Harmonic modelling for simulation of HVDC converter stations and wind farms connected to a transmission system

Large capacity offshore wind farms, onshore wind farms and HVDC connections will be common place in the next decade. In the UK, offshore transmission networks are built to accommodate the growth of offshore wind farm connections, leading to the integration of DC (CSC and VSC type HVDC) and AC connections for offshore wind farms and European network integration. These connections are harmonic sources into the transmission system. Therefore, detailed power quality studies for the connections need to be performed by utilities, wind farm and HVDC developers to derive the harmonic limits. The limits become a contractual agreement between the utility and the customer; this is to comply with the relevant engineering standards. For example, `Engineering Recommendation G5/4´ is applied to the connections in the UK as referred to by the UK Grid-code. This paper presents the different technical modelling and assessment criteria for wind farms and HVDC converter stations connected to the UK transmission system.