Inverter control modelling for distributed generation feeding into a utility network

With increasing levels of small-scale distributed generation (DG) systems connecting into the electrical grid, there is a growing awareness of potentially adverse interactions between these systems and the grid because of their differing responses to steady state and transient network events. To study these issues, it is important to use simulation models of both the grid network and the DG inverter systems that are sufficiently detailed to realistically represent their real world physical system behaviours. However, inverter systems are usually simulated in detail using specialist packages, which are not particularly suited to modelling larger scale power systems. Similarly, power system simulation packages typically represent inverter systems using simpler averaged models, which do not adequately reflect the inverter´s real dynamic response to transient events. This paper addresses this issue, by presenting a detailed power inverter model developed within the DIgSILENT power network simulation package, which is sufficiently detailed to represent the inverter operation up to the PWM switching frequency, but is still computationally viable for use with larger scale system studies. The DIgSILENT model has been validated against a detailed PSIM inverter model, which has been verified in previous work against a physical experimental system.