Fault (Three-Phase)

Signal-enabled or time-based, single-phase, two-phase, or three-phase, grounded or ungrounded fault

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Libraries:
Simscape / Electrical / Utilities

Description

The Fault (Three-Phase) models any permutation of a single-phase, two-phase, or three-phase grounded or ungrounded fault. The block can impose both time- and event-based faults. The block can impose one or both type of faults, consecutively, at the same time, or for an overlapping time period.

For a time-based or temporal fault, specify the fault activation time using the block Fault start time parameter. The fault becomes inactive when the fault duration that you specify elapses.

For an event-based fault, specify the fault activation threshold using the block Threshold parameter. An external control signal F enables the fault. The fault is active when F is greater than the threshold. The fault is inactive when F is less than or equal to the threshold.

The block can represent these permutations:

• Single-phase-to-ground fault (a-g, b-g, or c-g)

• Two-phase fault (a-b, b-c, or c-a)

• Two-phase-to-ground fault (a-b-g, b-c-g, or c-a-g)

• Three-phase fault (a-b-c)

• Three-phase-to-ground fault (a-b-c-g)

The figure shows the equivalent circuit diagram for the block.

To determine the resistance in the equivalent circuit, apply the relevant equations from the table.

Failure mode		Value of R a	Value of R b	Value of R c	Value of R g
None / inactive		$$\frac{1}{G_{pn}}$$	$$\frac{1}{G_{pn}}$$	$$\frac{1}{G_{pn}}$$	Infinity / open circuit
Single phase to ground	a-g	$$R_{pn}$$	$$\frac{1}{G_{pn}}$$	$$\frac{1}{G_{pn}}$$	$$R_{ng}$$
	b-g	$$\frac{1}{G_{pn}}$$	$$R_{pn}$$	$$\frac{1}{G_{pn}}$$	$$R_{ng}$$
	c-g	$$\frac{1}{G_{pn}}$$	$$\frac{1}{G_{pn}}$$	$$R_{pn}$$	$$R_{ng}$$
Two phase	a-b	$$R_{pn}$$	$$R_{pn}$$	$$\frac{1}{G_{pn}}$$	Infinity / open circuit
	b-c	$$\frac{1}{G_{pn}}$$	$$R_{pn}$$	$$R_{pn}$$	Infinity / open circuit
	c-a	$$R_{pn}$$	$$\frac{1}{G_{pn}}$$	$$R_{pn}$$	Infinity / open circuit
Two phase to ground	a-b-g	$$R_{pn}$$	$$R_{pn}$$	$$\frac{1}{G_{pn}}$$	$$R_{ng}$$
	b-c-g	$$\frac{1}{G_{pn}}$$	$$R_{pn}$$	$$R_{pn}$$	$$R_{ng}$$
	c-a-g	$$R_{pn}$$	$$\frac{1}{G_{pn}}$$	$$R_{pn}$$	$$R_{ng}$$
Three phase	a-b-c	$$R_{pn}$$	$$R_{pn}$$	$$R_{pn}$$	Infinity / open circuit
Three phase to ground	a-b-c-g	$$R_{pn}$$	$$R_{pn}$$	$$R_{pn}$$	$$R_{ng}$$

where:

• R_a is the resistance between the a-phase and the neutral point of a wye connection.

• R_b is the resistance between the b-phase and the neutral point of a wye connection.

• R_c is the resistance between the c-phase and the neutral point of a wye connection.

• R_g is the resistance between the neutral point of a wye connection and electrical reference.

• R_pn is the value of the Faulted phase-neutral resistance parameter.

• R_ng is the value of the Faulted neutral-ground resistance parameter.

• G_pn is the value of the Unfaulted phase-neutral conductance parameter.

Ports

Conserving

~ — Three-phase port

electrical

Expandable electrical conserving three-phase port for connecting the fault to the system.

Input

F — Externally triggered fault control input

physical

Physical signal scalar control input port for enabling an externally triggered fault.

Dependencies

To enable this port, on the External Trigger settings, set the Enable external fault trigger parameter to Yes.

Output

X — Fault state

physical

Physical signal scalar output port for reporting the fault state:

• 1 — Faulted

• 0 — Unfaulted

Dependencies

To enable this port, on the Main settings, set the State port parameter to Visible.

Parameters

Modeling option — Whether to model composite or expanded three-phase ports

Composite three-phase ports (default) | Expanded three-phase ports

Whether to model composite or expanded three-phase ports.

Composite three-phase ports represent three individual electrical conserving ports with a single block port. You can use composite three-phase ports to build models that correspond to single-line diagrams of three-phase electrical systems.

