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SPWM type static var compensator with continuously bi-directional reactive power control capability

Dianli Xitong Zidonghua/Automation of Electric power systems 2008年第15期32卷 75-78页

作者： Shan, Renzhong Yin, Zhongdong Xiao, Xiangning Song, Qipeng Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

This paper proposes a novel static VAR compensator, which can regulate capacitor and inductor continuously. The proposed compensator uses the SPWM type inverter to regulate the voltage on the compensating capacitors and inductors directly, therefore can continuously control the compensator bi-directional outputs. It is very useful in the low and medium voltage distribution system. The compensator overcomes harmonics problem associated with the conventional thyristor controlled reactor (TCR), and the capacity of the inverter is only 25% of its compensation capacity. The main circuit consists of three-phase four-leg inverters, which can efficiently compensate unbalanced reactive loads. Experimental results validate the compensator feasibility and efficiency.

关键词： Static Var compensators

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Quantitative uncertainty analysis for power system dynamic simulation based on stochastic response surface method

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Dianli Xitong Zidonghua/Automation of Electric power systems 2008年第20期32卷 11-14+100页

作者： Han, Dong He, Renmu Ma, Jin Huang, Xiaojing Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

In order to analyze the impact of variations of key parameters, such as load model and fault time etc., on power system dynamic stability, this paper applies a new method-the stochastic response surface method (SRSM) to analyze uncertainties of these parameters. Polynomial expressions between parameters and responses of system can be established by this method. Compared with the traditional approaches, the presented method can obtain statistical information with less simulation time. The case study on the IEEE 9-bus system demonstrates the validity of SRSM. Simulation results on the IEEE 39-bus system show that the uncertainties from key parameters, especially the different load model structures, have great impact on power system dynamic stability, which is directly related to the security and stability of power systems.

关键词： Monte Carlo methods

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Immune genetic algorithm based on regulating new definition of antibody density for power system reactive power optimization

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Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2008年第2期23卷 115-119页

作者： Li, Yulong Zong, Wei Lu, Xianyan He, Qiuyu Yuan, Qihong Wang, Qian Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

By integrating an immune genetic algorithm, a regulating strategy based on a new definition of antibody density for reactive power optimization in power system is proposed. Firstly, the penalty coefficient adjusted dynamically was applied to the objective function. Then artificial immunity mechanism is introduced into the genetic operation. It is similar to consider to be each antibody on encoding. And then based on similar vector distance choice tactics were proposed, which keep the population diversity. At the same time, it can guarantee algorithms faster convergence. Thus simple genetic algorithm was correspondingly improved. Finally, the proposed method is applied to IEEE30 buses test systems. The result of calculation illustrates that the proposed hybrid strategy is effective. It shows that compared with SGA in the same condition, this approach can reduce remarkably iterative times and improve rate of convergence of the algorithm for reactive power optimization.

关键词： Genetic algorithms

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The Influence and Countermeasure to Transformer Differential protection of CT Saturation Caused by Ezternal Fault Removal

The Influence and Countermeasure to Transformer Differential...

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11th International Conference on Electrical Machines and systems(第11届国际电机与系统会议)

作者： Jun Gu Tao Zheng Shaofeng Huang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control (North China E Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control (North China E

The mal-operation of transformer differential protection will occasionally take place after the removal of external fault due to current-transformer (CT) saturation. Study show that CT saturation can be divided into three kinds. Firstly, the influencing factors of CT saturation and effect of CT saturation to transformer differential protection are studied. Secondly, this paper analyzes the characteristic of the operating point when differential protection is mal-operated because of CT saturation. At last a method of different time delay in different areas is presented to prevent the differential protection from maloperation. Simulation results validate its feasibility and reliability. It is significant if the method is realized for transformer protection.

关键词： Circuit faults Fault currents Current transformers Surge protection power system protection power system transients Hysteresis Magnetization processes Magnetic flux Saturation magnetization

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Study on assessment method of load's disturbance property

Study on assessment method of load's disturbance property

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3rd International Conference on Deregulation and Restructuring and power Technologies, DRPT 2008

作者： Jia, Xiufang Bo, Zhang Fazhan, Liu Minghao, Sun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China Zhengzhou Power Supply Company Zhengzhou 450012 Henan Province China

ISBN: (纸本)9787900714138

Assessment of load's disturbing property needs to be studied for confirming power quality responsibility and making a power price by its quality. In this paper, load's disturbing property is assessed by means of the analytic hierarchy process (AHP) and the grey relational analysis (GRA). First, the weight of index such as power factor, current total harmonic distortion, unbalance factor and reactive power fluctuation, which can characterize load's property, is obtained by AHP method. In order to assess the degree of load disturbance, a standard load in power system is defined. Then, based on the GRA, can get relativity degree between each disturbing load and standard load. Relativity degree can describe the gap between each disturbing load and standard load. The degree that disturbing loads creates influence to the electrical network is known by means of relativity degree. Finally, Calculating examples are brought forth to validate feasibility of the method. © 2008 DRPT.

