This document discusses power quality monitoring and analysis. It describes advances in monitoring equipment and software tools for analyzing measurement results. Power quality issues can be characterized in different categories such as disturbances, steady state variations, and harmonic distortion. Measurement data can be analyzed and presented in various formats such as individual events, trends, or statistical summaries to identify causes of power quality variations and their impacts.
Power Quality Disturbaces Clasification And Automatic Detection Using Wavelet...IJERDJOURNAL
Abstract— In this paper a development method to detect and classify the several power quality problems using the discrete wavelet transformation and artificial neural networks combined. There are several other methods in use to detect the same problem like Hilbert transform, Gabor transform, Gabor-Wigner transform, S transform, and Hilbert-Haung transform. The method of using wavelet and ANN includes the development of voltage waveforms of sampling rate and number of cycles, and also large number of power quality events with help of MATLAB software. The wavelet transformation and ANN tools used to get required coefficients. The obtained events of power quality monitored in each step to classify the particular event. These steps of the paper lead towards the automatic real time monitoring, detection and classification of power signals
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Power Quality Disturbaces Clasification And Automatic Detection Using Wavelet...IJERDJOURNAL
Abstract— In this paper a development method to detect and classify the several power quality problems using the discrete wavelet transformation and artificial neural networks combined. There are several other methods in use to detect the same problem like Hilbert transform, Gabor transform, Gabor-Wigner transform, S transform, and Hilbert-Haung transform. The method of using wavelet and ANN includes the development of voltage waveforms of sampling rate and number of cycles, and also large number of power quality events with help of MATLAB software. The wavelet transformation and ANN tools used to get required coefficients. The obtained events of power quality monitored in each step to classify the particular event. These steps of the paper lead towards the automatic real time monitoring, detection and classification of power signals
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Contingency plans based on N - 1 and N - 2 contingencies are already very much used by utilities . Artificial intelligent methods are new trends for analysing the contingency scenario along with state of art congestion management. This gives extra backup and b oost to reliable operation under contingent scenario of power system. This paper envisages the summary of all those efforts. This paper will help utilities to put more thinking in terms of recent developments in fast and intelligent computing methods. The paper highlights classical research and modern trends in contingency analysis such as hybrid artificial intelligent methods. Steady state stability assessment of a power system pursues a twofold objective:first to appraise the system's capability to withs tand major contingencies,and second to suggest remedial actions,i.e. means to enhance this capability,whenever needed. The first objective is the concern of analysis,the second is a matter of control.
A Review on Power System Voltage Stability and Optimization TechniquesIJERA Editor
Power system voltage stability is a one of the major focused areas in recent days due to mismatch between generation and demand. Maintenance of voltage stability is a challenging issue in planning and security assessment of power systems. Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the power system under normal operating conditions and after being subjected to a disturbance. Long-term voltage instability problems can occur in heavily loaded systems where the electrical distance is large between the generator and the load. Timely application of reactive power compensation or load shedding may prevent this type of voltage instability. System reactive power handling capacity can be improved with Flexible AC Transmission System (FACTS) devices. Identification of critical system locations to undertake appropriate remedial measures in operation is the concern. This paper reviews the performance of various types FACTS controllers in power system voltage stability problem and focuses on different optimization methods implemented for optimal placement and sizing of FACTS devices to minimize power losses.
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.
Power quality enhancement by improving voltage stability using dstatcomeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
An Overview of FACTS Controllers for Power Quality Improvementtheijes
Large penetration of non-conventional sources of energy (such as wind and solar) into the utility grid usually leads to power quality deterioration of the net system due to the intermittency nature associated with such energy sources. Power quality parameters that may likely be disturbed by such interconnection include voltage profile, frequency waveform, power factor, as well as active and reactive power of the power system. However, grid operators and consumers at all level of usage requires a perfectly balanced three phase a.c power of constant frequency and magnitude with smooth sinusoidal wave shape. In order to compensate for such disturbances, Flexible A.C Transmission System (FACTS) controllers were developed. This paper presents a technological review of different types of FACTS controllers and their application for power quality improvement in a grid network composing of conventional and non-conventional energy sources.
Power Quality Improvement by UPQC based on Voltage Source ConvertersIJRST Journal
In modern power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. Since most of the electronic equipment’s are nonlinear in nature these will induce harmonics in the system, which affect the sensitive loads to be fed from the system. These problems are partially solved with the help of LC passive filters. However, this kind of filter cannot solve random variation in the load current wave form and voltage wave form. Active filters can resolve this problem. However, the cost of active filters is high. They are difficult to implement in large scale. Additionally, they also present lower efficiency than shunt passive filters. One of the many solutions is the use of a combined system of shunt and active series filters like Unified Power Quality Conditioner (UPQC) which aims at achieving a low cost under highly effective control. The UPQC device combines a shunt active filter together with a series active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current or to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network, such that improved power quality can be made available at the point of common coupling. The control strategies are modeled using MATLAB/SIMULINK. The performance is also observed under influence of utility side disturbances such as harmonics and voltage sags. The simulation results are compared without and with UPQC for the verification of results.
A Literature Review on Experimental Study of Power Losses in Transmission Lin...paperpublications3
Abstract: The flexible Ac transmission system (FACTS) controllers can play an important role in the power system security enhancement. However, due to high capital investment, it is necessary to locate these controllers optimally in the power system. FACTS devices can regulate the active and reactive power control as well as adaptive to voltage-magnitude control simultaneously because of their flexibility and fast control characteristics. Placement of these devices in suitable location can lead to control in line flow and maintain bus voltages in desired level and so improve voltage stability margins. In the previous paper three type of FACTS devices used in transmission lines for improvement of voltage profile in the power system. This paper describes the simulation result of flexible Alternative Current Transmission Systems (FACTS) devices used in the disturbed power systems. Out of three types of FACTS device UPFC performances is considered to be best comparatively with respect to each of the three devices.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and Development is an international premier peer reviewed open access engineering and technology journal promoting the discovery, innovation, advancement and dissemination of basic and transitional knowledge in engineering, technology and related disciplines.
We follow "Rigorous Publication" model - means that all articles appear on IJERD after full appraisal, effectiveness, legitimacy and reliability of research content. International Journal of Engineering Research and Development publishes papers online as well as provide hard copy of Journal to authors after publication of paper. It is intended to serve as a forum for researchers, practitioners and developers to exchange ideas and results for the advancement of Engineering & Technology.
