电热型复合绝缘子防覆冰性能分析

Anti-icing Performance of Electrothermal Composite Insulators

复合绝缘子覆冰会对电网的安全运行造成威胁,将电热型涂料涂覆于复合绝缘子表面能有效防止覆冰。基于传热学理论,建立了复合绝缘子雨凇覆冰时的传热平衡模型,提出了临界防冰功率的计算方法并总结了其影响因素。复合绝缘子临界防冰功率介于0~136.8 W之间,临界防冰电流介于0~4.15 mA之间,环境温度与风速对临界防冰功率与电流有显著影响,而水滴中值体积直径影响较小。根据电路理论,给出了复合绝缘子电热功率的计算方法,推算出防冰用电热型涂层体积电阻率介于0.11 M?·cm与2.36 M?·cm之间。对涂覆石墨含量为20%、23%、25%电热型硅橡胶涂料的复合绝缘子进行了覆冰试验,试验表明以上绝缘子均有一定的防冰效果,防冰性能随涂层电阻的减小而提升。

Icing on composite insulators threatens safe operation of power grid. Electrothermal coating on the surface of composite insulators can effectively prevent icing. In this paper, based on the heat transfer theory, a heat transfer balance model of composite insulators in the glace weather was established. A calculation method of critical anti-icing power was put forward and its influencing factors were summarized. The critical anti-icing power of composite insulators was 0~136.8W and the critical current was 0~4.15mA. Ambient temperature and wind speed had a significant influence on them. However, the influence of medium volume diameter (MVD) of water drops was feeblish. According to the circuit theory, a calculation method of electrothermal power was put forward. The volume resistivity of the anti-icing coating was 0.11~2.36 M?·cm. Icing tests were carried out on the composite insulators coated with 20%, 23% and 25% electrothermal silicone rubber coatings. Results show that above insulators all have certain anti-icing ability. Besides, the anti-icing ability is improved with decrease of the resistance of the coating.