Study on power stability improvement of a Mini-Hydro Plant, Case study of MUSARARA Mini-Hydropower Plant

Abstract

Mini grid-connected hydropower plants contain small synchronous generators connected parallel to the grid. Voltage and frequency are the major variables which should be controlled to maintain the power stability of the system. The case study of my thesis is Musarara mini-hydropower plant which contains continuous voltage variation and frequency deviations. The plant does not contain the ability to maintain these challenges to increase its generation efficiency and due to this problem, it mainly fails to be synchronized with the grid. The aim of the research is to conduct power stability study of Musarara mini-hydropower plant, and the problem associated there and then design a controller that helps to improve the stability of the system. The PID controller for AVR system and load frequency control (LFC) system are proposed to improve the power stability of the generator. The AVR and LFC systems are modelled and simulated in MATLAB Simulink with the synchronous generator to verify the stability improvements. The results obtained after simulation show that the AVR with PID controller and LFC with PID controller give quick responses with minimum overshoots where the voltage is maintained at the terminal voltage of 1 per unit with the help of designed AVR with tuned PID controller. The tuned PID shows the reduced overshoot than the untuned PID controller i.e., it has been reduced from 26.3% to 4.42%, and the setting time has been reduced from 5.14 seconds to 3.33 seconds. With the LFC, the frequency returns to the original value of 50 Hz after the system is being subjected to the load changes because the tuned PID shows the reduced overshoot than the untuned PID controller i.e., it has been reduced from 25.9% to 2.17% and the rise time has been increased from1.74 seconds to 0.422 seconds.