Power Quality Enhancement using DSTATCOM by Immune Feedback Control Algorithmijtsrd
This paper proposes an immune feedback control algorithm for a three phase distribution static compensator DSTATCOM to mitigate several power quality problems such as harmonics, reactive power, and load unbalancing at distribution level. This control algorithm proposed for DSTATCOM, is validated for maintaining power factor to unity, load balancing, and harmonics reduction of supply currents. In this application, the proposed control algorithm on a DSTATCOM is implemented for the compensation of nonlinear loads. The simulations were performed in the environment of MATLAB SIMULINK. P. Thirumala | K. Mahesh "Power Quality Enhancement using DSTATCOM by Immune Feedback Control Algorithm" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-1 , December 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29812.pdf Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/29812/power-quality-enhancement-using-dstatcom-by-immune-feedback-control-algorithm/p-thirumala
Design of UPQC with Minimization of DC Link voltage for the Improvement of Po...IDES Editor
Devices such as power electronics converters, inject
harmonic currents in the AC system and increase overall
reactive power demanded by the equivalent loads are presents
non-linear characteristics. Also, the number of sensitive loads
that require ideal sinusoidal supply voltages for their proper
operation has increased. In order to keep power quality under
limits proposed by standards, it is necessary to include some
sort of compensation. The aim of this paper is to present a
unified power quality conditioner (UPQC) with minimization
of DC Link voltage for the improvement of power quality by
Fuzzy logic controller as compared with PI controller. By the
proposed system is comprised of series and shunt Inverters
which can compensate the sag, swell, unbalance voltage,
Harmonics and reactive power. PI and fuzzy logic controllers
are used to stabilize DC link voltage and balance the active
power between shunt and series inverters for the enhancement
of power quality.
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.
Frequency Response Assessment: Parameter Identification of Simplified Governo...Power System Operation
With a growing share of inverter-interfaced generation
in modern power systems, synchronous inertia is
declining. This leads to faster frequency drop after large
generation trip events. During low inertia conditions,
frequency containment reserves might not be sufficient
to arrest frequency before it reaches the threshold for
underfrequency load shedding. It is therefore becoming
increasingly important for system operators to be able to
assess frequency response in near real time. In contrast to
detailed models, simplified models offer short simulation
times and their parameters can be accurately identified
and adapted to changing system conditions in near real
time. In this paper, the parameters of governor response
models are identified by minimizing the error residuals
between the simulation models’ and the actual system’s
measured active power response. This is accomplished
by using historic event data from two system operators:
the Electric Reliability Council Of Texas (ERCOT) and
the Swedish Svenska kraftnät (Svk). Then, the respective
frequency response models are simulated to assess
frequency response. The results show that, despite their
simplicity, the models provide a very good fit compared
to the actual response. The models of ERCOT and
Svk are examined; however, a similar approach can be
employed to represent the frequency response of other
power systems.
Contingency plans based on N - 1 and N - 2 contingencies are already very much used by utilities . Artificial intelligent methods are new trends for analysing the contingency scenario along with state of art congestion management. This gives extra backup and b oost to reliable operation under contingent scenario of power system. This paper envisages the summary of all those efforts. This paper will help utilities to put more thinking in terms of recent developments in fast and intelligent computing methods. The paper highlights classical research and modern trends in contingency analysis such as hybrid artificial intelligent methods. Steady state stability assessment of a power system pursues a twofold objective:first to appraise the system's capability to withs tand major contingencies,and second to suggest remedial actions,i.e. means to enhance this capability,whenever needed. The first objective is the concern of analysis,the second is a matter of control.
A Review on Power System Voltage Stability and Optimization TechniquesIJERA Editor
Power system voltage stability is a one of the major focused areas in recent days due to mismatch between generation and demand. Maintenance of voltage stability is a challenging issue in planning and security assessment of power systems. Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the power system under normal operating conditions and after being subjected to a disturbance. Long-term voltage instability problems can occur in heavily loaded systems where the electrical distance is large between the generator and the load. Timely application of reactive power compensation or load shedding may prevent this type of voltage instability. System reactive power handling capacity can be improved with Flexible AC Transmission System (FACTS) devices. Identification of critical system locations to undertake appropriate remedial measures in operation is the concern. This paper reviews the performance of various types FACTS controllers in power system voltage stability problem and focuses on different optimization methods implemented for optimal placement and sizing of FACTS devices to minimize power losses.
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.
Power quality enhancement by improving voltage stability using dstatcomeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
An Overview of FACTS Controllers for Power Quality Improvementtheijes
Large penetration of non-conventional sources of energy (such as wind and solar) into the utility grid usually leads to power quality deterioration of the net system due to the intermittency nature associated with such energy sources. Power quality parameters that may likely be disturbed by such interconnection include voltage profile, frequency waveform, power factor, as well as active and reactive power of the power system. However, grid operators and consumers at all level of usage requires a perfectly balanced three phase a.c power of constant frequency and magnitude with smooth sinusoidal wave shape. In order to compensate for such disturbances, Flexible A.C Transmission System (FACTS) controllers were developed. This paper presents a technological review of different types of FACTS controllers and their application for power quality improvement in a grid network composing of conventional and non-conventional energy sources.
Power Quality Improvement by UPQC based on Voltage Source ConvertersIJRST Journal
In modern power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. Since most of the electronic equipment’s are nonlinear in nature these will induce harmonics in the system, which affect the sensitive loads to be fed from the system. These problems are partially solved with the help of LC passive filters. However, this kind of filter cannot solve random variation in the load current wave form and voltage wave form. Active filters can resolve this problem. However, the cost of active filters is high. They are difficult to implement in large scale. Additionally, they also present lower efficiency than shunt passive filters. One of the many solutions is the use of a combined system of shunt and active series filters like Unified Power Quality Conditioner (UPQC) which aims at achieving a low cost under highly effective control. The UPQC device combines a shunt active filter together with a series active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current or to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network, such that improved power quality can be made available at the point of common coupling. The control strategies are modeled using MATLAB/SIMULINK. The performance is also observed under influence of utility side disturbances such as harmonics and voltage sags. The simulation results are compared without and with UPQC for the verification of results.
