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Liang Y.,North China Electrical Power University | Liu J.,Tsinghua University | Zhang T.,Beijing Sifang Automation Co | Yang Q.,North China Electrical Power University
IEEE Transactions on Power Delivery | Year: 2017

Circulating current can be decomposed into double line-frequency positive-, negative-and zero-sequence components under unbalanced voltage conditions. First, in order to decrease peak/rms value of arm current, double line-frequency circulating current should be eliminated. Second, ac-side current that consists of positive-and negative-sequence components under unbalanced voltage conditions should be regulated to track the reference signal. Furthermore, fundamental frequency circulating current caused by asymmetry of the upper and lower arm should be also removed. To effectively control ac-side current and eliminate all circulating currents, an arm current control strategy based on a decoupler and proportional-integral controller plus the vector proportional integral (VPI) controller is proposed in this paper. The proposed control strategy works well under balanced and unbalanced voltage conditions as well as asymmetry of the upper and lower arm. In addition, this paper proposes a design procedure for the VPI controller to reduce the uncertainty of this process. A three-phase modular multilevel converter simulation model is set up on PSCAD/EMTDC to verify the effectiveness of the proposed control strategy. © 2016 IEEE.


Liu M.,Tianjin University | Wang C.,Tianjin University | Guo L.,Tianjin University | Zhao B.,Zhejiang Electrical Power Test and Research Institute | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Aimed at the island microgrid integrated with wind turbine, photovoltaic, diesel generator, energy storage, and desalination plant, a multi-objective optimal design model considering the allocation ratio of net present cost (NPC) in the full life cycle, the utilization of renewable energy and the pollutant emission level is proposed. The optimal number of distributed generators and the optimal capacity of energy storage are determined as optimization variables. Based on the established control strategy, a floating elitist preserved genetic algorithm is used to solve this problem. The island microgrid is designed and the simulation results are compared with the HOMER optimization results to illustrate that the proposed method is more reasonable and feasible than that of HOMER. © 2012 State Grid Electric Power Research Institute Press.


Liu M.,Tianjin University | Guo L.,Tianjin University | Wang C.,Tianjin University | Zhao B.,Zhejiang Electrical Power Test and Research Institute | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Considering the operating constraints of typical equipments in a hybrid isolated microgrid consisting of wind power, photovoltaic system, diesel generator, and battery storage, a coordinated control strategy is proposed. The control strategy aims at ensuring a long-term stable operation of the isolated microgrid and reducing the system cost over lifetime. A typical and practical isolated microgrid is simulated via a self-developed simulation tool named quasi-steady simulation and optimization tool for microgrid (QSOT-MG). The simulation results are compared with those of Hybrid2, a simulation tool developed by National Renewable Energy Laboratory (NERL) of USA. The effectiveness and correctness of the control strategy proposed are verified by comparison.


Ren Y.,Beijing Sifang Automation Co | Cao F.,Beijing Sifang Automation Co
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

The profile and technical philosophy of IEC 61850 Ed 2.0 are described. By comparison with IEC 61850 Ed 1.0, an analysis is made of the technical features of IEC 61850 Ed. 2.0 data model, substation configuration language and conformance test. A discussion is made of shifting from IEC 61850 Ed. 1.0 to IEC 61850 Ed. 2.0 with respect to the manufacturer and testing organization. © 2013 State Grid Electric Power Research Institute Press.


Xu Z.Y.,North China Electrical Power University | Xu Z.Y.,Beijing Sifang Automation Co | Su Z.P.,North China Electrical Power University | Zhang J.H.,North China Electrical Power University | And 3 more authors.
IEEE Transactions on Power Delivery | Year: 2014

A new interphase distance relaying algorithm for series-compensated transmission lines is proposed in this paper. The fault impedance can be correctively calculated using the proposed algorithm without requirement of the parameters of series capacitor device. The series capacitor can be simplified as a linearized impedance during the fault period, but its parameters can be used as variables in fault loop equations. The real-time digital simulator tests show that the proposed algorithm can obtain more accurate results than other traditional distance relaying algorithms for series-compensated transmission lines. © 1986-2012 IEEE.


