The access of distributed generation and demand response in active distribution network makes the operation of power grid complex and changeable. The intermittent and uncertain output of some distributed generation makes the voltage fluctuate greatly, which brings difficulties to the prediction of voltage. In order to reduce the impact of uncertainty of distributed generation output on voltage and obtain the real-time operation status and future development trend of active distribution network quickly and accurately, this paper proposes a voltage situation awareness method based on grey correlation analysis. A large number of historical data are used to establish the grey correlation model to predict the voltage situation and trend of distribution network, which provides the basis for the active voltage control.

To studies the relationship between the dielectric parameters and electric-field characteristics in water tree region in XLPE cables, liquid needle electrode and high-frequency high-pressure were used for water tree accelerated aging of XLPE cable samples, and the shapes of water trees were observed by microscope. Then a finite element simulation was constructed based on the shapes of water trees observed, and the influence of the dielectric parameters in water tree region on the electric field surrounding the water tree was analyzed by simulated calculation. The results show that the electric-field strength of water tree peripheral increases and the electric-field strength of tip decreases and the water tree peripherals can easily become the starting point for electrical trees, with the increasing of the dielectric constant and electrical conductivity of the water tree. On the contrary, with the decreasing of the dielectric constant and electrical conductivity of the water tree, the electric-field strength of tip increases and the electric-field strength of water tree peripheral decreases, and the tip can easily become the starting point for electrical trees.

Since the intelligent substation is different from the conventional substation in the maintenance system,this article explains the basic requirements and classification of their maintenance systems,analyzes the contents and points for attention of unit test,group test,single-interval test and double-interval test of the maintenance system of the intelligent electronic equipment,and provides suggestions based on the safety measures for regular inspection in operation.

Based on the characteristics of the three types of data from the system of WAMS (Wide Area Measurement System), SCADA (Supervisory Control And Data Acquisition) and Fault-recorder, this paper present an algorithm to do the voltage or reactive power optimization based on the primal-dual interior point method, and a new method to filter out the noise in state variable based on the standardized residuals. The flow chart proposes a new scheme to use the WAMS real-time data to improve the accuracy of voltage and reactive power control. Keywords: WAMS, voltage and reactive power control, primal-dual interior point method, standardized residuals.