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The main components of the PVGS is shown in the diagram below. A PV array along with a smoothing capacitor across its outputs is connected to a boost converter, which performs a DC/DC conversion of the generated energy to a higher voltage potential. This increased DC voltage, maintained across a second capacitor, is fed to a VSC which performs the necessary DC/AC conversion for connection to an external AC bus.

...

Mask and Parameters

PV

...

Array Tab

...

Name

Unit

Description

Parallel strings

-

Number of strings of series-connected modules that are connected in parallel. The default value is 5.

Series-connected modules per string

-

Number of PV modules connected in series in each string. The default value is 10.

Module

-

Select User-defined or a preset PV module from the NREL System Advisory Model database. Over 10,000 modules are listed from main manufacturers, sorted in alphabetical order. The NREL database includes manufacturer datasheets measured under standard test conditions (STC) (irradiance=1000 W/m2, temperature=25 degrees C).

When you select a module, this data from the NREL database updates when you apply your changes: Ncell, Voc, Isc, Vmp, Imp maximum power, as well as temperature coefficients of Voc and Isc. The function computes the five corresponding model parameters (IL, I0, nI, Rsh, Rs) using an optimization function and displays them on the right side of the dialog box.

When you select User-defined, you can enter your own specifications for the module data (Ncell, Voc, Isc, Vmp, Imp, and temperature coefficients of Voc and Isc). When you apply the changes, the function computes the five model parameters.

The default value is SunPower SPR-305E-WHT-D.

Maximum Power

W

Power obtained at maximum power point (Vmp, Imp). Pmax is computed as Pmax = Vmp × Imp. The default value is 305.2260 W.

Cells per module (Ncell)

-

Number of cells per module. The default value is 96.

Open circuit voltage Voc

V

Voltage obtained when array terminals are left open. The default value is 64.2 V.

Short-circuit current Isc

A

Current obtained when array terminals are short circuited. The default value is 5.96.

Voltage at maximum power point Vmp

V

Voltage at maximum power point. The default value is 54.7.

Current at maximum power point Imp

A

Current at maximum power point. The default value is 5.58.

Temperature coefficient of Voc

(%/deg.C)

Defines variation of Voc as a function of temperature. The open-circuit voltage at temperature T is obtained as

VocT = Voc (1 + beta_Voc(T–25)),

where Voc is the open-circuit voltage at 25 degrees C, VocT is the open-circuit voltage at temperature T (in degrees C), beta_Voc is the temperature coefficient (in %/degrees C), and T is the temperature in degrees C.

The default value is -0.27269 %/deg.C.

Temperature coefficient of Isc

%/deg.C

Defines variation of Isc as a function of temperature. The short-circuit current at temperature T is obtained as

IscT = Isc (1 + alpha_Isc(T–25)),

where Isc is the short-circuit current at 25 degrees C, IscT is the short-circuit current at temperature T (in degrees C), alpha_Isc is the temperature coefficient (in %/degrees C) and T is the temperature in degrees C.

The default value is 0.061745 %/deg.C.

Display I-V and P-V characteristics of...

-

To display the I-V and P-V characteristics of one module or of the whole array, for variable irradiance or for variable temperatures, select an option:

one module @ 25 deg.C & specified irradiances
array @ 25 deg.C & specified irradiances
array @ 1000 W/m2 & specified temperatures

The selected characteristics display when you click Plot.

The default value is array @ 25 deg.C & specified irradiances.

Irradiances

w/m2

This parameter is available only if Display I-V and P-V characteristics of is set to one module @ 25 deg.C & specified irradiances or array @ 25 deg. C & specified irradiances. Enter a vector of irradiances in W/m2. The default value is [ 1000 500 100 ].

T_cell

deg. C

This parameter is available only if Display I-V and P-V characteristics of is set to array @ 1000 W/m2 & specified temperatures. Enter a vector of temperatures in degrees C. The default value is [ 45 25 ] deg. C.

Light-generated current IL

A

Current for one module under STC, flowing out of the controllable current source that models the light-generated current. An optimization function determines this parameter to fit the module data. The default value is 6.0092 A.