Patent
Beijing Sifang Automation Co | Date: 2013-08-23

An anti-interference switch signal transmission circuit, in which a changeover contact is used at a signal terminal, wherein a normally closed contact is connected to DC, a normally open contact is connected to DC+, and a common terminal is connected to a switch signal acquisition circuit. When no signal exists, DC is connected to a positive input terminal of the switch signal acquisition circuit via the normally closed contact. Since a negative input terminal of the switch signal acquisition circuit is also connected to DC, even if interference is caused, no false signal is generated. When a signal exists, the position of the changeover contact changes and DC+ is connected to DC via the closed normally open contact through the switch signal acquisition circuit thus a loop is formed, so that the signal can be reflected. The interference problem is solved by connecting both the two terminals of the acquisition circuit to DC when no signal exists.


Patent
Beijing Sifang Automation Co | Date: 2013-10-28

This invention relates to a method for making 32-bit addressing of SV data by utilizing FPGA, which may be applied to processing digital sampling data in an equipment of an intelligent substation. Specifically, the method includes the following steps: FPGA receiving naked SV data packages generated based on IEEE802.3 standard; analyzing data structure of Ethernet frame; based on characteristics of the Ethernet frame of the SV data, the SV data of the network byte sequence being reorganized by utilizing ASN.1 coding rules, so that the SV data being converted into a data that can be directly accessed by 32-bit addressing processors. As a result, SV data decoding efficiency is improved greatly. This invention may make the decoding efficiency of 32-bit addressing processor improved by 5-10 times, thus solve problem of declined efficiency due to processing network byte order by splitting and reorganization.


Patent
Beijing Sifang Automation Co | Date: 2014-11-05

The present invention relates to an electrical connector, comprising a connector main body (1) and screws (2, 3). The connector main body (1) includes a housing (4), a multi-socket wire connection structure (5), a multi-socket plug-in connection structure (8), and a multi-socket wire disconnection structure (6). The screws (2, 3) are preferably set screws, which comprise a guide structure (9), a thread structure (10), a fall-off prevention structure (11), and a wrenching structure (12). The present invention has advantages of high connection density, ease of wiring connection, high efficiency, being shock-resistant, loosening-proof and reliable, while meeting the IEC 60603-2 standard.


Ren Y.,Beijing Sifang Automation Co | Cao F.,Beijing Sifang Automation Co
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

The new development and new application of IEC 61850 are analyzed. First, the profile of IEC 61850 is analyzed. Then the technical features of IEC 61850 Ed 2.0 are studied. Finally, the applications of IEC 61850 in different domains are treated including generation, transmission, transformation, distribution, dispatching and information security. For each domain, the standards and technical reports are given. IEC 61850-90-1, IEC 61850-90-2, IEC 61850-90-3, IEC 61850-90-4, IEC 61850-90-5 and IEC 61850-90-7 are analyzed. The application domain and technical features of each technical report are given with an overview of the unreleased technical report provided. © State Grid Electric Power Research Institute Press.


Trademark
Beijing Sifang Automation Co | Date: 2016-08-19

Protection, monitoring, control and automation devices, namely, power line conditioners, circuit breakers, pulse generators for testing electric current, electrical transformers, busbar, electrical reactors, bus coupler, capacitor for power generation, power transmission and distribution, all for transportation and renewable energy industries; Substation automation system comprising electrical controlling devices; Protection and fault information management system comprising electric sensors and sound alarms; energy management system comprising electric control devices for energy management; wide area measurement system comprising clamp meters for measuring electricity and electric meters; distribution management system for power grid comprising electricity distribution consoles; Protection and automation system comprising electric sensors and sound alarms; simulation and training system comprising computer hardware and virtual reality training simulator software in the field of power generation and electrical equipment; generator excitation system comprising static exciters; torsional stress protection and control system comprising transducers that utilize ultrasonic oscillations to treat and reduce stress and fatigue of metals and metal structures; microgrid automation system comprising electrical controlling devices; renewable energy automation system comprising electrical controlling devices; battery energy storage automation system for power generation comprising battery monitors; Power automation system for industrial and transportation comprising electrical power distribution units; Power system time synchronization device, namely, time switches; Power system communication interface device, namely, peripheral component interface (PCI) hardware; Operator interface devices, namely, electronic display interfaces; Phasor measurement unit, namely, clamp meters for measuring electricity; Local control unit, namely, electrical controllers; Intelligent gateway, namely, gateway routers in the nature of computer control hardware; Switching box, namely, electric switch housings; Telecontrol device, namely, electrical controlling devices; static VAR generator and static synchronous compensator, namely, voltage regulators.

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