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Kojima T.,BC Hydr Engineering | Cherukupalli S.,BC Hydr Engineering | McWhirter C.,BC Transmission Corporation
43rd International Conference on Large High Voltage Electric Systems 2010, CIGRE 2010 | Year: 2010

A bushing failure occurred on a 525 kV submarine cable termination at Cape Cockburn Terminal Station (CCB) on April 4, 2008 without an accompanying electrical failure. This CCB terminal, being on a remote island, neither accessible by land nor by helicopter after dark, could only be inspected on the following day. The bushing was upright but the damage was significant with wide open cracks. The insulating fluid inside the bushing had been drained completely resulting in a low pressure alarm and was accompanied by a reduction in flow of the insulating fluid. The insulating fluid was consequently being fed in to the cable only from the remote end, Texada East Terminal station (TXE) and the immediate reduction in the insulating fluid flow resulted in introduction of air in to the cable core through the broken termination bushing due to contraction of the insulating fluid after de-energization of the circuit. Being a rainy night, the air was suspected to be humid The length of the cable contaminated with "humid" air affecting the insulation integrity of the cable was later estimated to be between 100-150 m from the termination based on the circuit loading records and fluid flow settings at TXE pumping plant preceding the failure. Insulating fluid flow rate to the cable from the remote end was increased and the broken bushing was shrink wrapped to prevent further ingress of "moist"air into the broken bushing. The broken bushing was then temporarily replaced with a spare bushing soon after and filled with insulating fluid. This provided some time to examine the remedial options. This paper presents the sequence of events that followed the bushing failure, the repair options and the associated risks with each option, the cost/benefits of these various options, and the final solution. This paper describes how a novel method was adopted where the 9 km long large conductor cable was heated in-situ. It also presents how this very unique "cable insulation dehydration" effect was monitored, how the cable termination was restored, and circuit was placed back into service. Source

Yao Z.,BC Transmission Corporation | Atanackovic D.,BC Transmission Corporation
IEEE PES General Meeting, PES 2010 | Year: 2010

In real-time operations, online DSA applications can be used not only to perform security assessment for the current operating point but also to search boundaries of security region for operations staff to prepare for the next step generation dispatch and calculate transfer limits for market operations. This paper analyses the issues that were encountered when dealing with future re-configurations of power system resources in security region search. , which include: ▶ The approach to incorporate the Remedial Action Schemes (RAS) into the security region search in case where RAS are used to enhance power system security; ▶ The types of power system resources (in particular, generation and load in various areas and regions) that should be utilized in re-configurations for security region search based on the sink-source concept; ▶ The method to determine the levels of participation of the selected resources in order to form reasonable and realistic paths from the current operating point to the potential boundary of the security region. ©2010 IEEE. Source

Yao Z.,BC Transmission Corporation | Steed A.,BC Transmission Corporation | Dwernychuk G.,BC Transmission Corporation | Cave D.,BC Transmission Corporation
IEEE Power and Energy Magazine | Year: 2010

British Columbia Transmission Corporation (BCTC) in its System Control Modernization Project (SCMP) has integrated Powertech Labs' DSATools with Areva's energy management system (EMS) to perform online dynamic security assessment (DSA). The dynamic security of BC's power systems and overloading, voltage limit violation, voltage instability, frequency instability, and transient instability that are maintained by installing extensive remedial action schemes (RAS) or system protection schemes (SPS). The schemes maintains various credible single, double, and even triple contingencies with different kinds of actions involving generation shedding, load shedding, line tripping, and shunt switching. DSA software packages such as DSATools, ETMSP, PSLF and PSSE are not designed to model circuit breakers (CB) in a systematic fashion but CSA are modeled in a systematic fashion in EMS. The quality of a base case generated from EMS for online DSA experienced inaccuracies in state estimation (SE) solutions ruining the time domain simulations. Source

Vinnakota V.R.,BC Transmission Corporation | Brewer B.,AREVA | Atanackovic D.,BC Transmission Corporation | Steed A.,BC Transmission Corporation | And 2 more authors.
IEEE PES General Meeting, PES 2010 | Year: 2010

Due to recent changes in electric power system structure and market driven operational changes electric power system operation has increased in its complexity. Engineers and Energy Management System (EMS) suppliers are driven to enhance existing tools and add new tools for control room operators for consistent and faster decisions. Among the two well recognized quality indicators of electric power system operation, viz., voltage and frequency, frequency is being maintained within a very narrow band using formal tools such as Automatic Generation Control (AGC) in North American power networks. Voltage is by and large controlled in real time by experienced dispatchers with the help of "information support" tools or informal tools. Use of formal tools such as the one based on Optimal Power Flow (OPF) technology, described in this paper, for the dispatchers to support and augment their decision making in real time for voltage control is yet to evolve in control centers. This paper describes implementation efforts and issues of one such optimization tool Voltage-Var Dispatch (VVD) to provide control recommendations in real time for system voltage control. The authors share their experiences of implementing VVD that recommends shunt reactors /capacitor, synchronous condenser, static var compensator and generating unit MVAR output controls for controlling Transmission system voltages in real time in the province of British Columbia(BC) , Canada. ©2010 IEEE. Source

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