Inverter control method

In power system, there are three ways to control Inverter.
1) P/Q control method
2) V/f control method
3) Droop control method

1. Distributed Generation and Micro grid ASSIGNMENT Submitted By, Bhavisha Patel

2. TOPIC List control modes of inverter for Distributed Generation(DG). Explain any of two in detail.

3. V/f control In V/f control, the inverters output constant voltage and frequency to ensure continual operation of slave DGs and sensitive loads after the micro grid is isolated from the grid. Given the limited capacity of the micro grid in islanded operation, once power shortfall occurs, it is necessary to shed some less important loads to ensure continuous supply to sensitive loads. As such, this control mode requires the ability to respond to and trace load switching. Figure A shows the schematic diagram of V/f control, where outer-loop voltage control and inner-loop current control are adopted and the reference voltages V ldd * and V ldq * and measured voltages V ldd and V ldq are specified

4. Figure A: Diagram of V/f control.

5. Droop control Droop control is realized by simulating the droop characteristic of generators in a traditional grid and controlling the output voltage and frequency of the voltage source inverter (VSI) according to variation of the output power. The control strategy is based on inverter parallel-connection technology. As all DGs are integrated to the micro grid via inverters, the micro grid in islanded operation is equivalent to multiple inverters being connected in parallel, and the active and reactive output of individual inverters are, respectively, Where V is the integration voltage, Vn the output voltage of the inverter power supply, Xn the output impedance of the inverter power supply, and δn the included angle between Vn and V .

6. Figure B : Droop Characteristics