Sizing of Neutral Reactors for Magnetically Controlled Shunt Reactors Connected Directly to Power Lines

In recent years there has been a growing interest in application of 220-500 kV MCSR as line reactors, caused by the need to increase throughput capacity of power lines. When MCSR is connected directly to power line, it should perform all functions of a fixed line reactor, including secondary arc extinction during single-phase auto-reclosing (SPAR) cycles. A feature of MCSR design is the presence of a delta-connected winding, which causes strong electromagnetic coupling between phases of MCSR and increases the secondary arc in-feed current. Therefore, it is of scientific and practical interest to develop measures aimed at limiting the arc current to a level, at which reliable SPAR is ensured, also minimizing recovery voltage and, as a consequence, reducing SPAR dead time. One of the possible solutions is to use a neutral reactor in combination with boosting MCSR reactive power consumption. The paper is dedicated to the development of this approach. Quasi-stationary modes of MCSR with a neutral reactor are considered during SPAR dead time from the point of view of the impact on the secondary arc current. A comparison is made with a traditional solution - fixed line shunt reactor with a neutral reactor, when both solutions provide the same degree of compensation of the arc in-feed current.