For each Simulation type, Simulation Wizard creates two alternative Simulation scenarios.  We call these 'annual' and 'time span'.  By default, Simulation Wizard displays the 'Annual' scenario.  Use the 'sub-tab' icons located within the Simulation tab to toggle between 'Annual' and 'Time span' simulation...

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Use this link to read about scenarios and their difference...  SCENARIOS EXPLAINED


This article is not intended to explain Simulation Wizard functions.  Use this link you want learn about Simulation Wizard function...  FUNCTIONS EXPLAINED


For this explanation of chart results data, we'll focus on an 'Annual' scenario and then explain where 'time span' differs...


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Lets break our chart down into columns and rows to help explain how the data in the chart is arrived at...


Column 1: System hours run:


'Annual' or 'Time span'


For practical reasons, Utilisation data is segmented into 10% rows (e.g. it would be impractical to display the chart on screen or print the chart if the segment resolution was for example 1%).  Use Graph Wizard or Chart Wizard to review utilisation in detail!


Beneath the 90 - 100% segment there's rows for 'system off load', 'system stopped' and 'system shutdown'.  Observe that 'off load', 'stopped' and 'shutdown' utilisation relate to the system and not an individual item of equipment!  So for example, 'system off load' is the period of utilisation where no item of equipment is in the load state and one or more item of equipment is in the off load state.


Columns 2: Utilisation hours:


Utilisation hours is the number of annualised hours the system will operate within the segment.


'Annual'


The hour data displayed will firstly depend on whether or not the Simulation is linked to an audit...

  • If the Simulation is not linked to an audit, Simulation Wizard offers completely hypothetical hour data.  That hypothetical data establishes a scenario where equipment utilisation peaks at 60 - 70%.
  • If the Simulation is linked to an audit, hour data is established from the relational audits 'flow data' stream.  Simulation Wizard...
    • Takes the flow data stream
    • Segments the flow range into the 10% segments
    • Looks across the flow data stream and allocates a sample to a segment (Note: SCADAR data logger sample resolution is fixed to 1 second sampling and cannot be modified!)
    • Applies a Wizard rule for 'system off load' (discussed elsewhere)
    • Applies the System shutdown hours provided during the Audit Wizard step
    • Verifies that the column adds up to 8760 hours (or 1 year)


In 'Time span'


If the Simulation is not linked to an audit, Simulation Wizard offers a hypothetical 168 hour (1 week) scenario.  That hypothetical data establishes a scenario where equipment utilisation peaks at 60 - 70%.


If the Simulation is linked to an audit, hour data is the number of hours the system operated within the segment during the audit.  The rules applied are identical to those described above.


Column 3: System flow:


Consistent with utilisation hours, system flow data displayed will depend on whether or not the SImulation is linked to an audit...

  • If the Simulation is not linked to an audit, Simulation Wizard offers completely hypothetical flow data.  That hypothetical data establishes a scenario where equipment utilisation peaks at 60 - 70%.
  • If the Simulation is linked to an audit, flow data is established from the relational audits 'flow data' stream.  Simulation Wizard...
    • Takes the flow data stream
    • Segments the flow range into the 10% segments
    • Looks across the flow data stream and allocates a sample to a segment (Note: SCADAR data logger sample resolution is fixed to 1 second sampling and cannot be modified!)


Note:


This article continues with the assumption that the reader understands the difference between a Simulation that is 'linked' or 'not linked' to an audit (i.e. hypothetical data versus actual data)!


Column 4: Installation average input kW (RED):


'Annual'


The value displayed is the 'average kW' required to produce the amount of flow in the given segment (e.g. 0 - 10%, 10 - 20% etc)...

  • Simulation Wizard knows the kW required to produce flow...
    • Irrespective the unit of measure displayed (e.g. cfm), behind the scenes Simulation Wizard uses m³/min in its mathematical calculations
    • kW resolution is proportional to 0.1 m³/min of flow
    • Simulation Wizard starts with the kW for the smallest amount of flow in the corresponding segment
    • It then looks at all kW values for each 0.1m³/min step that falls within a given segment
  • Simulation Wizard calculates an 'average kW' using all of the kW values and the number of steps in a segment to establish an 'average kW' value

'Time span'

In time span Simulation Wizard is not trying to 'annualise' the data, consequently the information displayed can be more accurate...
  • Simulation Wizard knows the actual kW required to produce the actual flow at an actual point in time...
    • Simulation Wizard groups actual data into the corresponding segments
    • And then uses the number of samples to derive an 'average kW' value for that segment 


Column 5: Proposed average input kW (BLUE):


The values in the 'Proposed' or BLUE column use the same calculations.  Variation between the 'Installation' or RED column and the BLUE column is derived from...

  • Re-ordering the equipment on the BLUE line
  • Changing the pressure settings of the equipment on the BLUE line
  • Removing equipment from the BLUE line
  • Adding alternative equipment to the BLUE line
  • Enabling Metacentre system control
  • Changing the target pressure of the BLUE line


Column 6: Input kW variance of BLUE compared to RED:


Column 6 = Column 4 minus Column 5


Columns 7 & 8 displayed in 'Annual' Simulation only:


Column 7: Annual kW variance of BLUE compared to RED:


Column 7 = Column 6 expressed in kW hours per annum


Column 8: Annual monetary variance of BLUE compared to RED:


Column 8 = Column 7 expressed in monetary terms using the average kW hour tariff


Columns 7, 8 & 9 displayed in 'Time span' Simulation only:


Column 7: Savings:


Column 7 = Column 6 (kW variance) x Column 2 (utilisation hours)


Column 8: kW savings per annum:


Column 8 = Column 7 extrapolated to 1 year...

