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This paper presents an output power smoothing method by a simple coordinated control of DC-link voltage and pitch angle of a wind energy conversion system (WECS) with a permanent magnet synchronous generator (PMSG). The WECS adopts an AC-DC-AC converter system with voltage-source converters (VSC). The DC-link voltage command is determined according to output power fluctuations of the PMSG. The output power fluctuationsin low- and high-frequency domains are smoothed by the pitch angle control of the WECS, and the DC-link voltage control, respectively. By using the proposed method, the wind turbine blade stress is mitigated as the pitch action in high-frequency domain is reduced. In addition, the DC-link capacitor size is reduced without the charge/discharge action in low-frequency domain. A chopper circuit is used in the DC-link circuit for stable operation of the WECS under-line fault. Effectiveness of the proposed method is verified by the numerical simulations. [ABSTRACT FROM AUTHOR]

With the increasing trend of connecting high penetrations of wind energy conversion systems (WECSs) to the transmission networks comes the challenge of updating the grid code for the connection of megawatt-class wind turbines. Starting with each WECS entity in the wind farm, the specifications would require the ability to complement some of the power system control services - voltage and frequency control - currently carried out by conventional synchronous generation. This paper investigates output power stability of a WECS ma highly fluctuating wind environment. Based on a performability model, a control strategy is devised for maximizing energy conversion in low to medium winds, and maintaining rated output in above rated winds while keeping torsional torque fluctuations to a minimum. Control is exercised via collective blade pitch control as well as generator torque control. The fundamental philosophy behind the proposed control strategy for the wind turbine coupled to an asynchronous doubly fed induction generator is general and can be easily extended to other WECS configurations. [ABSTRACT FROM AUTHOR]

The rapid expansion of wind power generation has brought problems involving lightning strikes to the fore. Many such incidents have damaged not only the wind turbine that was actually struck but also other turbines that were not, a phenomenon that has yet to be fully explained. In this paper, the authors present a case study using a wind farm model with multiple wind turbines connected to a power system. The aim is to clarify the influence of the grounding system on surge propagation from a wind turbine that has been struck to others which have not, during a winter lightning strike. Sensitivity analyses show that the surge propagated to nearby wind turbines can sometimes become large, depending on the conditions of the grounding system, and result in the burnout of surge arresters in turbines that have not been struck, especially during winter lightning strikes. [ABSTRACT FROM AUTHOR]

Wind energy is not constant and windmill output is proportional to the cube of wind speed, which causes the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce fluctuation, different methods are available to control the pitch angle of blades of windmill. In a previous work, we proposed the pitch angle control using minimum variance control, and output power leveling was achieved. However, it is a controlled output power for only rated wind speed region. This paper presents a control strategy based on average wind speed and standard deviation of wind speed and pitch angle control using a generalized predictive control in all operating regions for a WTG. The simulation results by using actual detailed model for wind power system show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A hybrid power system uses many wind turbine generators in isolated small islands. The output power of wind turbine generators is mostly fluctuating and has an effect on system frequency. In order to solve this problem, we propose a new power system using renewable energy in small, isolated islands. The system can supply high-quality power using an aqua electrolyzer, fuel cell, renewable energy; and diesel generator. The generated hydrogen by an aqua electrolyzer is used as fuel for a fuel cell. The simulation results are given to demonstrate the availability of the proposed system in this paper. [ABSTRACT FROM AUTHOR]