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Utilities use the bus/branch model for planning and operations studies. In the bus/branch model, bus numbers are used as unique identifiers. However, bus numbers can change due to addition of equipment, specific substation configurations (splitting buses) or due to equipment outages. This often creates problems because many auxiliary files used in power system studies need to be modified. If the node/breaker...
This paper identifies the issues of using the bus/branch model for operations studies for current hour, next hour and future hours. Need for node/breaker model for contingency analysis is discussed. Major improvements needed to bus/branch model for contingency analysis in the area of contingency definition and contingency analysis is presented. Need to model Remedial Action Schemes (RAS) independent...
This paper discusses a technique to implement Remedial Action Schemes (RAS) or Special Protection Systems (SPS) for Variable Transfer Limits (VTL) computation. Need for RAS implementation for VTL calculations are discussed. The technique presented can be applied to the bus/branch model as well as for the node/breaker model. Advantages of using the State Estimator cases for VTL calculations are discussed...
This paper discusses need for Variable Transfer Limits in the Northwest. The paper presents a novel method to compute Variable Transfer Limits (VTL) using the node/breaker model State Estimator (SE) cases. Advantages of using the node/breaker model for VTL calculations are discussed. A detailed 6 step process to compute Variable Transfer Limits are presented. Interesting sample results are presented...
This paper discusses issues and solutions when utilizing the node/breaker model to identify voltage instability. This paper describes the reasons why current PV tools generate unrealistic over optimistic static voltage stability limit for bus/branch model and at the same time generate very conservative limit for node/breaker model. The necessary improvements to generate realistic voltage stability...
Increasing installations of large amounts of renewable generation are contributing to a transition of the Electric Power industry operating model away from base loaded generating resources and power transfers between Balancing Authorities (“BAs”) that are generally fixed for an hour. In contrast, Variable Energy Resources can change generation many times within an hour. In addition, when wind generation...
This paper describes Bonneville Power Administration (BPA) experience and justification of implementing node/breaker Full Topology model implementation for operations studies. Focus of this implementation is to increase reliability and accuracy by using a real-time case using the more-realistic Full-Topology model. Major changes needed to the bus/branch planning model to work with node/breaker model...
This paper discusses the BPA experience of implementing Remedial Action Schemes (RAS) in operations studies. The previous methodology of manually including each RAS action as part of the applicable contingency definition is both time consuming and error prone. A more holistic approach was chosen with the goal of allowing automatic deployment of RAS based upon the initial conditions and changes in...
Demand continues to increase while transmission line construction is being constrained by multiple factors—economic, environmental, and political. Effective and efficient utilization of transmission lines is thus of great importance in an open access environment. Large blocks of power are transferred from areas with inexpensive generation to heavy load demand areas or areas with high generation costs...
Experiments are described in which tin was diffused into GaAs in a closed ampoule. When the ambient arsenic vapour pressure was low the results were not reproducible, and severe deterioration of the surface was observed. Evidence is produced which suggests that both evaporation and condensation occurred during these diffusions. The problem was completely solved by employing a high-vapour pressure...
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