Description of the "ZIP Loads" component from the Residential Energy Library.
Modeling Description
The "ZIP Loads" implements a Constant Power Load (CPL) with its power references computed by a sum of polynomial ZIP load models.
ZIP load models are a common tool used in the study of power systems. The ZIP model, named after the types of loads it simulates—constant impedance (Z), constant current (I), and constant power (P)—helps engineers and researchers better understand how different types of electrical loads will behave under varying voltage conditions. This model is particularly useful when analyzing power quality and system stability in residential, commercial, and industrial settings. In this context, the ZIP Load component in our Residential Energy library lets you simulate the complex behaviors of various household appliances under different electrical load conditions.
As shown in the block diagram of Figure 1, the load component aggregates up to five home appliances, each with its own transient and ZIP coefficients. The transient logic implements a look-up table with the input data on the component’s parameterization (mask), and it is triggered with a rising edge of the Scada Input which Enables/Disables the load operation. The transient outputs are connected to the ZIP model, which provides the CPL’s active/reactive power references according to the ZIP coefficients and the RMS voltage load. The ZIP component implements the Equations 1 and 2.
The home appliances are categorized according to 10 load types as detailed below. Table 1 shows the category ZIP parameterization.
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General Incandecent Lamp (GIL): "Incandescent Lamp".
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Compact and Linear Fluorescent Lamps (CFL/LFL): "Fluorescent Lamp".
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Light-Emitting Diode (LED): "LED Light Sources".
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Resistive: "Washer dryer (heating)", "Shower/Water/Space heater".
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Switch-Mode Power Supply with no Power Factor Correction (SMPS_noPFC): "Consumer Electronics (Low-Power)".
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Switch-Mode Power Supply with Passive Power Factor Correction (SMPS_pPFC): "Consumer Electronics (CRT/Plasma TV)", "Microwave Oven".
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Switch-Mode Power Supply with Active Power Factor Correction (SMPS_aPFC): "Consumer Electronics (LCD/LED TV)".
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Single-Phase Induction Motor with Resistive Start-Inductor Run and Quadractic Torque (RSIR_QT): "Washer dryer (centrifugal pump)".
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Single-Phase Induction Motor with Resistive Start-Inductor Run and Constant Torque (RSIR_CT): "Refrigerator/Freezer".
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Single-Phase Induction Motor with Capacitor Start-Run with Constant Torque (CSR_CT): "Washer dryer (drum rotation)", "Food Processors".
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Single-Phase Induction Motor with Capacitor Start-Run with Quadractic Torque (CSR_QT): "Washer dryer (water pump)".
Category |
PF |
ZIP-P |
ZIP-Q |
||||
---|---|---|---|---|---|---|---|
Z |
I |
P |
Z |
I |
P |
||
GIL |
1.00 |
0.43 |
0.69 |
-0.12 |
0.00 |
0.00 |
0.00 |
CFL/LFL |
-0.91 |
-0.01 |
0.06 |
0.05 |
0.10 |
-0.73 |
-0.37 |
LED |
-0.137 |
0.23 |
0.85 |
-0.08 |
-1.05 |
0.04 |
0.01 |
Resistive |
1.00 |
1.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
SMPS_noPFC |
0.994 |
0.00 |
0.00 |
1.00 |
-3.63 |
9.88 |
-7.25 |
SMPS_pPFC |
0.97 |
0.00 |
0.00 |
1.00 |
0.45 |
-1.44 |
1.99 |
SMPS_aPFC |
1.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
RSIR_QT |
0.62 |
0.10 |
0.10 |
0.80 |
1.40 |
-0.91 |
0.50 |
RSIR_CT |
0.62 |
0.63 |
-1.20 |
1.57 |
1.40 |
-0.91 |
0.50 |
CSR_CT |
0.90 |
0.50 |
-0.62 |
1.11 |
1.54 |
-1.43 |
0.89 |
CSR_QT |
0.90 |
0.22 |
0.08 |
0.69 |
1.54 |
-1.43 |
0.89 |
Component Description
The "Static Loads - ZIP" component is found under the Loads Category of the Residential Energy library. In Table 2, the schematic symbol and properties window of the component are shown. The "General" tab contains the circuit’s nominal voltage/frequency ratings to which the loads are connected. The execution rate of the signal-processing elements of the component is also parameterized on this tab. The other tabs are used for the load configuration. In the "Load Type" property, the user defines the kind of home appliance in a pre-defined list (Home Appliance List Categorization). The ZIP coefficients are automatically computed according to the "Load Type" defined. It is also possible to manually specify the ZIP coefficients by choosing the "User Defined" option in the "Load Type" property. An inrush behavior can be enabled through the "Enable Transient" checkbox. The transient curve is defined through the "Initial Value", "Final Value", and "Time Constant" properties. The "Preview" button shows the current transient behavior.
A signal-processing input port "en" at the top of the component icon turns all the loads on/off. Besides that, internal Scada Inputs are created to turn each load on/off separately.
Component | Component dialog window | Component parameters |
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References
[1] - A. J. Collin, I. Hernando-Gil, J. L. Acosta and S. Z. Djokic, "An 11 kV steady state residential aggregate load model. Part 1: Aggregation methodology," 2011 IEEE Trondheim PowerTech, Trondheim, Norway, 2011, pp. 1-8, doi: 10.1109/PTC.2011.6019381.
[2] - Tsagarakis, G., Collin, A. J., & Kiprakis, A. E. (2013). Statistical Review of UK Residential Sector Electrical Loads. ArXiv. https://doi.org/10.1515/ijeeps-2013-0078
[3] - A. J. Collin, G. Tsagarakis, A. E. Kiprakis and S. McLaughlin, "Development of Low-Voltage Load Models for the Residential Load Sector," in IEEE Transactions on Power Systems, vol. 29, no. 5, pp. 2180-2188, Sept. 2014, doi: 10.1109/TPWRS.2014.2301949.