generator respectively, until steady state is reached with no circulating current.
Diesel Power Generation Plants with Multiple Machines in Parallell and on the...Living Online
This document discusses diesel power generation plants with multiple engines running in parallel and connected to the electrical grid. It covers the key components and subsystems of these plants, including fuel storage, air intake, exhaust, auxiliary power requirements, and typical layouts. The objectives are to provide emergency or supplemental power for industrial facilities and small communities that lack reliable main power sources. Larger plants require additional infrastructure like heat recovery boilers, fuel treatment systems, and switchgear to control and distribute the generated electricity.
This document contains diagrams and information related to electrical systems. It includes a cover page labeled "Legend", followed by pages containing single line diagrams of electrical components and connections. The final page discusses the synchronizing function of electrical systems.
This document provides an overview of the EE2402 Protection & Switchgear course presented by C.Gokul. It includes the course syllabus, units covered, textbook references and introductory content on power system basics, components, faults, protection elements, relay terminology and essential qualities of protection systems. The key topics discussed are types of faults in power systems, importance of protective schemes, elements of a protection system including current transformers, voltage transformers, relays and circuit breakers. Neutral earthing methods with a focus on Peterson coil are also introduced.
Electrical Commissioning and Arc-Flash Safety presentationMichael Luffred
Electrical Commissioning and Arc Flash Safety training presentation given November 21, 2013. Mike Luffred presented this information as a technical seminar for the National Capital Chapter region (PA/NJ/DE/VA/MD/DC) of the Building Commissioning Association. The presentation was given at the Eaton Experience Center in Warrendale, PA to help commissioning engineers understand the importance of arc flash safety in the industry.
Pressure relieving valves like safety valves and safety relief valves are used in thermal power plants to prevent overpressure in pressurized systems. There are different types including safety valves, safety relief valves, and power operated relief valves. Safety valves open fully at a set pressure while safety relief valves can open proportionally. Standards like ASME Section I provide requirements for safety valve installation, capacity, materials, and settings to ensure systems are properly protected from overpressure. Safety valves are part of defense-in-depth protection schemes used in power plants to prevent accidents.
Operation and Maintenance of Diesel Power Generating PlantsLiving Online
Diesel generating plants always have an important role in power plants as well as in industries and commercial installations to meet continuous and emergency standby power requirements for day to day use. A good knowledge of basic operation principles, layout requirements, associated components and maintenance practices for diesel power plants help the career development of many engineers and technicians in today’s world. Whatever your role in industry - designer, purchase engineer, installation contractor or maintenance engineer, a solid knowledge of diesel power plants is always useful. This workshop is designed to familiarise you with various aspects of diesel generating power plants for practical application.
Examples will be taken from various industrial standard practices regarding the construction, layouts, application and maintenance procedures followed for reliable and trouble free operation of diesel power plants. The various tests to be conducted during commissioning and maintenance checks to ensure proper and long term operation of diesel power plants will also be covered in the workshop.
Some of the essential systems such as fuel oil layouts, lube oil requirements, control circuitry, etc will also be discussed.
MORE INFORMATION: http://www.idc-online.com/content/operation-and-maintenance-diesel-power-generating-plants-28
MY PROJECT-automatic load sharing of transformer by using GSM tecnique.nikhilhiware
This document summarizes a student project on automatic load sharing of transformers using GSM technique. The objectives are to protect domestic and power transformers from overload by sharing the load between two parallel transformers when the load increases above a threshold. A PIC microcontroller monitors the current and voltage, and controls relays to disconnect one or both transformers if the load is too high. It can also send load information via text message using a GSM modem. The circuit includes transformers, rectifiers, regulators, relays, current and voltage measurement circuits connected to the PIC microcontroller. This helps prevent overheating, increases transformer life, and acts as an uninterruptible power supply.
Microcontroller based transformer protectioAminu Bugaje
This document provides an introduction and background to a project on designing a microcontroller-based transformer protection system. It discusses how transformers are critical components in power systems that require protection against faults like short circuits, overcurrent and overvoltage. The document then reviews previous work on transformer protection and outlines the objectives of this project, which are to design current and voltage sensing circuits, develop a microcontroller algorithm for overload, overvoltage and undervoltage protection, and test the system's performance. The chapter concludes by outlining the scope and limitations of the project, which involves both hardware and software design to develop a protection system that can monitor transformer parameters and trip circuit breakers or relays during faults.
This document discusses switchgear, its types and components, as well as maintenance procedures. It begins by defining switchgear and its purposes of controlling, protecting and isolating electrical equipment. It then discusses low voltage and medium voltage switchgear, and lists the basic functions of switchgear as electrical protection, safe isolation from live parts, and local or remote switching. The document goes on to discuss periodic and preventive maintenance of switchgear.
The document provides information about diesel generators, including what they are, how they work, their main components and functions. Some key points:
- A diesel generator is a combination of a diesel engine and an electric generator that generates electrical energy. The diesel engine powers the generator through the motion of its crankshaft.
