||Having reliable and stable power supply is essential to the power generation of cogeneration plants. If a power blackout occurs and cannot be restricted to a local area, the subsequent major power blackout may result in substantial losses. The sample cogeneration plant that had undergone multiple reactive power disturbance events, which increased the system voltage and injected the reactive power into the generators, resulting in generator trip due to loss of field. On June 20, 2012, the sample cogeneration plant caused a major power blackout, reflecting that the power system still possessed various shortcomings. For example, the five tie lines in the ML1, ML2, and HF areas were connected to the same bus, resulting in an overly concentrated load. Loads in these three areas were considered critical loads; hence, during the island mode operation, many critical loads must be shed, leading to substantial production losses. The ML2A area did not contain any generator; hence, the island mode operation of this area required shedding every load. After discussion between units of the plant, improvement measures were proposed according to the aforementioned shortcomings to reconfigure the load feeders. Because the cogeneration plant needs to maintain a continuous production process, a six-phase restructuring plan was proposed to gradually modify the load structure of the power system. Previously, a research team has analyzed the modified system of the sample cogeneration plant of its load flow and transient stability, and completed a power system defense plan in April of 2017. The plan reveals that the modified system still possessed problems concerning reactive power disturbance. Therefore, this study conducted a load flow analysis on the restructuring plan to identify which restructuring stage led to the reactive power problem, and improvement measures were proposed accordingly. In addition, reactive power disturbance were evaluated to determine whether under those circumstances, the generators did not trigger the loss-of-field protection mechanism during a leading power factor operation. These evaluations addressed concerns about service reliability.