The Harmonic Suppression Of Microgrid Based On The Parallel Operation Of Multiple APF

Since the micro network contains a large number of rectifier/inverter devices and nonlinear loads, this is bound to produce a large number of harmonics,which will influence power quality,and even impact it connect to the grid. This paper aims to the harmonic problem in micro network, proposed to solve harmonic problems by multiple APF parallel operation, using current sharing strategy for the controling of multiple APF parallel operation,greatly reduced the harmonic content at the exit of the micro source,the proposed scheme is simple and reliable,and have good extend ability,high dynamic performance but also can reduce the cost.This article was studied mainly from the following aspects:(1)This paper described the importance of the development of micro-network, as well as the research and development status of the micro network at home and abroad, proposed the harmonic problem in micro-network.Aim to the harmonic problems of micro-network, its sources, the harm and the existing governance method was analyzed, as well as the advantages and disadvantages of the various treatment methods. Proposed to solve harmonic problems by multiple APF parallel operation, using current sharing and current limiting control strategy for the controling of multiple APF parallel operation, the method is simple, reliable, high dynamic performance, scalability, reliability and can reduce costs.(2)Using the simulation software of PSCAD/EMTDC to build a model of governance devices and systems. Simulation using two shunt APF parallel operation to governance the harmonic of micro-network in networked mode, each APF had independent harmonic detection module. Simulation verified the ip-iq detection method was effective, compensation current which using the deadbeat control method can keep pace with the instruction current waveform,and almost there was no delay. Then builded a overall simulation model in networked mode, the wind power and photovoltaic (pv) model was established,verified by PQ control can make the active and reactive power of photovoltaic and wind power be stabilized after a certain period of time to achieve the desired control effect.(3)Finally, analysed the effect of governance,by observing the compensation current of two APF,the used current sharing strategy reached evenly harmonic compensation design goals,which was conducive to long-term stability of the running of parallel compensation device.By observing the current harmonic distortion rate before and after governance,verified the effect of multiple APF parallel operation in governing harmonic of micro-network. By increasing the load, verified when load had a sudden change, two parallel running APF based on current share strategy can quickly react to complete compensation task, the dynamic performance of the system is good. By quitting or increasing one of the APF,observed another APF can timely manner to increase or decrease the compensating current, that verified the redundancy of the system was good, the high reliability and the high scalability,we can increase the quantity of APF to meet the different needs of task of harmonic governance.The article aims to the harmonic problems in micro network brought by the large number of rectifier/inverter devices and nonlinear loads, proposed to solve harmonic problems by multiple APF parallel operation,and its topology and control techniques were studied,the simulation verified its availability,reliability,dynamicity and scalability. The research content can provide experience and reference basis for the harmonic suppression of micro network and traditional power grid.