Voltage And Frequency Regulation For Distribution

Abstract

Microgrids comprising the renewable energy resources are the new face of modern elec tricity infrastructure. These grids work autonomously, have their own control architecture and give support to the utility grid in case of any failure. Most of the energy resources in microgrids are renewable like solar, wind etc. These resources have an intermittent nature making the control architecture an essential tool for its better performance. The induction of excessive renewable resources in the utility grid causes serious stability problems as these resources have intermittent nature. Therefore, an efficient control system is the main priority in these types of grids. The control system that is designed for microgrids requires to control some important parameters like voltage and frequency, active/reactive power bal ancing, power flow etc. Regulation of voltage and frequency within its nominal values is the most important parameter that ensures the stability of microgrid. The disturbance in voltage and frequency occurs due to variation in both generation and load. A centralized control approach is adopted in this research work using classical PID con troller to tackle this problem of voltage and frequency regulation. An isolated microgrid model is integrated in a Simulink interface tool using solar, wind and battery as resources. The centralized PID controller is implemented on load bus bar of 0.4 KV. This PID con troller is then tuned with closed loop PID autotuner block in real time as load and gen eration of the isolated microgrid are not constant. A detailed comparison of simple PID and PID with autotuner block is done using the frequency and voltage response of both techniques in constant and varying load scenarios. Results and calculation of various pa rameters shows that the PID working with closed loop autotuner has better performance compared to the simple PID whose gains are calculated at the start using conventional technique like Ziegler-Nichols method. This is because the PID used with autotuner block has its gains updated by observing the real time response of the system whereas simple PID tries to tackle the constantly varying load conditions based on its initial gain values. The performance of control strategy is also observed using real site data of solar and wind for Nooriabad, a city of Sindh Province in Pakistan