As the inverter-based generation increased in the electric generation, the grid is weakened and the inertia and short circuit power is lost. The main aim of the thesis is to demonstrate that the installation of synchronous condenser can improve the frequency waveform during a power transient and the terminal voltage of the inverter during a fault.
A small 50 MW grid with 25 MW synchronous generation and 25 MW solar farm supplying a 50 MW load is simulated in PSCAD. A 5 MW additional load will be added and the frequency waveform is observed. A synchronous condenser will be added and the difference in frequency waveforms are compared.
The next simulation is about voltage on the inverter terminal during a three-phase fault. A solar farm is connected to a short transmission line and the other end of the transmission line is a voltage source. A short circuit will be produced at the voltage source and the voltage waveform of the inverter terminal is observed. A synchronous condenser will be added and the difference in voltage waveforms are compared.
The simulation showed the initial rate of change of frequency and the frequency nadir during a power transient improved by the connected synchronous condenser.
The voltage of the inverter terminal had a slight improvement with the connection of the synchronous condenser. However, better improvements were observed in the output power of the inverter and the DC link voltage. The inverter is less likely to be disconnected due to lower rise of the DC link voltage during a three-phase fault near the inverter.
The inertial response can be improved with the installation of a synchronous condenser. The rate of change of frequency is reduced directly due to the improved inertial response. The frequency nadir can be increased depends on the situation and it can be increased in this simulation. The output power of the inverter can be increased if there is a synchronous condenser supporting the voltage by providing large amount of reactive power. The accumulation of energy in the DC link capacitor is reduced and so is the DC link voltage. The chance of the inverter remains connected improved because of the smaller increase in DC link voltage.