Research On Shunt Active Power Filter Detection And Compensation System Under Inter-harmonics Environment

Supply security has become an important technical support for coal miningequipment safe operation. With the development of the coal industry, a lot of powerelectronic devices were used. There are new power quality problems in the mine grid.SAPF was used for harmonic and inter-harmonics compensation in this paper, whenthe content of inter-harmonics in the grid is significantly. The research was made onthe design of shunt APF detection and compensation system.Power defined theory is the assumption of the grid voltage and current detection.In this paper, with the discussion of different definitions of power theory, a modifiedform of power definition was given. SAPF performance was affected byinter-harmonics in the grid. CPT method was given which can be widely used inthree-phase current detection circuit. Respectively, simulation experiments were madeunder different grid environments, including steady-state, load mutation, three-phaseunbalance and voltage variation. It was shown that with CPT method, the variouscomponents of grid current can be effectively detected. The correctness of theharmonic current detection can be ensured.With the new power electronic devices application in the grid, theinter-harmonics effect would become more serious. It is need to design SAPFcontroller for inter-harmonics to fit the new environment. In this paper, based onrepetitive and PI complex controller, with EID controller, inter-harmonics andinterference suppression performance was improved. With Matlab and three-levelexperiment platform, simulation and experiment was made for control systemverification. The results proved that the system can effectively compensate theinter-harmonics.Capacity limitation is key factor restricting the compensation effect of SAPF.The SAPF compensation capacity can be effectively enhanced by device switchingfrequency reduction. Starting from the complex vector analysis, SAPF complex vectoranalysis model and signal flow diagram were given. The complex vectormathematical model of the SAPF with low switching frequency was studied. For lowswitching frequency condition, the SAPF system was designed and the performanceof controller was analyzied. Experiments showed that at low switching frequency,with complex vector controller, the compensation effect of SAPF was improved and SAPF control system stability was enhanced.Single-period repetitive controller can not compensate inter-harmonics in controlof the fundamental and its integer harmonics. The stability of the system will beimpacted by the model parameter variations. In this paper, based on the study ofmultiple-period repetitive controller, multiple-period parallel repetitive controller wasproposed. Based on the small gain theorem, robust performance was analyzed. Basedon MPPRC, the SAPF harmonic compensation system was designed. By thethree-level test platform and simulation, whether for a single harmonic compensationor for different harmonics compensation together, harmonics content was significantlyreduced. It was shown that the design of the control system was reliable and thecompensation effect was obvious.