电力变压器油箱内部故障压力特征建模及仿真

Modeling and Simulation of Pressure Characteristics of Power Transformer Tanks' Internal Faults

鉴于变压器内部故障后压力升高可能导致油箱开裂、起火及爆炸等事故,长期以来,电力变压器一般装有瓦斯继电器和压力释放阀用于故障切除及油箱过压力释放。但由于业界对其深入研究不足,且鲜有理论创新和性能改进,目前广泛使用的瓦斯继电器存在速动性不足、可靠性较低及阈值难以整定等缺陷。通过分析变压器内部故障造成油箱内压力升高的瞬态物理过程,建立了变压器油箱内部故障压力震源及其波传播的数学模型,有限元仿真变压器内部故障后油箱内压力升高变化情况,得到不同时刻下油箱内部压力分布云图及不同位置压强升高曲线。仿真计算结果揭示了变压器电气网络故障与油箱内非电气量表象之间的关系,为研究基于故障压力特征的数字式瓦斯保护提供理论基础和仿真平台。此外,通过与电力变压器油箱内电弧故障压强升高试验结果的比较,验证了所建模型及仿真手段的正确性。

In view of the transformer internal fault that would lead to the tank cracking, fire, explosion and other serious accidents, power transformers are usually equipped with pressure relief valve and gas relay. However, due to the lack of theoretical innovation and performance improvement, the deficiencies of speed and reliability remain in the existing protections. This paper provides a theoretical foundation and a simulation platform for the study of＇novel transformer digital gas protection based on fault pressure characteristics, by establishing the mathematical model of transformer tank internal fault pressure source and its wave propagation transient process. The internal pressure change process after various types of faults are simulated by FEM. This paper obtains the tank internal pressure distribution at different time and plots pressure rise curve of four positions inside the simulation tank after interturn short circuit fault. In addition, by comparing with the real transformer arc fault test results, the model proposed in this paper was verified.