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Long D.,Guangxi University | Long D.,Guangxi Power Grid Corporation
China International Conference on Electricity Distribution, CICED | Year: 2014

We address the problem of security constrained unit commitment (SCUC) with power flow constraints, capturing the uncertainty of wind power and demands. We propose a modeling and algorithmic strategy based on the framework of approximate dynamic programming (ADP). A stochastic optimization model is developed for the SCUC problem with power flow constraints. We demonstrate the methodology using both stochastic and deterministic formulations of the SCUC problem. Th is paper describes the handling of power flow constraints and different sources of uncertainty. The application on IEEE-30 to -300 bus systems and a Polish-2737 bus test system fully validate the effectiveness of the ADP-based modeling and algorithmic strategy. © 2014 IEEE. Source


Bao H.,Guangxi University | Bao H.,Guangxi Power Grid Corporation | Wei H.,Guangxi University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014

A computation method for probabilistic optimal power flow (POPF) for power systems with large-scale wind farms based on unscented transformation (UT) technique is proposed. UT technique is employed to transform the POPF problem into the deterministic OPF problem with a few samples to be solved with the interior point method. The randomness of the wind farms' output power and the uncertainty of the bus load power are considered, the calculation accuracy of the probability characteristic parameters of the variables in the model of POPF using this method under different wind power capacities in power systems is discussed. The numerical results of IEEE 30-bus, 57-bus, 118-bus standard systems and a real system S-1047 indicate that, compared with Monte Carlo (MC) method, the proposed approach for POPF based on UT technique can remarkably reduce the computing time while keeping a high accuracy. It is easy to implement and facilitates handling of the correlation of the random variables, while providing a powerful tool for the solution and practical application of the POPF problem. Source


Niu H.-N.,China Agricultural University | Huang X.-Q.,Guangxi Power Grid Corporation | Cai Z.,China Agricultural University | Yang M.-H.,China Agricultural University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

For the limitations of the existing methods of probabilistic load flow calculation with wind power generators (WPGs), a method of probabilistic evaluation of voltage limit violations of power system is proposed, which adapts to a variety of wind speed distribution. Based on division of WPG's output probability space, the system wind power output scenario division method is given; through probabilistic load flow calculation under every system scenario, the probability for the voltage limit violations of every bus under given scenario are calculated. At last probability for the voltage limit violations of every bus, and the index of probability for the voltage limit violations of system and bus group are calculated respectively. This method is applied to a IEEE30 system with wind farm, the index of probability for the voltage limit violations of power system, under four different windy seasons, is given in the example, and the results verify the effectiveness of the method proposed. Source


Chen J.-Y.,Guangxi Power Grid Corporation | Cai H.-M.,Guangxi Electrical Power Institute of Vocational Training | Su H.-Y.,Xiangtan Power Supply Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

Aiming at many kinds of uncertain information in the power generation system reliability evaluation under the electric power market condition, a power generation system reliability flexible evaluation model which contains evaluation theory, evaluation index, and evaluation method is proposed based on blind number theory. This model uses the blind number to express node information, which effectively deals with the impact of primitive parameter uncertainty on the reliability evaluation. The reliability index's sensitivity formula is used to effectively find the weak link restricting system reliability, and then the reliability cost-benefit assessment for the power generation system is carried out. The numerical example of IEEE-24 buses reliability test system demonstrates the correctness and availability of the proposed approach. Source


Cai H.-M.,Guangxi Electrical Power Institute of Vocational Training | Chen J.-Y.,Guangxi Power Grid Corporation | Su H.-Y.,Guangxi University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

In order to improve the diagnosis ability of dissolved gas analysis, a novel method for the power transformer fault diagnosis based on gray cloud model is proposed. Softening factor is introduced via entropy theory, and the classification limit single value for canonical matrix of the power transformer fault diagnosis is transformed into the concept of interval numbers limit value. The gray cloud model is used to reflect the fuzziness and randomness of the classification limit value for the power transformer fault diagnosis, which is composed of the peak value, the boundary value of left and right endpoint, the entropy, and the hyper entropy. The subjectivity of the diagnosis results is effectively reduced by establishing the importance information unascertained rational numbers of indicators for the power transformer fault diagnosis, through which the weight value of each index is obtained. A gray clustering algorithm based on gray cloud whitening weighting function is used to analyze and judge the fault pattern of the power transformer. The actual numerical example results show that the proposed method has high degree of diagnosis accuracy, and is characterized by fast diagnosis and good real-time, demonstrating the model is practical and effective. Source

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