- In a diesel engine, fuel is injected into compressed hot air in the combustion chamber, where it ignites due to the high temperature from compression. This powers the crankshaft across 4 strokes: intake, compression, power, and exhaust.
- The main components of a diesel generator are the engine, alternator, fuel system, governor, voltage regulator, cooling/exhaust
The document describes the key components and operation of an AC generator. It includes:
- The main components are the field, armature, prime mover, rotor, stator, and slip rings. The rotor and stator can each be the field or armature depending on the generator type.
- In operation, the prime mover rotates the rotor through the stationary field, inducing voltage in the armature windings. Slip rings allow a continuous connection to the rotating armature.
- Losses occur from internal resistance, hysteresis in the iron cores, and mechanical factors like bearing friction. Efficiency is the ratio of output to input power. Generators are rated by voltage, current, power
Transformer protection using microcontroller and gsm technologyKartik Patel
This document describes a project to protect transformers from overload conditions using a microcontroller and GSM technology. It includes a block diagram and explanation of the circuit diagram. The key components are a step-down transformer, rectifier, microcontroller, current transformer, voltage transformer, and relays. The microcontroller monitors the current and voltage, and can trigger the relays to disconnect the transformer if the load exceeds safe levels, while also sending a message via GSM to alert authorities. The objectives are to prevent transformer damage from overloading and allow for load sharing to increase lifespan.
Dokumen tersebut membahas tentang sistem pentanahan pada sistem listrik, termasuk definisi, tujuan, jenis-jenis sistem pentanahan titik netral dan pentanahan peralatan, serta faktor-faktor yang mempengaruhi besarnya tahanan pentanahan."
Main equipment in the power plant is Generator. It's cost is much higher than any other equipment so we will have to protect the generator from all the possible faults and errors.
Voltages and currents present at the generator's rated voltage and current are provided as examples. Sample relay setting calculations are shown for generator protection elements including 59N neutral overvoltage, 27TN third harmonic undervoltage, 46 negative sequence overcurrent, and coordination between protective devices. Formulas for calculating voltage and current settings from generator nameplate data are demonstrated.
This document discusses power electronics and phase-fired controllers. It describes how phase-fired controllers can synchronize with input modulation and are used to control the amount of voltage, current, and power delivered to a load. Buck and boost converters also work on this principle. The document lists components commonly used in power electronics like ICs, SCRs, pulse transformers, transistors, and potentiometers. It provides details on the pins and functions of the TCA 785 IC. In closing, it mentions some applications of phase-fired controllers like motor speed control, buck, and boost regulators, and voltage/power control.
Reactive power compensation is used to improve the performance of AC power systems. There are various methods of reactive power compensation including shunt compensation, series compensation, static VAR compensators, and static synchronous compensators. Shunt compensation devices such as capacitors and reactors are connected in parallel to transmission lines to regulate voltage. Series compensation uses capacitors connected in series to transmission lines to increase power transfer capability. Static VAR compensators and static synchronous compensators use thyristor-based voltage sourced converters to dynamically inject or absorb reactive power and control voltage. Reactive power compensation provides benefits such as improved power factor, voltage regulation, reduced losses, and increased power transfer capacity.
This paper presents a novel control strategy for the compensation of voltage quality issues in power system networks with AC drives. Voltage quality is one of the key parameter for power engineers and to deliver the power with good quality should be given at most priority. Voltage quality mitigation in power system network is done by employing dynamic voltage restorer (DVR). DVR consists of power switches and power switches are to be controlled. DVR in this paper is controlled using a novel control strategy. A novel control strategy can effectively control DVR by improving voltage quality reducing the adverse effects of voltage sag and voltage swell in power system networks. The paper presents the DVR controlled with novel control strategy for electrical machine (induction motor) drive load application.
This document discusses power control in power systems and summarizes key concepts. It outlines four main constraints: 1) active power constraint, 2) reactive power constraint, 3) voltage magnitude constraint, and 4) load angle constraint. It also describes different reactive power compensation devices and methods for voltage control, including excitation control, tap changing transformers, and the use of capacitors, reactors, and FACTS devices. Load flow analysis is presented as a balanced mechanism between demand and generation under changing load conditions.
This document discusses power control in power systems and summarizes key concepts. It outlines four main constraints: 1) active power constraint, 2) reactive power constraint, 3) voltage magnitude constraint, and 4) load angle constraint. It then defines active and reactive power, explains the need for reactive power compensation, and lists various reactive power compensation devices. The document also discusses excitation control and voltage regulation in generating stations, voltage control using tap changing transformers, and other voltage control methods.
This document discusses voltage regulation on electric power distribution systems. It begins by describing the problem of voltage drops caused by line losses and increasing load density. It then explains how voltage regulators work to continuously monitor and adjust output voltage by changing transformer taps. The document covers the construction, basic theory of operation, and implementation of single-phase voltage regulators. It also compares voltage regulators to load tap changers and provides an example case study of commissioning a regulator.
