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Environment block for Simscape Electrical Specialized Power Systems models

**Library:**Simscape / Electrical / Specialized Power Systems

The powergui block allows you to choose one of these methods to solve your circuit:

Continuous, which uses a variable-step solver from Simulink

^{®}Discretization of the electrical system for a solution at fixed time steps

Continuous or discrete phasor solution

The powergui block also opens tools for steady-state and simulation results analysis and for advanced parameter design.

You need the powergui block to simulate any Simulink model containing Simscape™ Electrical™ Specialized Power Systems blocks. It stores the equivalent Simulink circuit that represents the state-space equations of the model.

When using one powergui block in a model:

Place the powergui block in the top-level diagram for optimal performance.

Make sure that the block is named

`powergui`

.

**Note**

The powergui block becomes disabled during model update. To ensure proper model execution, do not restore the library link for the powergui block.

You can use multiple powergui blocks in a system that contains two or more independent electrical circuits that you want to simulate with different powergui solvers. For example, this system simulates the upper electrical circuit in discrete mode and the bottom circuit in continuous mode. The system compares the simulation performance of the two methods.

To do so, put each circuit in a different subsystem, and then add a powergui block inside each subsystem.

When you use more than one powergui block in a model:

Do not place a powergui block in the top-level diagram.

Place every independent model in a different subsystem.

Place a single powergui block in the top level diagram of every subsystem.

**Note**

Do not include commented-out powergui blocks in your model. Doing so will prevent the model from simulating.

`Simulation type`

— Simulation type`Continuous`

(default) | `Discrete`

| `Phasor`

| `Discrete phasor`

Simulation type for the model:

`Continuous`

— Perform a continuous solution of the model.`Discrete`

— Perform a discretization of the model using the sample time specified by the**Sample time (s)**parameter.`Phasor`

— Perform continuous phasor simulation of the model at the frequency specified by the**Frequency (Hz)**parameter.`Discrete phasor`

— Perform a phasor simulation at fixed time steps specified by the**Sample time (s)**parameter, and at the frequency specified by the**Frequency (Hz)**parameter. The`Discrete phasor`

solver uses simplified machine models that produce simulation results similar to transient stability software.

`Sample time (s)`

— Sample time for discretization`50e-6`

(default) | positive scalarSample time used to discretize the electrical circuit, in s. The powergui block displays the value of the sample time.

To enable this parameter, set **Simulation type**
to `Discrete`

or `Discrete phasor`

.

`Frequency (Hz)`

— Frequency for phasor simulation`60`

(default) | positive scalarFrequency, in Hz, for performing the phasor simulation of the model. The powergui block displays the value of the phasor frequency.

To enable this parameter, set **Simulation type**
to `Phasor`

or `Discrete phasor`

.

`Steady-State`

— Display steady-state voltages and currentsbutton

Open the Steady-State Voltages and Currents Tool dialog box to display
the steady-state voltages and currents of the model. For more
information, see `power_steadystate`

.

`Initial State`

— Display and modify initial capacitor voltages and inductor currentsbutton

Open the Initial States Setting Tool dialog box to display and modify
initial capacitor voltages and inductor currents of the model. For more
information, see `power_initstates`

.

`Machine Initialization`

— Initialize three-phase networks containing three-phase machinesbutton

Open the Machine Initialization Tool dialog box to initialize three-phase networks
containing three-phase machines so that the simulation starts in steady
state. The Machine Initialization Tool offers simplified load flow
features, but can still initialize machine initial currents of your
models. For more information, see `power_loadflow`

.

`Impedance Measurement`

— Display the impedance versus frequencybutton

Open the Impedance vs Frequency Measurement Tool dialog box to display the impedance
versus the frequency, as defined by the Impedance
Measurement blocks. For more information, see `power_zmeter`

.

`FFT Analysis`

— Perform Fourier analysis of signalsbutton

Open the FFT Analysis Tool dialog box to perform Fourier analysis of
signals stored in a structure with time format. For more information,
see `power_fftscope`

.

For an example that uses the FFT Analysis tool, see Performing Harmonic Analysis Using the FFT Tool.

`Use Linear System Analyzer`

— Time and frequency domain responsesbutton

Open the Linear System Analyzer dialog box to generate the state-space model of your
system (if you have a Control System Toolbox™ license) or to view time and frequency domain responses.
For more information, see `power_ltiview`

.

