利用两台主变压差形成环流进行保护向量测试

为了改变很多变电站在启动送电时无低压侧出线负荷或负荷暂时很小而导致向量测试困难的现状,文章提出了一种利用两台主变通过调档形成环流从而完成保护向量测试的方法。利用两台自耦主变调不同档位,使得两台主变绕组形成压差,从而形成高中压侧环流或高低压侧环流,实现主变差动及后备保护向量测试和各侧相应流变接入母差向量工作。工程实际测试数据表明,该方法能有效解决出线负荷较低的变电站向量测试的困难,证明了方法的正确性和可行性。

Using Dropout Voltage of Two Main Transformers to Form Loop Current to Complete the Measurement of Protection Vector

Many transformer substations have no outgoing line load at low voltage side, or the load is very small temporarily when the substations start power transmission;this causes the difficulties in vector test. To change this status quo, the paper proposes the following method:using two main transformers to form circulating current by shifting gears, thus completing the protection vector test. Different gears are shifted by the two main autotransformers;this makes the windings of the two main autotransformers form dropout voltages, thus forming the circulating current at high and middle voltage side or at high and low voltage side. It can realize the main transformer differential motion and backup protection vector test, and the corresponding current change at each side can be connected to busbar differential vector protection work. The actual test data of the engineering indicate that this method can effectively solve the difficulty in vec-tor test at the transformer substations with the low outgoing line load;the data prove the correctness and feasibility of this method.