- Frequency control is important to maintain required receiving end voltage and stable operation when systems are interconnected. Automatic generation control (AGC) is used to maintain power balance and constant system frequency as load changes.
- AGC has three components - primary control provides immediate response to load changes, secondary control corrects tie-line flows, and economic dispatch schedules units economically. It acts based on changes in generator speed and frequency.
- For multi-area systems, AGC must restore frequency and scheduled tie-line flows in each area while ensuring areas absorb their own load changes. Area control error (ACE) is used to adjust control settings to drive ACE to zero and balance the system.
This is a special type of turbo generator which may find its usage in typical chemical plants. Here the steam in turbine comes from sulphuric acid plant.So no need of coal handling plant like in thermal power plants.
There are numerous systems in use today that convert the fixed
voltage and fixed frequency a.c. supply into variable voltage or /and variable frequency supply using power semiconductor devices. The simplest forms of ac-to-ac converters are the a.c. voltage controllers that
convert fixed voltage fixed frequency into variable voltage fixed frequency. These voltage controllers are also called a.c. choppers or a.c. voltage regulators. Some of the applications are motor drive systems; electric furnaces heat control, light dimmers, HVAC systems, welding and other industrial applications. This chapter discusses the single phase and three-phase a.c. voltage controller (a.c. choppers) and their performance with resistive and resistive-inductive loads.
The ac-to-ac power converters available in industry today do not actually convert power directly from a.c. power of one frequency to a.c. power of another frequency. Instead, these converters first convert
electrical power to d.c. using a rectifier, and then convert power back into a.c. using an inverter.These are called two-stage converters. However,
a cycloconverter is a frequency changer that converts an a.c. supply of fixed input frequency directly to an a.c. output of another frequency.
Cycloconverters not only eliminate the problem of having multiple systems to perform a single function, they also limit the flow of power to a single switch at any one period in time. Therefore, there is no bus link,
d.c. or otherwise, included in a cycloconverter topology between power input and power output.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
There are two broad classes of power system stability:
1) Steady state stability - The ability of a system to maintain equilibrium after a small disturbance.
2) Transient stability - The ability to maintain synchronism during large disturbances like faults.
Factors influencing transient stability include generator loading, fault conditions, clearing time, reactances, and inertia. Methods to improve it include high-speed excitation, series capacitors, fault clearing and independent pole operation.
The document provides an overview of STATCOM technology and AMSC's D-VAR STATCOM system. Key points:
- A STATCOM is a power electronics device that injects reactive current into the power system to control voltage or power factor. It contains DC capacitors, converter transformers, converters using IGBTs/GCTs, and filters.
- AMSC's D-VAR STATCOM provides dynamic reactive capability in both leading and lagging modes. It has an overload capability of 2.67 times its continuous rating.
- The D-VAR system can perform various functions including voltage control, power factor control, damping power oscillations, and integrating capacitor/reactor banks.
- D-VAR STAT
Automatic voltage regulations And V curves of alternatorsMUDASSARHABIB5
This document discusses automatic voltage regulation and V-curves in alternators. It begins by defining voltage regulation as the change in terminal voltage from no-load to full-load conditions. It then describes different types of voltage regulators, including manual and automatic voltage regulators. For automatic voltage regulators, it discusses the components, circuit concept, and functions of electronic voltage regulators. Finally, it explains V-curves, which plot the variation of armature current with changes in field current, and describes the three stages of under excitation, normal excitation, and over excitation.
##CONTENT##
Introduction
Voltage control
Power system control
Control of reactive power and power factor
Interconnected control and frequency ties
Supervisory control
Line compensation
Series compensation
Series and shunt compensation schemes for ac transmission system
This document discusses automatic generation control (AGC) systems. It begins with an overview of AGC and its purpose to maintain power balance and constant frequency in an electric grid. It then covers modeling of AGC for single and multi-generator systems, including control block diagrams. It also introduces the concept of area control error (ACE) and simplified control models for multi-area AGC systems used in power pool operations.
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Emergency Generator - Paralleling Switchgear Power Switching Control
1. Emergency GeneratorEmergency Generator -- ParallelingParalleling
Switchgear Power Switching ControlSwitchgear Power Switching Control
Methodologies for LV and MVMethodologies for LV and MV
ApplicationsApplications
Thomson TechnologyThomson Technology
PRESENTED BYPRESENTED BY
Douglas KristensenDouglas Kristensen –– Manager, US SalesManager, US Sales
2. PSG Power Switching Control Methodologies
for LV and MV Applications
OUTLINE:
Overview/Introduction
Basic Theory
Design/Application
Control Applications/System Operation
4. PSG – Typical Applications
Distributed Generation
Applications
Auto Standby
Applications
Prime Power
Applications
5. PSG – Typical Application Solutions
System Applications:
Distributed Generation – Utility paralleling for
extended or softload closed transition transfer with Auto
Standby functionality.
Auto Standby – Traditional islanded operation with
distributed emergency loads and/or ATS.
