Research On Voltage Control Of Active Distribution Networks With Highly Integrated Power Electronic Converters

With the increasing penetration of distribution generations(DGs),the risk of reverse power flow and voltage violations are exacerbated in active distribution networks(ADNs).Especially,the intermittent resources and new loads,such as wind turbine,photovoltaic(PV)and electric vehicles,have significant uncertainties in spatial and temporal distribution,frequently resulting in a rapid fluctuation of feeder power or power imbalance between feeders,which causes serious voltage problems.However,conventional voltage regulation devices limited by the adjustment ability are difficult to meet the requirement of real-time voltage control with high precision when DGs fluctuate frequently.Therefore,this paper focuses on the voltage control of ADNs with highly integrated power electronic converters.The main work is summarized as follows:1)A centralized voltage control strategy of SOPs is adopted because SOPs are system-side power flow control devices.A voltage control model of ADNs containing SOPs is built by considering the constraints of network topology,power flow,system operation and SOP operation.Cone programming is used for this large scale nonlinear programming problem.A case study on IEEE 33-node system verifies the effectiveness and efficiency of cone programming and the centralized control strategy.2)A localized voltage control strategy of DGs applied on demand-side is proposed.A parameters tuning model is built for localized control.In day-ahead schedule stage,the parameters of this strategy are centrally optimized by forecasting data.In inter-day control stage,the localized control strategy is applied based on local voltage measurement.Then mixed-integer second-order cone programming(MISOCP)is utilized to solve this model rapidly.A case study on PG&E 69-node system shows localized control can effectively improve voltage profile based on local measurement.3)By the coordination of centralized and localized strategy,a parameters tuning model is built for the voltage control of ADNs.So a global optimum can be approached as much as possible with moderate computational burden.A case study on the PG&E 69-node system shows the strategy can reduce the power losses and mitigate voltage fluctuation,which can even reach to the effect of centralized control.