Disconnectors reliability on the French grid and means to reduce the consequences of their failures on the electrical system

摘要

The function of a disconnector is quite simple on a mechanical and electrotechnical level: to isolate or to connect part of a grid on various electrical nodes, to establish an electrical continuity and to allow the transfer of current between 2 isolated parts of a substation. This apparent simplicity has probably led to pay less attention to the reliability of this equipment by being satisfied, for example, with an indirect signaling of the position of its HV contacts, and the lack of information to apprehend if they are still able to fulfill their function over time. Indeed, the active part and the control cabinet of these devices are constantly subjected to external climatic conditions which generate, on one hand, more important aging phenomena than for other equipment, with 2/3 of the hotspots detected on the network, and on the other hand, makes its kinematics subject to mechanical seizures. However, any network operator knows that the consequences of a disconnector failure (bus bar fault, total loss of the substation) are very disproportionate with the anomaly causing this failure (loss of clamping in the linkage, erroneous information). After a summary of the behavior of the disconnectors on the French grid and the main consequences for the system operation, this article presents the ongoing developments, tested as demonstrators in some RTE substations to make these devices more reliable. These developments are based on communication and lean on: - Torque measurements in the control cabinet that detect either an early seizure in the kinematic and require intervention for maintenance or a break in kinematics by the detection of sub-torque. - Pressure and temperature measurements at the male and female contacts of the live parts in order to guarantee the closed position of the disconnector to the operator with a nominal transit capacity and to follow up this pressure and temperature evolution with time to detect any aging of the device. - The measurement of the actual position of the active parts when opening to guarantee the minimum isolation distance, especially when the disconnector is operated remotely. A presentation of the implementation of these different solutions and their benefits for a Transmission System Operator is carried out.