Smart Hybrid AC/DC Microgrids

4Smart Interfacing Power Electronics Converter Control

4.1 Primary Control of Power Electronics Converters

A typical structure of three‐phase power electronic converters is shown in Figure 4.1. The converter can be an interfacing converter (IFC) from a distributed energy resource (DER) or IFCs linking AC/DC subgrids in the smart hybrid microgrids (the DER includes both distributed generations (DGs) and energy storage systems (ESSs), which can export active power to the grid). Here the converter uses an LCL filter, which is now widely used for grid‐connected converters. To operate such a converter, primary control plays an important role. Primary control of power electronics converters refers to the control scheme used to regulate the basic control variables – current, voltage, power, etc. and ensure important performance like stability, robustness, settling time, etc. In other words, primary control is the fundamental of the converter control system [1]. Due to the demands on control bandwidth and dynamic performance, primary controls are generally applied in local control systems, and all the control variables are directly sampled with low latency and proper bandwidth.

Power converters can have different operating modes in a microgrid, which can be:

• Bi‐directional power control mode: in this mode, the power converter follows a given AC voltage and focuses on controlling the power flow in both directions.
• DC‐link voltage control mode: the power converter adjusts its active ...