文档介绍：Impedance Model-Based SSR Analysis for TCSC
Introduction
The utility industry has been concerned with subsynchronous resonance (SSR) issues in Type-3 wind generator with series-compensated network.
The authors have published a series of papers on this topic employing eigenvalue-based analysis and frequency domain impedance-based analysis.
Compared with eigenvalue-based analysis where an entire system’s dynamic state matrix, eigenvalues, and participation factors will be examined, impedance modeling approach is a frequency domain approach.
Introduction
a simple example of impedance-based stability analysis.
The current in the system can be written as
Introduction
for the stability analysis, it has been assumed that the source voltage is stable when it is unloaded and the load current is also stable when powered from an ideal source. This is the same as both V (s) and ZL1(s) are stable, such that stability of the current (Is(s)) depends on the stability of second term in the equation.
Naturally, a circuit analysis problem now converts to a feedback control problem and
the stability of the system can be judged by the loop gain .
Nyquist stability criterion can be applied to detect instability for this feedback control system.
Introduction
To examine the impact of line parameters on SSR,
we only need to concern the line impedance model.
Therefore, impedance modeling approach can provide insights into investigation of resonance stability.
And the dynamic phasor-based modeling approach can be used to develop impedance model for TCSC.
Impedance Model of TCSC
With the assumption of a sinusoidal imposed voltage, the fundamental frequency current through a thyristor-controlled reactor (TCR) can be obtained and further the inductance can be expressed as
Impedance Model of TCSC
Therefore, a simple TCSC impedance model per-phase can be expressed as
Impedance Model of TCSC
The dynamic phasor model for the fundamental volta