A Literature Review on Experimental Study of Power Losses in Transmission Lin...paperpublications3
Abstract: The flexible Ac transmission system (FACTS) controllers can play an important role in the power system security enhancement. However, due to high capital investment, it is necessary to locate these controllers optimally in the power system. FACTS devices can regulate the active and reactive power control as well as adaptive to voltage-magnitude control simultaneously because of their flexibility and fast control characteristics. Placement of these devices in suitable location can lead to control in line flow and maintain bus voltages in desired level and so improve voltage stability margins. In the previous paper three type of FACTS devices used in transmission lines for improvement of voltage profile in the power system. This paper describes the simulation result of flexible Alternative Current Transmission Systems (FACTS) devices used in the disturbed power systems. Out of three types of FACTS device UPFC performances is considered to be best comparatively with respect to each of the three devices.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and Development is an international premier peer reviewed open access engineering and technology journal promoting the discovery, innovation, advancement and dissemination of basic and transitional knowledge in engineering, technology and related disciplines.
We follow "Rigorous Publication" model - means that all articles appear on IJERD after full appraisal, effectiveness, legitimacy and reliability of research content. International Journal of Engineering Research and Development publishes papers online as well as provide hard copy of Journal to authors after publication of paper. It is intended to serve as a forum for researchers, practitioners and developers to exchange ideas and results for the advancement of Engineering & Technology.
Power Quality Enhancement using DSTATCOM by Immune Feedback Control Algorithmijtsrd
This paper proposes an immune feedback control algorithm for a three phase distribution static compensator DSTATCOM to mitigate several power quality problems such as harmonics, reactive power, and load unbalancing at distribution level. This control algorithm proposed for DSTATCOM, is validated for maintaining power factor to unity, load balancing, and harmonics reduction of supply currents. In this application, the proposed control algorithm on a DSTATCOM is implemented for the compensation of nonlinear loads. The simulations were performed in the environment of MATLAB SIMULINK. P. Thirumala | K. Mahesh "Power Quality Enhancement using DSTATCOM by Immune Feedback Control Algorithm" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-1 , December 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29812.pdf Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/29812/power-quality-enhancement-using-dstatcom-by-immune-feedback-control-algorithm/p-thirumala
Design of UPQC with Minimization of DC Link voltage for the Improvement of Po...IDES Editor
Devices such as power electronics converters, inject
harmonic currents in the AC system and increase overall
reactive power demanded by the equivalent loads are presents
non-linear characteristics. Also, the number of sensitive loads
that require ideal sinusoidal supply voltages for their proper
operation has increased. In order to keep power quality under
limits proposed by standards, it is necessary to include some
sort of compensation. The aim of this paper is to present a
unified power quality conditioner (UPQC) with minimization
of DC Link voltage for the improvement of power quality by
Fuzzy logic controller as compared with PI controller. By the
proposed system is comprised of series and shunt Inverters
which can compensate the sag, swell, unbalance voltage,
Harmonics and reactive power. PI and fuzzy logic controllers
are used to stabilize DC link voltage and balance the active
power between shunt and series inverters for the enhancement
of power quality.
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.
Frequency Response Assessment: Parameter Identification of Simplified Governo...Power System Operation
With a growing share of inverter-interfaced generation
in modern power systems, synchronous inertia is
declining. This leads to faster frequency drop after large
generation trip events. During low inertia conditions,
frequency containment reserves might not be sufficient
to arrest frequency before it reaches the threshold for
underfrequency load shedding. It is therefore becoming
increasingly important for system operators to be able to
assess frequency response in near real time. In contrast to
detailed models, simplified models offer short simulation
times and their parameters can be accurately identified
and adapted to changing system conditions in near real
time. In this paper, the parameters of governor response
models are identified by minimizing the error residuals
between the simulation models’ and the actual system’s
measured active power response. This is accomplished
by using historic event data from two system operators:
the Electric Reliability Council Of Texas (ERCOT) and
the Swedish Svenska kraftnät (Svk). Then, the respective
frequency response models are simulated to assess
frequency response. The results show that, despite their
simplicity, the models provide a very good fit compared
to the actual response. The models of ERCOT and
Svk are examined; however, a similar approach can be
employed to represent the frequency response of other
power systems.
IRJET-Review on Power Quality Enhancement in weak Power Grids by Integration ...IRJET Journal
Prathmesh Mayekar, Mahesh Wagh, Nilkanth Shinde "Review on Power Quality Enhancement in weak Power Grids by Integration of Renewable Energy Technologies", International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
During Last decade power quality problems has become more complex at all level of power system. With the increased use of sophisticated electronics, high efficiency variable speed drive, power electronic controllers and also more & more non-linear loads, Power Quality has become an increasing concern to utilities and customers. The modern sensitive, Non-linear and sophisticated load affects the power quality. This paper deals with the issues of low power quality in weak power grids. Initially the various power quality issues are discussed with their definition or occurrence and then finally the solution to mitigate this power quality issues are discussed. The innovative solutions like integration of renewable energy systems along with energy storage to enhance power quality by interfacing with custom power devices are explained in detail. Nearly all sorts of solution for mitigating power quality issue require some sort of DC source for providing active power, which can be supplied by renewable energy source. Also the various energy storage systems are studied.
Voltage Flicker Analysis and its Mitigation by STATCOM for Power Quality Impr...IJMTST Journal
Voltage flicker is considered as one of the most severe power quality problems (especially in loads like electrical arc furnaces) and much attention has been paid to it lately. The reason for this disturbance is mainly due to the large nonlinear loads such as electric arc furnaces. Due to the latest achievements in the semiconductors industry and consequently the emergence of the compensators based on voltage source converters, FACTS devices have been gradually noticed to be used for voltage flicker compensation. This paper covers the contrasting approaches; dealing with the voltage flicker mitigation in three stages and assessing the related results in details. Initially, the voltage flicker mitigation, using FCTCR (Fixed Capacitor Thyristor Controlled Reactor), was simulated. Secondly, the compensation for the Static Synchronous Compensator (STATCOM) has been performed. The voltage flicker compensation by 8– pulse as well as 12 – pulse static synchronous compensator (STATCOM) has been performed. This paper deals with the voltage flicker mitigation and reduction in total harmonic distortion (THD) and compared the results in detail. The obtained results show that STATCOM is very efficient and effective for the compensation and mitigation of voltage flicker and harmonics all the simulation results have been performed on the MATLAB Software.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Modeling Analysis& Solution of Power Quality Problems Using DVR & DSTATCOMijsrd.com
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a disoperation of end use equipment. Utility distribution networks, sensitive industrial loads, and critical commercial operations all suffer from various types of outages and service interruptions which can cost significant financial loss per incident based on process down-time, lost production, idle work forces, and other factors. With the restructuring of Power Systems and with shifting trend towards Distributed and Dispersed Generation, the issue of Power Quality is going to take newer dimensions. The aim therefore, in this work, is to identify the prominent concerns in the area and thereby to recommend measures that can enhance the quality of the power, keeping in mind their economic viability and technical repercussions. In this paper electromagnetic transient studies are presented for the following two custom power controllers: the distribution static compensator (DSTATCOM), and the dynamic voltage restorer (DVR). Comprehensive results are presented to assess the performance of each device as a potential custom power solution.
