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State Grid Corporation of China, State Grid Smart Grid Research Institute and North China Grid Company | Date: 2017-02-15

A passive high-voltage direct-current circuit breaker and an implementation method therefor. The high-voltage direct-current circuit breaker is connected in a direct-current system in series, and comprises an energy absorption branch, a main branch and a current transfer branch which are connected in parallel, wherein the current transfer branch comprises first current transfer branches (T1, T2) and second current transfer branches(T3, T4); the energy absorption branch is composed of a nonlinear resistor (MOV); and the main branch comprises at least two groups of high-speed mechanical switches (Kl, K2) and at least two groups of full controlled device modules which are connected in series. Since the circuit has a simple topology structure, is simple and convenient to control, and is flexible to apply, the energy required by injecting a current into a capacitor can be obtained from a system without configuring an auxiliary power source, thereby improving the reliability of an apparatus. The used power electronic devices are mainly half controlled thyristors, so that the series connection technology is mature, the capability for current segmentation is strong, the level of withstand voltage is high, the expansion capability is strong, and the costs of devices are low.

State Grid Corporation of China, State Grid Smart Grid Research Institute, China Epri Electrical Power Engineering Co. and North China Grid Company | Date: 2016-01-06

The present invention provides a direct current circuit breaker and its implementation method, which includes the cutout circuit, the commutation circuit and the energy absorption circuit connected in parallel, wherein the cutout circuit includes cutout inductance and cutout unit connected in series, the commutation circuit includes commutation inductance, commutation unit and mechanical switch connected in series, commutation unit has a smaller on-resistance compared to cutout unit. The direct current circuit breaker topology of the present invention is novelty, concise, fully functional, easy to control and can flexible extend to apply to different voltage occasion. Through using power semiconductor switch module to cut off the current, It will have a quickly action, without generating electric arc, while the modular construction also reduces the consistency requirements of the power electronic component, and easy to realize the voltage-sharing of the power semiconductor in series, the capacitor included in the module also plays a role of limiting the current. Commutation circuit and cutout circuit through the full-bridge structure can realize the shunt, reduce the current stress of the power electronic component, and also reduce the component cost.

North China Grid Company, Hangzhou Houda Automatic System Co. and State Grid Corporation of China | Date: 2013-06-19

It is disclosed that an integrated testing apparatus for electric meter being characterized in that it includes a main mounting plate at the four corners of which an inner cover opening hook, a SIM card crimping terminal, an cover opening device, and a network registered jack plugging device being disposed respectively, and at the centre of which a RS232 plug gripping device being disposed. The present invention achieves various actions such as gripping, plugging in and out, rotation or transposition by integrating the inner cover opening hook, the SIM card crimping terminal, the cover opening device, and the network registered jack plugging device, RS232 plug gripper within a main mounting plate, and utilizing the 3-dimensional motion of the manipulator, as well as auxiliary locating by visual locating device, which promotes operation for testing the channels of an electric meter using an entity apparatus with its simple structure, lower cost and high efficiency.

Kang C.,Tsinghua University | Jia W.,Jibei Grid Co. | Xu Q.,Tsinghua University | Liang J.,Jibei Grid Co. | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

As a kind of intermittent power source, wind power makes power systems be confronted with challenges on operation security and stability. The power grid has potential to guide the accommodation of wind power in a wider geographical region, especially in real-time dispatch. The thesis considered constraints of branch power flow and node voltage, took into accounts capability of wind power accommodation (CWPA) of the system and nodes, analyzed the relation among the CWPAs of different nodes, and supported real-time dispatch. An evaluation method of CWPA in real-time dispatch considering security constraints of power grid was proposed, which aims at a certain period in real-time dispatch and evaluates CWPAs of the system and different nodes. Example analysis of IEEE 39-bus test system verified the effectiveness of the proposed evaluation method.

Wang D.,NARI Group | Chen Z.,North China Grid Company | Tu M.,NARI Group | Yang Z.,China Electric Power Research Institute | Ding Q.,NARI Group
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Reserve demand is an important constraint in the optimization for daily generation scheduling, which is also important for the safe grid operation. With large-scale wind power integration, the traditional method of the reserve setting based on conventional energy resources cannot meet the demand of the grid operation security. Considering the intermittence of the wind power, and economical and security factor, an associated model between prediction error of wind farm output and varying reserve capacity is established by using clustering analysis to sift the data of wind farm output. Analysis of actual system examples shows the effectiveness of the proposed model. © 2012 State Grid Electric Power Research Institute Press.

