Transmission network expansion planning problem face many uncertainties in electricity market, in the paper, two uncertain factors of capacity of new-added generation company and load are considered, expected value objective and expected value constraints are adopted in the transmission planning model, a novel expected value bi-level programming model of transmission expansion planning is presented. The upper level objective is the minimization of transmission network investment cost and operation cost expected value, the upper level constraints are the number of new-added lines restraints. The lower level objective is electric power operation cost expected value, the lower level constraints include system normal operation restraints and N-1 operation restraints and system load shedding expected value restraints. Two uncertain factors are considered in the model, which satisfy different probability distribution function. Monte Carlo method is adopted to analyze the uncertain factors and expected value function. Hybrid algorithm integrated improved niche genetic algorithm with prime-dual interior point method is proposed to solve the proposed model. The results of 18-bus system were proved that the proposed model and algorithm were valid.

This paper analyzed the phase selection principle based on mutation amount of phase-current,and discussed the application of the phase selection method to the single-phase automatic reclosing of high-voltage transmission line.MATLAB7.0 was employed to simulate both phase selection methods according to respective mutation amount of phase-current differential and mutation amount of phase-current,and the simulation results were analyzed referring to the relay protection module and the single-phase automatic reclosing module.The simulation via MATLAB exhibits the effectiveness in fault-phase selection of single-phase automatic reclosing.

In order to demonstrate the wind turbine in the laboratory, this paper first analyzed the operation principles, the power and torque characteristics of the wind turbine and direct current (DC) motor, then it investigated the operation characteristics of the wind turbine in contrast to those of the DC motor. The torque imitation scheme was provided, which imitates the torque characteristics of wind turbine by controlling the armature current of DC motor. The scheme has good performance and high feasibility. At last, the simulation of wind turbine operation characteristics was performed, the simulation was done under two typical conditions of variable wind speed and variable machine rotational velocity. The characteristics curves are presented in the paper. The simulation curves are highly consistent with theoretical datum. The torque imitation scheme of wind turbine characteristics can be conveniently used in the study of wind power generation in the laboratory.

This paper presents an improved control method based on very-short-term forecast. The voltage and reactive power data queues are acquired from electric line with. high speed, then the values after a certain time is predicted adaptively using improved least-square method. On the base of improved "nine-area" control method, the real time value, and the predict value, and the parameters' changing speed are analyzed comprehensively with fuzzy logic, providing the best control decision. With this control scheme, the sensibility and reliability are enhanced, the disqualification time of the electric parameters is decreased, and the times to adjust the transformer taps and the capacitors are decreased too.