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.
The electricity supply industry is undergoing a profound transformation worldwide. Market forces, scarcer natural resources, and an ever-increasing demand for electricity are some of the drivers responsible for such unprecedented change. Against this background of rapid evolution, the expansion programs of many utilities are being thwarted by a variety of well-founded, environment, land-use, and regulatory pressures that prevent the licensing and building of new transmission lines and electricity generating plants.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
A Voltage Controlled Dstatcom for Power Quality Improvementiosrjce
Due to increasing complexity in the power system, voltage sag is becoming one of the most significant
power quality problems. Voltage sag is a short reduction voltage from nominal voltage, occurs in a short time.
If the voltage sags exceed two to three cycles, then manufacturing systems making use of sensitive electronic
equipments are likely to be affected leading to major problems. It ultimately leads to wastage of resources (both
material and human) as well as financial losses. This is possible only by ensuring that uninterrupted flow of
power is maintained at proper voltage levels. This project tends look at the solving the sag problems by using
custom power devices such as Distribution Static compensator (D-STATCOM).Proposed scheme follows a new
algorithm to generate reference voltage for a distribution static compensator (DSTATCOM) operating in
voltage-control mode. The proposed scheme ensures that unity power factor (UPF) is achieved at the load
terminal during nominal operation, which is not possible in the traditional method. Also, the compensator
injects lower currents therefore, reduces losses in the feeder and voltage-source inverter. Further, a saving in
the rating of DSTATCOM is achieved which increases its capacity to mitigate voltage sag. Nearly UPF is
maintained, while regulating voltage at the load terminal, during load change. The state-space model of
DSTATCOM is incorporated with the deadbeat predictive controller for fast load voltage regulation during
voltage disturbances. With these features, this scheme allows DSTATCOM to tackle power-quality issues by
providing power factor correction, harmonic elimination, load balancing, and voltage regulation based on the
load requirement.
Enhancement of Voltage Stability on IEEE 14 Bus Systems Using Static Var Comp...paperpublications3
Abstract: This paper investigates the effects of Static Var Compensator (SVC) on voltage stability of a power system. One of the major causes of voltage instability is the reactive power limit of the system. Improving the system’s reactive power handling capacity via Flexible AC transmission system (FACTS) devices is a remedy for prevention of voltage instability and hence voltage collapse. The effects of Static Var Compensator (SVC) in static voltage stability margin enhancement will be studies. Prediction of the stability margin or distance to voltage collapse is based on the reactive power load demand. The load is connected to several selected buses. The analysis is performed for IEEE 14 Bus system. Then, the most critical mode is identified for each system. IEEE standard test system has been considered and Load flows were computed by using Newton Raphson method with the help of MATLAB and a weak bus is identified.
A Review on Optimization Techniques for Power Quality Improvement using DSTAT...ijtsrd
As demand for electricity has risen exponentially, power production and transmission are affected by scarce energy, environmental constraints and other losses. Soft computing methods to fix the sag, swell and disruption of the supply voltage in the distributed device. At present, a broad variety of highly versatile controls that leverage on newly available power electronics components are evolving for custom power applications. Control electronic equipment intended to improve the stability and efficiency of electricity flows in low voltage distribution networks. The control algorithm is used to derive the fundamental weighted value of the active and reactive power components. Using a digital signal processor, DSTATCOM is built and its output as a DSTATCOM is found to be satisfactory for different types of loads. Amit Radhakrishna Parhad | Pramod Kumar Rathore "A Review on Optimization Techniques for Power Quality Improvement using DSTATCOM (Neural Network Approach)" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-4 , June 2021, URL: https://www.ijtsrd.compapers/ijtsrd42403.pdf Paper URL: https://www.ijtsrd.comengineering/electrical-engineering/42403/a-review-on-optimization-techniques-for-power-quality-improvement-using-dstatcom-neural-network-approach/amit-radhakrishna-parhad
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Interpretation and analysis of power quality measurements lo max
1. 1
Interpretation and Analysis of Power Quality Measurements
Christopher J. Melhorn
Electrotek Concepts, Inc.
Knoxville, Tennessee
Mark F. McGranaghan
Electrotek Concepts, Inc.
Knoxville, Tennessee
ABSTRACT
This paper describes advances in power quality
monitoring equipment and software tools for analyzing
power quality measurement results. Power quality
monitoring has advanced from strictly problem solving
to ongoing monitoring of system performance. The
increased amount of data being collected requires more
advanced analysis tools. Types of power quality
variations are described and the methods of
characterizing each type with measurements are
presented. Finally, methods for summarizing the
information and presenting it in useful report formats
are described.
INTRODUCTION
Power quality has become an important concern for
utility, facility, and consulting engineers in recent years.
End use equipment is more sensitive to disturbances that
arise both on the supplying power system and within the
customer facilities. Also, this equipment is more
interconnected in networks and industrial processes so
that the impacts of a problem with any piece of equipment
are much more severe.
The increased concern for power quality has resulted
in significant advances in monitoring equipment that can
be used to characterize disturbances and power quality
variations. This paper discusses the types of information
that can be obtained from different kinds of monitoring
equipment and methods for analyzing and presenting the
information in a useful form.
Important objectives for the paper include the
following:
• Describe important types of power quality
variations.
• Identify categories of monitoring equipment
that can be used to measure power quality
variations.
• Offer examples of different methods for
presenting the results of power quality
measurements.
• Describe tools for analyzing and presenting
the power quality measurement results.
