Abstract: According to the hierarchical and zoned dispatching characteristics of multi-area interconnected AC/DC power systems,an optimal distribution method of active power for tie-lines in long-distance AC/DC parallel trans- mission channel is proposed on the basis of a given total power exchange schedule among regions.In the optimiza- tion model,the minimum active power loss of AC/DC tie-lines is used as the objective function,and,security con- straints of the inter-province AC tie-line sections,as well as the constraints of power regulation range and regulation frequency limit of DC tie-lines,are taken into consideration,Then,a power transmission schedule of AC/DC chan- nels is obtained.Instead of DC power flow model,a practical model called simplified AC power flow model is pro- posed,which is used to calculate the transmission power of inter-province AC tie-lines with hundreds of kilometers in length more accurately.Moreover,for the purpose of satisfying the constraints of DC tie-line power regulation frequency limit and the minimum duration limit of each power state of DC tie-lines,an improved three-stage method is applied to the optimization model.Thus,the optimization model can be decoupled in each dispatch period,and each sub-model can be parallelly computed in each dispatch period.Finally,by taking a practical large-scale AC/ DC interconnected multi-area power system for example,the correctness and effectiveness of the proposed optimiza- tion model and the corresponding solving algorithm are both verified.

Key words: AC/DC parallel transmission channel, active power optimal distribution, DC power flow model, sim- plified AC power flow, improved three-stage method