Operation And Planning Method Of Soft Open Point For Multiple Scenarios In Active Distribution Network

With the rapid development of power electronic technologies,power electronic converters play important roles in the control of distributed generation(DG)and AC/DC conversion,and gradually become the core devices of active distribution networks(ADNs).Soft open points(SOPs)based on fully controlled power electronic devices,provide fast and accurate power control,which will influence power flow distribution of the whole system and then bring a series of benefits such as power losses reduction,voltage profile improvement and so on.To solve a series of new problems brought by accessing SOPs to ADNs,such as operation optimization,self-healing control and optimal siting and sizing,this thesis focuses on the topics of the operation and planning method of SOPs.The main contributions of this thesis are summarized as follows:1)For the operation control of ADNs,under the normal operating condition,a voltage and VAR control(VVC)method based on SOPs and a coordinated operation optimization method considering both SOPs and tie switches are proposed in this thesis.From the perspective of economic operation and voltage control of ADNs,a time-series optimization model of ADNs containing SOPs is built by comprehensively considering the network topology constraints,power flow constraints,system operation constraints and SOP constraints.Under the fault condition,a fault restoration method of ADNs based on SOPs is developed and a power supply restoration model of ADNs based on SOPs is established.Case studies based on different IEEE test cases are analyzed to demonstrate the effectiveness of SOPs and the proposed solving methods.2)Considering the randomness and volatility brought by DGs and loads in ADNs,this thesis proposes a robust operation strategy of SOPs for ADNs with uncertainties.A robust operation strategy of SOPs considering voltage level and power losses is built.The robust model is solved by column-and-constraint generation algorithm.Monte Carlo simulation on different IEEE test cases is used to illustrate that compared to deterministic optimization strategies,the robust operation strategy of SOPs can mitigate the voltage violations with lower network losses.3)In consideration of the siting and sizing problem of SOPs with high investment cost,this thesis constructs typical scenarios by scene generation technology based on Wasserstein distance,and proposes an optimal allocation method of SOPs considering the characteristics of DGs in ADNs.A siting and sizing model of SOPs is established with the objective of minimum annual expense.The method is tested on different cases to determine the location and capacity of SOPs and achieve better economic benefits.4)The optimal operation and planning problems of SOP in ADNs essentially belong to large-scale mixed-integer nonlinear programming(MINLP)programme and cannot be solved efficiently.This thesis develops second-order cone programming(SOCP)and hybrid optimization method based on simulated annealing and SOCP to solve the optimal operation and planning problems of SOPs,which is suitable for the large-scale ADNs with high penetration of DGs.Case studies were carried out on previous modeled systems to illustrate the improved convergence and computational efficiency of the proposed method.