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Extra high speed hybrid protection scheme for high voltage transmission line

INTERNATIONAL JOURNAL OF ELECTRICAL power & ENERGY systemS 2014年 63卷 83-90页

作者： Zou, G. B. Gao, H. L. Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Peoples R China

To improve the reliability of traveling wave protection, this paper proposes a hybrid protection scheme based on the traveling wave polarity comparison principle and current differential principle. In this scheme, the traveling wave relay is primary and the current differential relay is supplementary. Two complementary relays simultaneously operate to ensure that the hybrid protection has a good performance. For the general faults, the traveling wave relay can fast discriminate internal faults from external faults using the polarity characteristics of initial current traveling wave. For some special fault conditions, the identification result for fault is determined by the current differential relay. Therefore, the sensitivity and reliability of traditional traveling wave protection may be greatly improved. Using the same hardware platform and only requiring current signal, the hybrid scheme is easily achieved. Simulation results verify that the hybrid protection has fast speed and high reliability level. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Hybrid protection Extra high speed Traveling wave relay Current differential relay Polarity comparison

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Real-time optimal voltage control using measurement-based aggregate load model

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ELECTRIC power systemS RESEARCH 2014年第Nov.期116卷 293-300页

作者： Zhang Yan Zhang Wen Chu Xiaodong Liu Yutian Shandong Univ Minist Educ Key Lab Power Syst Intelligent Dispatch & Control Jinan 250061 Peoples R China

Focused on long-term voltage stability, this paper presents a real-time voltage control scheme using measurement-based aggregate load model to restore system voltages following a contingency. According to the load power restoration feature and wide area measurements, the load model is formulated and corrected in receding horizons, which transforms the hybrid differential-algebraic equations of the power system model into nonlinear algebraic equations with discrete events. A deformed Euler state predictor is proposed to predict system response based on the measurement-based model. The optimal control behaviors are calculated using model predictive control method. By eliminating dynamic equations using wide area measurements, the computation time is significantly reduced. The validation and effectiveness of the proposed method is verified by the simulation analysis on the Nordic 32 20-generator 52-bus test system. (c) 2014 Elsevier B.V. All rights reserved.

关键词： Real-time voltage control Measurement-based load model Model predictive control Long-term voltage stability Load power restoration

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Dead-time elimination method of nine-switch converter

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IET power ELECTRONICS 2014年第7期7卷 1759-1769页

作者： Gao, Feng Tian, Hao Li, Nan Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Peoples R China

This study presents a novel dead-time elimination method for operating nine-switch converter. The proposed method assumes the unique switching cells of nine-switch converter to operate under several subintervals divided during a fundamental period. Owing to the unidirectional conduction characteristics of switching cells, the nine-switch converter can operate without dead-time protection. Besides, for a special subinterval during which none of switching cells can be adopted, a novel switching signal transformation method is proposed to fully eliminate the dead-time protection during the operation of nine-switch converter. Matlab simulations and experimental results verify the effectiveness of proposed modulation scheme.

关键词： switching convertors dead-time elimination method nine-switch converter unidirectional conduction characteristics switching cells switching signal transformation method Matlab simulations modulation scheme

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Enhancing optimal excitation control by adaptive fuzzy logic rules

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INTERNATIONAL JOURNAL OF ELECTRICAL power & ENERGY systemS 2014年第Dec.期63卷 226-235页

作者： Zhang, Hengxu Shi, Fang Liu, Yutian Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Peoples R China

Generator excitation system plays an important role in maintaining power system stability. A new fuzzy control strategy is introduced to enhance excitation control by online coordinating Automatic Voltage Regulator (AVR) and power system Stabilizer (PSS) control tunnels. The method automatically adjusts the weights of the AVR tunnel and PSS tunnel on-line according to different operating conditions by a set of fuzzy logic rules, aiming to improve the overall optimal excitation control performance by the coordination of voltage control and dynamic stability control. The requirements of excitation control in different circumstances are studied, and the fuzzy rules of the coordination are presented. The structure of the presented controller is simple and clear while the conventional design methods in AVR and PSS control tunnels can be kept without change. Numerical simulation results on two cases under different disturbances demonstrate that the proposed controller can get a good performance for a variety of the operating conditions. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Automatic Voltage Regulator (AVR) power system Stabilizer (PSS) Excitation controller Fuzzy logic rules Coordination control

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Short-circuit Field Tests of Shandong Rongcheng Wind Farms and Measured Data Analysis 12

Short-circuit Field Tests of Shandong Rongcheng Wind Farms a...