Prime Power – Prime source of power operating 24/7
with load demand control to maximize efficiency.
6. Distributed Generation (DG) Switchgear Systems
Parallel operation of single or multiple generators to
the utility grid or on an isolated bus as emergency
standby power.
These systems can provide auto synchronizing, soft
load Closed Transition Transfer with automatic
load(kW) and power factor control (kVAR).
Continuous parallel operation with the utility can be
utilized for, load testing, load demand management
and cogeneration applications.
7. Auto Standby (AS) Switchgear Systems
To provide automatic standby power
during a utility power failure.
Single or multiple generator
systems with automatic
synchronizing and paralleling
control.
Designs with integral transfer
switches or external distributed
transfer switch schemes.
ATS may incorporate Open
Transition or Closed Transition
(Momentary Operation).
8. Prime Power (PP) Switchgear Systems
To provide power & control for
applications where local utility is
unreliable, unavailable or
uneconomical to install.
Single or multiple generator systems
with automatic synchronizing.
Prime Power sites require unique
control solutions because of their
critical nature.
These systems can incorporate
automatic synchronizing, soft
transfer, fuel economizing or run-time
hour balancing.
11. Basic TheoryBasic Theory –– SynchronizingSynchronizing
Generators may only be synchronized together provided they
have:
Same number of phases
Same phase to phase voltage
Same phase rotation
PHASE SEQUENCE
VA
VB
VC
V
L-L
VL
120º N
VL
VL
EQUIVALENT OR NET
EFFECTIVE VOLTAGE
3 PH = VL-L = 3 x VL-N
3
3 PHASE
12. Generators are “In Synchronism” only when:
Phase voltages match
Frequencies match
Phase angles match
0
90º 180º 270º 360º0º
PHASE VOLTAGE
MISMATCH
PHASE ANGLE
MISMATCH
VX
VY
0
90º 180º 270º 360º0º
PHASE VOLTAGES
MATCHED
PHASE ANGLE
MISMATCHED
VX
VY
0
90º 180º 270º 360º0º
PHASE VOLTAGES MATCHED
PHASE ANGLES MATCHED
VX = VY
SYNCHRONIZED
Basic TheoryBasic Theory –– SynchronizingSynchronizing
13. FREQUENCY
COMPARITOR
PHASE
ANGLE
COMPARITOR
VOLTAGE
COMPARITOR
K1
GEN. INCOMING
VOLTAGE
BUS VOLTAGE
AUTO OR MANUAL
SPEED
AVR
K1
GENERATOR BREAKER
CLOSE SIGNAL
CC
TYPICAL AUTOMATIC SYNCHRONIZER
VOLTAGE
ENGINE
GOVERNOR
Typical automatic synchronizers provide the following
functions:
Control speed (frequency) of incoming generator set.
Match incoming & bus frequencies & phase angles.
Provide breaker close signal when “in synchronism”.
Optional voltage matching control.
Basic TheoryBasic Theory –– SynchronizingSynchronizing
15. Basic TheoryBasic Theory –– Automatic Load SharingAutomatic Load Sharing
Automatic load sharing is required between generators to
maintain maximum capacity of the system.
Generator capacity is divided into two basic types:
Kilowatt (kW) Load - Power is provided only by the primer
mover (engine) i.e. horsepower
Kilovar (kVAR) Load - Power is provided only by the
alternator (i.e. generator)
Phase Angle
kVA
kW
kVA INDUCTIVE
(LAG)
kVA CAPACITIVE
(LEAD)
NET kVAR
(LAG)
kVAR
GENERATOR
ENGINE
kVAR
kW
16. 63.0
61.5
60.0
58.5
57.0
Hz
0% 100% kWeGENERATOR LOAD
RUNNING
CONDITION
AT TIME OF
PARALLELING
SET SPEED
SET SPEED
SET SPEED
FIXED UTILITY
AND BUS
FREQUENCY
DIESEL GENERATOR
5% DROOP GOVERNOR
- VARIOUS SET SPEEDS
Basic TheoryBasic Theory –– Kilowatt (kw) Load SharingKilowatt (kw) Load Sharing
Once engines are synchronized together they must share real
power (kW) to balance capacity.
Two types of kW load sharing systems may be used.
Droop (varying frequency)
Isochronous (constant frequency)
17. Basic TheoryBasic Theory -- Kilowatt (kW) Load SharingKilowatt (kW) Load Sharing
Typical Isochronous Load Sharing:
Control kW by adjusting engine governor (fuel)
Increase or decrease in fuel changes kW (speed frequency is held
constant)
Load balance between generators is set as a percentage load
LOAD SHARING
LINES
ENGINE
GENERATOR #1
GOVERNOR
AVR
AUTOMATIC
VOLTAGE
REGULATOR
kW
SENSOR
PT
CT
FUEL (SPEED)
BIAS SIGNAL
52-G1
SPEED ADJUST
kW LOAD
SHARING
MODULE
kW LOAD
SHARING
MODULE
ENGINE
GENERATOR #2
GOVERNOR
AVR
AUTOMATIC
VOLTAGE
REGULATOR
kW
SENSOR
PT
CT
FUEL (SPEED)
BIAS SIGNAL
52-G2
SPEED ADJUST
18. Basic TheoryBasic Theory -- kVAR (Reactive) Load SharingkVAR (Reactive) Load Sharing
Once generators are synchronized together, they must share
reactive load (kVAR or power factor) to balance capacity.
