Withstand Test Researches Of AC 500 KV Submarine Long Oilpaper Cable

The project of power grid connection between main power grid of China Southern Grid (CSG) and Hai Nan power grid is applied oil-type submarine cable across the Qiong Zhou channel. It is the first grid connection project across the channel in China which is extra high voltage, long distance, and large capacity. This project is adopted 500kV oil-type paper insulation submarine cable. Due to fabrication, transport, installation etc. were affected by many factors, it require on-site withstand voltage test method to assess the insulation quality of laying device after installation that can ensure the Han Nan submarine cable connection reliability. Nevertheless, not only have not the test practical experience but also have not a unified criterion of electrical test of 500kV oil-type paper insulation submarine cable in China at present. Hence, it is significant important to the on-site test method research of submarine insulation situation.Through the research work of experience of oil-type cable commissioning test at home and aboard, and it was used simulation calculation and strict argument to ensure the Hai Nan 500kV power grid connection project of oil-type submarine cable commission withstand voltage test which was the negative polarity DC high voltage test. Moreover, research the long distance 500kV oil-type submarine test method, testing device development, security arrangement, charging current control mode, electrical distribution situation inside submarine cable during voltage raising and discharge period, fault situation analysis, testing result analysis and estimation etc. that supported enabling technologies to on-site withstand voltage test. It was first time to realize successfully on-site withstand voltage test of 500kV long distance oil-type submarine cable in China. There are main research methods and achievements:principle of testing analysis:First, it used the combination method of modeling calculation and comparing arguments. Ensuring the voltage polarity is negative and voltage raising method of testing is cascade voltage raising method. Secondly, according to the formula and finite element analysis method calculated the submarine cable and its destination inner electrical distribution which was supporting basis to testing parameter selection and possible generated fault analysis. Thirdly, it applied analytic method and finite element method to simulate the electrical potential and distribution in space which is supporting basis to select testing security distance. Fourthly, it simulated the possible generated fault condition in testing period and constituted relative solutions. Testing equipment institutionIt has researched a new type direct voltage current generator for large capacity testing equipment (have acquired new utility model patent) and a ultra high power remote control discharge equipment (It is auditing patent of invention)Achievements of on-site implementationFrom theory research results, it have complied the scheme of Hai Nan power grid connection project cable on-site withstand voltage test and prepared work elaborately and strict organized implementation that all three 500kV long distance oil-type submarine cables of Hai Nan power grid connection project have passed the assessment. The successful withstand voltage test of long distance oil-type submarine cable have accumulated a wealth of experience of relative work development in the future.Through conclusion and refinement research results, it have constituted"extra high voltage long distance oil-type cable on-site withstand voltage test guide rule", it have filled up relative area blank in domestic. It have applied occupation standard to China Electricity Council.