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12th International Conference on Fuzzy systems and Knowledge Discovery (FSKD)

作者： Wang, Chunyi Yi, Xiuqing Cao, Zenggong Mu, Hong Wang, Hongtao Shandong Univ Tradit Chinese Med State Grid Shandong Elect Power Co Jinan Shandong Peoples R China Shandong Univ Tradit Chinese Med Inst Technol Jinan Shandong Peoples R China Shandong Univ State Grid Shandong Elect Power Co Jinan 250061 Shandong Peoples R China Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Shandong Peoples R China

ISBN: (纸本)9781467376822

In order to verify the short-circuit current characteristics of wind farms and the effects on power grids due to the large scale wind farms integration at Rongcheng substation, Shandong Electric power Company organized the three phase and single phase short circuit tests on Jun 12th, 2014. By using the field tests data got from the digital fault recorder, the short-circuit current characteristics of different types of wind turbines are compared. The wind turbine's contributions of the Squirrel Cage Induction Generator (SCIG), Doubly Fed Induction Generator (DFIG) and Permanent Magnet Synchronous Generator (PMSG) to the system short-circuit current are analyzed in detail. In addition, the short-circuit current characteristics of wind farms are summarized and deeply understood from the field tests data. With the analysis results, the Shandong Rongcheng wind farms short-circuit field tests will have a very good reference and directive significance to the large scale wind power centralized integration of the actual power grids.

关键词： wind turbine wind farm short-circuit tests short-circuit current characteristics

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The Fitting Method of Wind power Forecast Error under power-time Dimension

The Fitting Method of Wind Power Forecast Error under Power-...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Zhaoqing Wang Chengfu Wang Jun Liang Xueli Wang Libin Yang Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Jinan China State Grid Shandong Electric Power Maintenance Company Jinan China State Grid Qinghai Electric Power institute Xining China

ISBN: (纸本)9781467371070

Randomness and volatility are the inherent attributes of wind power, and the present method for forecasting wind power is not accurate enough. However, the exact description of forecast error has obvious effect on optimized scheme of power flow calculation, unit commitment and operation in the power system with wind power. The wind forecast error is different under the power dimension and correlative under time dimension, so it can describe the actual wind power attributes more accurately on the basis of fitting the forecast error divided into different groups according to the power-time attributes. The parameters distribution like normal distribution can not describe the error in different bins accurately, but this paper proposed non-parameter kernel density estimation (NKDE) to fit the error data in various bins, which is also suitable for various forecast methods. If ignoring the characteristic of NKDE, it has poor fitting effect because of too many bins and too few data in some bins. This paper proposed a method to reduce the number of bins to improve the fitting effect and reduce calculation time. Results for this case show the proposed probability density function (pdf) is more close to the actual wind power error distribution.

关键词： error analysis fitting effect power-time dimension correlation

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The application of TCSC for damping inter-area oscillations

The application of TCSC for damping inter-area oscillations

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Jingli Liu Lei Ding Deyu Cai Zhiming Song Key Laboratory of Power System Intelligent Dispatch and Control Ministry of Education Shandong University Jinan China Shanghai Electric Power Corporation Ltd Shanghai China State Grid of China Technology College Jinan China

ISBN: (纸本)9781467381338

This paper presents a wide area control scheme using TCSC for damping inter-area oscillation. In general, TCSC are facilitated over long transmission lines to enhance the power transmission capability. As the inter-area oscillations are associated with heavy power transfer over long transmission corridors, the small signal/oscillatory stability can be improved if an additional damping control can be integrated into the control scheme of TCSC. The paper presents the classic and additional damping control scheme of TCSC. The typical two-area power system and control scheme that are built using `DIgSILENT powerFactory', and the damping control is tested through the classic modal analysis and simulations in time domain.

