Area Interconnected Power System Research Articles

Hybrid Fuzzy Load Frequency Controller for a Two Area Interconnected Power System

This work addresses the special requirements of Automatic Generation Control in Modern interconnected Power system. In order to track the system frequency and handling the power system stability issues many control strategies has been suggested by the researchers .A new Hybrid fuzzy approach is introduced here .Fuzzy Logic controller with Mamdani interface having five member ship functions is tested with the Thermal Thermal and hydro thermal system Further hybrid Fuzzy controller is also tested with the same system and results are compared for the both The system Which is having Hybrid Fuzzy concept and thereby the response of frequency and tie line power can be improved substantially following a load change in any area. Further dynamic responses for small perturbation have been observed, considering HFLC and integral controller and the results of both have been compared.

LFC of an Interconnected Power System with Thyristor Controlled Phase Shifter in the Tie Line

paper presents the analysis of the load frequency control (LFC) of a realistic two area interconnected power system having diverse sources of power generation. A Thyristor Controlled Phase Shifter (TCPS) is used in series with AC tie line for improving the dynamic performance of the LFC system. The power system simulation is done using MATLAB Simulink and control problem is solved using MATLAB programming. An optimal output feedback control strategy using TCPS with pragmatic viewpoint is presented. Optimal gain settings of the output feedback controller with and without TCPS are obtained following a step load perturbation in either of the areas by minimizing the quadratic performance index. Simulation results show that due to the presence of TCPS, the dynamic performance in terms of settling time and overshoot is greatly improved. The system with TCPS is capable of suppressing the area frequency and tie line power deviations more effectively under the occurrence of area load perturbations.

Fuzzy based HVDC regulation controller for load frequency control of multi-area system

This paper investigates the load frequency control (LFC) problem for a multi-area power system taking into consideration system parameter variations. This paper proposes an intelligent control scheme for LFC of interconnected power systems. A fuzzy logic based integral controller is proposed for two-area power system interconnected via parallel AC/DC transmission link, which is also referred as asynchronous tie-lines. The linear model of AC/DC link with HVDC regulation controller is developed and the system responses to sudden load change are studied. The simulation studies are carried out for a two area interconnected power system with non-reheat steam turbine for simplicity and without loss of generality. Suitable solution for LFC problem of two-area electrical power system is obtained by means of improving dynamic performance of power system under study. Robustness of controller is also checked by varying parameters. Simulation results indicate that the proposed control scheme work well when compared with others.

Optimal Decentralized Load Frequency Control in a Parallel AC-DC Interconnected Power System Through HVDC Link Using PSO Algorithm

A new design of decentralized load-frequency controller for interconnected power systems with ac-dc parallel using Particle Swarm Optimization (PSO) algorithm is proposed in this paper. A HVDC link is connected in parallel with an existing ac tie-line to stabilize the frequency oscillations of the ac system. Any optimum controller selected for load frequency control of interconnected power systems should not only stabilize the power system but also reduce the system frequency and tie line power oscillations and settling time of the output responses. In practice Load Frequency Control (LFC) systems use simple Proportional Integral (PI) or Integral (I) controller parameters are usually tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamic performance for various load change scenarios in multi-area power system. For this reason, in this paper the PI and I control parameters are tuned based on PSO algorithm method for the LFC control in the two-area power system. A two area interconnected thermal power system is considered to demonstrate the validity of the proposed controller. The simulation results show that the proposed controller provides better dynamic responses with minimal frequency and tie-line power deviations, quick settling time and guarantees closed-loop stability margin.

