New measurands for converter-dominated power systems
As electrical power networks become dominated by converter-connected devices, the system behaviour becomes increasingly a function of digital power-electronic control algorithms. The controls are embedded within generators, loads, storage devices and HVDC interconnectors. These controls are unique to every manufacturer, and can be updated periodically, or even in real-time. Some devices behave as current sources, some devices behave as voltage sources, and some devices may be able to switch between the two modes. Some devices cause harmonic and unbalance “pollution”, while other devices tend to “mop up” the pollution. Some devices can provide services such as fast frequency response, inertia, synchronising torque, fast fault current infeed, and grid “stiffness”, but the behaviour is determined by control software which can be changed in real time. Defining, measuring, and distinguishing between these services in real-time is far from trivial. The network operator needs to provide certain levels of such critical services at all times, but to do so requires mandation through grid codes, or payment incentive mechanisms. This raises the question of how to test, verify and/or meter the complex services that a device is providing, in real time, using an appropriate assessment device. This presentation explores a range of entirely new measurands and measurement devices which may need to be developed over the next 5-10 years, in order to support the transition to a stable converter-dominated EU power system.
About the speaker
Andrew Roscoe is a Senior Lecturer in the Department of Electronic and Electrical Engineering at the University of Strathclyde. His research interests are focussed on power systems with high penetrations of converter-connected resources: converter control techniques and “grid-forming” converters, frequency and ROCOF measurement and management, and real-time power hardware-in-the-loop and simulation techniques. He is a member of the IEEE Synchrophasor working group, a member of the CENELEC TC8X “System aspects of electrical energy supply” WG07 “Power frequency measurement for DER management”, and a member of the ENTSO-E Expert Group on “Fault Current Contribution and Converter performance related aspects in power systems with 50-100% penetration of RES”.