Analysis tools for processing measurement data will
be described. These tools can present the information as
individual events (disturbance waveforms), trends, or
statistical summaries. By comparing events with libraries
of typical power quality variation characteristics and
correlating with system events (e.g. capacitor switching),
causes of the variations can be determined. In the same
manner, the measured data should be correlated with
impacts to help characterize the sensitivity of end use
equipment to power quality variations. This will help
identify equipment that requires power conditioning and
provide specifications for the protection that can be
developed based on the power quality variation
characteristics.
CATEGORIES OF POWER QUALITY
VARIATIONS
It is important to first understand the kinds of power
quality variations that can cause problems with sensitive
loads. Categories for these variations must be developed
with a consistent set of definitions so that measurement
equipment can be designed in a consistent manner and so
that information can be shared between different groups
performing measurements and evaluations. An IEEE
Working Group has been developing a consistent set of
definitions that can be used for coordination of
measurements.[1]
Power quality variations fall into two basic categories:
1. Disturbances. Disturbances are measured by
triggering on an abnormality in the voltage or
the current. Transient voltages may be
detected when the peak magnitude exceeds a
specified threshold. RMS voltage variations
(e.g. sags or interruptions) may be detected
2. 2
when the RMS variation exceeds a specified
level.
2. Steady State Variations. These include
normal RMS voltage variations and harmonic
distortion. These variations must be measured
by sampling the voltage and/or current over
time. The information is best presented as a
trend of the quantity (e.g. voltage distortion)
over time and then analyzed using statistical
methods (e.g. average distortion level, 95%
probability of not being exceeded, etc.).
In the past, measurement equipment has been
designed to handle either the disturbances (e.g.
disturbance analyzers) or steady state variations (e.g.
voltage recorders, harmonics monitors). With advances in
processing capability, new instruments have become
available that can characterize the full range of power
quality variations. The new challenge involves
characterizing all the data in a convenient form so that it
can be used to help identify and solve problems.
Table 1 summarizes the different categories and lists
possible causes and power conditioning equipment
solutions for each category.
Steady State Voltage Characteristics
There is no such thing as steady state on the power
system. Loads are continually changing and the power
system is continually adjusting to these changes. All of
these changes and adjustments result in voltage
variations that are referred to as long duration voltage
variations. These can be undervoltages or overvoltages,
depending on the specific circuit conditions.
Characteristics of the steady state voltage are best
expressed with long duration profiles and statistics.
Important characteristics include the voltage magnitude
and unbalance. Harmonic distortion is also a
characteristic of the steady state voltage but this
characteristic is treated separately because it does not
involve variations in the fundamental frequency
component of the voltage.
Most end use equipment is not very sensitive to
these voltage variations, as long as they are within
reasonable limits. ANSI C84.1 [7] specifies the steady
Table 1. Summary of Power Quality Variation Categories
Power Quality
Variation Category
Method of
Characterizing Typical Causes
Example
Power Conditioning
Solutions
Impulsive Transients
Peak magnitude,
Rise time,
Duration
Lightning,
Electro-Static Discharge,
Load Switching
Surge Arresters,
Filters,
Isolation Transformers
Oscillatory Transients
Waveforms,
Peak Magnitude,
Frequency Components
Line/Cable Switching,
Capacitor Switching,
Load Switching
Surge Arresters,
Filters,
Isolation Transformers
Sags/Swells
RMS vs. time,
Magnitude, Duration Remote System Faults
Ferroresonant Transformers,
Energy Storage Technologies*,
UPS
Interruptions Duration
System Protection
(Breakers, Fuses),
Maintenance
Energy Storage Technologies*,
UPS,
Backup Generators
Undervoltages/
Overvoltages
RMS vs. Time,
Statistics
Motor Starting,
Load Variations
Voltage Regulators,
Ferroresonant Transformers
Harmonic Distortion
Harmonic Spectrum,
Total Harm. Distortion,
Statistics
Nonlinear Loads,
System Resonance
Filters (active or passive),
Transformers (cancellation or
zero sequence components)
Voltage Flicker
Variation Magnitude,
Frequency of Occurence,
Modulation Frequency
Intermittent Loads,
Motor Starting,
Arc Furnaces Static Var Systems
* Note: Energy Storage Technologies refers to a variety of alternative
energy storage technologies that can be used for standby supply
as part of power conditioning
(e.g. superconducting magnetic energy storage, capacitors, flywheels, batteries)
3. 3
state voltage tolerances for both magnitudes and
unbalance expected on a power system. Long duration
variations are considered to be present when the limits are
exceeded for greater than 1 minute.
Figure 1. Example 24 hour voltage profile illustrating
long duration voltage variations.
Harmonic Distortion
Harmonic distortion of the voltage and current results
from the operation of nonlinear loads and devices on the
power system. The nonlinear loads that cause harmonics
can often be represented as current sources of harmonics.
The system voltage appears stiff to individual loads and
the loads draw distorted current waveforms. Table 2
illustrates some example current waveforms for different
types of nonlinear loads. The weighting factors indicated
in the table are being proposed in the Guide for Applying
Harmonic Limits on the Power System (Draft 2)[2] for
preliminary evaluation of harmonic producing loads in a
facility.
Harmonic voltage distortion results from the
interaction of these harmonic currents with the system
impedance. The harmonic standard, IEEE 519-1992 [2],
has proposed two way responsibility for controlling
harmonic levels on the power system.
1. End users must limit the harmonic currents
injected onto the power system.
2. The power supplier will control the harmonic
voltage distortion by making sure system
resonant conditions do not cause excessive
magnification of the harmonic levels.
Harmonic distortion levels can be characterized by the
complete harmonic spectrum with magnitudes and phase
angles of each individual harmonic component. It is also
common to use a single quantity, the Total Harmonic
Distortion, as a measure of the magnitude of harmonic
distortion. For currents, the distortion values must be
referred to a constant base (e.g. the rated load current or
demand current) rather than the fundamental component.
This provides a constant reference while the fundamental
can vary over a wide range.
Table 2. Example current waveforms for various
nonlinear loads.
