Control and quantification of kinetic energy released by wind farms during power system frequency drops

Abstract

High wind energy penetration levels in modern power systems draw attention towards wind farms expected role during frequency drops. Wind farms positive contribution required by system operators basically depends on the amount of kinetic energy stored in wind turbines rotating parts and how to manage it during frequency deviations elimination. This study presents an algorithm to estimate and control the quantity of extractable kinetic energy stored in a wind farm during frequency drops. Moreover, it manages stored kinetic energy release within a given time span to achieve positive participation in frequency drops clearance. The proposed method is based on tuning the tip speed ratio before and during the frequency drop according to several factors. The recovery time required by the wind turbine to retain its normal speed is also a function of several parameters including turbine inertia and the incoming wind speed. The proposed algorithm's impact on power system frequency is analysed by assessing the expected enhancement in frequency deviation. A hypothetical grid is considered as the benchmark including detailed modelling for wind speeds, wind turbine and wind farm to improve the creditability of the obtained results. Presented research work outcomes highlight the impact of wind farms replacement for conventional generators. Executed simulations proved that applying the proposed algorithm neutralises wind energy penetration influence on system frequency response, even more, it causes solid improvements unless the incident wind speed is too slow or the frequency drop is too high. Simulation environments are MATLAB and Simulink

Utilising stored wind energy by hydro‐pumped storage to provide frequency support at high levels of wind energy penetration

“…Literature proposed modified operation algorithms to make the WT provides virtual inertial response, and primary support. Such algorithms force the WT to deviate from MPT during normal operation, hence some energy is wasted [6,31].…”

“…Proposed algorithm evaluates ∆P sfixed in per unit through two different methods. The first one sets a predetermined value for ∆P sfixed based on WFs aggregated rating at certain moderate reference frequency drop (in this research; ∆f R = 0.3 Hz) using (6). This equation reflects that, HPSS carries on the role which WFs should play in response to frequency drops.…”

“…The authors preferred to focus on the impact of high and low thresholds for ∆P s-fixed , therefore ∆P s-fixed is not determined using (7), to avoid the dependence on RoCoF. Alternatively, two different values for R WFs are applied, namely, 6% and 10% such that ∆P s-fixed is predetermined using (6). In words, ∆P s-fixed = 0.37 and 0.62 p.u.…”

“…Thereupon, certain ratio from stored kinetic energy is extracted by decelerating WT speed to certain threshold [5,6]. The influence of WFs integration in conventional power systems on system inertia was studied in [7].…”

Frequency Regulation Analysis of Power Systems with High Penetration Wind Power

“…Wind power penetration level is increasing, which takes a threat to power systems frequency stability: 1) VSWTGs cannot provide frequency regulation services due to through power converter integrate into grid and Maximum Power Point Track (MPPT) operation [3]; 2) large-scale wind plants replace the traditional generators, which decreases the capability of inertia response and primary frequency regulation in power systems [4]. Therefore, frequency regulation of power systems with high penetration wind power is need to research topic.…”