Uros Kerin

Small signal security index for contingency classification in dynamic security assessment

This paper presents a security index for quantifying the small signal security of power systems. The index refers to the characteristics of system oscillation modes and delivers the degree of change in system security due to contingencies. The index can be of supplemental use in power system contingency screening and ranking. Moreover, the paper suggests the concept of aggregating the index with the established index for dynamic security inference. The aggregation concept allows individual application of each of the indexes in partial security investigations or application of both in the complete security investigations.

Transient stability contingency screening and ranking based on data mining

Contingencies can impact security of power system operations. Severity of contingencies varies with pre-fault conditions. Therefore, it is of interest to use a database of analyzed pre-fault scenarios in order to recognize scenarios similar to the current, thus eliminating the need for continual and extensive on-line CSR, limiting this process only to faults identified as critical in similar cases from a database. Smart grid applications have recently been developed in order to perform supervisory functions, with the crucial goal of reducing the risks associated with insecure operating conditions. CSR belongs to this type of applications. This paper presents a novel approach for carrying out CSR, based on data mining. Considering operational statistics related to loading condition changes, a database was built and employed for system state clustering. Data mining techniques are used for real-time similar state(s) recognition. The proposal is tested on the IEEE 39-bus system. Results demonstrate feasibility of the proposal in on-line CSR.

Dynamic security assessment in system operation and planning — First experiences

This paper presents some results of the first experiences with the operation of the Dynamic Security Assessment (DSA) system. The DSA is a part of a comprehensive network security solution and is based on fast time domain contingency simulations, considering main stability issues in transmission networks, voltage stability, transient stability and small signal stability. The DSA system uses the actual and near future operating points as starting points for the dynamic contingency simulations. The results of the dynamic security analyzes are reduced to one index, represented by a color scheme similar to a traffic light. In case of security problems, the user is led through different layers of visualization to be able to find out the reasons for the problem and identify the events leading to instability.

Dynamic security indication in power systems with large amount of renewables

This paper presents an approach to assess dynamic security of power systems with large amount of renewable generation. The approach involves use of various computational techniques for determining system stability and information on system condition as it operates. It combines simulation domain with control room applications and can be of significant help in alarming power system operators to potentially dangerous conditions. The paper shows main elements of the approach and suggests how it can be implemented into a control room so as to enhance dynamic management and maintaining of power system security.

PMU and DSA based wide area control system: Concept and application in large longitudinal system

In the last ten years PMUs (Phasor Measurement Units) play a more and more important role for the on-line monitoring and analysis of the state of the electrical systems. The reasons for this development are dynamic loading of transmission systems, demand on flexibility of generation, high penetration of renewable generation and decentralized load and generation centers. PMUs today allow measuring current and voltage phasors and execute functions such as power swing recognition and island detection. Indices can be created on basis of measurements, which can be used for alarming, protection and control. A combination of measurements and indices allow for creating an overall PMU index which describes the online state of the system and consequently the change of state (tendency) of the system. The information is created in the phasor data processor (PDP) which can exchange data with a dynamic security assessment (DSA) system or/and SCADA system in order to monitor local and global system states for stability, continuous steady state analysis, short term / forecast stability analysis and remedial actions. Finally, combining PDP, DSA and SCADA enables to enact a wide area protection and control arming and disarming pre-calculated system integrity schemes.

Assessment of power system dynamic security by relying on conventional simulation domain

A contingency evaluation procedure is presented able to efficiently classify system states by completely relying on conventional time domain simulation. The classification is made on the basis of dynamic security criteria including threshold levels of important system parameters and limits of system stability. Dedicated time-domain methods are used for the screening process. All are well established and available in the associated literature. The methods are implemented into the PSS®NETOMAC simulator and controlled through a wrapper interface so as to allow high-level of automatism and flexibility of computations.