Power System Studies - The What

Published:
By Jeff MacKinnon, P.Eng., PE



Definition:

A group of studies used to analyze a power systems response to events over different time periods.

The time periods

There are three over all time periods that a power system study will look at, they are:

  • Transient
  • Dynamic
  • Static

Transient studies look at the over all power system response to an event over a very short period of time. This time period can be from a portion of a cycle to 1 or 2 seconds. An example of a transient study would be analyzing the system response of a capacitor bank being switched on to the system, and verifying that it won't introduce an instability.

Dynamic studies look at the power system response over seconds to a minute until the system has reached a new steady state. An example of a dynamic study is starting a large motor, line an ID Fan. Motors have high starting currents and can have major impacts on the system voltage.

Static studies review the system in a steady state and is used to report the values. Load Flows, also referred to as Power Flow studies are good examples of this. They are used to determine the voltages, currents, and power factor at all the buses and cables within the power system.

Studies includes in the Power System Analysis

industrial control system in modern dairy factory

There are many different studies that can be included in a Power System Study report, a few of the more common are:

  • Short Circuit
  • Protection Coordination
  • Incident Energy
  • Load Flow
  • Dynamic Motor Starting
  • Transient Stability
  • Power Quality
  • Harmonic Analysis

They all have a place in the report, but some are more used than others, for example the four studies that I recommend that all facilities have are:

  • Short Circuit
  • Protection Coordination
  • Incident Energy
  • Load Flow

With these studies a facility will have most of the information required to troubleshoot problems, control change management, improve operation, make better maintenance and capital decisions just to name a few.

Power System Study Report

When the power system report is generated, don't leave it on the shelf to gather dust. NFPA 70E and CSA Z462 both require that the incident energy study be maintained and updated at least once every five years. Also there is great information in the report that can be leveraged when making critical decisions in your day to day operation of your business.

This concludes part 1 of our series on Power System Studies, on Wednesday I will talk about what the purpose of the four studies I recommended are for, and then on Friday it will be all about how you can leverage them to make better decisions at your facility.

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This post is part 1 of the "Power System Studies" series:

  1. Power System Studies - The What
  2. Power System Studies - The Critical Four
  3. Power System Studies - The Why and How