`Hysteresis Design`

— Design hysteresis characteristic for the saturable corebutton

Open the Hysteresis Design Tool to design a hysteresis characteristic for the saturable
core of the Saturable Transformer block and the
Three-Phase Transformer blocks (Two Windings and
Three Windings). For more information, see `power_hysteresis`

.

`RLC Line Parameters`

— Compute RLC parameters of an overhead transmission line button

Open the Compute RLC Line Parameters Tool to compute the RLC parameters of an overhead
transmission line from the conductor characteristics and tower geometry.
For more information, see `power_lineparam`

.

`Generate Report`

— Generate report of steady-state variables, initial states, and machine load flowbutton

Open the Generate Report Tool dialog box to generate a report of
steady-state variables, initial states, and machine load flow for a
model. For more information, see `power_report`

.

`Customize SPS blocks`

— Create custom blocks button

Open the power_customize dialog box to create custom Simscape
Electrical Specialized Power Systems blocks. For more information,
see `power_customize`

.

`Load Flow`

— Perform load flow and initialize three-phase networks and machinesbutton

Open the Load Flow Tool dialog box to perform load flow analysis and initialize
three-phase networks and machines so that the simulation starts in
steady state. The Load Flow Tool uses the Newton-Raphson method to
provide a robust and faster convergence solution compared to the Machine
Initialization Tool. The Load Flow Tool offers most of the functionality
of other tools available in the power utility industry. For more
information, see `power_loadflow`

.

`Max iterations`

— Maximum iterations used by Load Flow Tool`50`

(default) | positive integerMaximum number of times the Load Flow Tool iterates until the P and Q
powers mismatch at each bus is lower than the **PQ
tolerance** parameter value (in pu/Pbase). The power
mismatch is defined as the difference between the net power injected
into the bus by generators and loads and the power transmitted on all
links leaving that bus. For example, if the base power is 100 MVA and
**PQ tolerance** is set to `1e-4`

,
the maximum power mismatch at all buses does not exceed 0.1 MW or 0.1
Mvar.

`Frequency (Hz)`

— Frequency for load flow computations`60`

(default) | positive scalarFrequency, in Hz, used by the Load Flow Tool to compute the normalized Ybus network admittance matrix of the model and to perform the load flow calculations.

`Base power (VA)`

— Base power used by Load Flow Tool`100e6`

(default) | positive scalarBase power, in VA, used by the Load Flow Tool to compute the
normalized Ybus network admittance matrix in pu/Pbase and bus base
voltages of the model, at the frequency specified by the
**Frequency (Hz)** parameter for load flow
computations.

To avoid a badly conditioned Ybus matrix, select a base power value in the range of nominal powers and loads of the model. For a transmission network with voltages ranging from 120 kV to 765 kV, a 100 MVA base is usually selected. For a distribution network or for a small plant consisting of generators, motors, and loads that have a nominal power in the range of hundreds of kilowatts, a 1 MVA base power is better adapted.

`PQ tolerance (pu)`

— Tolerance between P and Q`1e-4`

(default) | positive scalarTolerance between P and Q when the Load Flow Tool stops to iterate.

`Voltage units`

— Voltage units used by Load Flow Tool`kV`

(default) | `V`

Voltage units used by the Load Flow Tool to display voltages.

`Power units`

— Power units used by Load Flow Tool`MW`

(default) | `kW`

| `W`

Power units used by the Load Flow Tool to display powers.

The load flow parameters are for model initialization only. They do not have an impact on simulation performance.

`Disable Specialized Power Systems warnings`

— Disable warnings during analysis and simulation`off`

(default) | `on`

Control display of Simscape Electrical Specialized Power Systems warnings during model analysis and simulation.

`Display Specialized Power Systems compilation messages`

— Display echo messages during analysis`off`

(default) | `on`

Control display of the command-line echo messages during model analysis.

`Use TLC file when in Accelerator Simulation Mode and for code generation`

— Use TLC state-space S-functions`off`

(default) | `on`

Select to use TLC state-space S-functions (`sfun_spssw_contc.tlc`

and
`sfun_spssw_discc.tlc`

) in accelerator mode and
for code generation.

Clear this checkbox if you notice a slowdown in performance when using accelerator mode
when compared to previous releases. This slowdown occurs if you have the
LCC compiler installed as the default compiler for building the external
interface (`mex`

).

To enable this parameter, set **Simulation type**
to `Discrete`

.

`Disable ideal switching`

— Control model switching devices as current sources`off`

(default) | `on`

Select to model switching devices as current sources. By default, this option is not selected, which corresponds to the recommended setting for most of your applications.

Modeling switches, such as circuit breakers or power electronic devices, as current sources implies that the on-state switch resistance (Ron) cannot be zero. In this modeling method, the switches cannot be connected in a series with an inductive circuit or with another switch or current source.

When this option is enabled, you must add a circuit (R or RC snubber) in parallel with the switches in your model so that the switches' off-state impedance has a finite value. If your real circuit does not use snubbers, or if you want to simulate ideal switches with no snubber, you must at least use resistive snubbers with a high resistance value to introduce a negligible leakage current. The drawback of introducing such high-impedance snubbers is that the large difference between the on-state and the off-state switch impedance produces a stiff state-space model.

To enable this parameter, set **Simulation type**
to `Continuous`

.

`Disable snubbers in switching devices`

— Control snubber devices of power electronic and breaker blocks`off`

(default) | `on`

Select to disable the snubber devices of the power electronic and breaker blocks in your model.

To enable this parameter, set **Simulation type**
to `Continuous`

and clear **Disable
ideal switching**.

`Disable Ron resistances in switching devices`

— Control internal resistance of switches and power electronic devices`off`

(default) | `on`

Select to disable the internal resistance of switches and power electronic devices and to force the value to zero ohms.

To enable this parameter, set **Simulation type**
to `Continuous`

and clear **Disable
ideal switching**.

`Disable forward voltages in switching devices`

— Control internal forward voltage of power electronic devices`off`

(default) | `on`

Select to disable the internal forward voltage of power electronic devices and to force the value to zero volts.

To enable this parameter, set **Simulation type**
to `Continuous`

and clear **Disable
ideal switching**.

`Display circuit differential equations`

— Display differential equations in Diagnostic Viewer`off`

(default) | `on`

Select to display the differential equations of the model in the Diagnostic Viewer when the simulation starts.

To enable this parameter, set **Simulation type**
to `Continuous`

and clear **Disable
ideal switching**.

`Automatically handle Discrete solver and Advanced tab solver settings of blocks`

— Set descretization method automatically`off`

(default) | `on`

Select to automatically set the discretization method to ```
Trapezoidal
robust
```

in models that contain at least one of the
following blocks:

Asynchronous Machine

Permanent Magnet Synchronous Machine

Simplified Synchronous Machine

Synchronous Machine

Surge Arrester

Variable Resistor

Variable Inductor

Variable Capacitor

Nonlinear Resistor

Nonlinear Inductor

Variable-Ratio Transformer

Any transformer blocks that are modeling saturation

If your model contains none of these blocks, the discretization method
is automatically set to ```
Tustin/Backward Euler
(TBE)
```

.

To enable this parameter, set **Simulation type**
to `Discrete`

.

