Consideration of Active Power in the SVC Control System for Flicker Mitigation in Wind Farms

Voltage flicker caused by fast power fluctuations is one of the main power quality concerns in grid‐connected wind farms, especially in distribution networks with low reactance‐to‐resistance ( X / R ) ratios. Static VAr compensators (SVCs) are commonly used to mitigate flicker by regulating reactive power; however, conventional SVC control strategies usually neglect the effect of active power variations. This assumption can be acceptable in transmission networks with high X / R ratios, but it is not sufficiently accurate in low‐ X / R distribution networks, where active power variations have a noticeable effect on voltage fluctuations. Therefore, this paper proposes an improved SVC control strategy in which the active power of the wind farm is explicitly included in the compensation process. Moreover, to reduce the adverse effect of the inherent SVC delay caused by power calculation and thyristor firing, a prediction‐based delay compensation approach is applied using adaptive filtering methods, including normalised least mean squares and recursive least squares algorithms. The proposed approach is evaluated using real voltage and current measurements obtained from the Manjil wind farm in Iran under different network X / R ratios. The results show that, in low‐ X / R networks, using SVC without considering active power is not effective for flicker mitigation and can even increase the flicker level compared with the uncompensated condition. A similar behaviour is observed for static synchronous compensator (STATCOM) control when active power is neglected. In contrast, when active power is included in the SVC control, the short‐term flicker severity index is reduced by 33% for X / R = 1 and by 44% for X / R = 0.5. By adding the proposed delay compensation controller to the SVC and predicting both active and reactive powers, the flicker reduction is further improved to 44% for X / R = 1 and 54% for X / R = 0.5. The results obtained from STATCOM also confirm the importance of active power consideration, as the flicker reduction reaches 48% for X / R = 1 and 57% for X / R = 0.5 when active power is included in the STATCOM control. For high‐ X / R networks, the effect of active power becomes negligible, indicating that conventional reactive‐power‐based compensation is mainly suitable for transmission networks, while active‐power‐aware control is essential for effective flicker mitigation in low‐ X / R distribution systems.