Before running the simulation, you will first disable the "Step Vref" block by multiplying the time vector by 100. The value of the fault impedance has been programmed to produce a 30% voltage sag at bus B2.
#STATCOM MATLAB SIMULINK MODEL SERIES#
A remote fault will be simulated on both systems using a fault breaker in series with a fault impedance. If you double-click on the "SVC Power System" (the magenta block), you will see a SVC connected to a power grid similar to the power grid on which our STATCOM is connected. We will now compare our STATCOM model with a SVC model having the same rating (+/- 100 MVA). STATCOM compared to a SVC under fault condition If you then run a simulation, you will see that the measured voltage Vm now follows perfectly the reference voltage Vref.ΔΆ. Set the droop parameter to 0 and the voltage regulator gains back to 5 (Kp) and 1000 (Ki). For a given maximum capacitive/inductive range, this droop is used to extend the linear operating range of the STATCOM and also to ensure automatic load sharing with other voltage compensators (if any). This is due to the regulator droop (regulating slope) of 0.03 pu. Looking at the Vm and Vref signals, you can see that the STATCOM does not operate as a perfect voltage regulator (Vm does not follow exactly the reference voltage Vref). You should observe a much faster response with a small overshoot.
![statcom matlab simulink model statcom matlab simulink model](https://image.slidesharecdn.com/modelingandsimulationofadistributionstatcomd-statcomforpowerqualityproblems-voltagesagandswellbasedo-181023091501/95/modeling-and-simulation-of-a-distribution-statcom-d-statcom-for-power-quality-problemsvoltage-sag-and-swell-based-on-sinusoidal-pulse-width-modulation-spwm-2-638.jpg)
To see the impact of the regulator gains, multiply the two gains of the Vac Regulator Gains by two and rerun the simulation. This time constant depends primarily on the power system strength at bus B2 and on the programmed Vac Regulator gains of the STATCOM. Looking at the Qm signal we can determine that the closed-loop time constant of the system is about 20 ms. The signal Qref (magenta trace) is not relevant to our simulation because the STATCOM is in "Voltage regulation" and not in "Var Control". The second graph displays the reactive power Qm (yellow trace) absorbed (positive value) or generated (negative value) by the STATCOM. The first graph displays the Vref signal (magenta trace) along with the measured positive-sequence voltage Vm at the STATCOM bus (yellow trace). Run the simulation and look at the "VQ_STATCOM" scope. Also, make sure that the fault breaker at bus B1will not operate during the simulation (the parameters "Switching of phase A, B and C" should not be selected). This block should be programmed to modify the reference voltage Vref as follows: Initially Vref is set to 1 pu at t=0.2 s, Vref is decreased to 0.97 pu then at t=0.4 s, Vref is increased to 1.03 and finally at 0.6 s, Vref is set back to 1 pu. Close the STATCOM dialog block and open the "Step Vref" block (the red timer block connected to the "Vref" input of the STATCOM). Also, the "droop" parameter should be set to 0.03 and the "Vac Regulator Gains" to 5 (proportional gain Kp) and 1000 (integral gain Ki). Verify that the "Mode of operation" is set to "Voltage regulation" and that "External control of reference voltage Vref" is selected.
![statcom matlab simulink model statcom matlab simulink model](https://www.mathworks.com/help/examples/simscape_product/win64/ssc_simple_mechanical_system_01.png)
Open the STATCOM dialog box and select "Display Control parameters".
![statcom matlab simulink model statcom matlab simulink model](https://ch.mathworks.com/help/examples/sps_product/win64/power_statcom_gto48p_01.png)
We will now verify the dynamic response of our model. This impedance represents the transformer leakage reactance and the phase reactor of the IGBT bridge of an actual PWM STATCOM. On the AC side, its total equivalent impedance is 0.22 pu on 100 MVA. If you open the STATCOM dialog box and select "Display Power data", you will see that our model represents a STATCOM having a DC link nominal voltage of 40 kV with an equivalent capacitance of 375 uF. This STATCOM is a phasor model of a typical three-level PWM STATCOM. The STATCOM is located at the midpoint of the line (bus B2) and has a rating of +/- 100MVA. When the STATCOM is not in operation, the "natural" power flow on the transmission line is 930 MW from bus B1 to B3. The power grid consists of two 500-kV equivalents (respectively 3000 MVA and 2500 MVA) connected by a 600-km transmission line. Contrary to a thyristor-based Static Var Compensator (SVC), STATCOM output current (inductive or capacitive) can be controlled independent of the AC system voltage. Based on a voltage-sourced converter, the STATCOM regulates system voltage by absorbing or generating reactive power. The Static Synchronous Compensator (STATCOM) is one of the key FACTS devices.