Series Compensation to Increase Power Flow: A Case Study on the Irish Transmission System

Ireland presents an interesting case study for transmission network strengthening. The majority of load in the country is located at the nation’s capital, Dublin, in the East, while most of the new conventional generation and renewable generation are found in the South-West. Power is transferred between the two via a 400 kV network. This leads to large cross- country power flows. This power distribution disparity is due to increase. A large thermal generating station which is connected to the 400 kV system in the West, will close by 2025. This generation will be replaced partially with wind generation in the South West, which is connected at 110 kV and 220 kV. This can cause power flow to avoid the 400 kV network, leading to less efficiency, overloading and other issues associated with power flow on lower voltage networks.In this paper, the application of series compensation on the 400 kV transmission network in Ireland for increasing power transfer capability is investigated and a viable solution is found. The lower voltage network is modelled to investigate the effects of 400 kV series compensation on the rest of the network. With our series compensation solution on the 400 kV network, power flows are successfully reduced on the 110 kV network as the lower reactance of the 400 kV network now attracts power to flow through the more stable and less lossy 400 kV network.