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In order to solve the problem of short-circuit current exceeding the standard in the development of 500kV power grid, a new current limiting device based on high coupled split reactor and parallel circuit breaker is adopted, which can realize the function of equalizing the current of circuit breaker in steady-state operation and limiting current of circuit breaker in transient fault. Due to the introduction of an additional circuit breaker and a high coupling reactor in the current limiting device, there is a large transient voltage in the break of the circuit breaker and in the coupling coil when the fault occurs. In this paper, the overvoltage distribution in the new current limiting device is studied. Firstly, the basic structure of HCSR and the topological structure of main circuit are introduced, and the calculation formulas of coupling reactor and distributed capacitance are deduced. Then, the steady-state current sharing and transient current limiting processes of the parallel circuit breakers are described, and the technical effects of the current sharing process are analyzed and deduced. Last, this paper focuses on the analysis of the operation circuit in the current limiting process, and makes a theoretical analysis and a brief derivation of the current and overvoltage in the breaking process of two circuit breakers with different actions.

With the increasing of wind power penetration rate in large power grid, it is of great importance to analyze the impact of wind power on unit commitment of power system and economic dispatch. In the security-constrained unit commitment problem, the introduction of wind turbine can reduce the operating cost of thermal power units and improve the economy of system operation. Because the energy storage system has the characteristics of fast two-way regulation, it can improve the power grid’s ability to absorb wind power and the economy of the system operation. By controlling the charging and discharging of energy storage, it can provide certain flexibility for determining the system unit commitment scheme. Therefore, by considering the forecast error influences of wind power and load, this paper introduces the energy storage system into the security-constrained unit commitment of power system with wind power. Moreover, the constraint condition of rotating reserve opportunity based on trust theory is introduced to avoid over configuration of backup. Thus, the uncertainty of wind power can be effectively improved and the operation cost of the system can be reduced. In addition, the paper compares and analyzes the changes of unit commitment status and system operation cost with or without energy storage, as well as the influence of energy storage parameters and the way of access system (close to wind power side, load side and decentralized access) on the unit commitment model under wind power curtailment condition. Finally, the linearized security-constrained unit commitment model is analyzed and validated with 10 units system.

At present, with the comprehensive promotion of distribution network construction, the demand of reliability for electricity is getting higher and higher. Therefore, the investment planning model for distribution network, which focuses on the overall load growth within the region, is not applicable. In this paper, a distribution network planning model that considering different customers’ reliability requirements is proposed. Firstly, the fuzzy binary contrast strategy is adopted to quantify the reliability requirements of different customers in the region. The neural network is used to mine the correlation model between reliability indices of the different power supply requirements and corresponding reconstruction measures. Then, the optimal model of distribution network planning with the target of reliability indices and the constraint of investment cost is established. As a result, the proposed model fully meets the reliability requirements of customers and forms the optimal investment planning scheme of the distribution network. Finally, the results of the IEEE 33 test system verify the rationality and feasibility of the proposed model.