Study on DC voltage control of hybrid active power filters

This paper presents a DC voltage control analysis for hybrid active power filters (HAPF) under current-mode control scheme. Based on the analysis, it is clearly shown that adding the instantaneous DC voltage control signal as a reactive control parameter is more effective than adding the signal as an active control parameter for the DC voltage control. A control strategy is introduced to improve the performance of DC voltage control during start-up process. Finally, simulation results are given to verify the correctness of the DC voltage control analysis and illustrate the advantages of the control strategy for the start-up process.

I. Introduction

Due to the proliferation and development of power electronics equipments (nonlinear loads) in utility power system, the power quality problems such as reactive power, current harmonics and neutral current in power system are deteriorated [1]–[2]. These power quality problems may affect the safety operation and increase the loss of the power grid and electrical equipments. In order to solve the power quality problems, power filters are widely used. Passive filter (PF) has been widely applied to suppress current harmonics and improve power factor due to its low cost and simplicity. However, it has some drawbacks such as resonance problems, low dynamic response, dependent filtering characteristics, etc. [3]–[4]. Active power filter (APF) can overcome the above mentioned drawbacks inherent in PF, but the initial and running costs of the APF are much higher than the PF [5]–[6], Therefore, it comes up with a hybrid active power filter (HAPF), which combines the advantages of PF and APF, and it is characterized by low cost and good performance [7]–[8].