Suzhou Power Supply Company

Suzhou, China

Suzhou Power Supply Company

Suzhou, China
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Wang Q.,Suzhou Power Supply Company | Xue A.,North China Electrical Power University | Zhang X.,Suzhou Power Supply Company | Shen W.,Suzhou Power Supply Company
Dianwang Jishu/Power System Technology | Year: 2017

Droop control can improve frequency response characteristics of doubly-fed induction generators (DFIGs). It also affects coupling between dynamic characteristics of DFIGs and synchronous generators, influencing system small-signal dynamic stability. In this paper, influence mechanism of DFIG droop control on system small-signal dynamic stability was studied based on damping torque analysis (DTA) method. Firstly, basic principle of droop control was presented. Then, based on an extended two machines system, relationship between frequencies of DFIG access point and synchronous generators were derived. Mechanism of DFIG droop control affecting small-signal stability was revealed with DTA. On this basis, effects of droop control gain on system oscillation mode and its relationship with DFIG location and synchronous machine inertias were analyzed. Finally, effectiveness of the theoretic analysis was verified based on modal analysis method. Analysis results show that droop control nature and extent influencing system oscillation mode are related to DFIG location and system inertia distribution. © 2017, Power System Technology Press. All right reserved.

Shan X.,NARI Group | Zhao J.,Suzhou Power Supply Company | Zhang J.,NARI Group | Li W.,East China Gird Co. | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

An on-line integrated fault diagnosis method of power grid based on three-state (steady, dynamic and transient state)data is proposed. Firstly, proceeding from the data characteristic and the status quo of dispatch automation, an analysis is made of the necessity of on-line fault diagnosis using the three state data. Secondly, starting from the aspects of accuracy, real-time, comprehensiveness of on-line fault diagnosis, a technology of data mining and co-processing based on multi-source information is proposed. Lastly, a look-ahead of the future developing direction in the field of on-line fault diagnosis is given. © State Grid Electric Power Research Institute Press.

Zhou W.,Shanghai JiaoTong University | Zhang P.-C.,Shanghai JiaoTong University | Yang X.-X.,Suzhou Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

Traditional simulation models for computer protections are generally off-line and open-loop, so they fail to meet the need of real time testing as well as research for relay protection. This paper mainly analyzes the significance of the research for real-time closed-loop digital simulation system, indicating that this system can serve as a platform for research, fault analysis, experiment testing as well as education. It illustrates two typical application scenarios of the simulation system and discusses their strengths as well as limitations. According to the classification of protection functions by IEC61850 standard, the paper develops abundant real-time simulation components for protection. Finally, a functional-block diagram protection system based on IEC 61131-3 is developed and embedded in the RTDS, which forms a real-time closed-loop digital simulation system for computer protections. The "soft protection system" has been fully tested, which demonstrates its real time, closed-loop and correct operation based on RTDS.

Zhou J.,Hohai University | Yuan Y.,Hohai University | Yu J.,Suzhou Power Supply Company
DRPT 2011 - 2011 4th International Conference on Electric Utility Deregulation and Restructuring and Power Technologies | Year: 2011

With large-scale integration of wind power, load flow distribution is highly uncertain. It is unrealistic to adopt traditional deterministic load flow calculation for system operation. What is more, load flow in some transmission lines may be increased to a level where a random event could cause the network collapse. A method of combined cumulants and Gram-Charlier expansion (CCGCE) to calculate probabilistic load flow distribution and a research on relieving transmission congestion by FACTS are proposed in this paper. On the basis of a thorough analysis of the international and domestic researches, this thesis firstly introduces mathematical models, including wind power, FACTS and system models. There are two typical FACTS instruments. One is the SVC, modeled with two ideal switched elements in parallel: a capacitance and an inductance. The other is the TCSC, modeled with three ideal switched elements in parallel: a capacitance, an inductance and a simple wire, which permits the value zero. Secondly, it discusses the procedures of Genetic Algorithm, which includes forming initial population, defining fitness function, and application of crossover, mutation and so on. Thirdly, it carries out two simulations. The first simulation demonstrates the accuracy and computational efficiency of CCGCE method by comparing to Monte Carlo method. The second simulation is composed of two parts. The first part is to find out the appropriate location and capacity of FACTS, and the second part is to check the congestion relieving after the installment of FACTS by CCGCE method. Finally, it suggests that the CCGCE method can significantly reduce the computational time, while maintaining a high degree of accuracy on probabilistic load flow calculation, and concludes that after the installment of FACTS, the transmission congestion of power system containing wind farms can be relieved well. © 2011 IEEE.

