Large-Scale Inter-Regional Tie-Line Dispatching: A Decomposition-Coordination Framework

Abstract

As High Voltage Direct Current (HVDC) facilitates inter-regional power trading, the Network Flow (NF) based tie-line dispatching framework is employed for market clearing due to its effective quantification of transmission costs. However, the NF based framework encounters three limitations: the extensive model size, inefficient solution approach, and occasional infeasibility, which confine its applicability to large-scale problems. To address these concerns, a novel tie-line dispatching framework is proposed in this paper, including an enhanced modeling technique, an effective decomposition strategy, and an improved coordination algorithm to the optimization problem. Firstly, a dispatching model based on Minimum Power Unit (MPU) is introduced to eliminate the redundant information and reduce the scale of the problem. Secondly, a model decomposition strategy called Virtual Node Decoupling (VND) is presented to enhance computational efficiency. Lastly, a Checked Lagrangian Relaxation (CLR) algorithm is developed to rectify any infeasibility concerns. To validate the effectiveness of our proposed framework, a case study was conducted based on the IEEE-300 system. The outcomes demonstrate that the MPU-VND-CLR framework accurately acquires feasible dispatching solutions. Moreover, for large-scale problems with over 60,000 optimization variables, the model size experiences an impressive reduction by 1/8, while the solution time is significantly shortened to 1/3. This advancement makes it possible for accommodating a twenty-fold increase in market entities within the tie-line dispatching model.