Definition and classification of power system stability - revisited & extended

Since the publication of the original paper on power system stability definitions in 2004, the dynamic behavior of power systems has gradually changed due to the increasing penetration of converter interfaced generation technologies, loads, and transmission devices. In recognition of this change, a Task Force was established in 2016 to re-examine and extend, where appropriate, the classic definitions and classifications of the basic stability terms to incorporate the effects of fast-response power electronic devices. This paper based on an IEEE PES report summarizes the major results of the work of the Task Force and presents extended definitions and classification of power system stability

Application of real-time voltage security assessment to the Hellenic Interconnected System

The online voltage security assessment methods implemented at the national control centre of the Hellenic Interconnected System, within the framework of the OMASES project funded by the European Union are described. The heart of all computations is a fast time-domain method. Security is analysed with respect to power transfers in critical corridors or power consumption in load areas. Results take on the form of either precontingency secure operation limits, or postcontingency loadability limits, together with various diagnosis tips. Contingency filtering is performed to meet the real-time requirement. Typical results obtained during the test phase of the project are reported.Projet OMASE

Analysis of a voltage instability incident in the Greek power system

The paper reports on a 1996 incident in the Greek power system that had all the characteristics of voltage instability and the subsequent analyses and countermeasures. Voltage stability analysis is performed by both NTUA and ULg software tools that give identical simulation results. After the upgrades performed by PPC a considerable increase in the maximum power that can be fed to the Athens area is achieved. Finally, secure operation limits of the upgraded system are calculated

Basic Theoretical Concepts

Contents 2 BASIC THEORETICAL CONCEPTS 2-1 2.1 DESCRIPTION OF PHYSICAL PHENOMENON 2-1 2.1.1 Time Scales 2-1 2.1.2 Reactive Power, System Changes and Voltage Collapse 2-2 2.1.3 Stability and Voltage Collapse 2-4 2.1.4 Cascading Outages and Voltage Collapse 2-5 2.1.5 Maintaining Viable Voltage Levels 2-5 2.2 BRIEF REMARKS ON THEORY 2-6 2.3 POWER SYSTEM MODELS FOR BIFURCATIONS 2-8 2.4 SADDLE NODE BIFURCATION & VOLTAGE COLLAPSE 2-10 2.4.1 Saddle-node Bifurcation of the Solutions of a Quadratic Equation 2-11 2.4.2 Simple Power System Example (Statics) 2-11 2.4.3 Simple Power System Example (Dynamics) 2-12 2.4.4 Eigenvalues at a Saddle-node Bifurcation 2-14 2.4.5 Attributes of Saddle-node Bifurcation 2-18 2.4.6 Parameter Space 2-18 2.4.7 Many States and Parameters 2-18 2.4.8 Modeling Requirements for Saddle-node Bifurcations 2-21 2.4.9 Evidence Linking Saddle-node Bifurcations with Voltage Collapse 2-22 2.4.10 Common Points of Confusion 2-23 2.5 LARGE DISTURBANCES AND LIMITS 2-24 2.5.1 Dist

Advanced perspectives and implementation of dynamic security assessment in the open market environment

The paper provides a detailed overview of an on-going industrial-research project supported by the EU and involving a large Consortium of Industries, Research Centers, Universities and System Operators. The preliminary phase for analyzing and defining the requirements of a DSA (Dynamic Security Assessment) tool to be included in the EMS (Energy Management System) environment is reported. The decision process to define the hardware and software architecture adopted for the implementation of a prototype is explained. The main features of an advanced DSA tool should allow assessing and improving the network dynamic security into a deregulated market environment. The project development is subdivided into three phases (project requirements and calibration, prototype system development, on-site experimentation) that are reported in the paper. The theoretical bases of the application functions included in the DSA (TSA – Transient Stability Assessment, VSA – Voltage Stability Assessment, TS – Training Simulator and MS – Market Simulator) are described into detail. The final product will be tested on the field at two experimental sites provided by two existing TSOs (Transmission System Operators). The paper also reports the set-up of suitable scenarios for the validation phase of the DSA tool