In the complex power transmission environment, the electromagnetic characteristics of the 500kV JiuAn transformer substation node will change, which will make an important impact on the main equipment of substation. This paper makes in-depth study on the impact of complex power transmission environment on the main equipment, such as high voltage, long-term heavy load, changes of run mode and forced outage. On this basis, PSCAD Software is used to simulate this model, and the simulation result is analyzed. It is significant to ensure the security of main equipment of JiuAn substation.

State estimation of power system is the basis of all the high level application and analysis for dispatch centers. Against the bad convergence of the WLAV (weighted least absolute value)-based state estimation method, a new robust state estimation method based on exponential weight function (E-LAV) is presented in the paper. This method uses an exponential weight function to replace discontinues weight function of WLAV to improve the poor convergence. The results of the sample system of 4-node system and the IEEE 118-node system show that the E-LAV-based state estimation method not only owns the similar convergence as WLS-based method, and also owns a strong robustness. Through modifying the weight matrix of the least squares, the proposed new method has good prospects for application in practical engineering.

Reactive power optimization for distribution network with distributed generators is a complicated nonconvex nonlinear mixed integer programming problem. This paper built a mathematical model of reactive power optimization for distribution network and a new method to solve this problem was proposed based on semi-definite programming. The original mathematical model was transformed and relaxed into a convex SDP model, to guarantee the global optimal solution within the polynomial times. Then the model was extended to a mixed integer semi-definite programming model with discrete variables when considering discrete compensation equipment such as capacitor banks. Global optimal solution of this model can be obtained by cutting plane method and branch and bound method. Numerical tests on the modified IEEE 33-bus system show this method is exact and can be solved efficiently.

With the continuous improvement of wind power penetration, the impact of the random fluctuation characteristics of wind power on the frequency control of the power system is growing. Currently, researchers began to study the methods of wind farms participation in frequency control to reduce the frequency adjustment pressure of other power plants and increase the wind power penetration. However, the existing simulation software for the short and long term frequency control of the power system is not so good. So in order to analyze the impact of load fluctuations or wind farm power fluctuations on system frequency control, this paper propose a frequency fluctuation simulation method based on the quasi-steady-state method.

Large-scale wind power integrates in the grid to provide clean energy; however, it has a negative impact on the stable operation of the grid. To analysis the effect of wind power on frequency control, we need the help of simulation software. But, there has no frequency control mathematical model of wind farm in simulation software available for the user to choose. So this paper designs and establishes a frequency simulation platform, which provides the frequency control mathematical model of wind farms, hydroelectric power plants and thermal power plants. It can not only evaluate the impact of wind power fluctuations on frequency control, but also can quantitatively analysis of the system reserve capacity, as well as AGC performance monitoring function.