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Study On The Fault Split And Service Restoration Strategy Of Distribution System With Distributed Generators

Posted on:2011-07-21Degree:DoctorType:Dissertation
Country:ChinaCandidate:L ZhangFull Text:PDF
GTID:1102360305453239Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
The service restoration of the distribution power system is important in the restoration of the power system. In recent years, along with increasing global concerns for environmental protection and energy saving issues, and with wind power, photovoltaic power generation and other renewable energy technologies becoming more sophisticated, the Distributed Generation (DG) technology has become a hot research topic. The service restoration of the distribution power system is greatly influenced by the distributed generation. Based on the normal power supply to the distribution power system of the distributed, the research on their active roles to provide effective support in the distribution system operation is very important. The fault split and service restoration strategy of the distribution system with distributed generators and the control strategy of microgrids fed by synchronous generators and inverters are researched. The research contents and results are as follows:(1) The reactive power compensation ability of distributed generation is significant to the voltage stability of the islanding operation of the distributed generation. Based on this, the reactive power support ability of various DGs is analyzed. The voltage and reactive power control of the distributed power system with DGs is researched using the theory of the multi-agent system. Furthermore, by integrating the reactive power of the distributed generators (DGs) to be the control variables, the reactive power optimization problem in distribution power system with DGs is discussed.(2) Deeply considering the distribution network with DGs, operation of DGs in the event of fault is proposed. Constraint satisfaction problem (CSP) model is applied in the DG islanding after fault. The on-line island recognition and division are realized. The islanding algorithm based on CSP converges rapidly and the result could make the global restoration more convenient.(3) Based on the islanding operation, a restoration method based on the multi-agent genetic algorithm is proposed for the distribution networks with distributed generators (DGs). All agents in this algorithm which represent the restoration methods live in a lattice like environment, with each agent fixed on a lattice-point. In order to increase object function values, they compete with their neighbors, and they can also use knowledge. For the non-feasible solutions generated in the process of the algorithm, the method of the improved loop decomposition is proposed to eliminate the closed loops and islands. Finally, the example results indicate the feasibility of the proposed method. (4) The multi-agent genetic algorithm is applied on the multi-objective distribution service restoration model. The objective functions consist of the power losses, the number of the switches and the offset of the voltage, considering the priority of loads. Calculation example manifests the efficiency and feasibility.(5) In terms of the distribution system with DGs especially considering the operation of islanding operation of DGs, an AER (Agent-Environment-Rules) Constraint Satisfaction Problem (CSP) based model to solve the serve restoration problem in the event of a large-scale blackout in a power distribution network with DGs was proposed. The elements of the service restoration process are represented as Agent, environment and rules of the AER model. To speed up the online calculation, much quantitative calculation unrelated to the fault mode is performed offline. Finally, the example results indicate the superiority and effectiveness of the proposed method.(6) A control scheme of microgrids fed by synchronous generators and inverters is developed in this paper. Based on the P-f & Q-V droop control of the synchronous generators, the droop control of the frequency and voltage of microgrids using the d-q components of the inverters'output current is researched. The control schemes are designed to allow each type of generators to operate in both grid-connected and islanded modes. Moreover, the control schemes can correctly manage a microgrid during its transition from a grid-connected to an islanded operation. The simulation results show the validity of the proposed scheme.
Keywords/Search Tags:distributed generation, distribution power system service restoration, islanding, multi-agent, AER model
PDF Full Text Request
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