Showing papers on "Blackout published in 2001"

Modeling blackout dynamics in power transmission networks with simple structure

Abstract: A model for blackouts in electric power transmission systems is implemented and studied in simple networks with a regular structure. The model describes load demand and network improvements evolving on a slow timescale as well as the fast dynamics of cascading overloads and outages. The model dynamics are demonstrated on the simple power system networks. The dynamics depend weakly on the network topologies tested. The probability distribution functions of measures of the cascading events show the existence of power-dependent tails.

Vulnerability assessment and allocation of protection resources in power systems

Abstract: In electrical power grids, there exists the potential for disturbances, even small ones, to trigger cascading collapse and blackout of large portions of the grid. In this paper we propose a simple cascading collapse model. The purpose of the model is to identify topological and component differences that can be exploited for the allocation of protection resources and in designing preventive maintenance schedules. Numerical examples are given to illustrate how the model can be used for protection enhancements and in designing preventive maintenance schedules that reduce vulnerabilities due to hidden failures.

Defense Plan Against Extreme Contingencies

Abstract: This paper presents some of the short-term measures developed from the studies following the blackout in ~heBrazilian South/SoutheasdCenter- West power system in March llti 1999. 17re concept of Security Zones and Network Security Matrix is introduced. A new PLC-bo.red SPS was designed to create controllabiliip zones. ilris new scheme was named Security Control and is triggered by network topological changes. The Security Control is fast acting, with clearing times around 200 ms. A apical Securip Controller logic is presented, showing its benejits fGr the Bradian interconnected power system.

Application of a wide area back-up protection expert system to prevent cascading outages

Abstract: A strategy to prevent cascading outages in power systems is proposed in this paper. The strategy employs wide area back-up protection and artificial intelligence techniques to minimize the impact of a fault on a network. There are two ways in which wide-area backup protection can prevent cascading trips leading to a wide spread blackout: (1) precise location of a fault so that only the circuit breakers necessary to isolate the fault are tripped; and (2) avoidance of unnecessary trips, due to hidden failure or overloading, by blocking the trip signals of conventional back-up protection relays. The limitations of conventional back-up protection are examined and methods of improvement are presented.

Evidence for SOC in Electric Power System Blackouts

Abstract: We analyze a 15-year time series of North American electric power system blackouts for evidence of self-organized criticality Scaled window variance and R/S analysis of the time series shows moderate long time correlations The probability distribution functions of various measures of blackout size have a power tail Moreover, the same analysis applied to a time series from a sandpile model known to be self-organized critical gives results of the same form Thus, the blackout data is consistent with self-organized criticality Self-organized criticality, if fully confirmed in power systems, would suggest new complex systems approaches to understanding and possibly controlling blackouts

Development and Implementation Knowledge-Based System for On-Line Fault Diagnosis of Power Systems

Abstract: This paper demonstrates a novel knowledge-based system for on-line fault diagnosis of power systems. During operation, the software first identifies the blackout islands from the post-fault network topology. It then uses genetic-algorithm (GA)-based optimization for selecting the actual fault section(s) from the blackout islands. The bulk of the knowledge required by the software describes the current status of the power network. To speed up the on-line computation and to keep track of the current network status, two tree-search algorithms have been developed for automatic formation of blackout islands and the corresponding GA fitness function only for these blackout islands. Apart from being fully tested with sample power systems, the software has been put on field tests at the dispatching center of Zhejiang Provincial Electric Network in P.R. China since September 1997. Experience from the field tests has confirmed the effectiveness of the system for on-line fault diagnosis of large-scale power systems.

Service of informing blackout by using automatic dialing

Abstract: PURPOSE: A service of informing a blackout by using an automatic dialing is provided to inform a telephone subscriber the blackout by quickly sensing the blackout and performing automatic telephone dialing. CONSTITUTION: The device includes a blackout sensing part(110) which senses an on/off state of a commercial ac power to output a sense signal to a central processing unit(120). A ROM(140) stores a telephone number input by a user. A voice storing part(160) stores a voice message to be reproduced at the blackout. The central processing unit(120) performs an automatic dialing operation using the telephone number stored in the ROM(140) when the blackout is sensed by the blackout sensing part(110) and controls the voice storing part so as to send the stored voice message.

Relaying problems in the connection of a dispersed generating plant to the 132 kV network

Abstract: The problem of power swings as a consequence of transient performance of generators after fault removal is well known and easily faced if previously taken into account in the planning stage of a transmission network where large power plant are likely to be connected. On the contrary, this may result in a problem when power swings occur as a consequence of the connection of a power plant on a network planned to operate only supplying loads. False tripping of line distance relays is to be expected with the consequent risk of network separation in unexpected points, thus increasing the risk of network blackout. The paper illustrated the benefits obtained from a stability study in the setting of line distance relays previously installed on a 132 kV network, where a new 140 MW combined cycle power plant was set up. The simulation of several disturbances allowed the setting of the existing distance relays without adding any power-swing blocking function. The plant has been in operation for two years: few disturbances on the network have been experienced so far and no unwanted tripping of distance relays occurred.