Type of Load Typical Waveform
Current
Distortion
Weighting
Factor (Wi)
Single Phase
Power Supply
0 10 20 30 40
-1.0
-0.5
0.0
0.5
1.0
C
80%
(high 3rd)
2.5
Semiconverter
0 10 20 30 40
-1.0
-0.5
0.0
0.5
1.0
C
high 2nd,3rd,
4th at partial
loads
2.5
6 Pulse Converter,
capacitive smoothing,
no series inductance
0 10 20 30 40
-1.0
-0.5
0.0
0.5
1.0
C
80% 2.0
6 Pulse Converter,
capacitive smoothing
with series inductance > 3%,
or dc drive
0 10 20 30 40
-1.0
-0.5
0.0
0.5
1.0
C
40% 1.0
6 Pulse Converter
with large inductor
for current smoothing
0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
C
28% 0.8
12 Pulse Converter
0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
C
15% 0.5
ac Voltage
Regulator
0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
C
varies with
firing angle 0.7
Harmonic distortion is a characteristic of the steady
state voltage and current. It is not a disturbance.
Therefore, characterizing harmonic distortion levels is
accomplished with profiles of the harmonic distortion over
time (e.g. 24 hours) and statistics. Figure 2 illustrates a
typical profile of harmonic voltage distortion on a feeder
circuit over a one month period.
4. 4
Time Trend for Voltage THD
05/26 06/02 06/09 06/16 06/23 06/30 07/07
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Time
THD(%)
Time Trend for Voltage THD
05/26 06/02 06/09 06/16 06/23 06/30 07/07
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Time
Figure 2. Example Profile of Harmonic Voltage
Distortion on a Distribution Feeder Circuit.
Transients
The term transients is normally used to refer to fast
changes in the system voltage or current. Transients are
disturbances, rather than steady state variations such as
harmonic distortion or voltage unbalance. Disturbances
can be measured by triggering on the abnormality
involved. For transients, this could be the peak
magnitude, the rate of rise, or just the change in the
waveform from one cycle to the next. Transients can be
divided into two sub-categories, impulsive transients and
oscillatory transients, depending on the characteristics.
Transients are normally characterized by the actual
waveform, although summary descriptors can also be
developed (peak magnitude, primary frequency, rate-of-
rise, etc.). Figure 3 gives a capacitor switching transient
waveform. This is one of the most important transients
that is initiated on the utility supply system and can affect
the operation of end user equipment.
0 20 40 60 80 100
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
Time (mS)
Vlt(V)
34.5 kV Bus Voltage
Capacitor Switching Transient
Figure 3. Capacitor Switching Transient.
Transient problems are solved by controlling the
transient at the source, changing the characteristics of the
system affecting the transient or by protecting equipment
so that it is not impacted. For instance, capacitor
switching transients can be controlled at the source by
closing the breaker contacts close to a voltage zero
crossing. Magnification of the transient can be avoided
by not using low voltage capacitors within the end user
facilities. The actual equipment can be protected with
filters or surge arresters.
Short Duration Voltage Variations
Short duration voltage variations include variations in
the fundamental frequency voltage that last less than one
minute. These variations are best characterized by plots
of the RMS voltage vs. time but it is often sufficient to
describe them by a voltage magnitude and a duration that
the voltage is outside of specified thresholds. It is usually
not necessary to have detailed waveform plots since the
RMS voltage magnitude is of primary interest.
The voltage variations can be a momentary low
voltage (voltage sag), high voltage (voltage swell), or loss
of voltage (interruption). Interruptions are the most
severe in terms of their impacts on end users but voltage
sags can be more important because they may occur much
more frequently. A fault condition can cause a momentary
voltage sag over a wide portion of the system even
though no end users may experience an interruption. This
is true for most transmission faults. Figure 4 is an example
of this kind of event. Many end users have equipment
that may be sensitive to these kinds of variations. Solving
this problem on the utility system may be very expensive
so manufacturers are developing ride through
technologies with energy storage to handle these voltage
variations on the end user side.
Figure 4. Voltage Sag Caused by a Remote Fault
Condition.
5. 5
TYPES OF EQUIPMENT FOR
MONITORING POWER QUALITY
Multimeters or DMMs
After initial tests of wiring integrity, it may also be
necessary to make quick checks of the voltage and/or
current levels within a facility. Overloading of circuits,
under- and over-voltage problems, and unbalances
between circuits can be detected in this manner. These
measurements just require a simple multimeter. Signals to
check include:
• phase-to-ground voltages
• phase-to-neutral voltages
• neutral-to-ground voltages
• phase-to-phase voltages (three phase system)
• phase currents
• neutral currents
The most important factor to consider when selecting
and using a multimeter is the method of calculation used in
the meter. All of the commonly used meters are calibrated
to give an RMS indication for the measured signal.
However, a number of different methods are used to
calculate the RMS value. The three most common
methods are:
1. Peak Method. The meter reads the peak of the
signal and divides the result by 1.414 (square
root of 2) to obtain the RMS.
2. Averaging Method. The meter determines the
average value of a rectified signal. For a clean
sinusoidal signal, this average value is related
to the RMS value by the constant, k=1.1. This
value k is used to scale all waveforms
measured.
3. True RMS. The RMS value of a signal is a
measure of the heating which will result if the
voltage is impressed across a resistive load.
One method of detecting the true RMS value is
to actually use a thermal detector to measure a
heating value. More modern digital meters use
a digital calculation of the RMS value by
squaring the signal on a sample by sample
basis, averaging over a period, and then taking
the square root of the result.
These different methods all give the same result for a
clean, sinusoidal signal but can give significantly different
answers for distorted signals. This is very important
because significant distortion levels are quite common,
especially for the phase and neutral currents within the
facility. Table 3 can be used to better illustrate this point.
Each waveform in Table 3 has an RMS value of 1.0 pu
(100.0%). The corresponding measured value for each
type of meter is displayed under the associated
waveforms, per-unitized to the 1.0 pu RMS value.
Oscilloscopes
An oscilloscope is valuable when performing real time
tests. Looking at the voltage and current waveforms can
tell a lot about what is going on, even without performing
detailed harmonic analysis on the waveforms. You can get
the magnitudes of the voltages and currents, look for
obvious distortion, and detect any major variations in the
signals.
Table 3. Methods for Measuring Voltages and Currents with Multi-Meters.
