Modeling and Control of Modern Electrical Energy Systems

7Three-Phase DERs

Modeling of three-phase voltage source converter (VSC) was discussed in Section 2.8. It was shown that in the absence of a zero-sequence path for the current, the system can be modeled and controlled in the two-phase stationary () or rotating () domains rather than the original three-phase domain. The domain has conventionally been more popular due the property that the signals are of dc nature and simple integrating controllers can be used (instead of resonant controllers) to remove the steady-state errors (for the balanced grid situations).

This chapter delves into details of various control approaches for a distributed energy resource (DER) employing a three-phase VSC. The flow of the chapter is much similar to Chapters 5 and 6. We start with the power control approach using a current feedback loop (CFL), also called the grid-following (GFL) control. This is called the vector current control (VCC) in three-phase systems and is the most common approach due to its ability to limit the current. Both stationary, , and synchronous, , domain controllers are discussed. ...