# Droop Control of a Grid Supporting Inverter and Simulating it in Simulink

Control of DC/AC inverter using Droop Control:

I am having trouble taking this research papers proposal of how Droop Control can be used as a grid supporting voltage source and turning it into a reality within Simulink. I have two main problems with this model that I need some help on:

Droop Control of an inverter:

1. Droop Control of a synchronous generator controls the governor based on the prime mover speed, which is set by the grid it's connected to and the speed set point of the generator.

2. The figure above is a model taken from a research paper “Control of Power Converters in AC Microgrids”.

3. The active power reference and frequency reference are set, $$\P^*\$$ and $$\\omega^*\$$. The measured active power is subtracted from the reference and multiplied by the droop coefficient. This is then subtracted off the frequency reference and integrated to generate a rotor angle position $$\\theta\$$.

Some quick math tells me that if the generator is running under its reference speed then this controller takes the reference frequency and subtracts so then it's below its reference speed. So then it starts injecting power into the grid at a speed slower than the grid? That would be a dead short?

How do you calculate the droop coefficient for models in Simulink? There doesn't appear to be a way to limit the power output of the DC voltage source in Simulink. Is it set by the Droop Control Coefficient? I know droop coefficients are set by $$\\frac{\Delta \omega}{P_{max}}\$$. What would Power max be in this case? Do I set it to a fictitious number like 10 kW?