Advanced Materials Research Vols. 732-733

Abstract: With the UHV (Ultra High Voltage) power grid construction and the interconnection of regional power grids, the scale of power grids in China is increasing rapidly. At the same time, significant uncertainty and variability is being introduced into power grid operation with the integration of large-scale renewable energy in power systems. All of these pose an enormous challenge to the operation control of power systems in China. For a long time, online static security analysis, as an important part of EMS (Energy Management System), has been an effective tool for power grid operation. However, it is increasingly difficult for traditional static security analysis in serial computing mode to be online applied in bulk power grids in China. A new practical parallel approach for online static security analysis is put forward in this paper. A multithread parallelism is introduced into contingency screening, detailed contingency evaluation and decision support for reducing the execution time. By employing the multithread technology, the hardware resources of multi-processor/multi-core computer can be fully used and the program can be speeded up effectively. The performance of the parallel static security analysis is demonstrated by tests on two large-scale power systems. The test results show that the proposed method can be online applied in real bulk power grids.

Abstract: This paper puts forward a novel islanding detection method based on q-axis disturbance signal injection. This method, by introducing q-axis disturbance signal injection, makes the RLC load generate frequency offset to detect the island in the case that the power network is disconnected due to certain fault.The introduced q-axis disturbance signal injection method is connected with reactive power variation and frequency variation whose values are close to zero when photovoltaic system is operated in grid-connected mode. Therefore, the suggested method has the advantage of tiny harmonic distortion and good power quality. The simulation results based on the MATLAB/Simulink software show that the novel islanding detection method can detect the island in 1 second and has little effects on the system under the condition of the set parameters.

Abstract: It is essential for the small and medium-sized hydropower stations to choose a best project during the technological innovation and standardize management process. Thus, it can lay a solid foundation for the overall efficiency of enterprises in the future. Long Feng station is in the transition period after the acquisition and alteration, by data analysis, there are some questions: (1) management system is chaotic; (2) the overall quality is not high; (3) cost of power generation is high, but economic efficiency is low; (4) ecological environment pollution is serious; (5) living conditions of residents is threatened. To solve the above problems, this paper applies the OOPP theory as a guide and the Analytic Hierarchy Process as a tool in the alternative project analysis, combines the method of qualitative and quantitative, and finally can provide a valid scientific basis for decision to choose the best subproject.

Abstract: By the heuristic algorithm and particle swarm optimization algorithm combining hybrid particle swarm algorithm proposed combination of heuristic search and stochastic optimization,stochastic optimization process using a spanning tree and the loop matrix operations combined to ensure the system topology constraints to improve the efficiency of solution. The analysis shows that the proposed method calculation speed,easy to converge to the global optimal solution. It can effectively solve the problem of distribution network fault recovery.

Abstract: It’s important to improve the speed of security analysis of 96 period generation scheduling cases. Based on the characteristics of 96 period cases’ security analysis, four technical proposals were presented. They were following as fast scanning and analysis technology based on DC power flow screening, multiple thread parallel computing adapted to a multiple contingency case, multiple process parallel computing technology adapted to multiple period cases. Detailed test examples showed that the proposed methods could contribute much to fast security analysis of 96 period cases’ day-ahead dispatching schedule.

Abstract: This paper addresses the problem of failure analysis of 35-110 kV overhead transmission lines using the main methods: correlation analysis, regression analysis and expert judgment method. There are weaknesses identified of these analysis methods for power network district of the city for 35-110 kV overhead transmission lines.

Abstract: According to errors between the predicted values and the actual values, this paper establishes a fuzzy soft set in the form of membership function, then utilizes Dempster combination rule in evidence theory to synthesize the prediction results to obtain the weights of each single model, and thus builds a new hybrid combination forecasting model. The example shows that the proposed model can effectively improve the accuracy of mid-long term load forecasting, and is more accurate and credible than the combination forecasting model based on entropy or simply fuzzy soft set theory.

Abstract: VSC-HVDC (high voltage direct current based on voltage source converter) is a new HVDC transmission technology based on voltage source converter. Its converter uses thyristors with the current off capability such as IGBT or GTO. VSC-HVDC system can realize passive inverting by pulse width modulation (PWM) technique. This paper introduced the structure and the operating principle of the VSC-HVDC transmission system. In addition, we studied the mathematical model of the VSC-HVDC transmission system supplying passive network in ABC stable coordinate system and in DQ rotating coordinate system. Lastly, we built the physical model of the VSC-HVDC transmission system based on PSCAD/EMTDC simulation software. We carried on various types of fault simulation and analyzed the simulation result. The result of the paper may provide reference in the further study and application of the VSC-HVDC transmission technology in the future.

Abstract: By the heuristic algorithm and particle swarm optimization algorithm combining hybrid particle swarm algorithm proposed combination of heuristic search and stochastic optimization,stochastic optimization process using a spanning tree and the loop matrix operations combined to ensure the system topology constraints to improve the efficiency of solution. The analysis shows that the proposed method calculation speed,easy to converge to the global optimal solution. Development of distributed generation units, along with concerns raised over the security of supply has prompted many customers to consider the installation of their own local capacity for generating electricity (and heat). This paper proposes a methodology for optimizing the operation of a portfolio of distributed units, based on profit maximization using genetic algorithms. The method is tested on a set of distributed units, demonstrating the ability to find good solutions in an acceptable time period.

Abstract: This paper introduces the research on the Excitation Regulator of the Synchronous Generator with dual CPUs, based on Digital Signal Processor (TMS320LF2812). With the multiple functions of monitoring, analysis, controlling and protection, it overcomes the shortage of the domestic excitation device in terms of self-monitoring and self-protection,which effectively improves device reliability. By analyzing the allocation of reactive load of the interconnected Synchronous Motor group, the model of the digital excitation regulator by Simulink of MATLAB is produced. The results of the simulation show that the proposed regulation model are feasible, satisfying various running demands of the Synchronous Motor and Power System.