Effect Of Bilateral Contracts Research Articles

Evaluating the Impact of Bilateral Contracts on the Offering Strategy of a Price Maker Wind Power Producer

Due to the high penetration of wind power generation in power systems and electricity markets, wind power plants (WPPs) can, in some scenarios, influence the market prices and exercise market power in the day-ahead (DA) market. In order to evaluate the capability of WPPs to directly act as price-maker, this article proposes the strategic offering of a WPP in the DA market by using a bilevel stochastic optimization approach. The primary objective of the proposed model is to maximize the WPP's expected profit by strategically offering in DA market while minimizing the energy deviations in the regulating market. Moreover, the WPP can also sign bilateral contracts with customers to supply their required energy. In the subproblem, the system operator tends to minimize the sum of the total generation costs minus the sum of the total demand benefits. The effect of bilateral contracts on the strategic offering of WPP in the DA market and its impact on the transmission margin are also investigated. Results on real cases show that when the WPP enters into a bilateral contract, it should consider the effect of such contracts on the offering strategy to the DA market. The effects of bilateral contracts on the regulating market are also examined.

Load Shedding in Deregulation Environment and Impact of Photovoltaic System with SMES

Abstract With the continuous increase in the load, the frequency of the system goes on decreasing and it reaches to its minimum allowable value after the further increase in load will result in more frequent drop resulting in the need of load shedding. To avoid load shedding and control of the frequency of the systems some approach have discussed here. The paper includes modeling of SMES with solar PV array for frequency control of three areas interconnected thermal system in deregulated environment. A comparative analysis of different load frequency control scheme such as: i) Using conventional integral controller ii) Using PID controller, iii) Using additional sources of energy (PV with SMES) on the basis of load to be shed have been discussed. The effects of bilateral contracts on the dynamics of a system including three areas, each of which consisting of two GENCOS and two Discos has been discussed. A case study of contract violation of DISCO‘s also being incorporated. For all the three strategies the critical load at which frequency of the areas tries to go below minimum allowable range also has been calculated. With the help of MATLAB software using Simulink, results have been obtained. From the comparison results indicates that on using the third strategy (with additional sources) we are increasing the efficiency of the system. When using system with PID controller and additional sources, frequency of the system doesn’t go below minimum allowable range and there is requirement of load shedding has been eliminated.

Fractional-order Proportional-integral-derivative-based Automatic Generation Control in Deregulated Power Systems

—In this article, implementation of a fractional-order proportional-integral-derivative controller is proposed as supplementary automatic generation control of interconnected multi-area deregulated power systems that operates under the effects of bilateral contracts on the dynamics. The tuning of the fractional-order proportional-integral-derivative controller parameters is formulated as an optimization problem and solved by employing a genetic algorithm. The traditional automatic generation control loop incorporated with the concept of the distribution company participation matrix and fractional-order proportional-integral-derivative supplementary controller is simulated for different operating cases; a comparison among the conventional integral controller, hybrid fuzzy proportional-integral controller, genetic algorithm-tuned proportional-integral controller, and genetic algorithm-tuned proportional-integral-derivative controllers is presented. The simulation results show that the system employing a genetic algorithm-tuned fractional-order proportional-integral-derivative controller has better performance than the integer-order hybrid fuzzy proportional-integral, genetic algorithm-tuned proportional-integral, and genetic algorithm-tuned proportional-integral-derivative controllers in terms of settling time and overshoot.

Fuzzy Logic Based Load Frequency Control of Two Area Power System in Deregulated Environment

In this paper fuzzy logic based load frequency control (LFC) of two area power system in deregulated environment was studied. A two area system is considered in which all areas are interconnected by normal AC tie-lines. In the proposed system the effects of bilateral contracts between DISCOs and GENCOs are also considered. The performance of the fuzzy logic controller is tested on a deregulated two area load frequency control system for different operating conditions using MATLAB Simulink tool.

