Control of distribution static compensator with active damped inductor‐capacitor‐inductor filter using dual loop αβ‐frame current controllers for power quality improvement

Abstract

A distribution system is connected with many non-linear loads, and generated harmonies are mitigated by using distribution static compensator (DSTATCOM) which is coupled at the point of common coupling through a voltage source inverter (VSI) and filter circuit. High-frequency switching ripples are generated along with the output of the VSI during pulse width modulation switching. Inductor-capacitor-inductor (LCL) filter is used to suppress the high frequency switching noises. Still, the primary concern about the LCL filter is generation of resonance peak at the resonance frequency. The conventional synchronous reference frame dq current controller with LCL filter has a complex coupling between d and q axis; hence decoupling is very difficult. This research article presents a new technique based on active damped dual loop αβ-frame current controllers to control the DSTATCOM with LCL filter for achieving improved load compensation. The dual loop controller is enhanced by using capacitor current in the inside loop and grid current at the outside loop with proportional resonant (PR) regulator parallel with harmonic compensator (HC). The proposed method effectively dampens the resonance peak under stationary reference frame ðαβÞ: The PR controller offers unlimited gain at the fundamental frequency and HC can offer more gain at the specific harmonic frequencies. Hence, characteristics of the PR and HC controllers used together to achieve minimum steady-state error and the problematic decoupling are ignored. The complete DSTAT-COM model with proposed control scheme is discussed with PR and (PR + HC) controllers separately under balanced, unbalanced source voltage. Stability analysis is carried out through Bode and pole-zero plots to judge the performance of the proposed current controllers. The obtained results, including total harmonic distortion of the source current, are compared with conventional passive damped dq-frame current controller. K E Y W O R D Scurrent controller, distribution static compensator, harmonic compensator and pulse width modulation, power quality | INTRODUCTIONIn a distribution system (DS), the term power quality (PQ) means achieving a better quality of power with a reliable supply and improved quality in the voltage and current waveform. But various non-linear loads and apparatus are connected to the system; hence, harmonics are generated and affect the consumers. Many conflicts such as impulses, voltage sag, swell, notches, and unbalances in the voltage and current are degrading the quality of power. Therefore, to improve the PQ, compensation devices and technologies have been developed. Custom power devices (CPD) are classified as shunt and series connected devices [1]. Among, distribution static compensator (DSTATCOM) is a shunt-connected expedient used to obtainThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.