The Need for Regulatory & Policy Framework for Ancillary Services & Alternative Energy Options in the Indian Power Sector Drivers of Ancillary Services in India Sanjoy K. Parida Assistant Professor Department of Electrical Engineering Indian Institute of Technology Patna
Presentation Layout• Introduction• Ancillary services provision from DERs• Scope to promote ancillary services in India• Conclusion
Ancillary Services• The literal meaning of the word ancillary is providing support or help.• Generally, the System Operator (SO) procures ancillary services for ensuring security, reliability and quality of the power supply to the consumers.• Ancillary services can be provided by generators, Load Serving Entities (LSEs) and transmission operators.• Ancillary services are classified, procured and remunera - ted depending upon the operational practices of the Electricity Supply Industry (ESI).
Classification of Ancillary Services Ancillary Services FCAS NCAS Primary FC VCAS Secondary FC Primary VC Tertiary FC Secondary VC Tertiary VC SRAS PFCASRef: Guide to ancillary services in the National Electricity Market, National Electricity Market Management Company.
Frequency Control Ancillary Services A certain amount of active power, called frequency control reserve, is kept available to perform this task. Three levels of control are generally used to achieve FCAS: (i) Primary frequency control, (ii) Secondary frequency control and (iii) Tertiary frequency control. Primary frequency control requires a response period of 5 to 10sec, secondary frequency control requires a response period of 10s to 15min and tertiary frequency control requires a response period of 10 to 30min. Frequency control reserves required to perform above control tasks can be of (i) positive frequency control reserve and (ii) negative frequency control reserve.
Network Control Ancillary Services These are the services required to maintain the network parameters within permissible range. VCAS are required for supporting the voltage to be maintained within the permissible limit. Three levels of control are generally used to achieve VCAS: (i) Primary voltage control, (ii) Secondary voltage control and (iii) Tertiary voltage control. PFCAS are needed for the purpose of improving Available Transfer Capability (ATC) and the performance of real time operation considering network constraints. System Restart Ancillary Services These are the services related to backup capacity of the system and the capacity that is required to return the system to a normal operation after a major or partial blackout.
Technologies Used for Provision of ASAncillary Services Technologies Used FCAS Governor, AGC, Rapid unit loading, Rapid unit unloading, Demand side management, Distributed energy resources (DERs) NCAS Generators, Capacitors, Inductors, Synchronous condensers, FACTS controllers, Distributed energy resources (DERs) SRAS Generators, Distributed energy resources (DERs)
Procurement of Ancillary Services Compulsory Provision • As part of connecting conditions, a fixed amount of ancillary services is provided. • Consequences: (i) volume of service provided may exceed what is actually needed, (ii) potentially low cost providers are treated on the same basis as more expensive one. Market Based Provision • Bilateral contracts: (i) this form of procurement lacks transparency, (ii) this type of negotiation can be long-term, complex and costly, (iii) because of high transaction cost of contracts, price and volume often remain fixed for a long time. • Both tendering process and creation of a spot market enhance transparency and foster competition.
Remuneration of Ancillary Services Structures of Remuneration • Availability cost • Utilization cost • Fixed cost • Variable cost • Opportunity cost Remuneration Methods • Regulated price • Pay as Bid price • Common clearing price
Summary of renewable technology capabilities to provide AS
Summary of non-renewable technology capabilities to provide AS
Economic Analysis• Cost of Electricity GenerationIt consists of three components.• Capital cost: Includes the cost of the plant, land acquisition, grid connection, initial financing cost.• Operating & Maintenance cost Includes insurance, rent, cost of labor and materials used for operation & maintenance.• Fuel cost
• Cost comparison with the conventional power generation technologies
Optimum Economic Dispatch• The aim is to load generating sets in response to demand changes so as to minimize the cost of supply. This is known as optimum economic dispatch (OED). C A K A K A PA ; for plant A CB K B K B PB ; for plant B• If plant A is a nuclear plant and plant B is a coal based thermal plant, then KA’ < KB’• the minimum cost Cmin occurs when the plant A takes as much of the load share as possible, i.e. it is loaded to its maximum level, with plant B brought in to cover the deficit.
• If there are ‘n’ plants available arrange the plants in order of increasing K′, the so - called merit order. Starting from the top of the list, the plants are then loaded (each up to the limit of its capacity) before the next plant on the list is brought into action.• Units with low operating costs run preferentially and therefore attract high load factors; they generate a disproportionately large share of electricity relative to their capacity. They are called base load plants , or high merit plants.• Units with high operating costs only run during peak demand, generate a disproportionately small share of the total electricity and are known as peaking plant.• Plants in between these two extremes are called intermediate plants or middle merit plants.
