Dynamic model and impact on power quality of large hydro‐photovoltaic power complementary plant

Summary In recent years, with the rapid growth of photovoltaic (PV) power development and utilization, part of the PV power could not be transmitted to the power grid owing to the impact of PV power fluctuation on power quality, leading to a serious PV power rejection in some areas in China. A high‐order model of a hydro‐PV power plant is developed in this paper not only to predict hydropower compensation for PV power fluctuation but also to consider the impact of complementary regulation on power quality. Compared with the existing complementary models, the presented model accurately reveals the effect of water hammer on power quality, low‐frequency power oscillation, and power antiregulation phenomenon during the complementary regulation. Although the complementary control of the hydro‐PV power plant helps to suppress power fluctuation, when the PV power and objective power are negative covariation, the hydropower needs more regulation, which will cause an increase in frequency fluctuation. Moreover, with the increase of the ratio of hydro‐PV power in the power grid, the frequency fluctuation amplitude increases accordingly. Especially, when PV power exceeds the regulation ability of the hydropower, the system frequency deviation will increase rapidly. These problems are worth the attention to the future development of PV power. Elastic water hammer model is considered in the hydro‐solar complementary system. Harmful phenomena have occurred during complementary regulation. Hydro regulates opposite to solar power change, causing frequency deviation increase.