A Policy Switching Approach to Consolidating Load Shedding and Islanding Protection Schemes

In recent years there have been many improvements in the reliability of critical infrastructure systems. Despite these improvements, the power systems industry has seen relatively small advances in this regard. For instance, power quality deficiencies, a high number of localized contingencies, and large cascading outages are still too widespread. Though progress has been made in improving generation, transmission, and distribution infrastructure, remedial action schemes (RAS) remain non-standardized and are often not uniformly implemented across different utilities, ISOs, and RTOs. Traditionally, load shedding and islanding have been successful protection measures in restraining propagation of contingencies and large cascading outages. This paper proposes a novel, algorithmic approach to selecting RAS policies to optimize the operation of the power network during and after a contingency. Specifically, we use policy-switching to consolidate traditional load shedding and islanding schemes. In order to model and simulate the functionality of the proposed power systems protection algorithm, we conduct Monte-Carlo, time-domain simulations using Siemens PSS/E. The algorithm is tested via experiments on the IEEE-39 topology to demonstrate that the proposed approach achieves optimal power system performance during emergency situations, given a specific set of RAS policies.Comment: Full Paper Accepted to PSCC 2014 - IEEE Co-Sponsored Conference. 7 Pages, 2 Figures, 2 Table

Simulación de un esquema de alivio de carga considerando el efecto de amortiguamiento de carga

El presente documento muestra el desarrollo de un sistema de protección mediante el uso de la metodología o cálculo del ROCOF (Rate of change of frequency) para conseguir un deslastre de carga adaptativo que permita una recuperación de frecuencia del sistema acelerado evitando que posibles fallos en diversas etapas del sistema lleven al colapso del mismo, para ello se hace uso del software especializado en sistemas de potencia denominado DIgSILENT PowerFactory para la simulación de eventos de fallo y análisis de todos los parámetros importantes de una red de transmisión, los resultados son comparados entre aquellos escenarios en los que el sistema de protección se encuentra desconectado y aquellos en los que el sistema ya se encuentra en operación bajo diferentes tipos de fallo y condiciones adversas. El sistema de protección es ensayado en un sistema tipo IEEE de 14 barras obteniendo mejoras en el valor final de frecuencia milisegundos o segundos después del evento de falla, la variación de frecuencia también encuentra puntos en los que ocasiona que la frecuencia caiga con menor rapidez y a la vez permite acercase a valores nominales con mayor rapidez frente a esquemas no adaptativos.This document shows the development of a protection system through the use of the methodology or calculation of the ROCOF (Rate of change of frequency) to achieve an adaptive load shedding that allows an accelerated system frequency recovery preventing possible failures in various System stages lead to the collapse of the system, for this purpose, specialized software is used in power systems called DIgSILENT PowerFactory for the simulation of failure events and analysis of all the important parameters of a transmission network, the results are compared between those scenarios in which the protection system is disconnected and those in which the system is already in operation under different types of failure and adverse conditions. The protection system is tested in a 14-bar IEEE type system obtaining improvements in the final frequency value milliseconds or seconds after the failure event, the frequency variation also finds points at which it causes the frequency to fall less quickly and At the same time, it allows to approach nominal values more quickly against non-adaptive schemes

Esquema de alivio de carga por subfrecuencia ocacionado por desastres naturales basado en segmentación óptima de cargas.

En el presente documento se realiza un esquema de alivio de carga basado en parámetros de priorización de carga, mediante algoritmos en MatLab y PowerFactory, con el objetivo de establecer una desconexión de carga mínima para asegurar la continuidad del funcionamiento del sistema de potencia, después de verse afectado por un desastre natural. Se implementan dos modelos de pruebas, el IEEE de 9 barras modificado y el IEEE de 39 barras, como caso inicial, cada sistema parte desde su punto de funcionamiento estable. Después, se simula el impacto de un desastre natural mediante la desconexión porcentual y aleatoria de generación, así pues, considerando un análisis de priorización de cargas, basado en parámetros técnicos, económicos y sociales, se procede a calcular y desconectar automáticamente la cantidad de carga necesaria, equivalente a la generación perdida, para que el sistema regrese a un estado de operación estable. Garantizando así, que el sistema conserve la continuidad de servicio en las zonas no afectadas y previniendo un colapso total del sistema (blackout).The following research is carried out to achieve a load-shedding scheme based on load prioritization parameters, using MatLab and PowerFactory algorithms whit the objective of set up a minimal load shedding to ensure the continuity operation of the electrical power system after being affected by a natural disaster. IEEE 9-bus modified test system and IEEE 39-bus system are implement. The initial study case of each system contemplates a stable operating point, which is affected by an external event, producing an aleatory and percentage disconnection of generation. Consequently, taking into account a load prioritization analysis based on technical, economic and social parameters is possible to calculate and disconnect automatically the minimal load quantity to reestablish the system. The aforementioned procedure ensures that system maintain continuity of service in no-affected zones and preventing the total outage of electrical power system (blackout)

Assessing Effectiveness of Research for Load Shedding in Power System

The research on loadshedding issues dates back to 1972 and till date many studies were introduced by the research community to address the issues. A closer review of existing techniques shows that still the effectiveness of loadshedding schemes are not yet benchmarked and majority of the existing system just considers the techniques to be quite symptomatic to either frequency or voltage. With an evolution of smart grids, majority of the controlling features of power system and networks are governed by a computational model. However, till date not enough evidences of potential computational model has been seen that claims to have better balance between the load shedding schemes and quality of power system performance. Hence, we review some significant literatures and highlights the research gap with the existing technqiues of load balancing that is meant for assisting the researcher to conclude after the selection process of existing system as a reference for future direction of study