Results on a Real-Time Wide-Area Control for Mitigating Small-Signal Instability in Large Electric Power Systems

Abstract

This paper proposes a real-time centralized controller for addressing small-signal instability related events in large electric power systems. The proposed system is meant to be a safety net type control strategy that will detect and mitigate small-signal stability phenomena as they emerge in the system. Specifically, it will use wide-area monitoring schemes to identify the emergence of growing or undamped oscillations related to interarea and/or local modes. Rules are developed for increasing Multi-Prony method's observability and depecdability. When the central control unit detects an oscillatory mode with low or negative damping ratio, say less than one percent, the controller devices, initially working in voltage regulation mode, into a full interarea active power damping operation for correcting the damping level of the problematic mode. This paper presents a set of rules and results for the application of a Multi-Prony algorithm in real-time for detecting the onset of the oscillations. This centralized wide-area controller is shown to be effective on a validated western American large-scale power system model of the August 10, 1996 blackout event.

Designing the Next Generation of Real-Time Control, Communication, and Computations for Large Power Systems

“…This work shows the effectiveness of this rule above by analyzing the nature of the interarea mode in the Kundur two-area system, and the rule is also verified in a WECC large-scale example, namely, a validated model of the 10 August 1996 western blackout from [27]. Specifically, the simulations in [28] show that the oscillatory WECC instability of 10 August 1996 could possibly have been prevented with the implementation of the proposed wide-area control. The rules for reliable oscillation detection were tested in [28] using the actual wide-area measurement data that was recorded during the 10 August 1996 disturbance.…”

“…11. The recent doctoral dissertation [28] at WSU provides a full design for the small-signal stability real-time controller. We discuss the salient features of the controller in this section.…”

“…The dissertation [28] proposes the following simple rule for the SVC PSDC design. The SVC is chosen so that it lies on the sending or the receiving end of a critical intertie line that is participating in the oscillatory mode.…”

“…Specifically, the simulations in [28] show that the oscillatory WECC instability of 10 August 1996 could possibly have been prevented with the implementation of the proposed wide-area control. The rules for reliable oscillation detection were tested in [28] using the actual wide-area measurement data that was recorded during the 10 August 1996 disturbance. Based on this data, if the threshold for controller action had been set at say 1 damping for any oscillatory mode, then the controller would have reliably concluded the emergence of the instability for the 0.25-Hz WECC interarea mode at about 34 s after the initiating disturbance of Ross-Lexington line outage.…”

“…On the other hand, Adelanto is located on the receiving end on the receiving end of the COI MW flow, and hence Adelanto PSDC is designed as a phase lag control with the COI MW flow as the PSDC input. Simulations in [28] show that the oscillatory instability of 10 August 1996 could have been prevented by triggering either of the two SVC devices into the PSDC operation as defined above. The two SVCs were operating in the normal voltage regulation mode during the 10 August 1996 event, and they experienced the diverging oscillations like the rest of the WECC system.…”