In relation to dynamic braking systems for bipole power transmission networks

A bipole power transmission network, comprising:

• a first power conversion means having a first alternating current, AC, side and a first direct current, DC, side, the first AC side for connecting to a first AC network;
• a second power conversion means having a second AC side and a second DC side, the second AC side for connecting to a second AC network;
• a first power transmission means;
• a second power transmission means;
• and
• a neutral arrangement;
• wherein
• the first and second power transmission means interconnect the first and second DC sides of the first and second power conversion means, thereby allowing the transfer of power between the first and second power conversion means;
• the first power conversion means, the second power conversion means, and the first power transmission means, together define a first transmission pole;
• the first power conversion means, the second power conversion means, and the second power transmission means, together define a second transmission pole;
• and
• the bipole power transmission network further comprises the dynamic braking system of any preceding claim, wherein the first dynamic braking unit is electrically connected between the first transmission pole and the neutral arrangement, and wherein the second dynamic braking unit is electrically connected between the second transmission pole and the neutral arrangement.

A computer implemented method of operating a dynamic braking system in a bipole power transmission network, the dynamic braking system comprising a first dynamic braking unit electrically connectable between a first transmission pole and a neutral arrangement of a bipole power transmission network, and a second dynamic braking unit electrically connectable between a second transmission pole and the neutral arrangement of the bipole power transmission network, wherein the first and second dynamic braking units are controllable in-use to regulate respective first and second electrical currents flowing through the first and second dynamic braking units between the first and second transmission poles and the neutral arrangement, the method comprising:

• determining an operating state of the bipole power transmission network;
• determining, based on the operating state, whether a third electrical current is permitted to flow through the neutral arrangement, the third electrical current being equal to a difference between the first and second electrical currents;
• and
• controlling the first and second dynamic braking units to:
• if the third electrical current is determined to be permitted to flow through the neutral arrangement, operate independently of each other;
• and
• if the third electrical current is determined not to be permitted to flow through the neutral arrangement, operate in coordination with each other to balance the first electrical current with the second electrical current, such that the third electrical current is substantially zero.