Two types of reactive load sharing systems may be used.
Reactive droop compensation (varying voltage)
Cross current compensation (constant voltage)
LOAD BUS
+
–
AVR1
52-G1
CT1
IG1
GENERATOR #1
I1
+
–
AVR2
CT2
IG2
GENERATOR #2
I2
LOAD BUS
+
–
AVR1
CT1
IG1
GENERATOR #1
I1
+
–
AVR2
CT2
IG2
GENERATOR #2
I2
REACTIVE DROOP COMPENSATION CROSS CURRENT COMPENSATION
52-G2 52-G252-G1
19. Design/ApplicationDesign/Application -- SwitchgearSwitchgear
Typical Genset
Manufacturer Engine Control
Speed
Control Loadsharing Synchronizing
MTU Onsite Energy
Integral Integral
Cummins
Integral Integral Integral Integral
Caterpillar
Integral Integral
Waukesha
Optional Integral
Fairbanks Morse
Integral Integral
GE/Jenbacher
Integral Integral Integral Integral
Deutz
Integral Integral Integral/droop
Indepedent OEMs
Optional Integral Optional Optional
Turbines
Integral Integral Optional Optional
Typical Engine/Gen Set Control ConfigurationsTypical Engine/Gen Set Control Configurations
21. GENERATOR #1
87G
32 40
81
O-U 27/59
51G 50/51
(27)
52-G1 25
GENERATOR #2
87G
32 40
81
O-U 27/59
51G 50/51
(27)
52-G2 25
PT PT
CT CT
24 24
46 46
Basic TheoryBasic Theory -- Protective Relaying forProtective Relaying for
ParallelingParalleling--GeneratorsGenerators
A LV synchronizing system requires more
protection than a non-synchronizing system.
Sync Check Relay (25)
Under/Overvoltage Relay (27/59)
Reverse Power Relay (32)
Overcurrent (50/51)
Under/Overfrequency Relay (81 O/U)
OPTIONAL
Volts/Hertz Over excitation (24)
Loss of Excitation Relay (40)
Negative Sequence Overcurrent (46)
Voltage Restrained Overcurrent (51/27R)
Ground Fault Relay (51G)
Differential Overcurrent Relay (87G)
22. Basic TheoryBasic Theory -- Protective Relaying forProtective Relaying for
ParallelingParalleling--GeneratorsGenerators
Reverse Power (32)
Protects generators from being driven as a motor when its prime mover (engine)
looses power. Generator windings will be damaged due to overheating caused by
motoring.
Reverse Power function senses kW power flow in the reverse or opposite direction,
and signals a breaker trip condition.
Reverse power setting has adjustable kW level trip point and time delay. Typical
relay setting is 5% of generator kW rating with a 2 second transient delay.
ENGINE
GENERATOR #1
kW
SENSOR
PT
CT
52-G1
TRIP
FOR kW
POWER
FLOW
K1
TRIP
32
REVERSE
POWER
RELAY
K1
ENGINE
GENERATOR #2
kW
SENSOR
PT
CT
52-G2
TRIP
FOR kW
POWER
FLOW
K1
TRIP
32
REVERSE
POWER
RELAY
K1
23. Sync Check Relay (25)
Protects generators from being connected together out of sync or not “In phase”.
Sync Check Relay senses voltages & phase angles between two sources. Relay
energizes output contact only when voltage, frequency and phase angle are within
acceptable limits.
Sync Check Relay is typically adjustable from 1% to 30% nominal voltage. Typical
setting is 5%.
Sync Check Relay is typically adjustable from 0 to 20 electrical degrees. Typical setting
is 10 degrees.
ENGINE
GENERATOR #1
PT
52-G1
K1
PT
CLOSE
ENGINE
GENERATOR #2
PT
52-G2
K1
PT
CLOSE
25 SYNC.
CHECK
RELAY
25 SYNC.
CHECK
RELAY
Basic TheoryBasic Theory -- Protective Relaying forProtective Relaying for
ParallelingParalleling--GeneratorsGenerators
24. Directional Overcurrent Relay (67)(Optional)
Protect utility from being fed from an alternative power source, or a
transformer being backfed higher than rated capacity.
Directional overcurrent relay senses current flow in both directions
and has two set points enabling different settings in either direction.
Directional overcurrents settings are based on site conditions, loads
and transformers and therefore have no typical settings.
Timed/Instantaneous Overcurrent Relay (50/51)
Protects the generator from external overcurrent faults in the system.