Fuzzy Logic and Genetic Algorithm based Automatic Generation Control of Two-Area Deregulated Power Systems

This paper illustrates the automatic generation control (AGC) of an interconnected two-area power system under deregulated environment. Two controllers viz., a Hybrid Fuzzy-PI (HFPI) controller and Genetic Algorithm based PI (GAPI) controller are proposed to improve the dynamic response of the power systems. The conventional two-area AGC system is modified to take into account the effects of bilateral contracts on the dynamics. In the HFPI controller, the parameters of the conventional PI controller are modified according to the principles of fuzzy logic whereas in GAPI controller, tuning parameter design criteria is reformulated as an optimization problem and the general rules of genetic algorithm (GA) are applied. The convergence and performance of the system are studied for different operating cases and a comparison among conventional integral (CI) controller, HFPI controller and GAPI controller are presented. The simulation results show that the HFPI controller proposed in this paper perform better than the conventional integral and GAPI controllers in terms of settling time and overshoot.

Performance evaluation of evolutionary designed conventional AGC controllers for interconnected electric power system studies in a deregulated market environment

Electric power industry is currently in transition from vertically integrated utilities to an industry that will incorporate competitive companies. This increases the complexity of the load frequency issue and calls for more insight and research. In this context, the tuning of a multi-area automatic generation control (AGC) system after deregulation and furthermore, the effect of reheat turbines dynamics in the power system performance, are not yet discussed in depth and are studied in this work. The effect of bilateral contracts on the dynamics of the system is taken into account and the concept of DISCO participation matrix for these bilateral contracts is simulated. Genetic algorithms are adopted in order to obtain the optimal parameters of the load-frequency controllers as well as of the frequency biases of thermal systems with reheat turbines. Also, since the optimum parameter values of the classical AGC have been obtained in the literature by minimizing the popular integral of the squared errors criterion (ISE) only, an effort is made in this study to show that this criterion does not give always the best system performance especially in a deregulated environment. In this work, we investigate the optimum adjustment of the load frequency controllers using a set of performance indices which are various functions of error and time. In this way, someone can observe the various performances that such a kind of power system might have when a different performance index is used. It should be noted that to the extent of the authors' knowledge, this kind of optimization has not been done yet in the literature. The performances of the tuned two–area AGC system are obtained using appropriate Matlab/Simulink models. Finally, it is envisaged that the synthesis procedure highlighted in this paper could be of practical significance for tuning conventional AGC controllers for an interconnected thermal-electric power system in a deregulated environment. Keywords: AGC, load frequency control, power systems, deregulation, bilateral contracts, genetic algorithms

05/02536 Bilateral based robust load frequency control

Load frequency control (LFC) has been one of the major subjects in electric power system design/operation and is becoming much more significant today in accordance with increasing size and the changing structure and complexity of interconnected power systems. In practice, power systems use simple proportional-integral (PI) controllers for frequency regulation and load tracking. However, since the PI controller parameters are usually tuned based on classical or trial and error approaches, they are incapable of obtaining good dynamical performance for a wide range of operating conditions and various load changes scenarios in a restructured power system. This paper addresses a new decentralized robust LFC design in a deregulated power system under a bilateral based policy scheme. In each control area, the effect of bilateral contracts is taken into account as a set of new input signals in a modified traditional dynamical model. The LFC problem is formulated as a multi-objective control problem via a mixed H2/Hinf control technique. In order to design a robust PI controller, the control problem is reduced to a static output feedback control synthesis, and then, it is solved using a developed iterative linear matrix inequalities algorithm to get a robust performance index close to a specified optimal one. The proposed method is applied to a 3 control area power system with possible contract scenarios and a wide range of load changes. The results of the proposed multi-objective PI controllers are compared with H2/Hinf dynamic controllers.

05/00181 Robust decentralized AGC in a restructured power system: Bevrani, H. et al. Energy Conversion and Management, 2004, 45, (1516), 2297–2312

This paper addresses a new decentralized robust strategy to adapt the well tested classical automatic generation control (AGC) system to the changing environment of power system operation under deregulation based on the bilateral AGC scheme. In each control area, the effect of bilateral contracts is taken into account in a modified traditional dynamical model as a set of new input signals. The AGC problem is formulated as a multi-objective control problem, and the mixed H2/Hinf control technique is used to synthesis the desired robust controllers for AGC design in a multi-area power system. A three area power system example with possible contract scenarios and a wide range of load changes is given to illustrate the proposed approach. The results of the proposed control strategy are compared with the pure Hinf method. The resulting controllers are shown to minimize the effect of disturbances and maintain robust performance.