Automatic Generation Control in Multi Area Interconnected Power System by using HVDC Links

T his paper investigates the effects of HVDC link in parallel with HVAC link on automatic generation control (AGC) problem for a multi-area power system taking into consideration system parameter variations. A fuzzy logic controller is proposed for four area power system interconnected via parallel HVAC/HVDC transmission link which is also referred as asynchronous tie-lines. The linear model of HVAC/HVDC link is developed and the system responses to sudden load change are studied. The simulation studies are carried out for a four area interconnected thermal power system. Suitable solution for automatic generation control problem of four area electrical power system is obtained by means of improving the dynamic performance of power system under study. Robustness of controller is also checked by varying parameters. Simulation results indicate that the scheme works well. The dynamic analyses have been done with and without HVDC link using fuzzy logic controller in Matlab-Simulink. Further a comparison between the two is presented and it has been shown that the performance of the proposed scheme is superior in terms of overshoot and settling time. DOI: http://dx.doi.org/10.11591/ijpeds.v2i1.182

Comparison of Meta Heuristic Optimization Methods in Load Frequency Control

In this paper an optimal load frequency controller for two area interconnected power system is presented to quench the deviations in frequency and tie line power due to different load disturbances. Here, a PI type controller is considered for LFC problem. The parameters of the proposed PI controller are tuned using Particle Swarm Optimization (PSO) method. A two-area electric power system with a wide range of parametric uncertainties is given to illustrate proposed method. To show effectiveness of the proposed method, a PI type controller optimized by Genetic Algorithms (GA) is designed in order to comparison with the proposed PI controller. The simulation results visibly show the validity of PSO-PI controller in comparison with the GA-PI controller.

Comparison of meta heuristic optimization methods in load frequency control

In this paper an optimal load frequency controller for two area interconnected power system is presented to quench the deviations in frequency and tie line power due to different load disturbances. Here, a PI type controller is considered for LFC problem. The parameters of the proposed PI controller are tuned using Particle Swarm Optimization (PSO) method. A two-area electric power system with a wide range of parametric uncertainties is given to illustrate proposed method. To show effectiveness of the proposed method, a PI type controller optimized by Genetic Algorithms (GA) is designed in order to comparison with the proposed PI controller. The simulation results visibly show the validity of PSO-PI controller in comparison with the GA-PI controller.

GASA Tuned Optimal Fuzzy Regulator for AGC of an Interconnected Power System

fuzzy AGC regulator design based on GASA tuning technique for interconnected power system is proposed in this paper. The investigations with the GASA tuned optimal fuzzy regulator are carried out on a two area interconnected power system consisting of power plants with different characteristics. Power system area-1 is having plants with reheat thermal turbines whereas area-2 has plants with hydro turbines. The dynamic response plots are obtained for 1% load disturbance in hydro area. The dynamic response plots are obtained for various system states with the implementation of conventional integral, fuzzy logic and GASA based AGC regulators designed in the study. The GASA technique is applied to tune the gains of fuzzy logic based AGC regulators also. The simulation results demonstrate superiority of GASA technique based optimal fuzzy AGC regulators over the others.

Genetic Algorithm Based Optimal Load Frequency Control in Two-Area Interconnected Power Systems

Load frequency control in power systems introduces as one of the most important items in order to supply reliable electric power with good quality. The goals of the Load Frequency Control (LFC) are to maintain zero steady state errors in a two area interconnected power system. To achieve this goal a fast controller with having no steady-state error will be necessary to be included in power systems. In this paper a new genetic algorithm based method is presented to obtain optimal gains of this controller included in two-area interconnected power system. Simulation results in comparison with correspondence methods confirm the efficiency of proposed method through fastdamping steady-state deviations in power and frequency with presence of step load disturbance.

Automatic generation control of interconnected power system with diverse sources of power generation

In this paper, automatic generation control (AGC) of two area interconnected power system having diverse sources of power generation is studied. A two area power system comprises power generations from hydro, thermal and gas sources in area-1 and power generations from hydro and thermal sources in area-2. All the power generation units from different sources are equipped with speed governors. A continuous time transfer function model of the system for studying dynamic response for small load disturbances is presented. A proportional-integral-derivative (PID) automatic generation control scheme is applied only to power generations from thermal and gas sources and power generation from hydro source is allowed to operate at its scheduled level with only speed governor control. The two area power system is simulated for different nominal loading conditions. Genetic algorithm (GA) is used to obtain the optimal PID gains for various cases using integral squared error plus integral time absolute error (ISE+ITAE) performance index for fitness evaluation. Some of the transient responses are shown for different nominal loading conditions due to step load disturbances in the system. Keywords: Two area power system, Diverse sources of power generation, Automatic generation Control , Genetic algorithm, PID controller

