Scientists from Chong Qing University and the Electricity Grids Planning Center of Guangdong Power Grid Corporation in China developed a new method for planning the stand-by capacities for electricity grids with high share of wind generation in the regions subject to tropical typhoons. Their study allowed for high level of accuracy in determining the required capacity margin to guarantee reliable power supply to cities and enterprises even during the times of disastrous typhoons, when wind turbines are compulsory shut down.
Wind generation, especially in the off-shore zones, is growing rapidly in the coastal areas of China: by the end of 2024, over 520 GW of wind generation capacities were commissioned in the country including 39 GW of the off-shore power plants. However, in case of a typhoon, the wind velocity in its center may exceed 25 m/sec, which is higher than the allowable limit for turbine operation. Hence, the entire wind parks may be shut down almost simultaneously, and an abrupt power shortage is observed in the gird (the losses may reach 1.4 GW of generation within just several hours). Standard methods of calculating the required stand-by capacity based on the possibility of one big generator failing, turn inefficient in such cases, because the losses are of much higher scale.
To cope with this challenge, the scientists proposed a two-stage approach. On the first stage, they applied a complex statistical simulation based on Markov’s multidimensional network and on the Monte-Carlo method and developed a set of possible typhoons scenarios. This simulation takes into account the dynamic change of the key parameters — typhoon motion patterns, the velocity and pressure in the center of a typhoon allowing for receiving realistic and varies scenarios including the most pessimistic ones. The decrease of wind generation and the change of load in the grid for the period of 96 hours (the standard duration of a typhoon) are calculated for each scenario.
The second stage was planning the stand-by capacities. At first the researchers defined the economically optimal amount applying the classical cost-benefit analysis to balance the costs of maintaining the stand-by capacities and the economic benefit from improving the reliability. The level of 480 MW turned out the optimal one for the tested system. However, the key novelty was testing the sustainability of such stand-by capacity. Simulating the system operation by hours, the researchers tested if it could withstand not only the typhoon per se, but also any additional failure of a major power plant.
The results showed that 480 MW of stand-by capacity was not enough to prevent outage in the extreme conditions. To exclude the risk of capacity shortage, the stand-by capacity had to be increased up to 516 MW. This is only 36 MW higher, but it was this comparatively small additional stand-by capacity that turned out to be key for assuring complete sustainability in the conditions of natural calamity.
The researchers emphasize the universality of the proposed approach, which may be used not only for typhoons, but for other extreme weather phenomena — ice rains, lengthy droughts or intense cold, which also can jeopardize the stability of the electricity grids operation.
