Frequently Asked Question

What type of load component to use in my model?
Last Updated 7 months ago

Typhoon HIL Control Center library offers different components to model loads in your schematics. Since these components differ in functionality, complexity, and resources utilization, the choice should be based on the requirements of your simulation and the available resources.

The main load components are described as follows:

a) Constant Impedance Load (documentation link here).

This is the simplest possible load component, consisting of a fixed three-phase R, RC or RL load, whose values are calculated based on the nominal parameters set in the component mask. Given its low resource utilization, with proper circuit partitioning, tens or even hundreds of them can be used, which is suitable for large power system models. As drawback, it is not possible to vary the power during simulation runtime. Also, the power will be constant under the assumption that the grid voltage and frequency are constant.

Example is available on the software installation: \examples\models\microgrid\meter and constant z load

b) VBR Variable Load (documentation link here). 

With this component you can vary the power setpoint during simulation runtime. It is also capable of keeping the reference power under varying voltage (usually within 20% of the nominal voltage). The component is implemented using the voltage-behind-reactance approach, where internal loops control the controllable voltage sources according to active and reactive power setpoints. Usually, tens of those can be put in a single model.

Example is available on the software installation: …\examples\models\microgrid\variable load\variable load

c) Variable Load (Generic) (documentation link here). 

This can be seen as an improved version of the VBR Variable Load component. In comparison to that component, the parametrization is easier, given that the internal controllers are automatically tuned based on the nominal parameters defined on the mask properties. Moreover, the component also has an in-built contactor and it includes basic protection functions, making it the ideal load type for microgrid applications.

Example is available on the software installation: … \examples\models\microgrid\variable load\variable load (generic)

d) Three-phase Variable Load (documentation link here). 

This is the most complex component in this list, occupying an entire FPGA core (with optional built-in core coupling). It is built based on variable impedance, i.e., using time varying elements (documentation link here). The main advantage of this component is its increased stability, the ability to provide non-symmetrical power output, and the ability to work under conditions of higher harmonic distortion. On the other hand, is it significantly more expensive in terms of resources utilization.

Example is available on the software installation: … \examples\models\microgrid\variable load\Three-phase Variable Load

Table 1 illustrates a comparison of resources utilization and available features for the abovementioned load components. 

Table 1 - Comparison of resources utilization and features availability for different load components.

Matrix Memory Utilization

Signal Processing Utilization

Max Number per Core

In-built protection

Unlocked models

In-built Contactor

Constant Impedance Load

Low

None

>10

No

Yes

No

VBR Variable Load

Low

Medium

05

No

Yes

No

Variable Load (Generic)

Medium

High

03

Yes

No

Yes

Three-phase Variable Load

High

High

01

No

No

Yes

Considering the signal processing utilization, the maximum number of variable load components per device type depends on the HIL device and can be estimated as shown in Table 2.

Table 2 – Estimation of the maximum number of load components per device type.

HIL402

HIL404

HIL602+, HIL604

HIL606

VBR Variable Load

20

20

30

40

Variable Load (Generic)

08

12

10

24

Three-phase Variable Load*

01

04*

01

06*

* Possible assuming CPU partitioning - KB article.

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