Diode saturation current I0

A

Saturation current of the diode modeling the PV array for one module under STC. An optimization function determines this parameter to fit the module data. The default value is 6.3014e-12 A.

Diode ideality factor

-

Ideality factor of the diode modeling the PV array. An optimization function determines this parameter to fit the module data. The default value is 0.94504.

Shunt resistance Rsh

ohms

Shunt resistance of the model for one module under STC. An optimization function determines this parameter to fit the module data. The default value is 269.5934 Ω.

Series resistance Rs

ohms

Series resistance of the model for one module under STC. An optimization function determines this parameter to fit the module data. The default value is 0.37152 Ω.

VSC Controller Tab

...

Name

Unit

Description

Nominal power Pn

VA

Nominal power of the converter in VA. Default is 60000.

Nominal frequency fn

Hz

This parameter allows the user to specify the nominal frequency in hertz. Default is 50.

Q regulator gain Kp

This parameter allows the user to specify the reactive regulator gain Kp. Default is 1.

Q regulator gain Ki

This parameter allows the user to specify the reactive regulator gain Ki. Default is 10.

P regulator gain Kp

This parameter allows the user to specify the active regulator gain Kp. Default is 0.8.

P regulator gain Ki

This parameter allows the user to specify the active regulator gain Ki. Default is 2.5.

Current regulator gain Kp

This parameter allows the user to specify the current regulator gain Kp. Default is 1.

Current regulator gain Ki

This parameter allows the user to specify the current regulator gain Ki. Default is 100.

Islanded mode voltage regulator gain Kp

This parameter allows the user to specify the islanded mode voltage regulator gain Kp. Default is 0.

Islanded mode voltage regulator gain Ki

This parameter allows the user to specify the islanded mode voltage regulator gain Ki. Default is 0.

DC voltage regulator enable

This parameter allows the user to specify the DC voltage regulator enable. Default is 0.

DC Link Voltage

V

This parameter allows the user to specify the DC link voltage. Default is 1000.

DC link voltage regulator Kp

This parameter allows the user to specify the DC link voltage regulator Kp. Default is 1.

DC link voltage regulator Ki

This parameter allows the user to specify the DC link voltage regulator Ki. Default is 10.

Current limit

This parameter allows the user to specify the current limit. Default is 1.2.

Sample time

s

This parameter allows the user to specify the block sample time in seconds. Default is 50e-6.

Prioritiy

The user is able to define whether the controller should prioritize active or reactive power via the usage of this parameter.
1: Active power given preference if the total power is more than the converter rating.
0: Reactive power given preference

Mode

The user is able to define the mode of PV in the network.
1: Grid connected,
0: Grid Forming.

Voltage Source Converter Tab

...

Two-level converter subsection

Name

Unit

Description

Model type

Average model (Uref-controlled) is the only type of converter model.

Diode on-state resistance

Ohms

Internal resistance of the diodes, in ohms. The default value is 1e-3.

Diode snubber resistance

Ohms

The snubber resistance, in ohms. Set the snubber resistance to inf to eliminate the snubbers. The default value is 1000.

Diode snubber capacitance

F

The snubber capacitance in farads. Set the snubber capacitance to 0 to eliminate the snubbers. The default value is 1e-6.

Diode forward voltage

V

Forward voltage, in volts, across the diode when it is conducting. The default value is 1e-3.

Current source snubber resistance

Ohms

The snubber resistance across the two current sources, in ohms. Set the snubber resistance to inf to eliminate the snubbers. The default value is inf.

Series RL branch subsection

Name

Unit

Description

Branch type

Series RL branch.

Resistance R

Ohms

The series branch resistances (chocke resistance), in ohms (Ω). Default is 0.01.

Inductance L

H

The series branch inductances (chocke inductance), in henries (H). Default is 0.0244.

Filters Tab

...

Voltage PV Filter Subsection

The filter absorbs output PV array voltage oscillation directly. So you will have a better DC waveform to provide to the DC-DC converter. Especially if your converter lacks a controller, it should have this filter to produce a pure DC wave and a suitable DC output voltage.

Name

Unit

Description

Branch type

Series RC branch.

Resistance

Ohms

The shunt branch resistance, in ohms (Ω). Default is 0.01.

