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Cross Cascades North Study Team Meeting

Date and Time: Tuesday Jan 10, 2012 2:00 - 4:00
Location: ColumbiaGrid/Fountain View Room
Type: Workgroup Meetings
Organizer: Gordon Comegys

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This meeting is to specifically address the section in the study plan concerning the post contingency capacitor switching (for convenience, an excerpt from the study plan is pasted below). The PowerWorld staff just completed the new feature for version 16 to convert the new WECC composite load model CMPLDW dynamics data into the powerflow model with static constant MVA, constant current, and constant impedance loads. The Time Step Simulation tool enhanced early in 2011 to include cut-in and cut-out switched shunt capacitor settings and transformer LTC tap changing time delays are used to approximate the mid-term dynamics with the composite load data.
Here is the excerpt from the study plan:

Mid-term Dynamics
WECC is obtaining data for the new composite load model. After the data accumulation is finished, the preliminary mid-term dynamics simulation will be repeated (the preliminary study assumed 100% constant current load). The preliminary mid-term dynamics investigation led the team to allow design with post contingency capacitor switching and very high critical voltage. The new study will still be considered preliminary, but with updated information. The estimated date for the data and the tools to update the simulation is February 2012.
Additional Background:
The WECC post transient methodology specifies contingency powerflow simulations are to be performed with (a) constant MVA loads in the absence of the distribution model to represent load conditions several minutes after the contingency and (b) model only post contingency automatic actions that will occur within 3 minutes of the contingency. This CCN study assumes 500kV shunt capacitors will reliably switch on in the post transient period (without loss of load and without hunting). This is a major assumption. It provides over 1000 MW’s of additional westside generator displacement capability before a voltage stability limit is reached. However, the scenario with capacitors switching during the post transient time frame has been studied only with approximate and preliminary data, which indicated that reliable post contingency capacitor switching could likely be designed. The new composite load model information will provide the added detail to reconfirm the post contingency capacitor switching assumption.


Member: Avista Corporation      Project: ColumbiaGrid     
Avista Corporation

"In ColumbiaGrid, we now have the ability to resolve the three fundamental transmission questions: What transmission facilities should be built? Who should build them? Who should pay for them? With ColumbiaGrid's independent staff and process to resolve disputes, we can answer these questions effectively and in a timely fashion to facilitate our region's new resource development needs."
~~ Jeff Schlect, Manager, Transmission Services, Avista