Performance Enhancement of Distribution System Using Optimal Allocation of Solar Based Distributed Generation and D-STATCOM (Case Study: Dilla Distribution System)

Abstract

The continuous increase in power demand, as well as urbanization, needs a high-quality and reliable power supply system. However, the existing passive distribution system faced different problems as a result can’t meet the increasing power demand reliably and securely. The main problems in the distribution system which indicate the performance are power loss, poor voltage profile, high power interruption, distorted voltage and current at the customer end, and unstable voltage in the node of the system. In this thesis work, the optimal size and placement of solar based distributed generation (DG) and distribution static compensator (D-STATCOM) in the distribution system were used to improve the performance. The study has been carried out on the Dilla distribution system on the Dilla one feeder which has 137 buses. The selected feeder has been modeled and load flow analysis has been simulated using the Backward-Forward Sweep (BFS) method implemented in MATLAB for evaluation of power loss and voltage profile of the feeder. Whereas, evaluation of basic reliability indices of the existing system with ETAP software. From BFS load flow result of the existing system, the total active and reactive power loss are 888,904 KW and 531.408 KVAr respectively and seventy-nine (57.66%) of buses are below the minimum standard level. And also, from ETAP simulation result the basic reliability indices are obtained and their values are a big difference to Ethiopian standard. An optimization problem has been formulated as multi-objective functions comprising total real power loss, total reactive power loss, and voltage deviation for optimal siting and sizing of DG and D-STATCOM using PSO algorithm. The simulation results were tested by considering different scenarios and each scenario has different cases based on a number of DG and D-STATCOM. Base case (scenario -I), Only DG integration (scenario -II), only D STATCOM integration (scenario-III), and simultaneously DG and D-STATCOM integration (scenario-IV) scenarios were considered. From the simulation results by taking reference of base case values the percentage active power loss reduction was 58.41%, 19.469 % and 77.175 % while the percentage reactive power loss reduction was 58.509 %, 19.498 % and 77.213 %for scenario-II, scenario-III, and scenario-IV best-case respectively. Also, the minimum voltage level in the base case is improved from 0.906p.u to 0.9783p.u, 0.9502 p. u, and 0.9796 p.u. As observed from those results scenario-IV is preferable for performance enhancement. The cost-effectiveness of the proposed solution was also analyzed and the payback period has become nearly five years.