A typical 50/51 relay has 3 protective elements: - instantaneous (for
extremely high fault current of short duration), short time (for high
short circuit fault conditions), and long time (for overload conditions).
The 50/51 relay should be set using the generators short circuit
decrement and overload curves to obtain a coordinated protective
system.
Basic TheoryBasic Theory -- Protective Relaying forProtective Relaying for
ParallelingParalleling--GeneratorsGenerators
25. Basic TheoryBasic Theory -- Protective Relaying forProtective Relaying for
ParallelingParalleling--GeneratorsGenerators
Volts/Hertz Over Excitation Relay (24) (Optional)
Provides protection for the generator during slow speed operation.
The excitation system is inhibited until a preset voltage and
frequency level has been reached. Typical applications are for
large generators directly connected to a step up transformer.
Loss of Excitation Relay (40) (Optional)
Protects generators from loss of excitation during parallel
operation. Relay provides additional generator protection. Primary
protection is provided by 27/59 relay and overcurrent relays.
Low cost methods – industrial grade protection using reverse
kVAR
Higher cost utility grade relay providing mho/distance function for
loss of excitation detection - typically used on larger and MV
generators.
Negative Sequence Current Relay (46) (Optional)
Provides generator protection from unbalanced loading conditions
which in turn causes damaging negative sequence current to flow.
Negative sequence current causes excessive heating in the
generator windings.
26. Basic Theory –
Protective Relaying for Paralleling-Generators
Under/Overvoltage Relay (27/59)
Protects system load & generators from abnormal voltage
conditions due to overload or generator excitation system fault.
One relay required per generator.
Over/Underfrequency Relay (81 O/U)
Protects system load and generators from abnormal frequency
conditions due to overload or engine governor system fault.
One relay required per generator.
27. Voltage Restraint Overcurrent Relay (51/27R) (Optional)
Protects the generator from external overcurrent faults in the system
which may occur at reduced levels of voltage. The overcurrent
setpoint is variable dependent upon generator output voltage.
Should a fault occur which reduces the generators output voltage, the
fault current will also be reduced. The 51/27R relay will detect this
condition and provide a lower trip setting to disconnect the generator
from the fault.
Differential Overcurrent Relay (87G) (Optional)
Protects generators from internal phase to phase or phase to ground
faults.
Typically utilized in LV distributed/cogeneration and prime power
applications and standard for most MV applications.
Basic Theory -
Protective Relaying for Paralleling-Generators
28. Ground Fault Protection (Optional)
Many methods of ground fault protection are dependent on
grounding systems used and zones of protection required.
Two basic grounding systems are used:
Solidly grounded neutral (low voltage only)
High resistance grounded neutral
Two basic zones of protection are provided:
System loads
Generators
Basic Theory -
Protective Relaying for Paralleling-Generators
29. Ground Fault Protection - Solidly Grounded Systems
Generator Zone Protection
Two typical methods:
Breaker overcurrent trip unit with built-in ground fault element (neutral grounded
at one point only).
Differential overcurrent relaying.
Load Protection
Ground fault relays required on load feeder breakers.
87G
GENERATOR #1
52-G1
LSIG
CT
ZONE OF
PROTECTION
87G
GENERATOR #2
52-G2
LSIG
CT
ZONE OF
PROTECTION
G U
AUTOMATIC
TRANSFER SWITCH
UTILITY
N
COMMON
GROUND POINT
GFR
GFR
ZONE OF
PROTECTION
LOAD
LOAD
NEUTRAL
PHASE
NEUTRAL
Basic Theory -
Protective Relaying for Paralleling-Generators
30. Ground Fault Protection - High Resistance Grounded Systems
High Resistance Grounded System Applications
Typically used for high voltage systems > 480V.
Avoids interconnecting generator neutrals.
Reduces high levels of ground fault current (very damaging).
System can still operate normally with a single ground fault condition.
Ground fault current is typically limited to 1Amp per 1000kVA system
loading for LV systems and vary for MV applications.
52-G1
NEUTRAL
GROUNDING
RESISTOR
GEN. #1
NEUTRAL
GROUNDING
RESISTOR
GEN. #2
52-G2
HIGH RESISTANCE GROUNDED GENERATORS
GEN. #1 GEN. #2
NEUTRAL
GROUNDING
RESISTOR
ARTIFICIAL
NEUTRAL
52-G2
HIGH RESISTANCE GROUNDED SYSTEM
WITH ARTIFICIAL NEUTRAL
52-G1
(NEUTRAL
ISOLATED)
(NEUTRAL
ISOLATED)
Basic Theory -
Protective Relaying for Paralleling-Generators
31. Review of the common power switching control
techniques used in industry today:
Open Transition
Momentary Closed Transition
Soft-Load Closed Transition
Continuous Parallel Generation for load testing and/or
distributed generation applications.
PSG - Methods for Power Switching Control
32. Open Transition Transfer with integral or external
distributed ATS:
Provide both mechanical and electrical interlocks to prevent
paralleling of utility and generator sources. This is typically
done with UL1008 ATS but may also include transfer pairs
in both LV and MV applications.
