The output of the PMSG based wind energy conversion system (WECS) is fluctuating in nature due to intermittency of wind speed. The distribution static synchronous compensator (DSTATCOM) incorporated with the battery energy storage system (BESS) is used to smooth the power produced from wind generator system. The control strategy of BESS/DSTATCOM and its integration to mitigate the power fluctuations of grid connected WECS is presented. Three-leg three-phase voltage source converter (VSC) based DSTATCOM is used and the battery current is controlled to smooth the net power injected to the utility grid from wind power generation system. The control strategy implemented has the capability of supplying the required amount of power to the utility with help of batteries. The PQ control strategy is employed to control the three-phase inverter for managing power exchange with the utility grid. The real time wind speed data is considered for the simulation study of the system. The effectiveness of the control strategy of the system is validated through the simulation results in MATLAB/Simulink environment.
2021-08-26 14:08:28
560KB
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摘要——由于风速的间歇性， 基于 PMSG 的风能转换系统（WECS） 的输出具有波动性。 将配电网静态同步补偿器（DSTATCOM） 与蓄电池储能系统（BESS） 相结合， 用于平滑风力发电系统产生的功率。 本文提出了 BESS/DSTATCOM 及其集成控制策略，以减轻并网 WECS 的功率波动。 采用基于 DSTATCOM 的三桥臂三相电压源型变流器（VSC）， 通过控制蓄电池电流来平滑风力发电系统注入电网的净功率。 所实施的控制策略具有在蓄电池的帮助下向公用电网提供所需电能的能力。 采用 PQ 控制策略对三相逆变器进行控制， 实现对与电网进行功率交换的管理。 系统的仿真采用了实时的风速数据。 在 MATLAB/Simulink 环境下， 仿真结果验证了该系统控制策略的有效性。
可用作参考文献、毕设外文翻译。
2021-08-26 14:08:28
801KB
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Abstract —— Due to network events and power system emergencies, doubly-fed induction generator (DFIG) based wind turbines can suffer from low voltage ride through which may result to the disconnection of the DFIG. Before connecting to the electricity grid again, DFIG has to be synchronized to minimize the transient effects and ensure smooth connection to the power grid. In this paper, a direct voltage control based synchronization technique is proposed for DFIG based wind turbines. Additional control features are added to original direct voltage control method for implementation of the proposed synchronization strategy. A grid connection logic is designed and presented for soft connection of DFIG to the grid. The proposed technique is implemented in a DFIG based wind turbine model and tested through simulations with various practical scenarios. Voltage transients, frequency analysis, voltage phase and system stability are analyzed in details and simulation results presented. From the results, it can be revealed that the proposed synchronization technique functions effectively and efficiently. It is also shown that by using the proposed technique, the process of synchronization and grid connection do not introduce any changes into the system, which may cause protection devices to trip or mal-operation.
2021-08-26 14:08:26
1.03MB
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Abstract —— Grid connected wind turbines may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a doubly fed induction generator developed in the simulation tool of PSCAD/EMTDC. Flicker emission of variable speed wind turbines with doubly fed induction generators is investigated during continuous operation, and the dependence of flicker emission on mean wind speed, wind turbulence intensity, short circuit capacity of grid and grid impedance angle are analyzed. A comparison is done with the fixed speed wind turbine, which leads to a conclusion that the factors mentioned above have different influences on flicker emission compared with that in the case of the fixed speed wind turbine. Flicker mitigation is realized by output reactive power control of the variable speed wind turbine with doubly fed induction generator. Simulation results show the wind turbine output reactive power control provides an effective means for flicker mitigation regardless of mean wind speed, turbulence intensity and short circuit capacity ratio.
2021-08-26 14:08:22
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ABSTRACT —— Unbalanced grid voltage sags are the severe challenge for wind power generation system which connected to the grid successfully. The dc bus voltage and output power will fluctuate under unbalanced grid voltage. Moreover, the voltage sags will lead to the increase of peak current, which will bring potential safety hazards to the operation of wind power system. This paper proposes a simple current limiting control scheme without auxiliary equipment, which based on the detailed analysis of the excessive peak current. In this scheme, the machine side converter (MSC) controller adjusts the electromagnetic power according to the power transmitted to the grid by the grid side converter (GSC). Meanwhile, it converts the unbalanced power on the dc-link into the rotor kinetic energy, avoiding the dc-link overvoltage. The GSC controller can not only ensure that the three-phase inverter currents are in the maximum safe range that the converters can bear, but also provide reactive power support for the grid. Furthermore, the fluctuations on dc bus voltage and output power can be eliminated effectively by using the GSC controller. The feasibility of the proposed scheme and the superiority over the traditional control schemes have been verified by simulations under different types of unbalanced voltage.
2021-08-26 14:08:20
2.76MB
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