`Discrete solver`

— Discrete solver to use to simulate model```
Tustin/Backward Euler
(TBE)
```

(default) | `Tustin`

| `Backward Euler`

Set to `Tustin/Backward Euler (TBE)`

to
simulate the model using a combination of the Tustin and Backward Euler
methods.

Set to `Tustin`

to discretize the electrical
model using the Tustin method. If you use this solver, you need to
specify the *Rs* and *Cs* snubber
values to avoid numerical oscillations when the firing pulses are
blocked (when the bridge is operating as a rectifier). You can use the
following formulas to compute the values of *Rs* and
*Cs*:

*Rs* > 2* *Ts* /
*Cs*

*Cs* < *Pn* /(1000*2*pi*
*f* * *Vn* ^2

where:

*Pn*is the nominal power of the single-phase or three-phase converter, in VA.*Vn*is the nominal line-to-line AC voltage, in Vrms.*f*is the fundamental frequency, in Hz.*Ts*is the sample time, in s.

These values are derived from these criteria:

The snubber leakage current at the fundamental frequency is less than 0.1% of the nominal current when power electronic devices are not conducting.

The RC time constant of the snubbers is larger than two times the sample time,

*Ts*.

**Note**

The *Rs* and *Cs* values that
guarantee the numerical stability of the discretized bridge can be
different from the actual values used in the physical
circuit.

Set to `Backward Euler`

to discretize the
electrical model using the Backward Euler method.

To enable this parameter, set **Simulation type**
to `Discrete`

and clear
**Automatically handle Discrete solver and Advanced tab
solver settings of blocks**.

`Interpolate switching events`

— Increase simulation speed`off`

(default) | `on`

Select to increase simulation speed by enabling the solver to interpolate in discrete models using power electronics. When selected, the solver captures gate transitions of power electronic devices occurring between two sample times, allowing larger sample times (typically 20×) than you use with the standard solvers. For example, simulating a 5 kHz PWM converter with Tustin (no interpolation) or Tustin/Backward Euler normally requires a 1.0 µs sample time (sampling frequency = 200 × PWM frequency) to obtain a good resolution on pulse generation and guarantee accurate results. With interpolation enabled, using a sample time as large as 20 µs executes faster while preserving model accuracy.

When you select this option:

Use a continuous pulse generator to guarantee the best accuracy on pulse generation. (Specify sample time =

`0`

in pulse-generation blocks.)In the Configuration Parameters dialog box, select a continuous, variable-step solver (

`ode45`

or`ode23tb`

with default settings). The continuous solver is required by the interpolation solver to compute the gate signals' time delays with respect to discrete sample times. The solver uses these pulse delays to interpolate between sample times and produce accurate results.

To see how interpolation increases accuracy and simulation speed, see the power_buck example model.

To enable this parameter, set **Simulation type**
to `Discrete`

, clear
**Automatically handle Discrete solver and Advanced tab
solver settings of blocks**, and set **Discrete
solver** to `Tustin`

.

`Use time-stamped gate signals`

— Capture evolution of states at different switching times`off`

(default) | `on`

When selected, the interpolation method computes model outputs at fixed sample times while taking into account switching events that occur between two sample times. The method receives pulses at fixed time steps and computes the time delays of the gate signals arriving within each time step. Computing the time delays enables the method to capture the evolution of states at different switching times.

When cleared, the interpolation method computes the time delays of the gate signal.

When selected, the block does not compute the time delays of gate signals. You then need to directly provide time-stamped gate signals to the switching devices in your model. For more information on the concept of time-stamped gate signals in Simscape Electrical Specialized Power Systems switching devices, see the power_buck example.

To enable this parameter, set **Simulation type**
to `Discrete`

, clear
**Automatically handle Discrete solver and Advanced tab
solver settings of blocks**, set **Discrete
solver** to `Tustin`

, and
select **Interpolate switching events**.

`Store switching topologies`

— Increase simulation speed`off`

(default) | `on`

Select to increase simulation speed by enabling the solver to store and reuse matrix computation results.

To enable this parameter, set **Simulation type**
to `Continuous`

or
`Discrete`

and clear
**Automatically handle Discrete solver and Advanced tab
solver settings of blocks**.

` Buffer size (MBytes)`

— Buffer size for saving computations`100`

(default) | positive scalarBuffer size for saving state-space matrix computations.

To enable this parameter, set **Simulation type**
to `Continuous`

or
`Discrete`

, clear
**Automatically handle Discrete solver and Advanced tab
solver settings of blocks**, and select **Store
switching topologies**.

`Start simulation with initial electrical states from`

— Initial state value`blocks`

(default) | `steady`

| `zero`

If you select:

`blocks`

— Initial state values defined in blocks are used for the simulation`steady`

— Forces all initial electrical state values to steady-state values`zero`

— Forces all initial electrical state values to zero

`Solver tolerance`

— Maximum solver error`1e-4`

(default) | positive scalarLargest acceptable solver error.

To enable this parameter, set **Simulation type**
to `Discrete`

and expand **Solver
details for nonlinear elements**.

`Maximum number of iterations`

— Iteration limit`100`

(default) | positive scalarMaximum number of iterations. Iterations stop when the
**Solver tolerance** is achieved, or when the
**Maximum number of iterations** is reached. A
solution is usually found within 1 to 3 iterations. An error message is
returned and simulation stops if a solution is not found when the
maximum number of iterations is exceeded.

To enable this parameter, set **Simulation type**
to `Discrete`

and expand **Solver
details for nonlinear elements**.

`Continue Simulation if maximum number of iterations is reached`

— Limit maximum number of iterations`off`

(default) | `on`

Select to limit the maximum number of iterations. This parameter is used for real-time applications. Usually, limiting the number of iterations to 2 produces acceptable results.

To enable this parameter, set **Simulation type**
to `Discrete`

and expand **Solver
details for nonlinear elements**.

Generate C and C++ code using Simulink® Coder™.

`power_customize`

| `power_fftscope`

| `power_hysteresis`

| `power_initstates`

| `power_lineparam`

| `power_ltiview`

| `power_loadflow`

| `power_report`

| `power_steadystate`

| `power_zmeter`

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