What Is Needed When Gathering Data For Power System Studies
Data Collection is about gathering the data necessary for building an accurate model of your power system. This model will be the basis for the various studies that we mentioned last week, and without accurate data the model will not be as useful as you need it to be.
Why having complete and accurate data is important
First the results from the power system model are only as good as the data that is used to create it. If the data is not correct, then the model that is created will not be accurate. In fact incorrect data will lead to poor results in the incident energy study which is very sensitive to the fault levels on the system. It is very important to get accurate impedance information, this includes cable configurations, transformer data, etc.
Collecting the data for the first time is a very labour intensive prospect, and can account to 50% of the cost of getting the initial study completed. That’s one of the reasons I mentioned before about getting the data together, and getting more than one report completed at the same time. The incremental cost in negligible compared to the total cost of the project.
When your facility has good single line diagrams, manuals, and data in other forms, this will speed up the collection process. However it is always a good idea to verify all this data in the field, especially for larger, active facilities where changes are being made on a constant basis. When this is completed once, the model can be used as a change management tool. One of the software vendors have a great webinar describing how you can use their software to manage change in the entire facility
How long to expect?
You can expect that the data gathering stage of the project will take about 2hours for every substation, switchgear lineup and MCC, and 0.1 hours for every load, including motors, panels, etc. If your facility is spread out or has a lot of specialty equipment these numbers may need to be increased. This will give you an idea on how long you can expect to take to gather all the data for your facility.
We have included forms in the content library that will help you gather this information. We based the information required on the recommendations of ETAP.
How much do you need to gather?
Depending on what set of studies you are planning to have completed, the detail of the data that needs to be gathered will be slightly different. It is my opinion that you have at least the 4 studies completed that we mentioned last week in, The Critical 4, they are Short Circuit, Protection Coordination, Incident Energy and Load Flow. These 4 studies build upon each other, and as such they need increasingly more and better detailed information. Lets start at the top, what do they all need?
- Utility information (MVA, X/R min and max)
- Nominal system voltage levels
- System configuration with the following equipment:
- Transformers (with impedance, voltage and configuration),
- Configuration switches and circuit breakers
- Switch gear, mccs, switchboards, etc down to the voltage level you are interested in
- Any large motors and other generation on the site.
With this minimal information you can prepare an adequate short circuit study that will give you values for the short circuit on any of the buses above. These will be very much worse case as we haven’t gathered any additional impedance information. This study would be useful for design and specification purposes when you are purchasing equipment for a new facility.
What’s Coming Up
On Wednesday I will lay out the specific data that is required for each of those critical four. They all build upon each other, and will require collecting data in the field and interviewing operators and maintenance to understand how the facility operates.
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