Qualification Process of a GIS 400 kV SF6 High Voltage Circuit Breaker Controlled Switching Solution

摘要

During the past decades and thanks to major improvement of intelligent electronic devices (IEDs) in terms of reliability and costs, controlled switching solutions applied to high voltage circuit-breakers have offered a relevant electronic alternative to more conventional methods, usually used to reduce the switching transients and electrical constraints on the equipment. These controlled switching solutions are now embedded into so-called point-on-wave (POW) controllers.The success of controlled switching relies on two fundamental principles:1. Identification of a target moment for connecting or disconnecting loads and sources favourable to transient mitigation;2. Reliable estimation of the duration of the operation for the device being controlled in order to achieve effective switching operation at the predetermined target.Thus, one of the challenges in controlled switching application lies in the prediction of the duration of the operation, subject to the contingencies of the operating conditions.This paper describes the detailed qualification process conducted for a controlled switching solution at 420 kV level together with the deployment on the field. A focus is made on 2 types of applications for which National Grid in UK requires implementation of controlled switching solution:1. Controlled de-energization of shunt reactor2. Controlled closing of capacitive loads at zero voltage which is recognized as the most difficult duty.The first qualification process is related to the POW controller ability to operate accurately according to a pre-set switching sequence under various ambient and severe EMV conditions particularly present in GIS substation. The second one is oriented to the associated high-voltage circuit-breaker and its parametric model is established according to the new IEC technical report TR 62271-302 [1] issued by IEC and based heavily upon the work of Cigré WGA3.07 [2]. The third one consists of associating the POW controller with the said circuit-breaker to operate in power laboratory live synchronized switching operations. Finally, some site live start-up observation and performance evaluation are provided as a conclusion of this process.