Capability evaluation of four-leg DSTATCOM for compensating multifarious loads

Abstract

A four-leg distribution static compensator (FL-DSTATCOM) has been investigated to achieve harmonic elimination, supply current balancing, compensation of reactive power and current in the neutral conductor of a three-phase, four-wire distribution system with various types of static, dynamic and combined loads. The capability of FL-DSTATCOM for compensating reactive power under dynamic condition is evaluated with induction machine having variable load torque. Also, the performance of FL-DSTATCOM is evaluated with combined load, which is a combination of dynamic and unbalanced static loads. The FL-DSTATCOM injects reactive and harmonics components of load current extracted using synchronous reference frame theory. With FL-DSTATCOM, the unbalanced, harmonic and reactive loads will appear to the main power supply as balanced, linear and unity power factor load. Hence, the main power supply would deliver only fundamental frequency positive sequence components of load current. The switching pulses are generated by employing hysteresis current controller. MATLAB/SIMULINK has been used for capability evaluation under multifarious loading conditions considering IEEE standard 519. The simulation results prove that the FL-DSTATCOM is capable of making the supply current as balanced and sinusoidal, maintaining the PF at point of common coupling near to unity and reducing the supply neutral current very close to zero.