The Research Of Filter Technology On Unified Power Quality Conditioner

Power quality issue is increasingly prominent due to the composition changes of power systems load and the further progress of the electricity market. So great attentions have been taken to the dynamic power quality phenomenon such as voltage sag, discontinuity, which frequently and randomly occurr and have serious harm to sensitive equipments, while they became a focus of power quality analysis. in order to improve power quality by taking reasonable measures. But the detection and control of dynamic power quality should be firstly considered.The magnitude and duration time of perturbation voltage are primary characteristics of dynamic power quality problem. During the analysis of dynamic power quality problem, it is very important to detect the perturbation signs. In this paper, the Fourier transformation method, wavelet method, artificial intelligence technology method and dq transform method based on instantaneous reactive power are introduced and summarized their advantages, disadvantages and application fields. A new detection method of dynamic power quality problem is proposed, combined the most staple and simple dq transform method with Order morphological transform. Firstly, the double dq transform and no time-delay single-phase dq transform are used to derive signs from detection device, secondly, the signs are dealed with by low-pass filter based on the Order morphological transform to obtain the positive, negative and zero sequence elements of the grid voltage. Finally the magnitude, duration time and jumping angle of perturbation voltage can be deduced.The grid voltage sags, asymmetry, flicker and harmonics can be compensated by the Unified Power Quality Conditioner (UPQC). it is considered one of the most effective means to deal with dynamic power quality problem because UPQC has good dynamic performance and the large capacity. This paper firstly analyzes UPQC opology, compensation principles and compensation strategies. Then the hysteresis current control, pulse width modulation and adaptive control methods are analyzed. the filter detection algorithm based on the dq transformation of order morphology is simulated, simulation results prove the detection, control algorithm is feasible and effective.