The Study On Grid-connected Operation Of Three-phase Four-wire Power Quality Manager

With the improvement of the quality of life in rural areas of China,the power load of rural power grids continues to increase,the types of loads are more abundant,urbanization and migration of migrant workers.The problem of harmonics,reactive current,and three-phase load imbalance is getting more and more serious,and it should be given corresponding attention,so that the quality of electric power can meet people's needs and improve the efficiency of production and life.Through research and investigation,it is found that the decline in the power quality of the rural power grid is mainly manifested in three aspects: increased harmonic current content,low power factor and three-phase load imbalance.For each problem,the domestic and foreign development history and current status are consulted.However,there are few research literatures on the comprehensive management of rural power quality.First,under the relevant national standards,the problems of harmonics,reactive power,and imbalance are quantified,the causes of these problems and the necessity of solving them are analyzed.Then,starting from the actual needs,the three-phase three-arm split capacitor topology of the power quality manager was determined,the software phase-locking method based on a single synchronous coordinate system and the fundamental wave extraction method for single-phase harmonic detection were used.At the same time,the parameters of the circuit are designed.After the equipment is connected to the grid,it encounters a series of problems: the equipment has insufficient compensation capacity under extreme unbalanced conditions,a large inrush current is generated when some loads start,the DC side voltage fluctuates under certain conditions,noise control and automatic The restart function,these actual problems are analyzed and gave corresponding solutions,which effectively improves the working ability and stability of the equipment.Finally,according to the problems of power quality management function and actual operation,corresponding simulations were built for simulation verification.The experimental platform also carried out corresponding simulations in actual work,proving the effect of power quality management and the ability to solve practical problems.