Executive Summary

Power system stability can be defined as the property of a power system to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance.

The dynamic behavior of power systems is rapidly changing due to the increasing penetration of converter interfaced technologies and the gradual decommissioning of the coal-based power plant, which lead to power flow redistribution among the networks.

As a result, various categories of stability, such as transient and small-signal stability (i.e., inter-area oscillations) may change and worsen. Moreover, currently unobserved converter driven resonance phenomena may arise.

To fulfill dynamic security of the managed power systems Transmission System operators are setting up advanced applications for monitoring and control of instability phenomena.
Phasor Measurement Unit technology and the Wide Area Monitoring System are universally recognized as enablers.

Mantaining the synchronism among the electric generators connected to the power system (i.e. rotor angle stability) and mantaining steady acceptable voltages at all buses (i.e. voltage stability) are the main concerns for most of the responses to the survey.

Expected future RES penetration will significantly impact the system stability, require likely the need for system defense plans upgrade for a secure and economic operation of the power systems.
Increasing attention to stability issues, demonstrated by the fact that almost all the interviewees developed a Wide Area Monitoring System with advanced application for stability monitoring.
Reduced stability margins can jeopardize the quality and reliability of supply.

Instability phenomena can lead to severe incidents such as islanding events, system splits, cascading faults, blackouts, and equipment damage.

A proper management of such phenomena requires the development of adequate monitoring system able to reliably capture in early warning the arise of stability issues assessing the severity and consequently trigger countermeasures activated by control room operators, that usually require costly power flow redispatching.