Correct option is A
· A DC reactor, also known as a smoothing reactor, is connected in series with each pole of a converter station primarily to prevent commutation failures in the inverter.
· Inverter commutation failures can occur due to disturbances or sudden changes in the DC current. These failures can cause the inverter valves to misfire, leading to potential system instability and loss of power transmission capability.
· The DC reactor helps by providing a smoothing effect on the current, reducing the rate of change of current (di/dt) during disturbances. This smoothing effect mitigates the chances of commutation failures by ensuring a more stable current flow through the inverter valves.
