Adaptive Optimization Of Collaborative Restoration Control Of Transmission And Distribution Systems

The purpose of power system restoration control is to restore power supply quickly,securely and economically after a blackout,reduce power outage losses and avoid the new instability risks brought by restoration measures.In recent years,the experience of blackout restoration around the world shows that the restoration processes of transmission system and distribution system are influenced by each other.Thus,it is necessary to carry out collaborative restoration control of transmission and distribution systems.However,it is difficult to accurately model the actual restoration control process,and there is high-dimensional uncertainty in the restoration control process and external environment,so it is necessary to adaptively adjust the restoration control measures according to the actual restoration control process.Therefore,it is of great significance to study the collaborative and adaptive restoration control method of transmission and distribution systems to improve the power system’s power outage prevention and restoration capability.The decision-making of collaborative restoration control of transmission and distribution systems is a multi-level,cross-regional and multi-stage time-space coupling problem,which is usually divided into two types of single-level decisionmaking problems: decision-making of transmission system restoration control and decision-making of distribution system restoration control.The research on transmission system restoration mainly focuses on partitioning methods and restoration plan optimization methods at different restoration stages of a partition,while the research on distribution system restoration mainly focuses on single-step or multi-step reconfiguration methods,without considering the adaptive decision-making of timespace coordinated restoration of transmission and distribution systems.Therefore,the purpose of this paper is to propose an adaptive decision-making method for collaborative restoration control of transmission and distribution systems after blackout.The main work and research results are as follows:1)A security risk evaluation method and an adaptive decision-making strategy dealing with the uncertainty of restoration control are proposed.First,the relationship between restoration control and security controls such as preventive control,emergency control and corrective control is expounded,and the uncertain factors affecting restoration control are analyzed.On this basis,by taking the security control cost as the consequence of an uncertain event,a security risk evaluation method of restoration plan based on sampling and simulation is proposed.Finally,the necessity of realizing adaptive decision-making of restoration control under the influence of uncertain factors is analyzed,and the adaptive decision-making strategy of restoration control based on model predictive control is proposed,which includes realizing restoration decisionmaking of a finite time-domain by using expert experience and sand table deduction methods,and realizing adaptive rolling optimization of the two parallel processes of restoration decision-making process and actual restoration process through system framework design.Both the security risk evaluation method and the adaptive decisionmaking strategy are applicable to the adaptive restoration decision-making research of transmission system,distribution system,and coupled transmission and distribution systems.2)An adaptive optimization method for multi-partition dynamic coordinated restoration of transmission system is proposed.First,the security risk is used to reflect the influence of uncertain factors,and an optimization model for transmission system restoration which can quantify the economy and security of a restoration plan uniformly is established.Then,based on the measurement and control conditions of the actual power grid automation systems and the multi-source data requirements of adaptive restoration decision-making,a decision support system framework for adaptive restoration control of transmission system is proposed,and an information interaction interface for collaborative restoration decision-making with distribution system is reserved.Further,based on the proposed framework,an adaptive management and control strategy of restoration process is proposed,which can realize the adaptive coordination of two parallel processes of restoration decision-making process and actual restoration process by distinguishing the influence of various uncertain events.Finally,a two-layer optimization method for dynamic coordinated restoration of multiple partitions of transmission system is proposed,including the partitioning method based on the actual power outage scenario,and the decision-making method for inter-partition connectivity based on restoration benefit and risk in the upper layer,and the restoration target optimization method considering factors such as direct and indirect restoration benefit,and the intra-partition restoration plan optimization method based on the index of net income per unit power consumption in the lower layer.Thus,the finite time-domain optimization and dynamic expansion optimization of multipartition restoration plan of transmission system under any total outage or partial outage scenario can be realized with the proposed two-layer optimization method.3)An adaptive optimization method for large-scale power outage restoration in distribution system is proposed.First,an optimization model of distribution system restoration considering the expected restoration benefit and security risk is established.Then,a decision support system framework for adaptive restoration control of distribution system is proposed,in which an information interaction interface for collaborative restoration decision-making with transmission system is reserved,and an adaptive management and control strategy of restoration process considering security control measures is proposed.Finally,on the basis of the proposed framework,considering the time-variant characteristic of power supports form transmission system at multiple buses and the characteristic of closed-loop design and open-loop operation of distribution system,a two-layer optimization method for dynamic coordinated restoration of multiple partitions of distribution system is proposed,including the optimization method of operation mode pre-adjustment of the electrified power grid based on the index of electrified load transfer demand,the partitioning method based on branch restoration benefit,and the decision-making method of inter-partition connectivity in the upper layer,and the intra-partition restoration plan optimization method considering the restoration benefit of generators in distribution system in the lower layer.Thus,the restoration decision-making of distribution system can be realized by coordinating the transmission system power supports and the distribution system generation with the proposed two-layer optimization method.4)On the basis of the above work,an adaptive optimization method of collaborative restoration control of transmission and distribution systems based on decoupling and iteration is proposed.First,the optimization model of collaborative restoration of transmission and distribution systems is established,and the idea of decoupling and iterative decision-making of transmission system restoration and distribution system restoration is put forward by analyzing the dynamic coupling relationship between transmission system restoration control and distribution system restoration control from the perspective of time,space and uncertainty.Then,the decision support framework for collaborative and adaptive restoration control of transmission and distribution systems is proposed,and the interactive information between transmission system restoration decision-making and distribution system restoration decision-making is classified.Finally,the online asynchronous and concurrent interactive strategy of different kinds of information between transmission system restoration decision-making and distribution system restoration decisionmaking is proposed,where the decision-making of transmission system and distribution system are loosely coupled.By iterating the information of power demand and power support capability,restoration instruction and restoration result,and power transmission plan and plan evaluation result between decision support systems of transmission system restoration and distribution system restoration separately,the collaborative and adaptive restoration optimization and restoration control of transmission and distribution systems is finally realized.