Performance analysis of FPGA controlled four-leg DSTATCOM for multifarious load compensation in electric distribution system

Abstract

A field programmable gate array (FPGA) controlled four-leg distribution static compensator (FL-DSTATCOM) has been implemented to achieve harmonic alleviation, supply current balancing, compensation of reactive power and current flow in the neutral conductor of a 4-wire 3-phase electric distribution system with static, dynamic and combined loads. The unbalanced non-linear and linear static loads are considered for analyzing compensation behaviour of FL-DSTATCOM. The practicability of FL-DSTATCOM for compensating reactive power under dynamic condition is evaluated with slip ring induction machine having variable load current. Also, the performance of FL-DSTATCOM is examined with combined load, which is a combination of dynamic and unbalanced static loads. The reference current signals are produced by using synchronous reference frame theory. Hysteresis band current controller is utilized for generating switching pulse for IGBT switches present in the FL-DSTATCOM. Independent modules are developed for realizing all the tasks in FPGA with the feasibility to reconfigure the hardware for any other application with similar requirements. The experimental results demonstrate that the FPGA controlled FL-DSTATCOM is capable of making the supply current as balanced and sinusoidal, maintaining the power factor at point of common coupling near to unity and reducing the supply neutral current very close to zero. Keywords: FPGA, FL-DSTATCOM, Verilog HDL, Power quality, Neutral current reduction, Unbalanced static load, Slip ring induction machine, Combined load