关键词： power capacitors Thyristors Damping Oscillators Economic indicators power system stability system performance

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DC fault analysis of VSC-HVDC and DC cable protection principle

DC fault analysis of VSC-HVDC and DC cable protection princi...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Pu Zhao Qing Chen Luhua Xing Key Laboratory of Power System Intelligent Dispatch and Control(Shandong University) Ministry of Education Jinan China Shandong University Jinan Shandong CN State Grid Shandong Electric Power Research Institute Jinan China

ISBN: (纸本)9781467381338

Voltage Source Converter (VSC) based HVDC (VSC- HVDC) transmission technology as a kind of new dc transmission, is attracting more and more research. VSCs are susceptible to cable short-circuit fault and ground fault. This paper focuses on the transient characteristics of electrical quantities in a two terminal VSC-HVDC system after the occurrence of short-circuit fault and ground fault. Equivalent circuits and equations are given to calculate the voltage and over-current in cable. Simulations are undertaken in PSCAD to verify the calculation results, and different fault points and fault resistances are considered. Due to the behaviors of DC voltage and cable over-current in faulty cable and non-faulty cable after the ground fault, a DC cable protection principle was proposed to determine the faulty cable and to decide fault within or outside the protected area.

关键词： Circuit faults power conversion power cables Capacitors Equivalent circuits Transient analysis

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Coordinated optimization for controlling short circuit current and multi-infeed DC interaction

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Journal of Modern power systems and Clean Energy 2014年第4期2卷 374-384页

作者： Dong YANG Kang ZHAO Yutian LIU State Grid Shandong Electric Power Research Institute Jinan 250002China Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong UniversityJinan 250061China

Due to increased penetration of renewable energies,DC links and other emerging technologies,power system operation and planning have to cope with various uncertainties and *** order to solve the problems of exceeding short circuit current and multi-infeed DC interaction,a coordinated optimization method is presented in this ***,a branch selection strategy is proposed by analyzing the sensitivity relationship between current limiting measures and the impedance ***,the impact of network structure changes on the multi-infeed DC system is *** the coordinated optimization model is established,which considers the cost and effect of current limiting measures,the tightness of network structure and the voltage support capability of AC system to multiple ***,the non-dominated sorting genetic algorithm II combining with the branch selection strategy,is used to find the Pareto optimal *** studies on a planning power system demonstrated the feasibility and speediness of this method.

关键词： Operation and planning Multiple DC infeed Short circuit current Sensitivity analysis Multi-objective optimization

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A general test scheme for electrical measurement and control unit and its application

A general test scheme for electrical measurement and control...

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

作者： Fei Wang Kui Wang Rui Wang Yuanyuan Geng Jing Xiao Key Laboratory of Power System Intelligent Dispatch and Control (Shandong University) Ministry of Education Shandong University Jinan Shandong Province China State Grid Shandong Electric Power Company Maintenance Company Jinan Shandong Province China

ISBN: (纸本)9781467371070

To improve the generality and flexibility of test scheme, a general digital and analog mixed test scheme, which is based on a computerized model and signal generator has been designed in this paper, the test scheme applies simulation software to produce any kind of digital test signal, which is then transferred to analog signal by signal generator to meet input requirements of the device under test. The measurement value of device under test can be compared with original input value to analyze the measurement precision under all conditions. A test example for PMU Light is given to describe the test process, and the test result shows that the test scheme proposed in this paper can produce any kinds of test signals, it is a general and flexible test means for electrical measurement and control unit with high accuracy.

关键词： Phasor measurement units power industry Decision support systems Measurement units Production Transforms

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