Description of the PV Array with Microinverters component in Schematic Editor.

The PV Array with Microinverters component, shown in Table 1, is a Schematic Editor library component from the Residential Energy library. It is capable of modeling the aggregate behavior of numerous solar panels connected to microinverters. It models the independent behavior of various PV panels and inverters in signal processing, then models the cumulative inverter behavior at its terminals.

Table 1. PV Array with Microinverters in the Residential Energy library
Component Component dialog window Component parameters

pv array with microinverters 01

pv array with microinverters 02

pv array with microinverters 03

pv array with microinverters 04

  • Number of panels (integer)

  • Nominal Panel Power (VA)

  • Initial Panel Voltage (V)

  • Nominal AC Voltage (line-line) (V)

  • Nominal DC bus voltage (V)

  • Nominal frequency (Hz)

  • Execution rate (s)

  • L Output Filter (Series) (H)

  • R Output Filter (Series) (Ω)

  • C Output Filter (Shunt) (F)

  • R Output Filter (Shunt) (Ω)

  • C DC Filter (F)

  • MPPT Update Rate (s)

  • MPPT Step Size (V)

  • Current Controller Kp (Inner Loop)

  • Current Controller Ki (Inner Loop)

  • Switching Frequency (Hz)

PV Array with Microinverters internal structure

The internal structure of the PV Array with Microinverters component is shown in Figure 1.

pv array with microinverters 05
Figure 1. Schematic diagram of the Microinverter Array component

PV model

The PV panels in the PV Array with Microinverters component are modeled using a signal processing based PV model. The IV curve is simulated at the execution rate of the signal processing components, defined by the Execution rate property. The IV curve is modeled using an EN50530 compatible PV model.

The PV panels each operate from the same panel definition, but can experience independently-varying irradiances. Individual irradiance values can be set from the SCADA Input components inside of the illumination subsystem. The inputs for the PV panel definition are provided in Table 2

Table 2. PV model parameter inputs
SCADA Input Description

(name).illumination.PVi

Irradiance of panel i in an array of n panels [W/m^2].

(name).temperature

PV panel temperature [°C].

(name).iscSTC

Short circuit current under standard test conditions.

(name).vocSTC

Open circuit voltage under standard test conditions.

(name).negCurrent

Flag indicating whether negative current values should be allowed.

(name).FFu

Ratio of FFu maximum power point to open circuit voltage.

(name).FFi

Ratio of FFi maximum power point to short circuit current.

(name).Cg

Cg correction factor [W/m^2].

(name).Cv

Cv correction factor.

(name).Cr

Cr correction factor [m^2/W].

(name).alpha

Coefficient describing how short-circuit current changes with temperature [%/°C].

(name).beta

Coefficient describing how open-circuit voltage changes with temperature [%/°C].

Maximum Power Point Tracking (MPPT)

MPPT is conducted using a perturb and observe algorithm, configurable from the Controller tab of the component mask. MPPT is conducted independently for each of the panels, allowing the panel models to operate independently at different irradiance values.

Inverter model

Inverter behavior is modeled in an average value manner at the terminals of the PV Array with Microinverters component. The output of the MPPT stage is the aggregate power of the independent panels being modeled. This aggregated power value represents the combined output of the various microinverters. This value is provided to an inverter controller that monitors the grid interconnection and produces an appropriate voltage waveform at the voltage source VspA as defined by the combined PV output power and a reference value for reactive power.

The list of measurements available in the PV Array with Microinverters component is shown in Internal analog measurements of the PV Array with Microinverters component.

Internal analog measurements of the PV Array with Microinverters component

Analog output variable name Description

(name).Vpv[i]

Voltage of PV panel i.

(name).ipv[i]

Current of PV panel i.

(name).MPPT.Ppv[i]

Output power of PV panel i.

(name).MPPT.Ptotal

Combined output power of all PV panels.