Thyristor-Controlled Series Capacitor (TCSC)

We implement the FACTS devices based on the following source:

A. Panosyan, “Modeling of advanced power transmission system controllers”, Ph.D. dissertation, Gottfried Wilhelm Leibniz Universität Hannover, 2010.

Thyristor-Controlled Series Capacitor (TCSC) device is a series element that controles the power flowing through its path by regulating its impedance. The TCSC device is very similar to the Static Var Compensator (SVC) - in fact, it is its series counterpart. Indeed, a TCSC device consists of a parallel circuit of a fixed capacitor and a reactor controlled by a pair of antiparallel thyristors. In contrast to SVC, a TCSC device is connected in series in the power system. For more context, be advised to read the documentation for the SVC elements:

Create Function

Input Parameters

net.tcsc

Parameter	Datatype	Value Range	Explanation
name	string		name of the TCSC
from_bus*	integer		index of the from bus where the TCSC is connected
to_bus*	integer		index of the to bus where the TCSC is connected
x_l_ohm*	float	\(\geq\) 0	impedance of the reactor component of TCSC
x_cvar_ohm*	float	\(\leq\) 0	impedance of the fixed capacitor component of TCSC
set_p_to_mw*	float		set-point for the power flowing through the TCSC element at the to bus
thyristor_firing_angle_degree*	float	:math:90 leq 180	the value of thyristor firing angle of TCSC
controllable*	boolean	True / False	whether the element is considered as actively controlling or as a fixed series impedance
in_service*	boolean	True / False	specifies if the TCSC is in service.
min_angle_degree	float	\(\geq\) 90	minimum value of the thyristor_firing_angle_degree
max_angle_degree	float	\(\leq\) 180	maximum value of the thyristor_firing_angle_degree

*necessary for executing a power flow calculation.

Electric Model

The series impedance \(X_{TCSC}\) of the TCSC element is calculated equivalently to SVC, according to the following equation:

\begin{align*} X_{TCSC} &= \frac{\pi X_L}{2 (\pi - \alpha) + \sin{(2\alpha)} + \frac{\pi X_L}{X_{Cvar}}} \end{align*}

The term \(X_L\) stands for the reactance of the reactor (x_l_ohm) and the term \(X_{Cvar}\) stands for the total capacitance (x_cvar_ohm). The thyristor firing angle \(\alpha\) is the state variable that on the one hand defines the impedance of the element, and at the same time is the result of the Newton-Raphson calculation. The admittance \(Y_{TCSC}\) equals \(-1j \frac{1}{X_{TCSC}}\).

The power flow through the TCSC element is described by the following equation:

\begin{align*} \begin{bmatrix} \underline{S}_{TCSC_i} \\ \underline{S}_{TCSC_j} \end{bmatrix} = \begin{bmatrix} \underline{U}_i \\ \underline{U}_j \end{bmatrix} \begin{bmatrix} \underline{Y}_{TCSC} & -\underline{Y}_{TCSC}\\ -\underline{Y}_{TCSC} & \underline{Y}_{TCSC} \end{bmatrix}^* \begin{bmatrix} \underline{U}_i \\ \underline{U}_j \end{bmatrix}^* \end{align*}

Result Parameters

net.res_tcsc

Parameter	Datatype	Explanation
thyristor_firing_angle_degree*	float	the resulting value of thyristor firing angle of svc [degree]
x_ohm	float	resulting value of the shunt impedance of svc [Ohm]
q_mvar	float	shunt reactive power consumption of svc [MVAr]
vm_pu	float	voltage magnitude at svc bus [pu]
va_degree	float	voltage angle at svc bus [degree]