ABB UNITOL 1020 Compact Digital Excitation Regulator AVR Replacement and Troubleshooting

In the operation and maintenance practice of power plants and industrial self owned power plants, the reliability of the excitation system directly determines the voltage stability, reactive power distribution capability, and fault ride through level of the entire unit of synchronous generators. Similar to the well-known scenarios of "Woodward shutdown module replacement" or "Honeywell safety system troubleshooting" among engineers, a large number of old units are still using analog or early digital automatic voltage regulators (AVRs). These devices face common challenges such as aging and drift of components, shortage of spare parts, and lack of fault diagnosis methods. When the excitation system experiences "no-load voltage instability" or "reactive power oscillation after grid connection", without complete diagnostic data support, on-site investigation often relies on extensive methods such as "changing boards and testing parameters", which is time-consuming and carries the risk of misjudgment.