Failure of a site to meet its required Registered Capacity in MW due to a shortfall in MVAr, is a major cause of delays, and disputes in the renewable energy sector. Such problems are easily avoided by carrying out an initial concept study in the early stages of a project.

The aim of a concept study is simple. Validate the system design and the inverter and transformer selection to demonstrate the site can meet its MW and MVAr performance requirements under the Grid Code or G99, before expensive long lead equipment is ordered. The study can be be used to check if the site needs reactive power compensation equipment. It can also be used to check if there will be any problems with transformer energisation and the need for specific inrush characteristics.

The PQ and VQ diagrams shown below are developed using an automatic script within DigSILENT powerfactory to check the site active and reactive power capabilities against the target Registered Capacity. Where shortfalls are identified the client can then make an informed decision, whether to accept a reduced site capacity, or purchase MVAr compensation equipment.

These studies are quick, easy to perform, and relatively low cost compared to the cost of the site and equipment and an excellent way for developers to mitigate risk. If you are interested please get in touch.

Note – if you are wondering why the VQ diagram shows a sawtooth profile around the edges, this is the script moving through the 132/33kV grid transformer tap settings, to optimise each result.