Abstract
For the controllability of the transmission power of DC transmission channels, the optimal power distribution (OPD) of AC-DC parallel transmission channels is an effective measure for improving the economic operation of an AC-DC interconnected power grid. A dynamic optimal power flow model for day-ahead OPD of AC-DC parallel transmission channels is established in this paper. The power flow equation constraints of an AC-DC interconnected power grid and the constraints of the discrete regulation requirement of the transmission power of DC channels are considered, which make the OPD model of the AC-DC parallel transmission channels a mixed-integer nonlinear non-convex programming (MINNP) model. Through a cone relaxation transformation and a big M method equivalent transformation, the non-convex terms in the objective function and constraints are executed with the convex relaxation, and the MINNP model is transformed into a mixed-integer second-order cone programming model that can be solved reliably and efficiently using the mature optimization solver GUROBI. Taking an actual large-scale AC-DC interconnected power grid as an example, the results show that the OPD scheme of the AC-DC parallel transmission channels obtained by the proposed algorithm can effectively improve the economical operation of an AC-DC interconnected power grid.
Highlights
In recent years, to deal with the issues of uneven distribution of power sources and loads in different regions, long-distance and large-capacity ultra/extra-high voltage transmission techniques have been widely applied to power grids in China
The main contributions of the current study are as follows: (1) A dynamic optimal power flow (OPF) model for day-ahead optimal power distribution (OPD) of AC-DC parallel transmission channels is established. This model accounts for the power flow equation constraints in an AC-DC power grid, the discrete gear position adjustment of the converter transformer ratio, and the regulation constraints of the transmission power of the DC lines in actual operation, which can meet the requirement of formulating the day-ahead OPD schedule of AC-DC parallel transmission channels in actual operation
From the optimization results of three different time intervals, it can be seen that the computational time for solving the mixed-integer SOCP (MISOCP) model was significantly reduced compared with the computational time for solving the mixed-integer nonlinear non-convex programming (MINNP) model
Summary
Algorithm for the Optimal Power Distribution of AC-DC Parallel Transmission Channels. Shunjiang Lin * , Zhibin Yang, Guansheng Fan, Mingbo Liu, Sen He, Zhiqiang Tang and Yunong Song. Received: 20 July 2019; Accepted: 16 September 2019; Published: 20 September 2019
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