Research On Detection And Control Methods Of Hybrid Power Quality Conditioner(HPQC)

In order to save energy and increase production efficiency,a large number of non-linear loads represented by power electronics are used in daily life,causing various voltage or current quality problems in the power grid and affecting the normal and safe operation of the power grid system.Different types of active power filters(APF)have different compensation characteristics due to their different topological structures and can only solve a single type of power quality problem.Unified power quality conditioner(UPQC)also has a function of compensating for voltage harmonics,ripple,and current harmonics,which can solve the power quality problem more comprehensively.However,the traditional UPQC always requires a relatively high voltage requirement on the DC side to make sure the normal work of the system and requires the use of a high-voltage switching device,which easily causes switching noise and power loss.The hybrid power quality conditioner(HPQC)topological structure is adopted in this paper on the basis of the traditional UPQC topological structure,and the single-tuned filter is connected to the system in parallel.,and this structure greatly reduces the DC-link voltage and the parallel-side active capacity,eliminating the need for coupling transformers to save system costs.This paper analyzes and studies HPQC in a comprehensive,detailed and in-depth manner for power quality problems in the power grid.Firstly,the working principle of active power filter is briefly introduced.The working principle of HPQC and the characteristics of filtering and fundamental wave are analyzed in depth,and the key device parameters in the system circuit are studied and designed.Passive filters are discussed and the passive filter with 7th-harmonic tuning is selected as the series filter on the system parallel side.Secondly,the theory of harmonic detection method for instantaneous reactive power theory is studied.Based on that,the synchronous coordinate transformation detection method and the improved synchronous phase-locked loop-free integrated detection method are studied.The three proposed detection methods are compared by simulation.Then,the hysteresis loop comparison control method is used on the system parallel side.According to the particularity of HPQC topology studied in this paper,a double closed-loop control strategy with 5th-harmonic control alone is adopted,and the series side is based on SVPWM control strategy.The fuzzy PI control is introduced into the DC side voltage control to achieve adaptive the adjustment of PI parameters.Finally,using the Matlab/Simulink software platform,the simulation method is used to verify that the detection methods and control strategies adopted in this paper are feasible and effective,and the system can solve power quality problems in the power grid.