Research On Strategy Of Emergency Power Control With HVDCs In Complex Systems

In recent years, there has been more and more HVDC transmission projects launched in China, and the network composition is becoming much more complex. On one hand, the increase of transmission lines makes the power system faced with some new safety and stability problems; on the other hand, it also brings a brainstorm in emergency control area. How to make full use of the fast and economic advantage of HVDC emergency control to improve the stability of power system and to achieve a perfect control effect through the corporation of multi-infeed HVDC transmission lines have been a critical technical problems, which is worth studying on.HVDC emergency control is usually realized by the emergency power support function. In order to solve the problems of technical parameters settings and application of emergency power support module, a new type of emergency power support technology, which is achieved by improving the traditional emergency power support module, is proposed in this paper. The power is stepped to the value set instead of ramping up, and signals capable of reflecting the stability of the system in real time area introduced to determine the amplitude value of the emergency power support. A description is made on the basic principle of the new emergency power support module, the method of parameter settings, and the selection of the feedback signals. Then, a new kind of emergency power controller is designed in this paper. A variable coordinated step power control strategy is proposed based on the step-power raising controller. The amount and rate of power increased in each DC transmission line is determined according to feedback signals. This new kind of emergency power transfer strategy can not only enable each DC transmission line to determine the raising amount and rate of power by themselves, but also make sure the full use of the transmission capacity of DC system with the voltage stability of converter bus considered.