Power System Online Stability Assessment using Synchrophasor Data Mining

Traditional power system stability assessment based on full model computation shows its drawbacks in real-time applications where fast variations are present at both demand side and supply side. This work presents the use of data mining techniques, in particular the Decision Trees (DTs), for fast evaluation of power system oscillatory stability and voltage stability from synchrophasor measurements. A regression tree-based approach is proposed to predict the stability margins. Modal analysis and continuation power flow are the tools used to build the knowledge base for off-line DT training. Corresponding metrics include the damping ratio of critical electromechanical oscillation mode and MW-distance to the voltage instability region. Classification trees are used to group an operating point into predefined stability state based on the value of corresponding stability indicator. A novel methodology for knowledge base creation has been elaborated to assure practical and sufficient training data. Encouraging results are obtained through performance examination. The robustness of the proposed predictor to measurement errors and system topological variations is analyzed. A scheme has been proposed to tackle the problem of when and how to update the data mining tool for seamless online stability monitoring. The optimal placement for the phasor measurement units (PMU) based on the importance of DT variables is suggested. A measurement-based voltage stability index is proposed and evaluated using field PMU measurements. It is later revised to evaluate the impact of wind generation on distribution system voltage stability. Next, a new data mining tool, the Probabilistic Collocation Method (PCM), is presented as a computationally efficient method to conduct the uncertainty analysis. As compared with the traditional Monte Carlo simulation method, the collocation method could provide a quite accurate approximation with fewer simulation runs. Finally, we show how to overcome the disadvantages of mode meters and ringdown analyzers by using DTs to directly map synchrophasor measurements to predefined oscillatory stability states. The proposed measurement-based approach is examined using synthetic data from simulations on IEEE test systems, and PMU measurements collected from field substations. Results indicate that the proposed method complements the traditional model-based approach, enhancing situational awareness of control center operators in real time stability monitoring and control

A standards-based service oriented architecture design for substation fault detection

Reliability and security in power supply is a measure of how well an electrical load meets the needs of a consumer at a given point in time. Achieving high levels of reliability requires large capital expenditure. A power system is therefore required to operate at optimal capacity in order to create a return on capital investment. In order to attain a high level of reliability in these operating conditions, there is a need to implement protection processes in power systems to reduce the number and severity of failures to protect components connected to the grid. In South Africa, the power grid has aged and traditional infrastructure that has historically supported consumers is unable to support future requirements. To ensure the continued growth and refresh of grid technologies, industry bodies and committees have established standards and guidelines that challenge the traditional approach to substation systems architecture. Reference process architectures, substation communication and information exchange standards have gained support from utilities and technology vendors over the last decade. A growth in the number of implementations of these standards is proving that the demand for systems integration and interoperability is high and will continue to grow in the future. This demand and its applicability to emerging systems architecture approaches, like service-oriented architecture, are considered in this dissertation. This dissertation uses standards, design patterns and emerging frameworks to deliver a service based fault detection application design. In order to deliver the fault detection process accurately, a subset of UML artefacts represents the fault detection requirements. UML is a basis for model driven design in software engineering. The dissertation proposes the design of a series of software components that are flexible, extensible and manage fault detection information needed to support reliability processes in substations. A deployment model implements the final application design to indicate the placement of specific components in a reference architecture used in this dissertation. The aim of the dissertation is to prove that an application for fault detection in substations can be modular, reusable and flexible in design by using existing software engineering methods and architecture design principles. Keywords: TM Forum NGOSS, IEC 61850, COMTRADE, Service Oriented Architecture, Fault Detection

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen