Multi-area Hydrothermal Power Research Articles

AGC of Multi-Area Hydro-Thermal Power Systems With GRC Non-Linearity and Classical Controller

In this article, the optimal gain value of classical controller gain values is obtained by using different performance indices in Automatic Generation Control. These are interconnected by the three areas of a hydro-thermal power system. The thermal and hydro areas are incorporated with a reheat turbine and a mechanical governor, respectively. The current article was created to select a suitable technique for the tuning of controller gain, when 1% of a step load is given to the thermal area (Area 1). The performance of several controllers, such as Integral (I), Proportional-Integral (PI), and Integral-Derivative (ID) were evaluated and were compared to the cases of with and without Generation Rate Constraint (GRC) non-linearity. The classical controller gain value optimization was performed using the Integral Time Square Error (ITSE), Integral Square Error (ISE) and Integral Time Absolute Error (ITAE) performance indices. The minimum optimal value of controller gain normally offers better dynamic response. The obtained results established that the optimization based on the ITAE-PI controller always guarantees superior dynamic performances compared to other indices and controllers.

Automatic Generation Control of Thermal-Thermal-Hydro Power Systems with PID Controller using Ant Colony Optimization

In this work, Artificial Intelligence (AI) based Ant Colony Optimization (ACO) algorithm is proposed for Load Frequency Control (LFC) of interconnected multi–area hydrothermal power systems. Area 1&2 are thermal power systems and area 3 is a hydro power system, all the areas are interconnected through the appropriate tie-line. Thermal and hydro power plants are applied with reheat turbine and electric governor respectively. Investigated power system initially applied with conventional Proportional-Integral (PI) controller and controller parameters are optimized by using trial and error method considering Integral Time Absolute Error (ITAE) objective function. After that, the system is equipped with Proportional – Integral – Derivative (PID) controller and controller parameters are optimized by using ACO algorithm with ITAE objective function. The superiority of the proposed algorithm has been demonstrated by comparing conventional controller. Finally, The Simulation results of multi-area power system prove the effectiveness of the proposed optimization technique in LFC scheme and show its superiority over conventional PI controller.

A novel hybrid PSO-PS optimized fuzzy PI controller for AGC in multi area interconnected power systems

Abstract In this paper, a novel hybrid Particle Swarm Optimization (PSO) and Pattern Search (PS) optimized fuzzy PI controller is proposed for Automatic Generation Control (AGC) of multi area power systems. Initially a two area non-reheat thermal system is used and the gains of the fuzzy PI controller are optimized employing a hybrid PSO and PS (hPSO-PS) optimization technique. The superiority of the proposed fuzzy PI controller has been shown by comparing the results with Bacteria Foraging Optimization Algorithm (BFOA), Genetic Algorithm (GA), conventional Ziegler Nichols (ZN), Differential Evolution (DE) and hybrid BFOA and PSO based PI controllers for the same interconnected power system. Additionally, the proposed approach is further extended to multi source multi area hydro thermal power system with/without HVDC link. The superiority of the proposed approach is shown by comparing the results with some recently published approaches such as ZN tuned PI, Variable Structure System (VSS) based ZN tuned PI, GA tuned PI, VSS based GA tuned PI, Fuzzy Gain Scheduling (FGS) and VSS based FGS for the identical power systems. Further, sensitivity analysis is carried out which demonstrates the ability of the proposed approach to wide changes in system parameters, size and position of step load perturbation The proposed approach is also extended to a non-linear power system model by considering the effect of governor dead band non-linearity and the superiority of the proposed approach is shown by comparing the results of hybrid BFO-PSO and craziness based PSO approach for the identical interconnected power system. Finally, the study is extended to a three area system considering both thermal and hydro units with different controllers in each area and the results are compared with hybrid BFO-PSO and ANFIS approaches.

Variable structure fuzzy gain scheduling based load frequency controller for multi source multi area hydro thermal system

In this paper, variable structure fuzzy gain scheduling is proposed for solving the load frequency control problem of multi source multi area hydro thermal power system. The two control areas are connected via tie line. Each area comprises of both hydro and thermal power plant. The area frequency and tie line power oscillates during load variations are controlled by primary governor controller and secondary Proportional Integral (PI) controller. The PI controller gains are tuned using Ziegler Nichols’ (ZN) method and Genetic Algorithm (GA). ZN method is for conventional bench marking and GA is based on search in the space. In both the methods, the gain values of PI controllers are fixed for any system changes and it is not acceptable. This problem is overcome by scheduling the gain based on system changes using Fuzzy Logic. Finally, Variable Structure System of switching P to PI controller during transient to steady state is integrated with fuzzy gain scheduling. On evaluating all the controller performance based on performance indices, variable structure fuzzy gain scheduling provides better response for multi source multi area hydro thermal power system.

Optimal generation scheduling for constrained multi-area hydrothermal power systems with cascaded reservoirs

The optimization problem in this paper is targeted at large-scale hydrothermal power systems. The thermal part of the system is a multi-area power pool with tie-line constraints, and the hydro part is a set of cascaded hydrostations. The objective is to minimize the operation cost of the thermal subsystem. This is an integer nonlinear optimization process with a large number of variables and constraints. In order to obtain the optimal solution in a reasonable time, we decompose the problem into thermal and hydro subproblems. The coordinator between these subproblems is the system Lagrange multiplier. For the thermal subproblem, in a multi-area power pool, it is necessary to coordinate the area generations for reducing the operation cost without violating tie limits. For the hydro subsystem, network flow concepts are adopted to coordinate water usage over the entire study time span, and the reduced gradient method is used to overcome the linear characteristic of the network flow method in order to obtain the optimal solution. In this study, load forecasting errors and forced outages of generating units are incorporated in system reliability requirements. Three case studies for the proposed method are presented.

Short-term resource scheduling in multi-area hydrothermal power systems

This paper describes the short-term resource scheduling problem in multi-area large-scale hydrothermal power systems. The description of the problem is comprehensive, providing information on important operating considerations and constraints which need to be modelled in practice. A rigorous and concise formulation of the problem is presented. The solution algorithm, which is based on Lagrangian relaxation, is described and its salient features are discussed. Numerical results and our experience with the solution algorithm are also presented.