Research On PQ Coordination Control Strategy Of Distributed Grid-connected Pv In Distribution Network

As an important Distributed Renewable energy,the potential value of photovoltaic is favored by all countries in the world.Operating under high permeability has become a new trend of development.When the photovoltaic system participates in the power supply as a distributed power source,with the continuous improvement of the penetration level of the distributed photovoltaic system in the distribution network,the over-voltage limit caused by reverse power flow and the unqualified power factor of users become urgent problems to be solved.When distributed photovoltaic(DPV)is connected to distribution network,how to formulate a reasonable and effective local control strategy for inverters and how to achieve regional voltage control by optimizing the operation of DPV has become a new requirement and a new height to improve the PV permeability.Therefore,it is of great theoretical significance and engineering value to reexamine the optimal operation and local control strategy of distributed photovoltaic access distribution network.Firstly,the mechanism of voltage overrun caused by distributed photovoltaic access to low-voltage distribution network is analyzed,and the idea of coordinated control strategy based on reactive power margin regulation of inverters and active power reduction is determined.Secondly,a control model with voltage as the main objective and power factor as the auxiliary objective is established to control the unqualified power factor of users when the voltage exceeds the limit.The multi-mode switching control is carried out for different working conditions of the system.On this basis,the single photovoltaic grid-connected system and several photovoltaic grid-connected systems are tested.The test results show that the local control strategy of voltage-power factor dual-mode inverters is correct.In the second part of this paper,a distributed photovoltaic grid-connected cluster based on network partitioning theory is adopted to solve the problem of voltage overstepping caused by high permeability distributed photovoltaic grid-connected.The coupling degree and voltage deviation between multiple nodes are considered as the premise,the active power and reactive power of inverters are taken as control variables,and the voltage sensitivity of nodes is considered.Voltage Control Strategy.Distribution network is divided into several zones with PV.For each sub-zone,the reactive power/active voltage zoning control scheme based on Lightning Algorithms(LFA)optimization method is adopted to adjust the voltage distribution.Finally,taking 33-node test system and typical field data of a project as an example,the optimal control strategy and algorithm of multi-node access distribution network are simulated and tested.The test results show that the proposed optimal zoning control strategy is correct,and the established optimal zoning voltage control model and algorithm are effective.