Robust decentralized AGC in a restructured power system

This paper addresses a new decentralized robust strategy to adapt the well tested classical automatic generation control (AGC) system to the changing environment of power system operation under deregulation based on the bilateral AGC scheme. In each control area, the effect of bilateral contracts is taken into account in a modified traditional dynamical model as a set of new input signals. The AGC problem is formulated as a multi-objective control problem, and the mixed H 2 / H ∞ control technique is used to synthesis the desired robust controllers for AGC design in a multi-area power system. A three area power system example with possible contract scenarios and a wide range of load changes is given to illustrate the proposed approach. The results of the proposed control strategy are compared with the pure H ∞ method. The resulting controllers are shown to minimize the effect of disturbances and maintain robust performance.

Bilateral based robust load frequency control

Abstract Load frequency control (LFC) has been one of the major subjects in electric power system design/operation and is becoming much more significant today in accordance with increasing size and the changing structure and complexity of interconnected power systems. In practice, power systems use simple proportional-integral (PI) controllers for frequency regulation and load tracking. However, since the PI controller parameters are usually tuned based on classical or trial and error approaches, they are incapable of obtaining good dynamical performance for a wide range of operating conditions and various load changes scenarios in a restructured power system. This paper addresses a new decentralized robust LFC design in a deregulated power system under a bilateral based policy scheme. In each control area, the effect of bilateral contracts is taken into account as a set of new input signals in a modified traditional dynamical model. The LFC problem is formulated as a multi-objective control problem via a mixed H 2 / H ∞ control technique. In order to design a robust PI controller, the control problem is reduced to a static output feedback control synthesis, and then, it is solved using a developed iterative linear matrix inequalities algorithm to get a robust performance index close to a specified optimal one. The proposed method is applied to a 3 control area power system with possible contract scenarios and a wide range of load changes. The results of the proposed multi-objective PI controllers are compared with H 2 / H ∞ dynamic controllers.

Robust decentralized AGC in a restructured power system

This paper addresses a new decentralized robust strategy to adapt the well tested classical automatic generation control (AGC) system to the changing environment of power system operation under deregulation based on the bilateral AGC scheme. In each control area, the effect of bilateral contracts is taken into account in a modified traditional dynamical model as a set of new input signals. The AGC problem is formulated as a multi-objective control problem, and the mixed H2/H∞ control technique is used to synthesis the desired robust controllers for AGC design in a multi-area power system. A three area power system example with possible contract scenarios and a wide range of load changes is given to illustrate the proposed approach. The results of the proposed control strategy are compared with the pure H∞ method. The resulting controllers are shown to minimize the effect of disturbances and maintain robust performance.

Robust AGC Traditional Structure Versus Restructured Scheme

In this paper, a decentralized robust approach is proposed for the Automatic Generation Control (AGC) system based on a modified traditional AGC structure. This work addresses the new strategy to adapt well-tested classical AGC scheme to the changing environment of power system operation under deregulation. The effect of bilateral contracts is considered as a set of new input signals in each control area dynamical model. In practice, AGC systems use simple proportional-integral (PI) controllers. However, since the PI controller parameters are usually tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamical performance for a wide range of operating conditions and various scenarios in deregulated environment. In this paper with regard to this problem, the AGC synthesis is formulated as an H∞ static output control problem and is solved using a developed iterative linear matrix inequalities (ILMI) algorithm to design of robust PI controllers in the restructured power system control areas. A three area power system example with possible contract scenarios and wide range of load changes is given to illustrate the proposed approach. The resulting controllers are shown to minimize the effect of disturbances and maintain the robust performance.

Robust LFC in a Deregulated Environment: Multi-objective Control Approach

This paper addresses a new decentralized robust load-frequency control (LFC) design in a multi-area power system under deregulation based on bilateral policy scheme. In each control area, the effect of bilateral contracts is taken into account as a set of new input signals to modify the traditional LFC structure. The LFC problem is considered as a multi-objective control problem and formulated via a mixed H2/H∞ control technique, then it is easily carried out to synthesis the desired low-order robust controllers by solving standard linear matrix inequalities (LMI). A three-area power system example with possible contract scenarios and a wide range of load changes is given to illustrate the developed approach. The results of the proposed multi-objective control strategy are compared with pure H∞ design. The resulting controllers are shown to maintain the robust performance and minimize the effect of disturbances and specified uncertainties.