How can I model a SVS for dynamic simulations?
There are three ways of modelling an SVC system:
- Using the SVS Interface in PowerFactory. There are a number of standard controls for SVS in the library that can be used. You will also find two standard frames in the global library (Refer to \Library\Standard Models\Composite Model Frames). This approach is used in the attached file SVCExampleWithInterface.pfd, the SVS interface is a PowerFactory element of the class ElmSvsctrl that is setting the number of connected capacitor blocks and the angle of the thyristor control of the reactance. It also initialises the controller output to zero. This should be used with care since the consideration of the SVS control limits will be then offset by the initial SVC admittance. The interface has the advantage that operates the parallel capacitors when required.
- It is also possible to control the SVS element without an interface. In this case the limits of the control must be properly considered for any initial condition. The parallel capacitors have to be separately modelled and explicitly controlled. See attached file SVCExampleWithoutSVSInterface.pfd. This could be done via a signal or event to the input 'nncap' of the ElmSvs.
- There is also a third possibility available. This could be used if the switching nature of the TSC (thyristor switched capacitors is not important). One could use in this case the input signal 'bsvs', this signal corresponds to the admittance of the whole SVS. A positive input is interpreted as capacitive reactive power while a negative value is interpreted as reactive power consumed by the TCR (thyristor controlled reactor). This implementation is shown in the example project SVCExampleContinuous.pfd.
For more information refer to the technical reference of the ElmSvs.