Simple operation with no additional protective relaying or
control requirements.
Load management is controlled via adding and/or dumping
of the transfer pairs.
PSG Power Switching Control – Open Transition
33. Momentary Closed Transition Transfer with integral or
external distributed ATS:
Provide momentary paralleling (less than 100ms) of utility and
generator sources.
This is typically done with UL1008 ATS but may also include
transfer pairs in both LV and MV applications.
Prevents all Power Interruptions due to Testing and Utility Power
Restoration.
Generator may be utilized for utility interruptible rate programs for
load displacement without affecting facility loads.
PSG Power Switching Control – Momentary
Closed Transition
34. Control and generator interface considerations:
Synchronizing is passive, utilizing “drift sync” between the two
sources ). When in sync and the voltage/frequency of the two
sources are within acceptable parameters the transfer is
initiated. Drift sync can attribute to extended transfer times or
failure to transfer (should be alarmed & monitored).
Standard ATS interface with new or existing engine
generator.
Block loading of generator and utility in less than 100
milliseconds if a single ATS is utilized.
Voltage and frequency transients to the load during transfer
operations.
PSG Power Switching Control – Momentary
Closed Transition
35. Protection Considerations:
All ATS vendors must provide electrical interlocks to monitor the
closed transition window and provide contacts to signal if the
Close Transition period were to exceed 100ms to trip utility or
generator source breaker feeding the ATS.
Some ATS vendors also provide additional protection enabling
isolation within the ATS by disconnection of the source being
transferred to and remaining on the original source and alarming
the condition.
As both of the operations and isolation result in the
disconnection of the two sources in no more than 200ms the
majority of Utility companies do not require any additional
protection.
Some Utility companies may (varies from region to region)
include 32 protection etc., this will provide a tertiary level of
protection to satisfy the utility.
PSG Power Switching Control – Momentary
Closed Transition
36. Soft Load Transition Transfer with integral or
external distributed ATS:
Provide paralleling control logic for utility and generator
sources for a short period of time, typically no more than 30
seconds.
Provide kW & kVAR control during the transition time.
This can be done with UL1008 ATS or PSG but due to the
enhanced control and interface requirement with the
engine/generators is more commonly seen as integral to
the PSG.
Prevents all Power Interruptions due to Testing and Utility
Power Restoration.
Minimizes voltage and frequency transients to the load during
transfer operations.
PSG Power Switching Control – Soft Loading
Closed Transition
37. “Zero” Power Transferring
Increases life of breaker contacts by transferring power
near zero levels.
Reduces power system transients during transferring (i.e.
no large load blocks applied on generator or utility) .
Generator may be utilized for utility interruptible rate
programs for load displacement without affecting facility
loads.
PSG Power Switching Control – Soft Loading
Closed Transition
38. Control and generator interface considerations:
Synchronizing is active, as a minimum only the generator
frequency is controlled (governor), however quite often both
voltage & frequency are controlled. The system will actively
synchronize the the two sources and only initiates breaker
closure/transfer when; Voltage, Frequency & Phase angle
differential of the sources are within acceptable limits.
Soft loading and unloading is managed by the kW ramp
rates of the generator(s) of the ATS or PSG control system.
Detailed interface requirements between the ATS and/or
PSG vendor and the generator supplier for coordination of
AVR and governor interface are required.
On site startup/commissioning will be required by both the
ATS/PSG vendor and generator supplier.
PSG Power Switching Control – Soft Loading
Closed Transition
39. Digital Auto Synchronizer / Load Sharing Module
Auto Synchronizer
Must be designed for use with supplied electronic engine governor
Adjustable gain/stability
Analog speed matching signal
Auto breaker close contact (voltage, slip freq, & phase angle)
Voltage matching is required for utility paralleling applications.
Voltage matching is not required for isolated generator systems and will enable faster
response than if voltage matching feature is applied.
One synchronizer per generator
kW Load Sharing
Must be designed for use with supplied electronic engine governor
Must provide isochronous load sharing (non-droop)
One load sharing module required per generator
Phase sensitive
(Note: May be integral with speed control or synchronizer.)
kVAR (Reactive) Load Sharing
Automatic voltage regulator must have load sharing capability (I.e. accept cross current or
droop CT input)
One cross current CT required per generator
Cross current CT can be in generator or switchgear
Phase sensitive
PSG Power Switching Control – Soft Loading
Closed Transition
40. Protection Considerations:
Most Utility companies will require separate control and
protection devices for this operation regardless of inherent
protection offered in the integrated transfer/synchronizing
and loading control devices provided by many ATS/PSG
vendors.