Expanded three-phase ports represent the individual phases of a three-phase system using three separate electrical conserving ports.

Main

Failure mode — Type of fault

None (default) | Single-phase to ground (a-g) | Single-phase to ground (b-g) | Single-phase to ground (c-g) | Two-phase (a-b) | Two-phase (b-c) | Two-phase (c-a) | Two-phase to ground (a-b-g) | Two-phase to ground (b-c-g) | Two-phase to ground (c-a-g) | Three-phase (a-b-c) | Three-phase to ground (a-b-c-g)

Type of fault to model. The visibility of related parameters depends on the fault model. Options are:

• None — Specifies that the fault is not active.

• Single-phase to ground (a-g)

• Single-phase to ground (b-g)

• Single-phase to ground (c-g)

• Two-phase (a-b)

• Two-phase (b-c)

• Two-phase (c-a)

• Two-phase to ground (a-b-g)

• Two-phase to ground (b-c-g)

• Two-phase to ground (c-a-g)

• Three-phase (a-b-c)

• Three-phase to ground (a-b-c-g)

Faulted phase-neutral resistance — Faulted phase-neutral resistance

1e-3 Ohm (default)

Resistance between the phase connection and the neutral point when the fault is active.

Dependencies

To enable this parameter set the Failure mode parameter to:

• Single-phase to ground (a-g)

• Single-phase to ground (b-g)

• Single-phase to ground (c-g)

• Two-phase (a-b)

• Two-phase (b-c)

• Two-phase (c-a)

• Two-phase to ground (a-b-g)

• Two-phase to ground (b-c-g)

• Two-phase to ground (c-a-g)

• Three-phase (a-b-c)

• Three-phase to ground (a-b-c-g)

Faulted neutral-ground resistance — Faulted neutral-ground resistance

1e-3 Ohm (default)

Resistance between the neutral point and the electrical reference when fault is active.

Dependencies

To enable this parameter set the Failure mode parameter to:

• Single-phase to ground (a-g)

• Single-phase to ground (b-g)

• Single-phase to ground (c-g)

• Two-phase to ground (a-b-g)

• Two-phase to ground (b-c-g)

• Two-phase to ground (c-a-g)

• Three-phase to ground (a-b-c-g)

State port — State port visibility

Hidden (default) | Visible

Option to hide or expose port x, a physical signal output port that reports the fault state:

• Hidden — Port x is not visible if you select this option.

• Visible — Port x is visible only if you select this option.

External Trigger

Enable external fault trigger — External fault model

No (default) | Yes

External fault model. Choose between

• No — Do not model an external fault. Physical signal input port F is not visible if you select this option.

• Yes — Model an external fault. Related parameters and physical signal input port F are visible only if you select this option.

Fault threshold — Threshold value that triggers the fault

0.5 (default)

The threshold value that triggers the fault when the external signal crosses it in the direction, specified by the fault condition. This parameter is visible only if the Enable external fault trigger parameter is set to Yes. The default value is 0.5.

Dependencies

To enable this parameter, set the Enable external fault trigger parameter to Yes.

External fault trigger — Fault condition

Faulted if F >= Fault threshold (default) | Faulted if F <= Fault threshold

Choose the fault condition:

• Faulted if F >= Fault threshold — The fault occurs when the external signal value becomes greater than, or equal to, the Fault threshold parameter value.

• Faulted if F <= Fault threshold — The fault occurs when the external signal value becomes less than, or equal to, the Fault threshold parameter value.

Dependencies

To enable this parameter, set the Enable external fault trigger parameter to Yes.

Fault resets when fault trigger reverts — Fault resets when fault trigger reverts

No (default) | Yes

Select Yes to have the fault reset when the trigger signal reverts. The default value is No.

Dependencies

To enable this parameter, set the Enable external fault trigger parameter to Yes.

Temporal Trigger

Enable temporal fault trigger — Temporal fault model

No (default) | Yes

Temporal fault model. Choose between

• No — Do not model a temporal fault.

• Yes — Model a temporal fault. Related parameters are visible only if you select this option.

Fault start time — Fault start time

1 s (default)

Simulation time that the block enters the fault state.

Dependencies

To enable this parameter, set the Enable temporal fault trigger parameter to Yes.

Fault duration — Fault duration

0.1 s (default)

Simulation duration time for the fault. The block exits the fault state when the duration time is over.

Dependencies

To enable this parameter, set the Enable temporal fault trigger parameter to Yes.

Parasitics

Unfaulted phase-neutral conductance — Unfaulted phase-neutral conductance

1e-6 1/Ohm (default)

Conductance between the phase connections and the neutral point when a phase is not involved in the fault.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2019b