Papers by Keyword: PSCAD/EMTDC

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Authors: Guang Hao Yang, You Bing Zhang, Ji Yun Yu, Hui Yong Liu
Abstract: In order to study the steady-state performance of modular multilevel voltage source converter (MMC-HVDC), a 21-level MMC-HVDC system is modeled by PSCAD/EMTDC software. This system uses the DC voltage and active power controls, which are designed by the fundamental operation principles and mathematical models of MMC-HVDC. By analyzing the steady-state performance of MMC-HVDC, the corresponding simulation waveforms verify the correctness and validity of the simulation model.
Authors: Yu Sheng Zhou, Yi Yang, Pan Zheng, Jian Wu Zheng
Abstract: Abstract: Once DG is connected into distribution system, the system will turn from single-source radical network to multi-source network. The power flow will also be changed, which might lead to unreliability of the relay protection. Firstly, the paper analyzes the factors which cause these issues, and then proposes a method to accomplish the procedure of restoration, which is based on pilot protection and over-current protection. The method can solve the problems caused by DG’s connecting into distribution system, and improve the efficiency of DG greatly at the same time. Finally, PSCAD/EMTDC simulation results verify effectiveness and correctness of the proposed method.
Authors: Xing Quan Ji, Gui Bin Liu, Lu Yu Cheng, Dan Li
Abstract: With the increasing proportion of distributed generation, higher requirement on power quality of distributed generation system is put forward by utilities. This paper first introduced the main indices and international standards related to power quality, and then built the DFIG dynamic model in which the double PWM converter and variable pitch control strategy were applied. Simulation of power quality of unbalanced system is conducted using PSCAD/EMTDC.
Authors: Chong Xin Xu, Yan Jun Jiao
Abstract: Power generation becomes a main way of using new energy. However, the access of distributed generation(DG) causes the ordinary protection system develop a series of problems. In this paper, the structure of distribution network with DG is introduced firstly.Secondly,it is analysed that the effect that DG brings to distribution network protection, and then a new protection scheme of distribution network with DG is put forward. The segment I, II of direction three-current protection on the line which is at the upstream of DG, and the next line’s segment I, II consists of a simple communication unit. Through the comprehensive judgment of two protections’ action results, fault can be isolated in minimum range quickly and accurately. Finally, the correctness and feasibility of the new protection principle are verified by simulating a 10KV distribution system.
Authors: Lei Dong, Wei Di Li, Wen Ping Zhou, Tian Jiao Pu
Abstract: As the voltage class and transmission capacity of power grid is increasing, the operating environment of JiuAn substation, which is one of the power supply sources of Ultra-High Voltage (UHV) transmission line, becomes more complex. A model of JiuAn substation and its complicated power supply environment is built using the power system software PSCAD/EMTDC, the parameters under typical kinds of fault are simulated, and MATLAB software is used to acquire relay protection feature from the simulation results. Based on the work above, relay protection security of JiuAn Substation under complex power transmission environment is analyzed, which will provide guidance for the substation operation.
Authors: Yuan Deng, Yang Gao
Abstract: In this paper, it uses PSCAD/EMTDC to build simulation system of STATCOM (Static Synchronous Compensator). According to the principle of coordinate transformation and the theory of instantaneous reactive power, it creates self-defined components in PSCAD/EMTDC. The working principle of the system is explained fistly.Then the theory of instantaneous reactive power and the diagram of simulation system is presented. Each functional module is also discussed in detail. Through the simulation test, it emphatically analyzes real-time tracking ability of the system when the capacitive and inductive loads are added. In this way, correctness and validity of the system has been proved.
Authors: Xiong Feng He, Xian Yun Li, Tong Zhou Ji, Hao Peng, Kun Liu
Abstract: For enhancing low voltage ride though (LVRT) capability, this paper proposes a new protection scheme of series dynamic breaking resistor (SDBR) connected to the grid-side inverter (GSI) of directly driven permanent magnet synchronous generator (D-PMSG) wind power system, which has a lot of advantages such as possessing low cost, simple structure and high reliability. The structure, switching control strategy and matched resistance of SDBR are researched. The proposed scheme was then applied to uplift GSI voltage during a fault, maintain active power delivered to grid, inhibit DC-link overvoltage and GSI overcurrent. The simulation analysis shows that the SDBR can substantially improve the LVRT capacity of D-PMSG wind power system in PSCAD/EMTDC.
Authors: Si Yu Chen, Ya Lou Li, Xiao Bo Hu, Li Zhao, Chao Xi Chen
Abstract: This paper introduces the topology and working principle of modular multilevel converter, simplifying its equivalent circuit before obtaining virtual equipotential. On the ground of the theoretical model of equivalent circuit, MMC-HVDC could adapt the same control strategy as the traditional method. So, on the platform of PSCAD/EMTDC, an eleven level MMC Dual-infeed HVDC system is established and nearest level modulation is adopted as its control strategy to sort voltage sharing of the modules. Experimental results prove the validity of the proposed model.
Authors: Fa Yun Ma, Hua Wei Li, Bing Guang Han, Jian Zhong Xu
Abstract: The high-speed railway based on electromechanical integration develops rapidly in China in recent years. In order to improve research for electrified railway, a model of AC-DC-AC electric locomotive is established using electro- magnetic transient software PSCAD/EMTDC. In this paper, a single-phase tri-level rectifier of unit power factor and its control strategy of direct transient current control method are introduced at first. And then the working principles of the voltage space vector control strategy of inverter and the vector control strategy of cage motors are analyzed. The inverter and the motors must be as a whole because of the realization of motor vector control based on SVPWM inverter. At last, a model is established and the correctness and effectiveness of the model can be verified by the corresponding theory results. The simulation model is useful for the analysis of low frequency resonance in locomotives. The results will be applied in the research of mechanics and electric coupling in high speed electrified railway.
Authors: Yuan Deng, Yang Gao
Abstract: There is not a component which can implement the algorithm of space vector pulse width modulation (SVPWM) in the PSCAD/EMTDC. The principle of SVPWM is explained firstly. Then the creating process of the self-defined component and the program flowchart of SVPWM are presented. The algorithms of the subroutine are also discussed in detail. Finally, the simulation is performed by using the self-defined component in the system. Simulation results demonstrate the correctness and validity of the inverter and self-defined component.
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