To Study and Survey About Load Frequency Control for Stability Improvement of Power

The modern power systems with industrial and commercial loads need to operate at constant frequency with reliable power. The load frequency control of an interconnected power system is being improved over the last few years. The goals of the LFC are to maintain stability improvement of power system. Fuzzy logic controller application of load frequency control (LFC) of a single area power system by using a fuzzy logic is presented. The study has been designed for a single area interconnected power system. The comparison between a conventional Proportional and Integral (PI) controller and the proposed artificial neural networks controller is showed that the proposed controller can generate the best dynamic response for a step load change. For this application, MATLAB-Simulink software is used.

MOEA based Design of Decentralized Load-Frequency Controllers for Interconnected Power Systems with AC-DC Parallel Tie-lines and Considering Nonlinearities

A new approach to the design of decentralised controllers, using Multi-Objective Evolutionary Algorithm (MOEA), for loadfrequency control of interconnected power systems with AC-DC parallel tie-lines and considering Governor Dead Band and Generation Rate Constraint nonlinearities, is proposed in this paper. The HVDC link is used as system interconnection in parallel with AC tie-line to effectively damp the frequency oscillations of AC system. The proposed controller satisfies two main objectives, namely, minimum Integral Squared Error of the system output and maximum closed loop stability of the system. Simulation studies are conducted on a two area interconnected power system with AC-DC parallel tie lines and considering nonlinearities. Results indicate that the proposed controller gives good dynamic responses and can guarantee the stability of the overall system in the presence of system nonlinearities and parameter changes.

MOEA based design of decentralized controllers for LFC of interconnected power systems with nonlinearities, AC–DC parallel tie-lines and SMES units

A new design of Multi-Objective Evolutionary Algorithm based decentralized controllers for load–frequency control of interconnected power systems with Governor Dead Band and Generation Rate Constraint nonlinearities, AC–DC parallel tie-lines and Superconducting Magnetic Energy Storage (SMES) units, is proposed in this paper. The HVDC link is used as system interconnection in parallel with AC tie-line to effectively damp the frequency oscillations of AC system while the SMES unit provides bulk energy storage and release, thereby achieving combined benefits. The proposed controller satisfies two main objectives, namely, minimum Integral Squared Error of the system output and maximum closed-loop stability of the system. Simulation studies are conducted on a two area interconnected power system with nonlinearities, AC–DC tie-lines and SMES units. Results indicate that the proposed controller improves the transient responses and guarantees the closed-loop stability of the overall system even in the presence of system nonlinearities and with parameter changes.

Design of decentralized load-frequency controllers for interconnected power systems with AC-DC parallel tie-lines and GDB nonlinearity using MOEA.

A new design of decentralized load-frequency controllers for interconnected power systems with AC-DC parallel tie-lines and governor dead band (GDB) nonlinearity using multi-objective evolutionary algorithm (MOEA) is proposed. A HVDC link is connected in parallel with an existing ac tie-line to stabilize the frequency oscillations of the ac system. The proposed control strategy is mainly based on a compromise between integral squared error and maximum stability margin criteria. A two area interconnected thermal power system is considered to demonstrate the validity of the proposed controller. The simulation results show that the system dynamic performance has been improved with increased stability margin when compared to a conventional controller.

Design of Decentralized Load-frequency Controllers for Interconnected Power Systems with AC-DC Parallel Tie-lines and GDB Nonlinearity Using MOEA

A new design of decentralized load-frequency controllers for interconnected power systems with AC-DC parallel tie-lines and governor dead band (GDB) nonlinearity using multi-objective evolutionary algorithm (MOEA) is proposed. A HVDC link is connected in parallel with an existing ac tie-line to stabilize the frequency oscillations of the ac system. The proposed control strategy is mainly based on a compromise between integral squared error and maximum stability margin criteria. A two area interconnected thermal power system is considered to demonstrate the validity of the proposed controller. The simulation results show that the system dynamic performance has been improved with increased stability margin when compared to a conventional controller.

