Research On Integrated Detection Algorithm Of Unified Power Quality Controller

The power electronization of the power system has changed the source-network-load characteristics of the power system,causing changes in the characteristics of power quality problems,bringing new problems in power quality.New problems caused by power quality affect people's production and all aspects of life,the Unified Power Quality Controller(UPQC)is a comprehensive power quality adjustment device that can centrally process the voltage and current integrated power quality problems in the power grid,and it greatly saves resource costs,therefore it has important research value.This paper firstly introduces the working principle and topology of UPQC,based on the three-phase three-wire topology to study the various parts of the topology.The two common types of single-phase UPQC and three-phase four-wire systems are introduced to analyze the applicable occasions.The series and parallel parts in UPQC are mathematically modeled,and their working characteristics and power flow are studied.Secondly,the detection and calculation methods of voltage and current in UPQC are analyzed.For the traditional phase-locked loop,there are various problems,this paper used the phase-locked loop based on the double second-order generalized integrator(DSOGI-SPLL)to extract the positive sequence components of fundamental voltage,and subtract the extracted voltage with the actual voltage can directly generate voltage compensation,which can save the use of the filter and the real-time detection is improved.Thirdly,the advantages and disadvantages of several common harmonic current detection methods are analyzed,finally,the unit power factor(UPF)harmonic current detection method based on the average power definition is adopted.Based on the original detection algorithm,the phase-locked loop of the second-order generalized integrator is directly extract the positive sequence components of fundamental voltage,and the result is used as the reference signal in the current detection method to suppress the voltage distortion.Theeffect on the traditional UPF is to achieve simultaneous detection of voltage and current.Finally,under the premise of the same compensation control strategy,the compensation effect of UPQC on voltage and current under three detection methods is compared.The simulation results show that under the conditions of voltage distortion and voltage drop,the comprehensive detection method studied in this paper can achieve effective compensation for voltage and current.And by constructing a semi-physical platform,the feasibility of the detection algorithm is verified.