Applying High Performance HMI Graphics to Substation HMI
In the process control field the concept of high performance graphics now seems to be well known and is having a growing adoption. But substation HMI graphics tends to be a more impenetrable field for high performance graphics.
High performance graphics advocates the use of gray backgrounds and reserves the stand-out colors like red, yellow and orange for the sole purpose of showing alarms. It also recommends presenting more information and less raw data, clearly showing what is good and what is bad and its trends. (See this other post for references).
Substation HMI graphics inherits standards since the semi-graphic, character based display systems, monochromatic or with 8–16 colors. I witnessed a migration from a semi-graphics system to a full graphics based system where the criteria for drawing the new screens was that they must be made equal to the old screens. “The operators can’t see things differently” is the most common excuse. The opposition to change in this field is immense.
Those old standards frequently use color like red and green for representing the circuit breaker states, black or dark backgrounds, colors like red and blue for busbars according to the voltage level, highly colored measurements, etc. This leads to screens like this:
Just google images for “power substation single line diagram hmi” to see some more examples.
The promiscuous usage of colors makes alarms much more difficult to see. Normal states should not use bright colors. Energized states are commonly represented by the red color, as it stands for “danger”. But look: energized it’s the normal, desired state of operation.
Switches and breakers are the most common elements of substations screens. Think about what states can be alarms for those equipments:
- Switch closed
- Switch opened
- Breaker closed
- Breaker opened
Switch states normally are not alarms (at least not for those who are in control of it), as it can only open or close by operator command. Breaker only close too by the operator, except for the recloser function, but in that case the alarm is the recloser operation, not the breaker state. The only state that can always be an alarm is the breaker opening, the alarm in this case is not the state opened but the transition from closed to opened by the protection operation. So I think there is no need to use showy colors to represent switches and breakers states, it’s preferable to use shades of gray and different shapes to represent states. The alarm of the protection opened breaker can be represented by a red polygon aside the breaker.
Alarm should be represented with different colors, text and shape as suggested by Hollifield. Ex. a red box or polygon with a “1” inside for priority 1 alarms like trips, a yellow triangle with a “2” for out of limit alarms, an orange inverted triangle with a “3” for low priority state alarms and a purple box or ellipsis for SCADA diagnostics alarms.
Busbar colors are also a big distraction as it is only a static object. For this I recommend using dark gray or at least very muted colors.
For the measurements I discourage the use of different colors for each type of value. The use of a single unobtrusive color, different from that of the static text, presenting the units of measurement with a light gray, can lead to a calmer design. Out of limits alarms can be shown with a yellow triangle at the side of the value, the measure can then be shown in red also.
Moving analog indicators for critical measures like busbar kV and transformer load with ok and bad regions greatly helps to see what is good or bad in a first glance at the screen. Trends for those critical measures for about the last 30 minutes are very useful too.
A hierarchical navigation system can be organized in this form:
- Level 1: power system level
- Level 2: substation unit level
- Level 3: substation subsystems detail level
- Level 4: scada system diagnostics, architecture level
Navigation links and screen naming show be consistently used and placed along different screens.
Reducing clutter by removing not useful static objects and data can make things more clean, the operator can focus on the useful information and identify problems much more fast and even before happening using the trends plot.
I know it’s very difficult to promote such changes but I think it’s time to try, to escape those old graphics standards and gain performance in the power system operation. Just let the operators experience this new way of displaying information and they will surely tell the difference.
Originally published at ricolsen1supervc.wordpress.com on July 2, 2013.
Premiado como o melhor trabalho do Grupo de Estudos de Operação de Sistemas Elétricos do XXIII SNPTEE.www.linkedin.com
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