| In recent years,with increasing energy depletion and environmental pollution problems,amounts of distributed energy resource(DER)based on renewable energy generation(REG)have integrated into power system,and how to realize the absorption of high-penetration REG has become the research focus and cutting-edge technology in the field of electrical engineering.Active distribution network(ADN)with the flexible network topology and the coordinated control of power flow,can satisfy the asorption demand of high-penetration REG such as wind power and photovoltaic,which is the main development direction of distribution network in the future.In this paper,active distribution network operation control method is researched considering high-penetration REG integration.The method takes full advantage of the coordinated regulation optimization ability of the contact/section switch,distributed generation,demand side response and soft open point(SOP),and realize the "source-network-load" collaborative optimization control,the maximization asorption of green energy and economic safe operation of active distribution network.The main work of this paper includes:(1)An active network configuration optimization and evaluation method is put forward,to adapt to the various operation states and typical scenarios resulted from REG random and volatile outputs.According to the different objective and time scale in different operation state,the start condition of the configuration optimization is proposed,then the configuration optimization decision model is established,which is solved by the Pareto multi-objective optimization technology and the corresponding algorithm.According to the network configuration schemes under different operation state,the evaluation method of active distribution network configuration scheme for typical operation scenarios is proposed.The simulation results show that the obtained network configuration scheme can effectively improve the key indicators in each operation state,and provide reasonable suggestions for the adjustment of network structure in active distribution network.(2)In order to alleviate the influence of REG forecast error on operation optimization,a day-ahead coordinated active power scheduling method is proposed.REG forecast errors are described by means of multi-state models,which are tackled with chance constrained programming in scheduling procedure.A hierarchical coordination optimization model including three levels is established to realize day-ahead optimal scheduling of active power in ADNs coordinated with network reconfiguration,seeking an optimal solution of network topologies and DERs outputs.Simulation results show that the model method can enhance the asorption ability of distribution network to REG,and significantly reduce the overvoltage and undervoltage risk due to REG forecast errors,meanwhile the difficulty of problem solving is decreased and solution efficiency is improve by the heuristic method.(3)The active distribution network feedback active control strategy considering the communication condition and equipment performance is put forward in inner-day time scale.By analyzing the characteristics of network communication conditions and control equipments,the requirements of three control modes including centralized control,distributed-centralized control and distributed control to communication condition and control equipment are studied.According to the network communication condition and the time response requirement,a control mode selection method is presented for the two kinds of control devices including controllable distributed generation and the direct control load.The closed-loop feedback optimal control model under different control modes is established,and different methods are proposed to solve the model under each control mode.The simulation results show that the proposed control strategy can realize fast power adjusting and optimizing under different scenarios by the control mode conversion in real-time scale,which is more in line with the requirements of actual operation control of ADN.(4)In order to further improve the ability of active distribution network flexible power control,SOP is introduced into ADN to give full play to its voltage-power regulation ability,and a SOP allocation optimization method is put forward based on SOP control mode conversion.An optimization method of SOP candidate locations is presented based on the technical index of power flow betweenness and voltage violation risk.Considering the influence of REG output randomness,a bi-level programming model of SOP allocation is established based on SOP control mode conversion.A hybrid algorithm combined particle swarm optimization(PSO)algorithm with second order cone programming(SOCP)m ethod is proposed to solve the bi-level model.Simulation studies are performed to verify the proposed method.The simulation results show that this method can effectively cope with the voltage security issues caused by REG random outputs,enhance the REG consumption,and guarantee the lower investment and operation costs on the basis of safe operation.(5)Based on the optimal allocation result of SOP,considering the forecast errors of REG,a two-stage coordination optimization control process of SOP and tie switch is proposed.Considering the factors such as network loss and wind and solar abandoning,an coordination optimization control of SOP and tie switch is established based on model prediction control in day-ahead and inner-day time scale.A transforming method of reconfiguration constraint based on second-order cone model is proposed,which realizes that the coordination optimization of SOP and tie switch is solved by mixed-integer second-order cone programming algorithm.The simulation results show that the proposed two-stage coordination optimization control process can fully consider the volatility and randomness of REG outputs,and eliminate the REG forecast errors' effect on the operation optimization.The proposed algorithm can realize the fast and accurate solution of large-scale mixed integer nonlinear optimization problem. |
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