Meter Type Circuit Sine Wave Square Wave Distorted
Wave
Light
Dimmer
Triangle Wave
-1.5
-1
-0.5
0
0.5
1
1.5
-1.5
-1
-0.5
0
0.5
1
1.5
-3
-2
-1
0
1
2
3
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Peak
Method
Peak / 1.414 100 % 82 % 184 % 113 % 121 %
Average
Responding
Sine Avg. x 1.1 100 % 110 % 60 % 84 % 96 %
True RMS RMS Converter 100 % 100 % 100 % 100 % 100 %
6. 6
There are numerous makes and models of
oscilloscopes to choose from. A digital oscilloscope with
data storage is valuable because the waveform can be
saved and analyzed. Oscilloscopes in this category often
have waveform analysis capability (energy calculation,
spectrum analysis) also. In addition, the digital
oscilloscopes can usually be obtained with
communications so that waveform data can be uploaded
to a PC for additional analysis with a software package.
Disturbance Analyzers
Disturbance analyzers and disturbance monitors form
a category of instruments which have been developed
specifically for power quality measurements. They
typically can measure a wide variety of system
disturbances from very short duration transient voltages
to long duration outages or under-voltages. Thresholds
can be set and the instruments left unattended to record
disturbances over a period of time. The information is
most commonly recorded on a paper tape but many
devices have attachments so that it can be recorded on
disk as well.
There are basically two categories of these devices:
1. Conventional analyzers that summarize events
with specific information such as over/under
voltage magnitudes, sags/surge magnitude
and duration, transient magnitude and
duration, etc.
2. Graphics-Based analyzers that save and print
the actual waveform along with the descriptive
information which would be generated by one
of the conventional analyzers.
It is often difficult to determine the characteristics of a
disturbance or a transient from the summary information
available from conventional disturbance analyzers. For
instance, an oscillatory transient cannot be effectively
described by a peak and a duration. Therefore, it is almost
imperative to have the waveform capture capability in a
disturbance analyzer for detailed analysis of a power
quality problem (Figure 5). However, a simple
conventional disturbance monitor can be valuable for
initial checks at a problem location.
Figure 5. Graphics Based Analyzer Output
Spectrum Analyzers and Harmonic Analyzers
Many instruments and on line monitoring equipment
now include the capability to sample waveforms and
perform FFT calculations. The capabilities of these
instruments vary widely and the user must be careful that
the accuracy and information obtained is adequate for the
investigation. The following are some basic requirements
for harmonic measurements used to investigate a problem:
• Capability to measure both voltage and current
simultaneously so that harmonic power flow
information can be obtained.
• Capability to measure both magnitude and
phase angle of individual harmonic
components (also needed for power flow
calculations).
• Synchronization and a high enough sampling
rate for accurate measurement of harmonic
components up to at least the 37th harmonic
(this requirement is a combination of a high
sampling rate and a sampling interval based on
the 60 Hz fundamental).
• Capability to characterize the statistical nature
of harmonic distortion levels (harmonics levels
change with changing load conditions and
changing system conditions).
Harmonic distortion is a continuous phenomena. It
can be characterized at a point in time by the frequency
spectrums of the voltages and currents. However, for
proper representation, measurements over a period of time
must be made and the statistical characteristics of the
harmonic components and the total distortion determined.
7. 7
Combination Disturbance and Harmonic
Analyzers
The most recent instruments combine limited
harmonic sampling and energy monitoring functions with
complete disturbance monitoring functions as well (Figure
6). The output is graphically based and the data is
remotely gathered over phone lines into a central
database. Statistical analysis can then be performed on
the data. The data is also available for input and
manipulation into other programs such as spreadsheets
and other graphical output processors.
ANALYZING POWER QUALITY
MEASUREMENT DATA
Analyzing power quality measurements has become
increasingly more sophisticated within the past few years.
It is not enough to simply look at RMS quantities of the
voltage and current. Disturbances that occur on the
power system have durations in the milli-second time
frame, equipment is more sensitive to these disturbances,
and there is more equipment connected to the power
systems that cause disturbances or power quality
problems. For these reasons, it is often necessary to
continuously monitor system performance and
characterize possible impacts of disturbances.
The data analysis system must be flexible enough to
handle data from a variety of monitoring equipment and
maintain a database that can be used by many different
applications. The concept is illustrated in Figure 7.
Event
Information
PQ Data
CHARACTERIZER
Database Manager
Site
Information
Event
Viewer
Protection
Analysis
Data
Trending
Energy
Analysis
Statistical
Analysis
Applications
PQ Monitoring
Database
Power
Quality
Monitoring
Instruments
Voltage
Recorders
InPlant
Monitors
Digital Fault
Recorders
Data
Translator
PQ Data
Interchange
Format
Data
Translator
Data
Translator
Data
Translator
Figure 7. Example Data Analysis System.
Different types of power quality variations require
different types of analysis to characterize system
performance. Some examples are given in the following
sections. With a flexible system, these applications can be
customized to individual user needs.
Transients
Transients are normally characterized by the actual
waveform, although summary descriptors can also be
developed for:
• peak magnitude
April 22, 1992 at 21:43:21 LocalIBM503E
Phase C-A Voltage
RMS Variation
Trigger
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
80
85
90
95
100
105
110
115
Time (Seconds)
Voltage(%)
0 25 50 75 100 125 150 175
-150
-100
-50
0
50
100
150
Time (mSeconds)
Voltage(%
Duration
0.150 Sec
Min
81.38
Ave
96.77
Max
101.4
BMI/Electrotek
November 19, 1991 at 06:07:56 PQNode LocalRGE_BETA
Phase A Voltage
Wave Fault
Trigger
0 10 20 30 40 50 60 70
-1.5
-1
-0.5
0
0.5
1
1.5
Time (mSeconds)
Voltage(pu)
Max1.094
Min-1.280
Uncalibrated Data
May 09, 1992 at 13:04:07 LocalIBM503M
Phase A Current
SS Wave
0 10 20 30 40 50
-600
-400
-200
0
200
400
600
Time (mSeconds)
Current(Amps)
0 10 20 30 40 50
0
20
40
60
80
100
Harmonic
Amps
Fund267.5
RMS 281.0
CF 1.772
Min -495.6
Max 498.0
THD 30.67
HRMS86.19
TIF/IT70249
Figure 6. Output From Combination Disturbance and Harmonic Analyzer.
8. 8
• primary frequency
• time of occurrence
• rate of rise
An example of this data in statistical form is presented
in Figure 8.
