ANALYSIS OF PUMPED HYDRO STORAGE SYSTEM INTEGRATED WITH RENEWABLE ENERGY SOURCES

Abstract

With the increasing consumption of electric power synergized by reduction in conventional source of power production the need to increase the share of power by Renewable energy sources has already became the immediate concern. But the problem with renewable energy sources apart from the cost of power production is that they are quite unanticipated and unwarranted. So, to absorb these sources into the power system network and maintain generation-load balance we need to store as well as complement these power sources with energy storage systems. Out of the available energy storage systems, pumped hydro storage comes as a better option to store relatively higher levels of energy with least environmental impacts wherever sufficient water body is available. Here a variable power drawing permanent magnet synchronous motor driven pumped hydro storage system is envisaged which, apart from storing energy can achieve load following, frequency regulation, reducing the burden on other plants on line in case of unanticipated power loss particularly in weak and standalone grids. In this report, the study and Simulation of an isolated grid integrated with photo voltaic solar power generating unit without any energy storage system is done to understand the necessity of energy storage system. To simulate variable power drawing PMSM driven hydro storage system, a variable speed PMSM with a pump type of load (Pload =Kload.w3) is considered. To achieve variable speed operation of permanent magnet synchronous motor, vector control of PMSM in constant torque angle (Id=0) method, is implemented.A converter coupled with an inverter fed from a3-phase balanced ac source is used for the purpose. The 3-phase ac source is replaced with a Diesel generator with some auxiliary load. A shunt active filter developed from the concept of instantaneous reactive power theory is simulated to filter harmonics. Then an isolated grid is being established by adding a feeder and distributed load to which a photo voltaic solar power generating unit is being integrated. To simulate the function of load following a light load scenario of power system is considered where in power output from the solar power generating unit is fluctuating. Corresponding to these power fluctuations the power drawn by the pumped hydro storage system driven by PMSM drive is made to vary such that it compensates unwarranted and intermittent power fluctuations and helps in the stability of the power system.