Automatic generation control of an interconnected hydrothermal power system
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Abstract:
This paper deals with automatic generation control of an interconnected hydrothermal system considering reheat type turbine in thermal plant area and low head turbine in hydro plant area using optimal controllers. The dynamical response of the load frequency control problem in an interconnected power system under consideration is improved with a practical viewpoint by designing the optimal output feedback controller. The optimal control methods are proposed and their dynamic responses are compared. The optimal control is determined by minimizing a performance index under the proposed output feedback conditions. The results indicate that the controllers exhibit better performance. In fact, the control systems designed on these methods satisfy the load frequency control requirements with a reasonable dynamic response.Keywords:
Automatic Generation Control
A new approach for the automatic generation control (AGC) of electric power networks is introduced. This approach also supports an economic dispatch feature which operates at a slower time scale and interacts with the AGC frequency stabilization function. AGC is separated into two subtasks: frequency regulation and tie-line flow control, and a hierarchy of controls are formulated to realize these two functions. The frequency regulation level, called secondary control, is decentralized, and optimized with respect to both frequency offset and change in generator governor controls. The tie-line flow control level, called tertiary control, is centralized, and works on a slower time scale than secondary control. Tertiary control compensates for inadvertent flows between areas by momentarily offsetting generator frequencies. These frequency offsets shift the phase angles found at tie-line terminals, and eventually realize the desired line flows. The role of economic dispatch (ED) is to reschedule the entire system to minimize overall generation cost. The proposed version of ED is centralized, and invoked at an even slower rate than tertiary tie-line regulation.
Automatic Generation Control
Economic Dispatch
Tie line
Governor
Frequency Regulation
Line (geometry)
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This paper focuses on load frequency regulation, as a major function of automatic generation control (AGC) in the context of a versatile power system structure, environmental constrains and emerging new uncertainties. Generation units models are determined in order to build a control diagram used for load dispatch. The optimal parameters for the secondary controller were determined using a gradient descent algorithm.
Automatic Generation Control
Load regulation
Frequency Regulation
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Load-frequency control (LFC) is a part of the Automatic Generation Control (AGC) in power systems, the aim of which is to maintain the system frequency and tie line flow at their scheduled values during normal period in an interconnected system. This research paper is devoted to explore the interconnection of the load frequency control of hydro power system and the thermal system. The thermal system is comprised with governor dead band, generation rate constraint and boiler dynamics where as the hydro system is comprised with generation rate constraint. The conventional PID controller does not have adequate control performance with the consideration of nonlinearities and boiler dynamics. To overcome this drawback, Genetic Algorithm helps in solving optimization problems by exploitation of random search. The aim of the proposed expert controller is to restore the frequency to its nominal value in the smallest possible time whenever there is any change in the load demand etc.
Automatic Generation Control
Governor
Frequency deviation
Tie line
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Indian electricity market has adopted a concept of frequency linked commercial tariff system, commonly referred to as availability-based tariff (ABT), where variation in system frequency is used as market signal to encourage utilities to change generation in real time operation. As frequency varies with real power imbalance, proper incentive is rewarded for automatic generation control (AGC) service provided by the generating utility for making up the real power mismatch. In ABT, the rate of unscheduled interchange (RUI) for AGC service is fixed depending upon the frequency condition prevailing at that time. The conventional AGC system though tries to bring the frequency error to zero but it would be an ineffective solution for participating generating utilities under ABT since incentive/penalty varies with frequency. This paper investigates the rules and advocacy of ABT more strategically and develops a model for AGC based on conventional if-then logics for load-frequency regulation scheme that will respond to the frequency-based price signal in a profitable manner. The proposed model is tested on IEEE 14 bus system and part of northern region grid of India.