• The total cost of generated energy by a power station, for example a nuclear power station, may be higher than that from a coal fired one, the OED requires that the nuclear station is fully loaded because of its very low incremental cost.• The rationale is that the loading priority is independent of the original capital sum expended in the construction of a power station. As the station is present and available it should be utilized fully because of its low running costs.• It may be concluded that as the energy supplied by RE sources (except biomass) is characterized almost entirely by a capital cost component, their incremental cost is negligible. Therefore the OED method would require them to provide at all times all the energy they are capable of delivering.
Structure of the Indian ESI Indian ESI NRG ERG NERG SRG WRG Delhi Punjab Bihar Assam Goa Chandigarh Tripura Kerala Jharkhand Madhya Pradesh Rajastan Meghalaya KarnatakaJammu & Kashmir Orissa Arunachal Pradesh Chhatisgarh Andhra Pradesh Haryana Manipur Sikkim MaharastraHimachal Pradesh Mizoram Tamil Nadu Uttar Pradesh West Bengal Nagaland Gujarat Uttaranchal
Operational Structure of ESI in India Other RLDCs ISGSs/ CGSs/ IPPs Offer Availability Disp. Sch. NLDC (ISO) MCV PXs RLDC (RSO) Traders & MCP Forecast Drawal. Sch. Traders Bid Bid SLDCs State Gen. SEBs/Discos
Frequency Regulation Service• The primary frequency control, which is provided by the governor action of a generator or automatic regulation of frequency sensitive load, is also know as frequency regulation.• With the transition from vertically integrated utilities to unbundled one frequency regulation transformed to a “service” from an “obligation”.• In India, this service is being provided by generators under Free Governor Mode of Operation (FGMO) complied with certain guidelines prescribed by CERC
FCAS from Generators Scheduled Secondary Control Loop Generation Nominal UI + Frequency Rate + Incremental Cost - + Droop Generator Change in Output Demand Power Gain Generator System Actual Valve Frequency Power Primary Control Loop Change in Tie line PowerRef: Tyagi et al. “A mathematical framework for frequency linked availability based tariff mechanism inIndia” Proc. of the National Power Systems Conference, December 2004, IIT Chennai, India.
FCAS from LSEsIncremental CostComparison UI Rate Total Demand + Captive Demand Generation Gridrequirement from - FrequencyCGSs/ISGSs/IPPs Next
EXPLOITATION OF RENEWABLESSome renewable technologies are small and modular, they can be sited in or near buildings as distributed generation (DG) where energy is used.It can be used as an important component in microgrid, which is defined as localized grouping of electricity generation, energy storage, and loads that operates within the grid or in islanded mode if possible.Renewables have great potential in providing Ancillary Services (AS). AS are the system support services required to maintain security and reliability of the system
INTEGRATED SYSTEMIn radial mode transmission there are sources of generation at one end with a transmission and distribution system having consumers at the other end.At the instant of failure of the generating station the whole system fail. As such there is no flexibility for the system.In integrated system all the generating stations are connected through a reliable mesh transmission network.Total load connected to the system is shared by all the generation stations.Demand of electricity vary place to place. Industrial load growth generally occurs adjacent to the cities and towns.
Continued….In India because of uneven distribution of natural resources, generating stations are located in few pockets far away from load centers.Also, some regions are surplus in generation and some regions are shortfall of generation as compared to load demand.Surplus generation is need to be transported to energy deficit regions, which improves the power-supply reliability and quality.Liberalization of the electricity market leads to new management structures for the operation and control of the electricity grid.
INTEGRATION BASED ON ATTRIBUTESI. TechnicalII. EconomicalIII. EnvironmentalIV. Resource availability
SUB-ATTRIBUTESTechnical Economical Environmental Resource availabilityEfficiency Investment cost Noise OilPower generation O&M cost NOx GasCapacity factor Electricity Price SO2 WindLife time CO2 SolarInstallation led COtimeStart up time HCForced outage rate PMMaintenanceFootprint
DG TECHNOLOGIES WITH RESPECT TO THE MAIN ATTRIBUTESEASTERN WESTERNREGION REGION
Conclusion• Indian power sector, Free Governor Mode of Operation (FGMO) is the sole mechanism to provide FCAS.• DERs are important resources for various kinds of AS.• Design of market mechanism with proper policy framework for provision of ancillary services.• UI may play very important role in AS provision.