Dynamic performance of a radial weak power system with multiple static VAr compensators

The authors describe the dynamic performance of a radial weak, heavily shunt-compensated power system, with three static VAr (volt-ampere reactive) compensators (SVCs) of relatively large rating installed at short distances from one another. Dynamic interactions between the SVC control systems and between them and the network are analyzed by using eigenvalues and frequency-response techniques. Some noteworthy effects concerning the SVCs´ regulator stability that can arise in such systems are described. These effects, revealed in the eigenvalue analysis, were confirmed in TNA simulations. A brief description of the mathematical formulation and the complete system data is also included. Among other results, it is shown that the operation of SVCs with low values of ESCR can exhibit oscillation mode frequencies above 5 Hz, depending substantially on SVC regulator gain. In such cases, the representation of both network dynamics and thyristor time delay is crucial in the analysis if the SVC regulator stability limits