pvl_snlinverter
Sandia photovoltaic inverter model.
Contents
Syntax
ACPower = pvl_snlinverter(Inverter, Vdc, Pdc)
Description
Computes the AC power output using the Sandia photovoltaic inverter model [1].
Inputs
- Vdc - a vector of modeled DC voltage.
- Pdc - a vector of modeled DC power.
- Inverter - A struct of parameters defining the inverter to be used. A library of inverter performance parameters are provided with PV_LIB (\Required Data\SandiaInverterDatabaseSAM2012.11.30.mat), or a library may be generated from a System Advisor Model (SAM) [2] library using the SAM library reader function pvl_SAMLibraryReader_SNLInverters. Required struct components are:
- Inverter.Pac0 - AC-power output from inverter based on input power and voltage, (W).
- Inverter.Pdc0 - DC-power input to inverter, typically assumed to be equal to the PV array maximum power, (W).
- Inverter.Vdc0 - DC-voltage level at which the AC-power rating is achieved at the reference operating condition, (V).
- Inverter.Ps0 - DC-power required to start the inversion process, or self-consumption by inverter, strongly influences inverter efficiency at low power levels, (W).
- Inverter.C0 - Parameter defining the curvature (parabolic) of the relationship between ac-power and dc-power at the reference operating condition, default value of zero gives a linear relationship, (1/W).
- Inverter.C1 - Empirical coefficient allowing Pdco to vary linearly with dc-voltage input, default value is zero, (1/V).
- Inverter.C2 - empirical coefficient allowing Pso to vary linearly with dc-voltage input, default value is zero, (1/V).
- Inverter.C3 - empirical coefficient allowing Co to vary linearly with dc-voltage input, default value is zero, (1/V).
- Inverter.Pnt - ac-power consumed by inverter at night (night tare) to maintain circuitry required to sense PV array voltage, (W).
Outputs
- ACPower - a vector of modeled AC power output
Note: When ACPower would be greater than Pac0, it is set to Pac0 to represent inverter "clipping". When ACPower would be less than Ps0 (startup power required), then ACPower is set to -1 * abs(Pnt) to represent tare losses.
Example 1
load 'SandiaInverterDatabaseSAM2014.1.14.mat'; % PV Powered PVP2500 is entry #793 Inverter = SNLInverterDB(793)
Inverter = struct with fields: name: {'PV Powered: PVP2500 240V [CEC 2006]'} Vac: 240 Pac0: 2500 Pdc0: 2.6301e+03 Vdc0: 219.2317 Ps0: 41.3618 C0: -1.2650e-05 C1: 6.6747e-05 C2: 0.0017 C3: 6.1375e-04 Pnt: 3.9000 Vdcmax: 500 Idcmax: 20 MPPTLow: 140 MPPTHi: 450 LibraryType: {'SandiaInverter'} LibraryName: {'Sandia Inverters'}
Assume DC power is 1,000 W and voltage is 400 V
Pdc = 1000; %DC power is 1000 W Vdc = 400; % DC violtage is 450 V ACPower = pvl_snlinverter(Inverter, Vdc, Pdc)
ACPower = 928.7350
Inverter efficiency can be calculated as:
Inverter_Efficiency = ACPower/Pdc
Inverter_Efficiency = 0.9287
Example 2
Pdc = 0; Vdc = 0;
When there is no DC power the inverter still draws power from the grid. This is expressed as a negative power output.
ACPower = pvl_snlinverter(Inverter, Vdc, Pdc)
ACPower = -3.9000
References
[1] King, D. et al., 2007. Performance Model for Grid-Connected Photovoltaic Inverters, SAND2007-5036, Sandia National Laboratories, Albuquerque, NM. Web Link
[2] System Advisor Model web page. Web Link.
See Also
Copyright 2014 Sandia National Laboratories