Application of Particle Swarm Optimization Approach to Optimal Tuning of Load Frequency Controller

The task of load frequency controller (LFC) is to maintain the area generation–demand balance by adjusting the outputs on regulating units in response to deviations of frequency and tie-line power exchange. In this paper, the gain of an integral controller for a two area interconnected power system is designed based on the particle swarm optimization (PSO) technique. PSO is a population based stochastic optimization technique derived from simulation of simplified social model. Simulation results on a two area network revealed that the proposed approach optimizes the parameter of integral controller by selecting the optimal gain, which dampens the frequency oscillations and change in tie-line power to zero following a step disturbance.

Differential Evolution Based Optimal Tuning of Load Frequency Controller

Load Frequency Controllers (LFC) are required to maintain constant power and frequency in inter-connected power generating systems. Differential Evolution (DE) based optimal tuning of load frequency controller of two area inter-connected power system is presented in this paper. The proposed method optimizes the parameter of Integral controller by selecting the optimal gain which drives the change in frequency in the two areas and change in tie-line power flow to zero within the shortest time span. Simulation results on two networks revealed that the proposed controller dampened the frequency oscillations and restores the system frequency and tie-line power to set value after a step load disturbance.

Frequency stabilization using fuzzy logic based controller for multi-area power system

In this paper, a fuzzy logic controller is proposed for load frequency control problem of electrical power system. The fuzzy controller is constructed as a set of control rules and the control signal is directly deduced from the knowledge base and the fuzzy inference. The study has been designed for a two area interconnected power system. A comparison among a conventional proportional integral (PI) controller, some other fuzzy gain scheduling controllers and the proposed fuzzy controller is presented and it has been shown that proposed controller can generate the best dynamic response following a step load change. Robustness of proposed controller is achieved by analyzing the system response with varying system parameters.

Decentralized biased dual mode controllers for load frequency control of interconnected power systems considering GDB and GRC non-linearities

A new design of decentralized biased proportional and integral dual mode controllers for load frequency control of interconnected power systems considering governor deadband (GDB) and generation rate constraint (GRC) non-linearities is presented in this paper. Any optimum controller selected for load frequency control of interconnected power systems should not only stabilize the power system but also reduce the system frequency and tie line power oscillations and settling time of the output responses. Hence, a simple design of biased controllers with proportional and integral modes using an integral square error (ISE) criterion and maximum stability margin (MSM) criterion based on minimum settling time for interconnected power systems are discussed. These controllers are designed and implemented in a two area interconnected thermal power system with GDB and GRC non-linearities. The proposed controller is found to be simple in structure and easy for implementation. The closed loop system was simulated, and the frequency and tie line power deviations resulting from a step load disturbance are presented. Comparison of the performances of the proportional plus integral biased controller and the proposed proportional (P) and integral (I) biased dual mode controllers shows that the system performance is improved significantly with the proposed controllers. Further, it is also shown that the biased dual mode controllers are found to be less sensitive to changes in system parameters.

Enhancement of load frequency stabilization effect of superconducting magnetic energy storage by static synchronous series compensator based on H∞ control

Abstract It is well known that the load frequency stabilization effect of superconducting magnetic energy storage (SMES) in an interconnected power system is restricted to its located area. The SMES almost has no frequency stabilization effect in another interconnected area. To enhance the frequency stabilization effect of SMES, the static synchronous series compensator (SSSC) can be applied as an auxiliary device. The SSSC can be used as an energy transfer device of the SMES to stabilize the frequency in another interconnected area. The proposed technique not only introduces a sophisticated frequency stabilization in deregulated power systems but also offers a smart energy management control of SMES. In addition, to take the robust stability of the controlled power system against system uncertainties into account, the H ∞ control is used to design robust frequency stabilizers of the SMES and SSSC. Simulation results in a two area interconnected power system confirm the high robustness of the frequency stabilizers SMES and SSSC against load disturbances and system uncertainties.