  • Remove 'system shutdown hours' from 8760 (1 year in hours) (so in the example image above, system shutdown hours is 2000 hours so this will leave 6760 hours where the system was either operating within a segment (e.g. 0 - 10%) or operating 'off load' or 'stopped')
  • Take the utilisation hours (column 2) for a segment or 'off load' or 'stopped' and extrapolate accordingly.  For example...
    • Lets assume that column 2 for 0 - 10% is 100 hours
    • And that the sum of all segments (including 'off load' or 'stopped') was 200 hours.  
    • 100 / 200 * (8760 - 2000) = 3380
  • Finally, multiply the above result (extrapolated utilisation hours for a segment) with column 6


Column 9: Savings per annum


Column 9 = Column 8 expressed in monetary terms using the average kW hour tariff


Other points:


Point 1: Simulation Wizard rule applied to 'off load' kW when Metacentre system control is enabled:


Fixed speed equipment:

 

On the BLUE line, Metacentre system controller can change the equipment used to produce the same flow when compared to the RED line. In other words, for the 'entire span' of the output flow, other equipment used also means other equipment operating in an offload state from time to time. Since a Metacentre system controller always uses the most efficient equipment available, logic says that an overall gain must be achieved during periods of time whilst operating off load.


The specific efficiency curve (shown below) takes into account that some equipment is running 'fully loaded' whilst one item of equipment will operate either loaded or unloaded (off load). This is calculated during the system load time.  The installation as such will also operate unloaded or off load from time to time (Due to equipment 'no load' run timers etc). These hours are also taken into account and they are independent of pressure.


Whilst operating off load, equipment is operating to 'free air', it's therefore difficult to identify which item of equipment will be the one operating. The percentage equipment is present on the output span provides an indication of 'how big' the probability is that an item of equipment will contribute to offload kW.

 

The following example shows how Simulation Wizard calculates this gain...

 

A 3 compressors scenario:

 

 

Unit

Compressor #1

Compressor #2

Compressor #3

Total

Full load kW

kW

188.5

112.3

43.9

 

Offload kW

kW

29.0

24.0

12.5

 

Full Output

m3

24.0

14.4

5.1

43.5

Output

%

0.55

0.33

0.12

100

 

 

 

 

 

 

 

Average output kW over entire output span on RED line:

 

((C1 offload kw x C1%span) + C2 offload kw x C2%span) + C3 offload kw x C3%span) +) / total span =

 

(29.0 * 55% + 24 * 33% + 12.5 * 12%) / 100% = 25.37


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Note: The above image is taken from a previous release of SCADAR.NET.  However, its relevance to the topic discussed here is unchanged!


Looking at the BLUE line you can see that over the entire span, the smallest (most efficient) item of equipment is used in 3 different areas, the middle size item of equipment in 2 different areas and the least efficient item of equipment only once. This fundamentally changes the 'span %' different equipment operates and favors the more efficient equipment to be operating in a load or off load state.


Once again, looking at the BLUE line in the example, you can see the smallest item of equipment is used 3 times over the entire output span. The middle is used on 2 occasions. Again, it is 'efficiency' which determines which item of equipment is used more often. Using a more efficient item of equipment, reduces the %span of less efficient equipment. The calculation for the BLUE line is as follows:

 

Average output kW over entire output span on BLUE line:

 

C1%new = C1%span – C2%span

C2%new = C2%span – C3%span

C3%new = C3%span – 0

 

((C1 offload kw x C1%new) + C2 offload kw x C2%new) x 2 + C3 offload kw x C3%new * 3) +) / total span =

 

(29.0 * 22% + 24 * 21% * 2 + 12.5 * 12% * 3) / 100% = 20.96

 

Average offload kW ratio = average BLUE / average RED

 

20.96 / 25.37 = 0.826 or 82.6 %

 

Conclusion for fixed speed equipment:

 

For any off load kilowatt consumed on the RED line, 82.6% will be consumed on the BLUE line or a gain of 17.4%


Variable speed equipment:

 

The variable speed scenario is more difficult to predict. Theoretically, off load operating times could or should be run down to zero 'IF' all equipment is appropriately sized.  However, when fixed speed equipment variants are used in combination with variable speed equipment, off load operating likely cannot be avoided and will result in some off load kW consumption.  The overall benefit will be greater due to the introduction of variable speed equipment. To demonstrate the significant benefit of introducing variable speed equipment when compared to fixed speed equipment yet retain some unavoidable off load kW, a reduction of 50% is used to calculate off load kW.


Conclusion for variable speed equipment:


Introducing variable speed equipment will always show a meaning full reduction inclusive off load.


Where system shutdown data originates:


For Simulations that are not linked to an audit, system shutdown hours are hypothetical.


For Simulations linked to an audit, system shutdown hour data data originates from Audit Wizard step 3 'create site & energy profile'


The chart coloured 'GREEN' or 'RED' area:


The chart coloured area summarises annual kW consumption for the equipment configuration on the RED line, annual kW consumption for the equipment on the BLUE line alongside annual savings for kW hours, monetary cost and CO² emissions.


The chart coloured area will be GREEN when the results of BLUE are better than RED.  Conversely the chart coloured area will be RED when the results of RED are better than BLUE.