Determination of security limits with respect to voltage instability at RTE

This paper reports on the implementation of Voltage Security Assessment tools in the energy management system of RTE, the French transmission system operator. In particular, secure operation limits are determined in voltage sensitive regions. This involves a load increase in the region of concern, covered by a power transfer from various locations throughout the system. The limit is the maximum load power increase such that the system can withstand every contingency of a list. A salient feature of the tool is the use of a simplified, fast time simulation based on the quasi steady-state approximation. This is justified by the presence of controls reacting to the load power increase and the contingency, which makes standard power flow computations inappropriate. The paper also describes the implementation of the tools in the energy management platform of RTE and shows some typical results.