Damir Novosel

Use of local measurements to estimate voltage-stability margin

Estimating the proximity of power systems to voltage collapse in real-time still faces difficulties. Beside the data management and computational issues, any central-control method is subject to the reliability of long-distance data communications. In the paper, the authors describe a new data-processing method to estimate the proximity to voltage collapse. The method (code-named SMARTDevice, for Stability Monitoring And Reference Tuning Device) employs only local measurements-bus voltage and load current-and calculates the strength of the transmission system relative to the bus. The collapse occurs when the local load approaches this value. The method is simple enough so that it can be implemented in a numerical relay. The performance of SMARTDevice is compared against the conventional undervoltage relays. It is shown that the latter can misoperate while the new device does not. SMARTDevice is in fact a new breed of voltage relay whose setpoint is automatically tuned to the power system condition.

Wide-Area Protection and Emergency Control

System-wide disturbances in power systems are a challenging problem for the utility industry because of the large scale and the complexity of the power system. When a major power system disturbance occurs, protection and control actions are required to stop the power system degradation, restore the system to a normal state, and minimize the impact of the disturbance. In some cases, the present control actions are not designed for a fast-developing disturbance and may be too slow. The report explores special protection schemes and new technologies for advanced, wide-area protection. There seems to be a great potential for advanced wide-area protection and control systems, based on powerful, flexible and reliable system protection terminals, high speed, communication, and GPS synchronization in conjunction with careful and skilled engineering by power system analysts and protection engineers in cooperation.

Dawn of the grid synchronization

In summary, the findings described in the article should serve as a base for deployment of individual roadmaps by the users and guide vendors to prioritize their development to support the grid revitalization and reliability for the 21st century.

Impact of renewable distributed generation on power systems

The traditional approach in electric power generation is to have centralized plants distributing electricity through an extensive transmission & distribution network. Distributed generation (DG) provides electric power at a site closer to the customer, eliminating the unnecessary transmission and distribution costs. In addition, it can reduce fossil fuel emissions, defer capital cost, reduce maintenance investments and improve the distribution feeder voltage conditions. In the case of small residential photovoltaic (PV) and wind systems, the actual generator locations and DG penetration level are usually not apriori known. The following study attempts to calculate the boundaries of the impact of randomly placed distributed generators on a distribution feeder. Monte Carlo simulations are performed, and boundaries for overall improvements are determined. The study shows that the knowledge of total penetration of small PV systems is sufficient to estimate the effects of DG on the feeder.

A new frequency tracking and phasor estimation algorithm for generator protection

Digital generator protection is a complex and difficult problem. Analog and solid state methods have been successfully applied to generator protection in the past and implementation of these functions in a digital device is a continuing trend. This paper explores a new method to implement frequency tracking and phasor estimation in a numerical relay. A new algorithm is presented which utilizes a variable window discrete Fourier transform (DFT) for frequency tracking. Use of the DFT to compute the phasor estimates at a frequency other than the assumed frequency is outlined first. Next, a new technique for tracking the frequency is outlined. The paper concludes with testing of the new algorithm.

Algorithms for locating faults on series compensated lines using neural network and deterministic methods

This paper investigates a scheme to improve the reach measurement of distance relays and fault locators for series compensated power lines. A deterministic method and a feedforward neural network method have been implemented for online calculation of the voltage across a nonlinear capacitor installation. These techniques are compared and incorporated into a new relaying scheme which is independent of the series capacitor installation, operation of the capacitor protection, and the surrounding power system elements. The proposed scheme is simple and accurate and requires only local voltage and current at the bus. Detailed testing using EMTP has been done to show the benefits of the new adaptive scheme. The results demonstrate the suitability of the techniques for real world applications.

Shedding light on blackouts

Analysis of recent disturbances reveals some common threads among them, leading to a conclusion that some disturbances can be prevented. As there are no perfect solutions to prevent blackouts, which are usually caused by a complex sequence of cascading events, a number of different measures need to be undertaken to minimize the impact of future disturbances. This paper attempts to list some of the common causes, to offer various solutions, and to highlight the need for prudent investment and deployment of well-defined and coordinated overall plans to prevent blackouts.

IEEE PSRC Report on Global Industry Experiences With System Integrity Protection Schemes (SIPS)

This paper is a summary of the IEEE Power System Relaying Committee report on the System Integrity Protection Schemes (SIPS) survey. The SIPS role is to counteract system instability, maintaining overall system connectivity, and/or to avoid serious equipment damage during major system events. The survey describes industry experiences with this category of protection schemes applied to protect the integrity of the power system. It is designed to provide guidance for SIPS users and implementers based on surveyed operating practices and lessons learned. The survey includes a global participation through the comprehensive effort of IEEE and CIGRE.

IEEE PSRC Report on Performance of Relaying During Wide-Area Stressed Conditions

This paper is a summary of the IEEE Power System Relaying Committee report. It describes the performance of protective relays during wide-area stressed power system conditions. First, the behavior of protection functions during dynamic operating conditions is described. Then, the lessons learned from studying recent wide area disturbances, as well as the operational history of protection performance during stressed system conditions, are analyzed. Finally, methods of implementing protective relay functions to prevent further propagation of system-wide disturbances are presented.

Performance evaluation of phasor measurement systems

After two decades of phasor network deployment, phasor measurements are now available at many major substations and power plants. The North American SynchroPhasor Initiative (NASPI), supported by the US Department of Energy and the North American Electric Reliability Corporation (NERC), provides a forum to facilitate cultivating the efforts in phasor technology in North America and globally. Phasor applications have been explored and some are in todays utility practice. The IEEE C37.118 Standard is a milestone in standardizing phasor measurements and defining performance requirements. To comply with the IEEE C37.118 and to better understand the impact of phasor quality on applications, the NASPI Performance and Standards Task Team (PSTT) has prepared two comprehensive documents which leverage prior industry work (esp. in WECC) and international experience. The first document describes PMU testing based on both IEEE C37.118 requirements and required dynamic performance tests. The second document describes characterization of PMUs and instrumentation channels based on practical information. This paper summarizes the accomplished PSTT work and presents the methods for phasor measurement evaluation to assure consistent PMU system performance.