Instability with Constant Power Load in 2-bus system

Question

Hello everyone,

I’m comparing load models in a simple 2-bus system using Typhoon HIL. With impedance loads, the system behaves correctly, but when using a constant power load the system becomes unbalanced.

At the load node, the power values are not as expected and oscillate between negative and positive values.

I’ve checked time step, execution rates, and parameters, but the issue persists.

Could this be due to the inherent behavior of constant power loads, or a modeling issue?

Thanks in advance.

Answer 1

Hi,

This might be related to the snubber resistors in the component, since it uses a current source to interact with the circuit (https://www.typhoon-hil.com/documentation/typhoon-hil-software-manual/References/constant_power_loads_sources.html#:~:text=Rsnb-,Snubber%20resistance,-.)

I propose using one of the following:
1. Constant impedance load https://www.typhoon-hil.com/documentation/typhoon-hil-software-manual/References/constant_impedance_load.html
2. Three phase variable load https://www.typhoon-hil.com/documentation/typhoon-hil-software-manual/References/three-phase_variable_load.html?hl=load

Comments

Hello,

Thanks for your prompt response. Do you know if the snubber resistance can be parameterized in this model? If so, how could it be done?

Any insight would be appreciate

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Well, you can always reduce that resistance until the model stabilizes. However, then the total power your load draws would differ from the setpoint to some extent.

Variable load components handle this stuff better, since they do some of that snubber parameterization internally.

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Got it, thank you for the feedback