A Simplified Harmonic Analysis Tool for Wind Farm Connections

A new connection to the electricity network requires the customer to undertake a detailed harmonic analysis study. In the UK, the study is required by the Distribution Network Operator (DNO) in order to demonstrate compliance with harmonic standards and in particular, to check whether or not the connection of the new equipment will cause harmonic limits to be exceeded and/or resonance issues with the network. The harmonic studies are both complex and costly, and are therefore not carried out until the project finances are secured, planning permissions granted and a grid connection offer has been signed. If the harmonic study then shows there to be a predicted problem, additional unplanned and expensive mitigation may be needed. These unplanned costs at a developed stage within the project lifecycle can cause serious and potentially project -threatening problems. A simplified Harmonic Analysis Tool (HAT) has been developed, which allows the user to carry out an early, simplified harmonic assessment based upon a limited set of technical information. This will allow any potential problems to be identified early, so the project can plan to provide the mitigation way in advance of commissioning the detail studies. The HAT has been tested against data produced by a professional software package called PSA. The results show that the HAT produces results which are repeatable and within acceptable accuracy levels, therefore giving the user confidence in the output from the tool.