Performance Evaluation of DSTATCOM for 180 km 33 kV Feeder from Shinyanga to Bariadi in Tanzania

Abstract

This article presents the performance evaluation of distribution static compensators (DSTATCOM) for the 180 km 33 kV line from Shinyanga to Bariadi in Tanzania. First, the voltage drop existing on the line is explained, and its negative consequences are mentioned. Secondly, the 180 km line is presented in the nominal 𝜋 model. Then, DSTATCOM capacitive and inductive dynamic ranges of ±1900 kVAr are calculated based on the system fault level. Using the energy storage of five cycles, a DC capacitor with a value of 0.19 mF is calculated. The DSTATCOM is designed using the voltage source converters (VSC) employing the neutral point clamped (NPC) topology. A proportional integral (PI) control algorithm was implemented to the DSTATCOM. Simulation of the modeled system of the feeder with DSTATCOM is carried out in MATLAB/Simulink environment for different loading conditions (light and heavy loading) to evaluate the steady-state performance. Simulation results reveal that for the light load of 0.45 MW, the receiving end voltage is 37.2 kV RMS and 31.5 kV RMS, before and after application of DSTATCOM, respectively. For the heavy load of 4.5 MW, the results are 28.45 kV RMS and 33.1 kV RMS, before and after application of DSTATCOM, respectively. The frequency-domain analysis reveals a gain margin of infinity implying stable system operation. The Nyquist plot shows no encirclement of the negative one point, further verifying the stability. It is concluded that the proposed DSTATCOM is capable of keeping both the voltage drop and rise of the line at acceptable levels for system stability of the Shinyanga-Bariadi feeder.