Wei Zhinong

Power system state estimation with unified power flow controller

With the flexible of AC transmission systems (FACTS) technique, the power flow in the interconnected power systems can be controlled flexibly. Unified power flow controller (UPFC) is one of the most important components of FACTS. Based on the conventional power system state estimation model, a kind of model for state estimation with UPFC is introduced in this paper, in which power injection model is used and the affect of UPFC on the power flow is transferred to the two nodes of the corresponding transmission line. This method can be integrated to the conventional state estimation program with the consideration of UPFC. The results demonstrate that the model is effective for practical use.

The intelligent control of DFIG-based wind generation

Doubly-Fed Induction Generator (DFIG) has been widely used in Variable-Speed Constant-Frequency (VSCF) wind energy generation system. Vector control has already been applied to the DFIG control, which makes the DFIG gain good performance in the wind energy capturing operation. In recent years, many researches of vector control take the following manner to track the largest wind energy under the rated wind speed. However, when wind speed increases, larger than the rated value, the output power can remain stable only by adjusting the pitch angle. Therefore, variable pitch control is a significant aspect of wind power. In order to improve the traditional vector control, intelligent control is proposed on the basic of the analysis of the dynamic mathematical model of DFIG and its stator-flux-oriented vector control. At low wind speed, based on fuzzy control, it is adjusted to get the maximum wind energy performance coefficient. At high wind speed, based on neural network control, pitch angle is adjusted to keep rated output power. The system is simulinked by MATLAB tool, and makes a satisfying result.

Power flow calculation for power system including offshore wind farm

This paper proposes a simplified steady-state equivalent model of asynchronous generators. With regard to the relationship between the wind velocity and generators active power, terminal voltage, reactive power, as well as the slip ratio, a method to calculate the power flow for power system including large-scale offshore wind farm is then proposed, using the DLL files called by UPI of PSASP. The feasibility of this model is finally validated through the WSCC 9 node system included in PSASP and the comparison between the newly outcomes and the result from the existed calculation of power flow for power systems including wind farm.

Impact of wind generators on power system state estimation

Based on simplified RX model of asynchronous generator, state estimation model containing wind generators is presented in this paper. Simplified RX model can be merged into traditional state estimation algorithm efficiently with the consideration of asynchronous generator and the impact of wind generators on power system state estimation is investigated. Compared with traditional RX model, the calculation is simplified and the accuracy still satisfies calculating need. The simulation results demonstrate that the introduced method is effective for practical use.

Research of Dynamic Reconfiguration of Feeder Based the Dynamic Swarm Optimization Algorithm

On the basis of reconfiguration algorithms of distribution system in possession, a new reconfiguration algorithms based on dynamic particle swarm optimization (DPSO) is proposed. It adopts the voltage stability of distribution system as the object function, and uses the improved particle swarm optimization algorithm which can trace dynamically the environment’s change to make the real-time dynamically reconfiguration of distribution system, and proposes a new coded form which divides the particle module according to the topological structure of distribution system, and then avoids the convergence precociously via the community characters of DPSO. And the method proposed is compared with the one which adopts the power loss of distribution system as the object function, then make a conclusion that it must be considered to find the balance between security and economics under the different conditions simultaneously.On the basis of reconfiguration algorithms of distribution system in possession, a new reconfiguration algorithms based on dynamic particle swarm optimization (DPSO) is proposed. It adopts the voltage stability of distribution system as the object function, and uses the improved particle swarm optimization algorithm which can trace dynamically the environment’s change to make the real-time dynamically reconfiguration of distribution system, and proposes a new coded form which divides the particle module according to the topological structure of distribution system, and then avoids the convergence precociously via the community characters of DPSO. And the method proposed is compared with the one which adopts the power loss of distribution system as the object function, then make a conclusion that it must be considered to find the balance between security and economics under the different conditions simultaneously.