Automatic Generation Control
Frequency deviation
Frequency grid
SIGNAL (programming language)
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Along with the massive application of automatic generation control(AGC)function of units,the participation of AGC units in the primary frequency regulation of power network has been becoming increasingly important.The paper discusses the conditions for the participation of AGC unit in the primary frequency regulation of network,parameters set-up and its actual application.Through the application tests and analysis,the advantages of participation of AGC units in the primary frequency regulation of network are brought forward.
Automatic Generation Control
Frequency Regulation
Power network
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Thepaper studies the effect of automatic generation control(AGC) on power frequency based on the full dynamic simulation. First modeling of AGC for the full dynamic simulation according to the three components of AGC, which is calculation of area control error (ACE), simulation of control strategy, and calculation of generating power regulation. Second the effect of key-parameters of AGC including dead band, transient frequency-deviation on and rate of generating power regulation on power frequency is studied by simulating. Finally, the paper takes Fujian power as an example to analyze the effect of AGC on under-frequency loading shedding(UFLS) by the serious faults and study on the coordination control between AGC and UFLS.
Automatic Generation Control
Frequency Regulation
Frequency deviation
Transient (computer programming)
Dynamic demand
Frequency band
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To fulfill the need of operating power systems more effectively through diverse resources, frequency control conditions for maintaining a balance between generators and loads need to be provided accurately. As frequency control is generally achieved via the governor responses from local generators and the automatic generation control (AGC) frequency control of the central energy management system, it is important to coordinate these two mechanisms of frequency control efficiently. This paper proposes a dynamic-model-based AGC frequency control simulation method that can be designed and analyzed using the governor responses of generators, which are represented through dynamic models in the planning stage. In the proposed simulation model, the mechanism of the AGC frequency control is implemented based on the dynamic models of the power system, including governors and generators; hence, frequency responses from the governors and AGC can be sequentially simulated to coordinate and operate these two mechanisms efficiently. The effectiveness of the proposed model is verified by simulating the AGC frequency control of the Korean power system and analyzing the coordination effect of the frequency responses from the governors and AGC.
Automatic Generation Control
Governor
Dynamic demand
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Secondary frequency control has been introduced through Automatic Generation Control (AGC) in India in 2018 on a pilot basis. This paper elaborates the various steps that were involved in the introduction of secondary frequency control. Details of the important resources identified for the implementation of AGC at load despatch centre and at power plants are elaborated. Regulatory framework evolved around secondary frequency control is discussed. The authors also present the core ideas around secondary frequency control and its future in India.
Automatic Generation Control
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The inverter-interfaced renewable energy is increasing in future new power systems, both the system rotary inertia and frequency regulation capacity of traditional units are decreasing and becoming increasingly insufficient. It is urgent to explore various types of frequency regulation resources, especially for inverter-interfaced units that show fast response speed. The heterogeneous frequency regulation resources generally have different system models, capacities, and response speeds, which challenges the automatic generation control (AGC). In this paper, to make the heterogeneous frequency regulation resources provide improved frequency regulation performance, a novel distributed cooperative AGC method is proposed. Firstly, a distributed consensus-based area control error (ACE) discovery algorithm is proposed. Then, each frequency regulation unit can participate in the frequency regulation with an individual PI controller based on the discovered ACE information. Finally, by controlling the low-speed AGC units to generate more power, it can release the power capacity of the high-speed AGC units to prepare for the following round of AGC services. Furthermore, the communication delays are also considered for the proposed distributed AGC algorithm design. The improved performance of the proposed AGC method is verified based on the simulation study of a two-area power system with five different kinds of frequency regulation units.
Automatic Generation Control
Frequency Regulation
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Citations (11)
Automatic generation control has been one of my interests since I first read Nathan Cohn's standard text. Automatic generation control has several major components: load frequency control, tie line flow control, and economic dispatch that have been defined and redefined over several decades. Changes in the operational structure, due to competitive market requirements, have changed this function. This author has summarized over ten years of his active research based on the accepted control standards for the load frequency control component.
Automatic Generation Control
Component (thermodynamics)
Automatic control
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Citations (8)