Tie-Line Scheduling Based on Equivalents of Regional Power Grids

Tie-line scheduling is a crucial issue to realize the hierarchical dispatch and control architecture in China. At present, tie-line schedule is determined manually by operators, which cannot provide satisfactory results to accommodate the variance of the operational status. Although the optimal tie-line schedule can be computed by joint optimization of multi-regional power grids, which involves the whole interconnected network model and is hard to maintain. In addition, the decentralized methods require frequent communications between different control centers, which are always inapplicable in practical engineer. To cope with this issue, this paper proposes a novel tie-line scheduling method based on the equivalent of regional power grids, which firstly employ an equivalent model to represent a group of units in each region. Then the cost function, ramping rate and other characteristics of the equivalent unit are accurately described by piecewise functions. Finally, the tie-line schedule can be obtained easily without synchronous coordination between control centers. Numerical tests demonstrate the effectiveness of the proposed method.