Kinetic Energy Of Wind Turbine Research Articles

A Coordinated Frequency Control in Microgrid Based on Asymmetric Synthetic Inertia Considering Rotational Speed of Wind Turbine

AbstractFrequency regulation is an important issue in isolated microgrids with inertia‐less variable renewable energy sources such as wind turbines (WTs) or photovoltaics (PVs) due to the small inertia of the overall system. Synthetic inertia control (SI) using the kinetic energy of WT can provide the microgrid with virtual inertia to mitigate frequency fluctuations. In order to improve the performance of SI, the authors have proposed an asymmetric synthetic inertia control (ASI) in which the virtual moment of inertia is alternating depending on the system frequency and the rate of change of frequency. By increasing the control gain only when the system frequency is moving away from the nominal value, it is expected that ASI contributes to the faster convergence of frequency control. However, another issue is interference between ASI and the rotational speed control for maximum power point tracking of WT. Hence, in this study, a coordinated frequency and rotational speed control strategy was proposed. The rotational speed control can be activated based on a mode‐switching logic when the interference does not occur. The effectiveness of the proposed control strategy was verified by numerical simulations using a microgrid model consisting of diesel engine generators, WTs, a photovoltaic, and a load. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Improved Frequency Control Strategy for Offshore Wind Farm Integration via VSC-HVDC

Voltage source converter based high voltage DC system (VSC-HVDC) has become a very promising solution to integrate offshore wind farm. However, the equivalent inertia of the modern power system with large renewable energy integration becomes small, which will arouse some frequency stability problems. To tackle this problem, this paper proposes an improved frequency regulation strategy for VSC-HVDC integrated offshore wind farm. Firstly, in the frequency decrease stage, the rotor kinetic energy of wind turbines (WTs) is used to suppress the decrease of the frequency, and the control parameters are determined to make full use of the mechanical power and rotor kinetic energy of WTs, the frequency nadir is improved. Secondly, in the rotor speed recovery stage, the DC capacitors of VSC-HVDC are used to release power to compensate the deficiency value of wind farm output power and avoid the secondary frequency drop (SFD) problem. Lastly, the simulation is conducted in PSCAD/EMTDC to validate the effectiveness of the proposed coordinated frequency control strategy.

Fuzzy-Adaptive Frequency Control of Power System Including Microgrids, Wind Farms, and Conventional Power Plants

In this paper, the effect of the increased penetration of wind farms (WFs) and microgrids (MGs) on the frequency control of power systems is studied. WFs are responsible to contribute in load frequency control of power system by changing their injected electrical power. A new control method is proposed to utilize the kinetic energy of wind turbines to support system frequency, considering minimum speed of their rotor. Also, distributed energy resources of MGs, in each area, are controlled to change their active power and adjust the injected power at point of common coupling after a disturbance in the power system. A modified hierarchical coordinated control is used for the optimal control of the entire system. In the first level of this hierarchical control system, each area is optimized and in the second level (coordinator), interactions between areas are adjusted for the global optimization. The parameters of the controller are adaptively adjusted by a fuzzy controller for the best performance in different operating conditions. It is shown that using the proposed control system, the frequency deviations of the power system will decrease.

Application of Bernoulli's law to check the limit value of converting coefficient of wind energy and wind turbine power

This paper presents an application of Bernoulli's law to check the Betz coefficient (the limit value of converting from wind energy to rotational kinetic energy of wind turbine). The calculation method is based on the principle of conservation of mass, conservation of energy, and the relationship between the pressure and speed of air flow moving through a turbine, which is placed in a flow tube. The results show that the limit value of conversion from wind energy to rotational kinetic energy of turbine obtained by our method is consistent with the Betz value published previously.

Stability Enhancement of a Power System Containing High-Penetration Intermittent Renewable Generation

This paper considers the transient stability enhancement of a power system containing large amounts of solar and wind generation in Japan. Following the Fukushima Daiichi nuclear disaster there has been an increasing awareness on the importance of a distributed architecture, based mainly on renewable generation, for the Japanese power system. Also, the targets of CO2 emissions can now be approached without heavily depending on nuclear generation. Large amounts of renewable generation leads to a reduction in the total inertia of the system because renewable generators are connected to the grid by power converters, and transient stability becomes a significant issue. Simulation results show that sodium-sulfur batteries can keep the system in operation and stable after strong transient disturbances, especially for an isolated system. The results also show how the reduction of the inertia in the system can be mitigated by exploiting the kinetic energy of wind turbines.

Coordinated control of TCPS and SMES for frequency regulation of interconnected restructured power systems with dynamic participation from DFIG based wind farm

Among the several wind generation technologies, variable-speed wind turbines utilizing doubly fed induction generators (DFIG) are gaining momentum in the power industry. Increased penetration of these wind turbine generators displaces conventional synchronous generators which results in erosion of system frequency. With this assertion, the paper analyzes the dynamic participation of DFIG for frequency control of an interconnected two-area power system in restructured competitive electricity market. Frequency control support function responding proportionally to frequency deviation is proposed to take out the kinetic energy of wind turbine for improving the frequency response of the system. Impacts of varying wind penetration in the system and varying active power support from DFIG on frequency control have been investigated. The presence of thyristor controlled phase shifter (TCPS) in series with the tie-line and Superconducting Magnetic Energy Storage (SMES) at the terminal of one area in conjunction with dynamic active power support from DFIG results in optimal transient performance for PoolCo transactions. Integral gains of AGC loop and parameters of TCPS and SMES are optimized through craziness-based particle swarm optimization (CRPSO) in order to have optimal transient responses of area frequencies, tie-line power deviation and DFIG parameters.