Zhao J.,Suzhou Power Supply Company | Ji K.,NARI Group | Sun D.,Jiangsu Electric Power Company | Gao Z.,NARI Group | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

To meet further requirements of smart grid development, it has become an extremely urgent demand to realize grid integration operation and coordination control based on panoramic information in provincial and local electric power dispatching center. This paper researches the key technologies of provincial and local integrated power grid dispatch based on grid model, data collection, functional application, etc, realizes dynamic interaction and on-demand sharing of the power grid model, graphics information, real-time data, historical data, fault information and other information, and explores several provincial and local integrated applications. This research topic is the main focus of the smart grid dispatching support system's pioneer projects in Jiangsu. © State Grid Electric Power Research Institute Press.

Ding H.,Suzhou Power Supply Company | Zhao J.,Suzhou Power Supply Company | Su D.,Jiangsu Electric Power Company | Yang Z.,NARI Group | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Based on IEC 61850 and IEC 61970, a power grid modeling strategy is presented to make transition from concentrated modeling for main control center to reference substation model on demand by different control centers. Then it solves on-demand sharing of grid model, substation's wiring diagram and measuring information between smart substations and control centers at all levels, and among control centers at all levels. The research result has been applied to Suzhou's 500 kV Changshu smart substation and smart grid dispatching technology support system pilot projects. © 2012 State Grid Electric Power Research Institute Press.

Guo F.,Shandong University | Zhu G.,Shandong University | Dong X.,Suzhou Power Supply Company
IEEE Industry Application Society - 51st Annual Meeting, IAS 2015, Conference Record | Year: 2015

To solve the problem of fault location in 20 kV medium-voltage distribution network cable line, a method based on sheath grounding current is presented in this paper. When unsymmetrical earth fault occurs, the sheath grounding current contains three ingredients. After analyzing the relationship between induced circulating current flowing in cable sheath and zero-sequence current flowing in the cable core, it is found that the sheath grounding current has characteristics obvious enough to distinguish internal or external fault type. Based on this, sheath grounding current overflowing criterion is proposed which is effective to locate the fault section of cable line. At last, validity of the sheath grounding current overflowing criterion is verified by RTDS simulation results. © 2015 IEEE.

Zhang S.,North China Electrical Power University | Li P.,North China Electrical Power University | Chen C.,North China Electrical Power University | Shi R.,Suzhou Power Supply Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

The variable space narrowing coefficient and the "secondary search" adjustment coefficient of the mutative scale chaotic optimization algorithm are studied, and their determining formulas are proposed. Along with the increase of "secondary search" number and the decrease of variables search space, the variable space narrowing coefficient and the "secondary search" adjustment coefficient decrease continuously to ensure the accuracy of optimization result. Numerical simulation and instance validation verify that, the proposed optimization algorithm is correct and effective. This algorithm is applied to the economic operation of micro-sources in microgrid and their outputs under different objective functions are analyzed.

Liu Z.,Jiangsu Electric Power Company | Liu Z.,Suzhou Power Supply Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2013

A method of rapid monitoring is proposed for the grounding fault and break fault of breaker, based on which, a monitoring system is designed. It consists of the instantaneous discrimination circuit for the instantaneous response to grounding fault and the delayed discrimination circuit for the fast response to break fault, without any possibility of misjudgment during the normal operation of breaker. It can also be used in conjunction with the trip circuit of failure protection to instantly trip the adjacent breaker during the grounding fault or break fault, which avoids the possible harm caused by the long delayed trip of failure protection to grid, equipment and personnel.

Liu Z.,SGCC | Liu Z.,Suzhou Power Supply Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2012

The protective performance of circuit middle breaker in the complete 3/2 connection mode is analyzed for the trigger-refuse-to-act fault and dead-zone fault, which shows that the existing breaker failure protection can not properly remove the dead-zone fault. A kind of breaker failure protection with autoreclosure is proposed, which is composed of the original breaker failure protection circuit, voltage detection device control circuit, autoreclosure circuit and voltage detection circuit. It tests the voltage of main equipment at specific time by the half-cycle detection device of residual-inductive voltage, judges if there is the dead-zone fault of the breakers adjacent to main equipment and then decides if it is necessary to reclose the relevant breakers for the power restoration of main equipment after the action of failure protection, which reduces the outage area during dead-zone fault. With the middle breaker in the complete 3/2 connection mode as an example, the performance of breaker failure protection with autoreclosure is discussed.

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