PSG Power Switching Control – Soft Loading
Closed Transition
41. GENERATOR
32 40
81
O-U 27/59
51G 50/51
52-G 25
32 67
81
O-U
27/
59/47
51G 50/51
52-U 25
PT PT
46
UTILITY
SUPPLY
Typical Utility intertie protective
relays:
Sync Check Relay (25)
Under/Overvoltage Negative-Sequence
Voltage Relay (27/59/47)
Overcurrent (50/51)
Under/Overfrequency Relay (81 O/U)
OPTIONAL
Reverse Power Relay (32)
Loss of Excitation Relay (40)
Negative Sequence Overcurrent Relay (46)
Directional Overcurrent Relay (67)
Note: Optional relays may be mandatory
dependent on the utility requirements
and/or equipment sizes and site
application requirements
PSG Power Switching Control – Soft Loading
Closed Transition
42. Anti-Islanding Protection:
Must correctly sense the loss of the utility supply during
parallel operation and immediately isolate the two supplies to
prevent back-feeding the utility supply. Primary protective
relays used are 27/47/59, 32 and 81 O/U.
Equipment Protection:
Generators, and utility transformers must be adequately
protected in cases of abnormal operation (i.e. equipment
failure).
Primary generator protection relays required are 50/51, 32,
27/59, and 81 O/U.
Primary utility protection relays are 50/51 and 27/59/47.
PSG Power Switching Control – Soft Loading
Closed Transition
43. Sync Check Relay (25)
A sync check relay must be connected across each circuit breaker to be synchronized.
Protects utility and generator from being interconnected out of sync or without power
sources.
Relay senses phase voltages, system frequency and phase angles to determine an “in-
sync” condition.
Breaker closure signal will only be issued when all conditions of voltage, frequency and
phase angle have been satisfied.
Typical relay settings are; max 0.1 Hz slip frequency, +/- 5 electrical degrees phase angle
and +/- 3% voltage difference.
Reverse Power Relay (32)
One reverse power relay is required for each generator and utility feeder (If generator
power is not to be exported into the utility grid).
Reverse power relays used on generator(s) prevent power (kW) flow into the generator for
anti-motoring protection, which can damage the synchronous alternator or the prime
mover.
Reverse power relays used on the utility supply prevent power (kW) flow into the utility
grid (typically undesirable-subject to utility company regulations).
Typical relay settings for generator applications are 5% of nominal generator kW rating
and 5% of nominal utility feeder size or equivalent kW level but usually not less than
100kW to allow the generator(s) to respond to load fluctuations.
PSG Power Switching Control – Soft Loading
Closed Transition
44. Over/Under/Negative Sequence Voltage Relay (27/59/47)
One voltage relay is typically required for each generator and utility
feeder.
Protects system load, generator and utility transformers from
abnormal voltage conditions (e.g. over, under and phase balance).
Negative Sequence Voltage function detects a voltage phase
unbalance condition typically caused by single phasing of a 3 phase
device (i.e. blown fuse on a motor or transformer).
Typical relay settings for generators will be +- 10% with 1-2 second
time delay. These settings must allow correct operation on isolated
loading conditions (i.e. block loading).
Utility feeder voltage relays setting will vary dependent upon typical
site conditions. The utility voltage relay settings will generally be set
to smaller tolerances than the generator relays to ensure immediate
Anti-Islanding protection. Typical settings are +- 5% with 0.2 second
time delay.
PSG Power Switching Control – Soft Loading
Closed Transition
45. Over/Under Frequency Relay (81-O/U)
One frequency relay is typically required for each generator and utility
feeder.
Frequency relays used on generators detect abnormal frequency
conditions and disconnect the generator from service.
Frequency relays used on the utility supply are for Anti-Islanding
protection. When an abnormal frequency is detected, the relay
operates immediately to trip off the utility supply.
Typical relay settings for utility supply must be set very tight-typically
+- 0.05 Hz with 0.1 second time delay.
Typical relay settings for generators will be +- 10% with 1-2 second
time delay. These settings must allow correct operation on isolated
loading conditions (i.e. block loading).
PSG Power Switching Control – Soft Loading
Closed Transition
46. Provides Soft Loading Closed Transition Transfer with
available continuous parallel operation with the utility and
is a function of the PSG.
Provide paralleling of utility and generator sources for
extended periods of time:
Load testing at 100% rated with facility load
Minimum risk to facility if there is problems with
engine/generators during testing
Utility load demand management programs
Distributed or Cogeneration
PSG Power Switching Control – Continuous
Parallel Operation
47. Control and generator interface considerations:
Synchronizing is active and controls interface to the generator
voltage/frequency will actively synchronize the two sources
and initiates connection when voltage/frequency of the two
sources are within acceptable parameters.
Soft loading and unloading is managed by the kW and kVAR
ramp rates of the generator(s) PSG control system.
Minimum utility import/export load levels are monitored and
controlled.
Base load of generator or utility sources are maintained during
parallel operation.
PSG Power Switching Control – Continuous
Parallel Operation
48. Protection Considerations:
Identical to Soft Load Closed Transition application with
the following additional considerations.
Allowable utility import/export load levels at the point of
common coupling.
PSG Power Switching Control – Continuous
Parallel Operation