Study Of Power Quality Impact On The Low Voltage Distribution Network In The High Penetration Of Distributed Photovoltaic Grid

While the country has given out a series of photovoltaic power generation subsidies policy as well as the roof of photovoltaic technology gradually mature in recent years, the domestic distributed photovoltaic capacity increase rapidly. However, distributed photovoltaic is invisibility and uncontrollable, which caused the challenge of safe and stable operation in traditional distribution network load terminal. It will be difficult to ensure the reliability and power quality of power consumer when distributed photovoltaic power supply high permeability. Therefore, the power supply departments need to master limit of the access of distributed photovoltaic capacity value in each feeder or each peak area, in order to take relevant measures.Firstly, this paper expounds on the distributed photovoltaic access capacity and access position change of voltage deviation and voltage fluctuation, harmonic distortion, three-phase imbalance degree of the influence of power quality indexes such as unity through theoretical analysis, then a distribution network for the actual model has been set up in DIgSILENT/PowerFactory simulation platform, the access capacity, access location, access voltage grade, busbar voltage, short circuit capacity of PCC point, load and the output correlation degree has been carried on the quantitative analysis in influence factors and influence level, the results show that access location and access capacity is the main influence factor, and verify the access capacity and access position changes on the power quality which verify the theory analysis conclusion.After exploring the influence factors and the influence level of power quality with distributed PV accessed in distribution network, an optimum calculation model based on the current injection method is proposed to meet the limit of power quality. The model is optimized by multiple national standard of power quality indexes, the peak value of the distributed power supply can be effectively given by the new or expanded and so on. The validity and practicability of the model are verified with test results of a 33 bus system and actual LCX system. For the features of lOkV typical line, the safety limits of distributed PV with power quality constraint is given according to the different types of different regions, the results can be reference for the power supply enterprise while checking distributed PV grid connected application.At the same time, in response to the existing lowly efficiency of dynamic reactive power compensation device for photovoltaic, this paper has proposed a distributed PV dynamic reactive power compensation device allocation strategy based on spectrum analysis. Reactive power demand will be with the method of spectrum analysis of time domain curve transformed to frequency domain curves, using three different types of dynamic reactive power compensation device of the differences in time response is divided into three bands, the demand for reactive power compensation spectrum different call different reactive power compensation device response spectrum. This method not only can be used to the new dynamic reactive power allocation strategy of distributed PV, but also can be applied to existing SVC to SVG upgrade plan in PV station, with a certain capacity of SVG can satisfy the dynamic reactive power demand of PV power station, without having to dismantle all of the SVC to modified full capacity SVG.