Advanced Materials Research Vols. 1070-1072

Abstract: With the significant development of wind power, it has been inevitable for wind farm cluster to integrate into the system from the grid end, therefore, the power grid loss problem of large-scale wind power integration is highlighted. At first, we construct a power transmission system model with large-scale wind power integration, get the power grid loss calculation formula of the system, and induce the change laws of the power grid loss by the constraints of power transmission channel flow. And then, based on the structure of Gansu power grid, we do some simulations about power grid loss distribution by the constraints of power transmission channel flow, and verify the correctness of theoretical derivation.

Abstract: In light of the rapid development of the electric power grid, the integrated application of distributed generation (DG) units can be considered as a key driver. Nevertheless, along with large number of DG units are connected into a distribution network, maybe different kinds of effects are accordingly induced. In particular, regarding the configured relay protection, its selectivity and sensitivity may be affected. In this paper, the penetration capacity analysis of DG considering overcurrent relay protection and flux-coupling type FCL is conducted. Under different fault conditions, the theoretical impacts of introducing DG on the fault current are investigated, and a flux-coupling type FCL is suggested to limit the fault current and potentially enhance the DG’s access capacity. Furthermore, the detailed simulation model of a typical distribution network integrated with the DG and FCL is created. From the simulation results, the employment of the FCL can effectively reduce the fault current’s negative influence on the DG, and improve the DG’s access capacity to a certain extent.

Abstract: The series compensator, such as the thyristor controlled types, is often applied to high-voltage transmission to control power flow distribution and avoid overload/overvoltage. Various power flow schemes are needed to quantify its control capability which is related to network topology and load level. Sensitivities of bus voltages and power flows to the controlled line reactance, current magnitude, and active power flow, are given to quantify the control effect of the controllable series compensation under different operation conditions. Feasible setting to the controlled parameters within the adjustable range of the series reactance is estimated. The proposed model is applied to the ultra high-voltage (UHV) transmission, whose line parameters are lumped from the distributed line model. The numerical results on WSCC 9-bus system are proposed to validate control effect and error of the proposed model.

Abstract: A new relay protection based on electronic communication is presented for the access of distributed generation. After distributed generation access to the system, distribution network power flow direction and short-circuit current level will change. This paper describes the effects of distributed generation on distributed network by building feeder system simplified PSCAD/ EMTDC model. According to the analysis, the new relay protection can improve the stability and reliability of distributed network.

Abstract: With constant improvement of intermittent energy source, its agglomeration effect and stochastic volatility will greatly influence the power system operation. It’s an inexorable trend that probabilistic power flow calculation shifts from offline analysis to real-time operation online. Among all probabilistic trend algorithms, probability flow calculation based on cumulant method is the fastest one; it has better prospect of online application. However, it requires random variables independent to each other, so the single slack bus always undertakes all unbalance power in conventional cumulant methods. When the fluctuation of system power injection becomes larger and larger, this calculation model will hardly adapted to the actual demand of the grid in the future. To improve the practicability, a improvement of probabilistic load flow based on cumulant method is proposed in this paper. By modify the calculation of the sensitivity matrix, the distribution of system unbalance power can be considered. The accuracy of this method is verified by the simulated analysis of the standard examples and actual power system model.

Abstract: In this paper proposed a method for regulating the voltage in the power system on the basis of cluster zoning using voltage sensitivity coefficient. The proposed method used to test calculations in the power supply system of the Far East with the cluster differentiation for different voltage classes and definition devices which should be coordinated while setting up. The algorithm of cluster zoning is implemented as VBScript for models in RastrWin software package.

Abstract: Life-cycle cost management is the foundation and techniques for life-cycle cost management. Petri nets has a graphical expression, can improve and add more features and information to Fault tree analysis, Markov equations and so on, raising the speed and accuracy of the entire system of risk assessment. The paper propose a risk assessment based on the life-cycle management approach, establish four state model to analysis transformer substation main wiring operation, discuss elements occurring planned maintenance events and breaker tripping phenomenon, and propose using the basic equations of Petri nets to determine system status and calculate the corresponding probabilities, quantitative analysis of the outage costs of the substation main connection off for running, and seek the best value under the run. In the example discussing and calculating the risk indicators of outage costs for different wiring schemes, the results demonstrate the feasibility of the proposed algorithm.

Abstract: In power operation, dispatching operation order sheet (DOOS) provides reliable guarantee for safe of power dispatching. The intelligence of power dispatching operation system (PDOS) is improved a lot through the effort of scientists during recent years. By using this system, the security of the power net is enhanced, and the working stress of the staff is lightened. However, such systems can not be fully popularized and applied as yet due to some reason.. This paper analyzes and researches two different aspects in order to enhance the universality of PDOS. On the one hand, a scheme of operating rules’ dynamic management is designed and implemented through analyzing the difference on operating requirement and content between itemized order tickets and comprehensive order tickets, which improves the flexibility of PDOS effectively. On the other hand, the PDOS is integrated with management information system (MIS) to realize the web-based broadcast of DOOS. The efficiency and applicability of this implementing scheme have been proved by practice.

Abstract: More and more distributed generations are interconnected to distribution network. Its operation state should be evaluated comprehensively and effectively. This paper gives index of each level to judge interconnecting operation through comparing guides of interconnecting distributed resources with electric power system in different countries. A comprehensive and complete evaluation model based on Analytical Hierarchy Process (AHP) and Fuzzy Synthetically Evaluating Method is proposed. The index weights are set through analyzing the relationship between each index, while certainties and uncertainties are described by setting membership grade. Finally, a demonstration is given and reasonable analysis results are attained, thus the feasibility and efficiency of the model that might be conductive to the description of interconnecting distributed resources with electric power system are verified.

Abstract: For increasingly complex often appear in the low frequency oscillation of interconnected power grid, rapid positioning disturbance source to ensure the rapid processing of the accident, reduce accident influence has become especially important, therefore in the national grid project of related study proposes a decomposition method and moment method based on the cut set energy partition layer and position of disturbance source theory, and success in the ground demonstration project construction disturbance source location system based on WAMS data sources; Disturbance source localization algorithm, this paper introduces the hardware structure and software structure of system, as well as the system functionality and performance, and use the actual power grid operation data and the simulation output case data validate the system to provide the source of disturbance in the practicality and accuracy of positioning function, system technical index has reached the requirement of demonstration project; For scheduling system was put into operation personnel to provide auxiliary decision becomes a powerful tool for rapid processing oscillation accident, to better ensure the safety of power grid operation stability.