Capacitance

F

The shunt capacitance, in farads (F). Default is 10000e-6.

Set the initial capacitor voltage

If selected, the initial capacitor voltage is defined by the Capacitor initial voltage parameter. If cleared, the software calculates the initial capacitor voltage in order to start the simulation in steady-state. Default is selected.

Capacitor initial voltage

V

The initial capacitor voltage used at the start of the simulation. The Capacitor initial voltage parameter is not visible and has no effect on the block if the Set the initial capacitor voltage parameter is not selected. Default is 500 which equals the half of the DC Link Voltage parameter.

Ripple Filter Subsection

The filter absorbs output PV array current oscillation directly. So you will have a better DC waveform to provide to the DC-DC converter.

Name

Unit

Description

Branch type

Series RL branch.

Resistance

Ohms

The shunt branch resistance, in ohms (Ω). Default is 0.005.

Inductance

H

The shunt capacitance, in farads (F). Default is 1e-3.

Set the initial inductor current

If selected, the initial inductor current is defined by the Inductor initial current parameter. If cleared, the software calculates the initial inductor currnet in order to start the simulation in steady-state. Default is unselected.

Inductor initial current

A

The initial inductor current used at the start of the simulation. The Capacitor initial voltage parameter is not visible and has no effect on the block if the Set the initial inductor current parameter is not selected. Default is 0.

Voltage DC Filter Subsection

The filter absorbs output DC-DC converter voltage oscillation directly.

Name

Unit

Description

Branch type

Series RC branch.

Resistance

Ohms

The shunt branch resistance, in ohms (Ω). Default is 0.02.

Capacitance

F

The shunt capacitance, in farads (F). Default is 12e-3.

Set the initial capacitor voltage

If selected, the initial capacitor voltage is defined by the Capacitor initial voltage parameter. If cleared, the software calculates the initial capacitor voltage in order to start the simulation in steady-state. Default is selected.

Capacitor initial voltage

V

The initial capacitor voltage used at the start of the simulation. The Capacitor initial voltage parameter is not visible and has no effect on the block if the Set the initial capacitor voltage parameter is not selected. Default is 1000 which equals the DC Link Voltage parameter.

MPPT Parameters Tab

...

Name

Unit

Description

Initial value for D output (Dinit)

The initial value for boost converter duty cycle. Default is 0.5.

Upper limit for D (Dmax)

The upper limit for boost converter duty cycle. Default is 0.9.

Lower limit for D (Dmin)

The lower limit for boost converter duty cycle. Default is 0.1.

Increment value used to increase/decrease (DeltaD)

The increment value used to increase/decrease boost converter duty cycle. Default is 3e-6.

Measurements Tab

...

Name

Unit

Description

Time constant

s

Low pass filter time constant for power measurements, in seconds. Default value is 0.05.

Nominal power of network

w

Nominal power of network, in watts. Default is 12e3.

Time constant for power measurement filter

s

Power measurement filter time constant for signal conditioning, in seconds. Default value is 0.05.

Time constant for voltage measurement filter

s

Voltage measurement filter time constant for signal conditioning, in seconds. Default value is 0.05.

Time constant for current measurement filter

s

Current measurement filter time constant for signal conditioning, in seconds. Default value is 0.05.

Inputs, Outputs, and Signals Available for Monitoring

Inputs

Name

Unit

Description

P ref

pu

Specify the active power reference of the PV Generation System.

Q ref

pu

Specify the reactive power reference of the PV Generation System.

Ir ref

W/m2

This input is connected to a Simulink signal that represents varying sun irradiance.

T ref

degrees C

This input is connected to a Simulink signal that represents varying cell temperature.

Curtail enable

This input is connected to a Simulink signal that represents curtailment signal status.

1: Curtailment is currently being implemented. 0: There is no curtailment in effect.

Trip

Boolean

This input is connected to a Simulink signal that determines PVGS Trip signal status.

1: The PVGS has been tripped; 0: The PVGS has not been tripped.

Reset

Boolean

Outputs

Name

Unit

Description

Measurements

-

Several measurements are stored in this bus.

A

 

Connection port to phase A of the grid.

B

 

Connection port to phase B of the grid.

C

 

Connection port to phase C of the grid.