大型主变压器强制油循环风冷系统不间断电源改造
Improvement of Large Main Transformer Forced Oil Circulation Air Cooling System on Uninterrupted Power Supply

变压器冷却系统的优劣决定了变压器的工作油温状态，影响变压器内部绝缘、运行寿命及带负载能力等。为保证冷却机组安全稳定运行，传统变压器冷却系统控制箱使用两路独立电源供电，但是在两路电源故障时，冷却系统控制回路由于无供电无法控制变压器油温，导致变压器被迫减负。针对此类问题，该文提出一种不间断电源改造方案，通过增加一路具有自启动功能的小型柴油发电机组作为备用电源，并对控制回路进行改进，实现双电源故障情况下自动切换到柴油发电机组供电的功能，以减少电源问题导致的冷却系统故障。目前，该方案已应用于某变电站主变控制系统，实际运行情况表明，该方案运行稳定可靠，特别是能够显著提高重点负荷的供电可靠性。此外，该方案改造成本较低，技术实现难度不大，具有推广价值。
Transformer cooling system determines its oil temperature when it is operating and affects the internal insulation, operating life and its load car-rying capacity, et al. To ensure the safety and stability of the cooling units, the control cabinet of the traditional power transformer cooling system uses two power supplies. However, when two power supplies both fail, the cooling system control circuit cannot control the transformer oil temperature without power supply, which causes the transformer to be forced to reduce its load. Aiming at these problems, this paper proposes a improvement scheme of uninterruptible power supply by adding a small diesel generator set with self starting function as the standby power supply. And it improved the control circuit, which can automatically switch to the diesel generator in case of dual power supply failure, so as to reduce the cooling system failure caused by power supply problems. At pre-sent, the scheme has been applied to the main power transformer control system of a substation. The practice operation shows that the scheme is stable and reliable, especially can significantly im-prove the power supply’s reliability of key loads. In addition, the reconstruction cost of this scheme is low, and the technical realization is not difficult, so it is worth popularizing.