Transient Magnitude
0.0 0.5 1.0 1.5 2.0
0
50
100
150
200
250
0
20
40
60
80
100
Magnitude (per-unit)
Ct
CumulativeProba
Samples:
Min:
Max:
Range:
Mean:
Std Dev:
Variance:
Std Err:
Mode:
Skewness:
Kurtosis:
561
1.05014
1.59
0.53986
1.14418
0.0825617
0.00681643
0.00348576
1.11834
1.73749
4.45834
Figure 8. Bar Chart for Transient Peak Voltage.
RMS Variations
RMS variations are generally characterized by the
RMS value vs. time or by the minimum magnitude of the
voltage during the event vs. the duration of the event.
Figure 1 was an illustration of a plot of magnitude vs. Time
for a 24 hour period.
This method is fine for looking at single sites and
single events. But when a whole system is involved,
either customer or utility, it may be preferable to look at a
range of events (e.g. one month, one year, etc.) for
multiple sites. This would give an indication as to what
type of RMS events are occurring on a given system. The
magnitude duration plot in Figure 9 illustrates the minimum
voltage (in percent) during the event and the duration of
the event (time in cycles that voltage was out of the
thresholds).
RMS Magnitude vs Duration
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
0
25
50
75
100
125
150
Duration (60 Hz Cycles)
VltMitd
Total Events:
Events Below:
Events Above:
Below CBEMA:
Above CBEMA:
149
141
8
26
0
Figure 9. Example Magnitude Duration Plot.
Another method for displaying this type of data is a
three dimensional bar graph where the count, magnitude,
and duration is shown. Figure 10 illustrates this type of
plot.
1-10
10-60
60-
180
180-
300
300-
3000
>3000
Duration(Cycles)
0
20
40
60
80
100
120
140
160
Magnitude(%)0
100
200
300
400
500
600
700
800
Count
RMS Variation Magnitude vs Duration vs Count
Figure 10. Three Dimensional RMS Variation Bar Graph.
Harmonics
Harmonics are characterized by individual snapshots
of voltage and current with the associated spectrums. It is
important to understand that the harmonic distortion
levels are always changing and these characteristics
cannot be represented with a single snapshot. Therefore,
time trends and statistics are needed. An example time
trend plot for one month was included in Figure 2. Figure
11 shows the statistics of the harmonic current level. This
would be good for comparison with IEEE-519 limits.
Histogram for Harmonic RMS Current
0 5 10 15 20 25
0
250
500
750
1000
1250
1500
0
20
40
60
80
100
Current (A)
Ct
CumulativeProba
Samples:
Min:
Max:
Range:
Mean:
Std Dev:
Variance:
Std Err:
Mode:
Skewness:
Kurtosis:
6691
4.93836
20.9626
16.0242
6.95771
1.9269
3.71296
0.0235567
6.06852
1.53821
1.2563
Figure 11. Histogram for Harmonic RMS Current for
Approximately Four Months.
SUMMARY
Systematic procedures for evaluating power quality
concerns can be developed but they must include all
levels of the system, from the transmission system to the
end user facilities. Power quality problems show up as
impacts within the end user facility but may involve
interaction between all levels of the system.
9. 9
A consistent set of definitions for different types of
power quality variations is the starting point for
developing evaluation procedures. The definitions permit
standardized measurements and evaluations across
different systems.
A data analysis system for power quality
measurements should be able to process data from a
variety of instruments and support a range of applications
for processing data. With continuous power quality
monitoring, it is very important to be able to summarize
variations with time trends and statistics, in addition to
characterizing individual events.
BIOGRAPHIES
Christopher J. Melhorn received an ASE from York
College of Pennsylvania in 1986 and a BSEET from the
Pennsylvania State University in 1989. Chris has been
employed with Electrotek Concepts, Inc. since 1990. His
experience at Electrotek includes working with EPRI and
utilities on case studies involving power quality issues.
He was also extensively involved in the EPRI DPQ project
site selection phase. Chris is presently involved in
developing new software for the power systems
engineering environment and working to increase
Electrotek's industrial based clientele.
Mark F. McGranaghan received a BSEE and an MSEE
from the University of Toledo and an MBA from the
University of Pittsburgh. Mark serves as Manager of
Power Systems Engineering at Electrotek Concepts, Inc.,
Mark is responsible for a wide range of studies, seminars,
and products involving the analysis of power quality
concerns. He has worked with electric utilities and end
users throughout the country performing case studies to
characterize power quality problems and solutions as part
of an extensive Electric Power Research Institute (EPRI)
project. He has also been involved in the EPRI
Distribution Power Quality Monitoring Project which is
establishing the baseline power quality characteristics of
U.S. distribution systems through a multi-year monitoring
effort. Mark was involved in the design and specification
of the instrumentation and software for this project.
REFERENCES
1. IEEE Working Group P1159, Recommended
Practice for Monitoring Electric Power Quality -
Draft 7, December, 1994.
2. IEEE Std. 519-1992, IEEE Recommended Practices
and Requirements for Harmonic Control in
Electrical Power Systems, IEEE, New York, 1993.
3. “Electrical Power System Compatibility with
Industrial Process Equipment - Part 1: Voltage
Sags,” Paper by the IEEE Working Group P1346,
Proceedings of the Industrial and Commercial
Power Systems Conference, 94CH3425-6, May,
1994.
4. CENELEC Standard CLC/BTTF 68-6 (Sec) 23,
“Voltage Characteristics of Electricity Supplied by
Public Distribution Systems,” June, 1993.
5. IEC Standard 1000-2-2, “Compatibility Levels for
Low Frequency Conducted Disturbances and
Signalling in Public Low Voltage Power Supply
Systems.”
6. IEC Standard 1000-4-7, “General guide on
harmonics and interharmonics measurements and
instrumentation, for power supply systems and
equipment connected thereto.”
7. ANSI C84.1-1989, American National Standard for
Electric Power Systems and Equipment - Voltage
Ratings (60 Hertz).
9. M. McGranaghan, D. Mueller, and M. Samotyj,
“Voltage Sags in Industrial Plants,” IEEE
Transactions on Industry Applications, Vol. 29,
No. 2, March/April, 1993.
10. L. Conrad, K. Little, and C. Grigg, “Predicting and
Preventing Problems Associated with Remote
Fault-Clearing Voltage Dips, “ IEEE Transactions
on Industry Applications, vol. 27, pp. 167-172,
January, 1991.
11. V. Wagner, A. Andreshak, and J. Staniak, “Power
Quality and Factory Automation, “ Proceedings of
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1396.