Neuro-Fuzzy Computational Technique to Control Load Frequency in Hydro-Thermal Interconnected Power System

Abstract

In this research work, two areas hydro-thermal power system connected through tie-lines is considered. The perturbation of frequencies at the areas and resulting tie line power flows arise due to unpredictable load variations that cause mismatch between the generated and demanded powers. Due to rising and falling power demand, the real and reactive power balance is harmed; hence frequency and voltage get deviated from nominal value. This necessitates designing of an accurate and fast controller to maintain the system parameters at nominal value. The main purpose of system generation control is to balance the system generation against the load and losses so that the desired frequency and power interchange between neighboring systems are maintained. The intelligent controllers like fuzzy logic, artificial neural network (ANN) and hybrid fuzzy neural network approaches are used for automatic generation control for the two area interconnected power systems. Area 1 consists of thermal reheat power plant whereas area 2 consists of hydro power plant with electric governor. Performance evaluation is carried out by using intelligent (ANFIS, ANN and fuzzy) control and conventional PI and PID control approaches. To enhance the performance of controller sliding surface i.e. variable structure control is included. The model of interconnected power system has been developed with all five types of said controllers and simulated using MATLAB/ SIMULINK package. The performance of the intelligent controllers has been compared with the conventional PI and PID controllers for the interconnected power system. A comparison of ANFIS, ANN, Fuzzy and PI, PID based approaches shows the superiority of proposed ANFIS over ANN, fuzzy and PI, PID. Thus the hybrid fuzzy neural network controller has better dynamic response i.e., quick in operation, reduced error magnitude and minimized frequency transients.

A utomatic G eneration C ontrol in Four Area Interconnected Power System of Thermal Generating Unit through Evolutionary Technique

“…To simplicity the frequency-domain analyses, transfer functions are used to model each component of the area. [4], [17], [18] Transfer function of governor is…”

“…As the demand deviates from its normal value with an unpredictable small amount, the operating point of power system changes, and hence, system may experience deviations in nominal system frequency which may yield undesirable effects. So the objective of AGC in interconnected thermal generating unit is to maintain the system frequency and tie line power at nominal value (60 Hz) [4], [5], [17], [18]. A control strategy is needed to maintain constancy of frequency and tie-line power and also achieves zero steady state error.…”

Hybrid technique for load frequency control of renewable energy sources with unified power flow controller and energy storage integration

“…In recent years, few optimal controllers are developed, viz fuzzy logic, 25 artificial NN, 26 distributed mode predictive controller, 27 and the PI, including PID controllers are popular in micro grids for load frequency control (LFC) owing to its simple with effective. Typically, the purpose of PI/PID controllers was for solving the complexity of LFC as well as upgrade the power system stability.…”