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Research On Hierarchical Voltage Control In Active Distribution Networks

Posted on:2017-02-12Degree:MasterType:Thesis
Country:ChinaCandidate:C LuoFull Text:PDF
GTID:2272330488483695Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
No matter from the human demand for environmental protection and energy crisis or the distribution network development, distributed generation(DG) access to active distribution network become the development trend of the future. In active distribution network, power flow will become complicated due to the power can be injected in network distributed, as well as the DGs output is uncertain and volatility, thus the traditional distribution network voltage control has facing serious challenges.According to the period and area, the distribution network voltage control can be divided into three levels:1) the tertiary voltage control, through reasonable schedule and control of the system equipments in a period of time to optimize the operation of the whole system;2) The secondary voltage control, its control area is less than the tertiary voltage control. When local voltage exceeded the security range, the secondary voltage control will change the controlled unit set voltage reference to maintain the voltage stability of this area according to predetermined control laws; 3) the primary voltage control, it is controlled by adjusting the generator automatic excitation regulator to ensure that the voltage tends to set value. Primary voltage control of related research is pretty mature, but the distribution secondary need to be further research.Based on multi-agent system, this paper proposes a voltage hierarchical decentralized control model. This method makes full use of the distributed generation (DG) reactive power output adjustment ability to realize distributed autonomous voltage control and dividing the network for several local control zones(LCZs) that size is adapt to the different system state and the center is DG node. Due to the fact that the active distribution node number is large as well as the operation situation is complex. Based on the multi-agent system architecture, this paper proposed a area——line——system three level voltage profile perception model using the data from the remote terminal unit(RTU) of measure.The reactive power optimization is usually single-object oriented, and the coordination between distributed generations (DGs) and traditional voltage control method is poor. In this paper a comprehensive voltage control optimization using a two-stage planning algorithm is proposed. In order to reduce the network loss and the number of equipment adjustment, improve the utilization of DG’s output, as well as to ensure meet the requirements of each node voltage constraints in power grid, the new comprehensive voltage control model is modeled by the two-stage planning, and use the differential evolution algorithm and dynamic programming (DP) algorithm to solve the model of two phase. The method based on the accurately predictions of load and DG’s output, as well as the DG’s output can be continuously controlled.In order to solve the problem that DG’s output uncertain and volatility, this paper adopt demand respond theory in the tertiary voltage control.based on the robust optimization theory, the new method will maximize the use of the local DG’s output and using demand response method to reduce the cost of distribution network operation.The proposed control method is designed and implemented with MATLAB and the IEEE 33 and PG&E 69simulation systems demonstrate the effectiveness of the method.
Keywords/Search Tags:active distribution, hierarchical voltage control, local control zone, multi-agent system, two-stage planning, adjustable robust optimization
PDF Full Text Request
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