Market Clearing with Participation of Cascade Hydropower Stations Based on Variable Dimension Reduction

The optimal dispatching model of cascade hydropower stations features vibration zones, time-delay and nonlinearity. As for the market clearing problem, it is required to increase more discrete variables. At the same time, the network security constraints of hydropower output channels in large hydropower provinces are complex, so that the calculation time increases significantly. In this paper, first, considering the hydro-power coupling constraints, the variables and constraints related to the vibration zone and water level are compressed; then, by Benders decomposition method, the clearing problem is decomposed into the main problem of optimization without security constraints and the sub-problem of network power flow security constraints. In the sub-problem, the unit adjustment value is screened to centralize the units that make a little contribution to security and economy, so as to achieve further compression of unit variable and reduction of solving dimension. Finally, we analyze the calculation example based on the actual power grid data, and the results show that the proposed variable dimension reduction method can effectively reduce the market clearing time with participation of cascade hydropower stations.