ENVIRONMENTAL BENEFITS OF AIS SUBSTATIONS WITH DISCONNECTING CIRCUIT-BREAKERS

摘要

A high voltage disconnecting circuit-breaker (DCB) combines the functions of a conventional circuit-breaker and adjacent disconnectors. Life cycle analysis of a 145 kV DCB in live tank design shows that the equivalent global warming potential (amount of CO_2 released to the atmosphere) is dominated by electric power losses during the service life. As a result of the low SF_6 content and leakage rate, the SF_6 contribution to the global warming potential is relatively low. With an electrically operated Motor Drive, the DCB (or conventional circuit-breaker) has a noise level around 20 dB(A) lower than when equipped with spring operating mechanisms. Use of DCBs means that conventional disconnectors are not required any more and this leads to simplification of the substation. Compared to solutions with conventional circuit-breakers and disconnectors there will be associated savings in environmental impact. An example for a 420 kV substation shows that the savings in global warming potential are of the order of 9 tons of CO_2 emission per bay and year. The major part of these savings is due to the reduction in electric energy consumption during the service life. These savings are about 10 times higher than the savings related to material and construction. The example is quite conservative, since only one conventional disconnector per circuit-breaker is replaced when DCBs are used. In many other cases two disconnectors are replaced, and the environmental savings are correspondingly larger. Substations with DCBs need less maintenance and have lower overall failure risks than corresponding conventional substations. For small substations with DCBs the required space is so much reduced that it is quite feasible to make indoor solutions based on standard AIS equipment. The building architecture can be adapted to local preferences and surroundings, and the substation easily be integrated into densely populated areas.