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The difference between parallel reactors and series reactors

Shunt reactor is generally connected to the end of the EHV transmission line and ground, reactive power compensation.

The parallel shunt reactors can compensate the capacitive charge current of the line, and the voltage of the system is restrained and the overvoltage of the operation occurs to ensure the reliable operation of the line.
Bus series reactors can constrain the short-circuit current and maintain a high residual voltage on the bus. The capacitor series reactor can constrain the higher harmonics, down reactance.
The series reactor is mainly used to limit the short-circuit current. It is suitable for series connection with the capacitor bank, so as to suppress the distortion of the grid voltage waveform, reduce the inrush ratio of the capacitor bank and control the overcurrent of the capacitor bank caused by the higher harmonics of the capacitor bank.

The parallel shunt reactor can compensate the capacitive charging current of the line and limit the system voltage rise and the operation overvoltage to ensure the operation of the line. Bus series reactor can limit the short circuit current, to maintain a high residual voltage bus. The capacitor series reactor can limit the higher harmonics, reducing reactance.
Series reactor and shunt reactors have obvious differences, series reactor mainly from the current limiting and filtering; shunt reactors mainly reactive compensation, the following details:

The main role of series reactor is to suppress high harmonics and limit the closing surge. Bus series reactor can limit the short circuit current, to maintain a high residual voltage bus. The capacitor series reactor can limit the higher harmonics, reducing reactance. Preventing harmonics from damaging the capacitors and avoiding excessive amplification and resonance of the harmonics from the access of the capacitor devices.

Shunt reactor reactive power compensation (generally connected to the end of the EHV transmission line between the ground). The parallel shunt reactor compensates for the capacitive charging current of the line and limits the system voltage rise and overvoltage operation to ensure the reliable operation of the line. For EHV long-distance transmission lines, the charging power of the line capacitors during no-load or light-load is very large. Generally, the charging power increases sharply with the flatness of the voltage. In addition to the huge charging power, the power frequency voltage increases In addition, it will increase the line power and power loss and cause self-excitation, over the same period difficulties and other issues.