Recently, renewable wind energy is enjoying a rapid growth globally to become an important green electricity source to replace polluting and exhausting fossil fuel. However, with wind being an uncontrollable resource and the nature of distributed wind induction generators, integrating a large-scale wind-farm into a power system poses challenges, particularly in a weak power system. In the paper, the impact of static synchronous compensator (STATCOM) to facilitate the integration of a large wind farm (WF) into a weak power system is studied. First, an actual weak power system with two nearby large WFs is introduced. Based on the field SCADA data analysis, the power quality issues are highlighted and a centralized STATCOM is proposed to solve them, particularly the short-term (seconds to minutes) voltage fluctuations. Second, a model of the system, WF, and STATCOM for steady state and dynamic impact study is presented, and the model is validated by comparing with the actual field data. Using simulated PV and QV curves, voltage control and stability issues are analyzed, and the size and location of STATCOM are assessed. Finally, a STATCOM control strategy for voltage fluctuation suppression is presented and dynamic simulations verify the performance of proposed STATCOM and its control strategy.

STATCOM Impact Study on the Integration of a Large Wind Farm into a Weak Loop Power System

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.

Flicker study on variable speed wind turbines with doubly fed induction generators

Models for wind turbine generating systems and their application in load flow studies

Global warming is attracting a growing interest worldwide for the generation of large-scale energy from renewable energy sources as it is free from greenhouse gas emissions. Wind energy is one of the most promising renewable energy sources due to its availability and low cost and due to the fact that it is more efficient and advanced in technology. Hence, harvesting of large-scale wind energy is of prime interest today. However, large-scale integration of wind energy sources creates environmental, economic, social and technical impacts that need to be investigated and mitigated as part of developing a sustainable power system for the future. Government, utilities and research communities are working together to increase penetration of wind energy into the power grid and overcome potential barriers associated with this. This paper presents an extensive and useful survey on wind energy technology and associated implementation issues including effects of wind farms on the nearby locality. This paper also reviews the social, environmental and cost-economic impacts of installing large-scale wind energy plants. Finally, potential technical challenges to the integration of large-scale wind energy into the power grid are reviewed in regard to current research with their available mitigation techniques.

Potential challenges of integrating large-scale wind energy into the power grid–A review

Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a megawatt-level variable-speed wind turbine with a full-scale back-to-back power converter developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated. Reactive power compensation is mostly adopted for flicker mitigation. However, the flicker mitigation technique shows its limits, when the grid impedance angle is low in some distribution networks. A new method of flicker mitigation by controlling active power is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the dc-link voltage of the full-scale converter. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation controller is an effective means for flicker mitigation of variable-speed wind turbines with full-scale back-to-back power converters during continuous operation.

Flicker Mitigation by Active Power Control of Variable-Speed Wind Turbines With Full-Scale Back-to-Back Power Converters

This paper presents an analysis and the modeling of the flicker emission of wind turbines. Measurements compared with international standards are discussed. The paper concentrates on the theoretical aspects of the flicker algorithm, wind turbine characteristics, and the generation of flicker during continuous operation of wind turbines.

Flicker Emission of Wind Turbines during Continuous Operation

This paper presents the modeling and analysis of the flicker of wind turbines. Special emphasis is on explaining the start-up procedure and deriving equations for the calculation of flicker produced by switching operations. The derived equations are compared with intemational standards. The paper includes measurements of the start and stop of different types of turbines. Finally, the paper makes a comparison of flicker limitations at wind parks.

A. Larsson

Papers

Flicker Emission of Wind Turbines during Continuous Operation

Flicker Emission of Wind Turbines Caused by Switching Operations