关键词： Analytic hierarchy process

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A new approach on implementing Hybrid dynamic simulation based on wide area measurements 16

A new approach on implementing Hybrid Dynamic simulation bas...

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16th power systems Computation Conference, PSCC 2008

作者： Han, Dong Ma, Jin Sheng, Wenjin He, Renmu Yue, Chengyan Zhang, Jin Germond, Alain Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing102206 China ABB Research Center Beijing China Ecole Polytechnique Federale de Laussane Switzerland

ISBN: (纸本)9780947649289

As the most important tool guiding the power system operation and control, digital simulation directly affects the secure and economic operation. Consequently, the dynamic simulation validation work has been highly focused recently. This paper proposes a new method to implement the Hybrid dynamic simulation. With this method, the data from Wide Area Measurements (WAMs) can be injected into the simulations, thus a big power grid is decoupled into several small systems. All data in these small systems are kept when the conventional digital simulation is carried out, while the boundaries of these small systems are replaced by the signals of WAMs. Then the space to search the erroneous component is limited to the decoupled system, which is much smaller with fewer components. Case studies show the efficiency of the proposed method in simulation validation work.

关键词： Geodesy

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Effect of uncertainty in load model on power system dynamic simulation

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第19期28卷 69-74页

作者： Han, Dong Ma, Jin He, Ren-Mu Yue, Cheng-Yan Zhang, Jin Rehtanz, C. Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Limited CNCRC Beijing 100016 China

In order to solve the disadvantages of Mont-Carlo simulation method used in typical uncertainty analysis, this paper adopted a new method-probabilistic collocation method (PCM) to analyze quantitative uncertainties of dynamic load proportion in dynamic simulation and stability analysis. A case study-New England 10-machine 39-bus system, verified the practicability and validity of the proposed method for uncertainty analysis in dynamic simulation. The results showed that the uncertainties in load composition at buses which are close to the fault site and at the buses that have heavy loads, have strong effects on transient stability, while some load buses that have heavy loads, is little far from the fault site, still have stronger effects on transient stability. It is concluded that the proposed method could directly describe the desired output as a polynomial of parameters. Consequently, the probability distribution of the response could be acquired by probability density function of parameters and much fewer simulations.

关键词： dynamic loads

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Reliability evaluation of distribution system with distributed generation based on Islanding algorithm

Reliability evaluation of distribution system with distribut...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies (DRPT)

作者： Guoquan Wang Zongqi Liu Nian Liu Jianhua Zhang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

Distributed generation (DG), which is interlinked with distribution system, will inevitably have an impact to system. In the paper, a reliability evaluation method is proposed, which is based on the analysis to the structure and power flow of distribution system with distributed generation. First, a new concept, the smallest unit, is put forward for improving the fault traversal networks times. The authors use the depth-first search in data structure to divide distribution system into several the smallest units, and propose the islanding operation mode to increase the reliability of the system. Distribution system will be automatically turned into the islanding operation mode once faults occur. To evaluate quantitatively the reliability of distribution system, Monte Carlo simulation method is used by simulating the running status of distribution system. At last, the calculation results of actual case show that the proposed method is available to evaluate the reliability of distribution system with distributed generation.

关键词： Distributed control power system reliability Switches Load flow Substations National security power system security Topology Data structures power system economics

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An integrated approach on allocating the congestion management cost under large consumers electricity direct purchase mode

An integrated approach on allocating the congestion manageme...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies (DRPT)

作者： Yanan Zheng Gengyin Li Ming Zhou Xuanxuan Liu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

With the start of trial operation of direct purchasing electricity for large consumers in China, the method on how to allocate the wheeling charges of large consumers is of vital theoretical and practical significance. An integrated method for allocating the congestion management cost of larger consumers is presented in this paper considering time-of-use (TOU) pricing in congestion period, power supply reliability and the use capacity of the line. Modeling the TOU index, power supply reliability index and use capacity of the line index is proposed. The weights of three indices are determined by interacting between the transmission utility and large consumers based on multilevel models to get comprehensive evaluation indices for all consumers. The integrated indices are used to allocate the cost. Test results show that the method can allocate the congestion cost more reasonably.

关键词： Energy management Costs Energy consumption power supplies power system modeling Pricing power generation IEEE members Load management power industry

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Research on adaptive single-pole reclosing technique for EHV/UHV transmission lines

Research on adaptive single-pole reclosing technique for EHV...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies (DRPT)

作者： Yan Xu Zengping Wang Haofang Liu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Heibei Province China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Heibei Province China

The character of the voltage at the end of the opened phase conductor was studied and an improved voltage criterion was proposed to distinguish between transient and permanent faults. The performance of the improved criterion is hardly influenced by the load currents of healthy phases, transmission line length, fault distance and fault earth resistance. For EHV/UHV lines with shunt reactors, the improved method is also effective when a calculated capacitive coupling voltage is employed. Simulation tests show that the conclusions drawn in this paper are correct.

关键词： Transmission lines Voltage power system transients power transmission lines Inductors Circuit faults Coupling circuits Shunt (electrical) Conductors Frequency

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