Sun R.,North China Grid Company | Zhang T.,North China Grid Company | Liang J.,North China Grid Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

With the fast development of wind power, the conflict between limited power system regulation capability and increased wind power becomes more and more intense. A comprehensive method of wind power integration capacity assessment is presented, based on power source composition, load characteristics and load regulation capability. Through this method, the impact of wind integration on the reserve capacity is analyzed and the system spinning reserve is calculated based on generation reliability; then wind integration capacity is evaluated according to regulation capability of conventional units. The integration capacity of each month in 2010 is calculated and test results show that the wind integration capacity is much smaller than the planning capacity. At last, measures for maximum wind power integration are put forward according to the wind power curtailment in power grid. © 2011 State Grid Electric Power Research Institute Press.

Wu X.,North China Electrical Power University | Zhang J.,North China Electrical Power University | Qiu W.,North China Electrical Power University | Zhang H.,North China Grid Company
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

Critical segments in power system are closely related to N-k contingency. Vulnerability evaluation has become a hot topic of preventing cascading failures. In order to identify the critical contingency paths, the method of N-k contingency path search and its failure probability model was proposed based on functional group decomposition. Utility theory was introduced to define the severity of the contingency. And a composite risk indicator for N-k contingency was obtained by integrating the various risk indicators, which was based on the entropy and the analytic hierarchy process. According to vulnerability functions of path risk and system structure, vulnerability indicators for N-k contingency were further proposed for the quantitative analysis of vulnerability on contingency paths and the whole grid. Taking a district grid in Henan for example, the vulnerable buses and lines in it were identified. The example analysis demonstrates that, compared with the vulnerability evaluation method considering risk only, the method considering risk as well as structure vulnerability is more accurate and its result is more instructive for power grid monitoring. © 2012 Chinese Society for Electrical Engineering.

Zhang Z.-W.,North China Grid Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

To solve the problem that the VS1 circuit breaker closing coil often burn-out when closing, using a instance to test and analysis at the scene, the reason of the closing coil burn-out is found, and the disposal methods for solving the malfunction are given. At the same time, to avoid the malfunction often appearing, summarizing some detail in routine maintenance.

Liu N.,North China Electrical Power University | Zhang J.,North China Electrical Power University | Zhang H.,North China Grid Company | Liu W.,North China Electrical Power University
IEEE Transactions on Power Delivery | Year: 2010

The security assessment is a key function that should be performed in advance of any security deployment. Since experiences of cyber attack in power control systems are still limited, a complete methodology of security assessment for communication networks of power control systems is needed. According to past research, the difficulties of security assessment include the security analysis of power control process, and the security degree of each control step. Therefore, the attack graph and multiple criteria decision-making (MCDM) are introduced to deal with these difficulties. The overall security assessment is decomposed into two parts. One is the security analysis model for power control systems using attack graph, includes the basic concepts definition, construction algorithm, vulnerability function of each control step, and connection model-based system vulnerability calculation. Another one is focused on the quantification of the security degree in each control stepa hybrid MCDM approach integrated with an analytic hierarchy process (AHP) and a technique for order preference by similarity to ideal solution (TOPSIS) are proposed to value the vulnerability factors derived by the security analysis model. Finally, an instance communication network of power control system is modeling to test the validity of security assessment. The result supports the usefulness of the security assessment. © 2010 IEEE.

Sun R.,North China Grid Company | Singh C.,Texas A&M University | Cheng L.,Tsinghua University | Sun Y.,Tsinghua University
Electric Power Systems Research | Year: 2010

Most of the reliability theory and applications are in the planning domain. When reliability concepts are applied in operations or operational planning, computational burden of the algorithms becomes a bottleneck as the speed of execution of algorithms becomes critical. This paper presents an efficient control variable based dagger sampling technique for reducing the computational effort in Monte-Carlo reliability evaluation for composite systems. The proposed variance reduction method is unique in combining the offline calculations with online computation. A large number of system states are simulated to calculate their consequences offline and stored. Short-term reliability sampling uses the information on offline computed consequences to construct a variance reduction function. In short-term reliability evaluation, the outage probability of each component is much smaller compared to long-term system reliability calculations. Dagger sampling is used to reduce the computation time under this condition. Test results on RTS show the improvement and effectiveness in convergence speed. © 2009 Elsevier B.V. All rights reserved.

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