Reactive Power Optimization Model And Linear Programming Algorithm In AC/DC Hybrid Power Systems

With the development of HVDC technology, AC/DC hybrid power system plays asignificant role in large-capacity and long-distance power transmission. For example, in theWest-to-East power transmission of China Southern Grid, the capability of DC systemsaccount for about60%of all the lines. Taking advantage of flexible operation mode of HVDCsystems and dispatching properly can effectively reduce the active power loss to the lines andimprove the economic benefit of the grid operation.In this paper, we firstly introduce the basic principle of HVDC power transmission andthe power flow calculation methods for AC/DC hybrid system. Compared with characteristicsof the above methods, a practical one is applied to successive linear programming (SLP).Based on the nonlinear model of reactive power optimization and power flow results, thesensitivity of state variables and control variables can be calculated, which is used to built theAC/DC hybrid system reactive power optimization linear programming model. In this paper,the model fully considers the actual operation requirements of the power system. The object isto minimize the active power loss, and inequality constraints in addition to considering thepower of transmission sections. At last, prime-dual interior point method is used to solve theproblem.The real-time data of China Southern Grid is used for test cases. Results verified that theproposed mathematical model and algorithm for AC/DC reactive power optimization can beeffectively applied to large-scale power grid. On the basis of large amount of results, wedeeply discuss the factors influencing real power loss of AC/DC power system.Based on the standard structure of Oracle database, an online software package forAC/DC hybrid system reactive power optimization is developed by using Java language,which provides interface for real-time data transmission from EMS. Combined with operationarrangement, the software achieves the purpose of optimizing the operation plan for future.Beyond that, the additional functions such as power flow calculation, loss statistical analysisand report generation can also satisfy the requirements of power system operation.