Online dynamic security assessment (DSA) technology is becoming an important component of advanced application tools in the control rooms of modern power grids. Here, we examine the concept of online DSA, including a sample application at Electric Reliability Council of Texas Inc., and how it provides increased security in comparison to conventional offline systems.
One of the main features of a future smart grid implementation is the reliable and efficient operation of the power system through better monitoring and control solutions. In these attempts, the contemporary Supervisory Control and Data Acquisition (SCADA) system is in a transient period, evolving into a Wide Area Monitoring and Control (WAMC) system. The main feature of this evolutionary system is the incorporation of methodologies that rely on the Synchronized Measurement Technology (SMT) that provides a more accurate visualization of the power system operating condition. Among these methodologies, the state estimator is the original application of the SMT.
The increased complexity of power networks due to the wide diffusion of distributed generation has led smart grid operators to implement suitable solutions for assuring robust control. In particular, two main strategies have been adopted: (i) use of interconnected devices (protection relays, energy meters, PMUs, etc.) equipped with some “intelligence”; (ii) the start of a mass deployment of such devices in many parts of the power network. This way, a huge amount of information can be gathered thus helping implement, in each instant, the “better” decision for the network operation.
Phasor Measurement Units (PMUs), which measure voltage and current synchronized phasors (synchrophasors), along with frequency and rate of change of frequency (ROCOF), are the emerging measurement devices for power network monitoring. Introduced in the late 1980s and first deployed in experimental systems in the early 1990s, they are now assuming a key role in protection and control of modern electric grids, in particular for state estimation in transmission networks.