Description of the "Power Electronic Loads" component from the Residential Energy Library.

Modeling Description

The "Power Electronic Loads" component implements typical home appliances as a generic Switch-Mode Power Supply (SMPS) circuit-based model. This approach can reproduce (with a good degree of accuracy) the instantaneous load current waveform, preserving some behavior from real devices like harmonic injections. This model is particularly useful when analyzing power quality in residential, commercial, and industrial settings. In this context, the "Power Electronic Loads" component in our Residential Energy library lets you simulate the complex non-linear behaviors of various household appliances under different electrical load conditions.

The component uses a simplified modeling of a general SMPS topology (shown in Figure 1). The library model uses the Inrush Current Protection (ICP), the Diode Bridge Rectifier (DBR), and the Power Factor Correction (PFC) block stages from the general SMPS topology. In order to optimize the core resources of the model, the Inrush Current Protection is put on the DC voltage side, which makes it possible to represent more than one electronic load using the same DBR.

pe load block diagram
Figure 1. Block diagram of a general SMPS topology.

The Figure 2 show the circuit representation of the "Power Electronic Loads" component. The ICP is modeled using a variable resistor representing a Negative Temperature Coefficient (NTC) resistor. The NTC resistance is given by an exponential curve with 1.0 seconds of time constant, initial and final value according to the "Rin" property (initial is 40 times the Rin value and final value, the Rin itself). Only loads without PFC or with passive PFC are considered. The PFC is modeled using an inductor in series with the NTC. The dc load is represented by a fixed resistor "Rdc" resistor. This approximation is made considering a constant DC voltage (commonly, a variable resistor is used in the function of the voltage). The resistor load is connected in parallel with the dc capacitor of the SMPS. Up to five home appliances are connected in parallel on the DC bus of the same SMPS. Each one is turned on/off through a non-ideal switch (not represented in the figure).

pe load thcc
Figure 2. Residential Energy library modeling.

The home appliances are categorized according to 3 load types as detailed below. Table 1 shows the category ZIP parameterization.

Home Appliance List Categorization
  • Compact and Linear Fluorescent Lamps (CFL/LFL): "Fluorescent Lamp".

  • Switch-Mode Power Supply with no Power Factor Correction (SMPS_noPFC): "Low-Power Consumer Electronics".

  • Switch-Mode Power Supply with Passive Power Factor Correction (SMPS_pPFC): "High-Power Consumer Electronics", "Microwave Oven".

Table 1. Load Types Parameterization

Category

Rin (pu)

Lin (pu)

Cdc (pu)

Rdc

CFL/LFL

\[2.16 \cdot 10^{-3}\]

\[6.0 \cdot 10^{-6} \]

\[0.25\]

\[R_{charge} = 0.01928 \cdot V_{dc}^2 + 11.69 \cdot V_{dc}+1110\]

\[R_{discharge} = 24.5 \cdot V_{dc}+94.29\]

\[Rdc = \frac{R_{charge} + R_{discharge}}{2}\]

SMPS_noPFC

\[0.0017\]

\[6.0 \cdot 10^{-6}\]

\[0.036\]

\[1.0~(pu)\]

SMPS_pPFC

\[0.0085\]

\[0.037\]

\[0.036\]

\[1.0~(pu)\]

Component Description

The "Power Electronic Loads" 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 load coefficients are automatically computed according to the "Load Type" defined. It is also possible to manually specify the coefficients by choosing the "User Defined" option in the "Load Type" property.

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.

Table 2. "Power Electronic Loads" in the Residential Energy library
Component Component dialog window Component parameters

pe load icon

pe load mask1

pe load mask2

  • General Tab

    • Nominal voltage [Vrms]

    • Nominal frequency [Hz]

    • Execution rate [s]

  • Load Tabs

    • Load type:

    • Demand [kVA]

    • Rin [Ω]

    • Lin [H]

    • Cdc [F]

    • Rdc [Ω]

References

[1] - Collin, Adam John. (2013). Advanced Load Modelling for Power System Studies. [Doctoral’s thesys, University of Edinburgh]. http://hdl.handle.net/1842/8890.