Question about VSG units

[xiaoheimai95]

Dear Dr. Cui and Jinning,
We would like to know whether VSG model (REGCV1) in our platform takes the threshold of current limiter into consideration. And if yes, can you give me some materials about that?

[jinningwang]

After checking the code and documentation, I don't think there is any Limiter in REGCV1.

I am happy to have a further discussion if you want to implement any practical or reasonable Limiter.

In the future, you can use the same procedures to check the detailed implementation of any model in ANDES. This is one of the advantages of ANDES over black-box software, as it allows you to know the details of the model and make any necessary modifications.

[xiaoheimai95]

That's so nice of you, Jinning! I have referred to some materails, and the current limitation mainly lies in Idref and Iqref, which will affect the output of Pe. Can you suggest where in the code I should make some changes?

[jinningwang]

There are some pre-defined blocks andes.core.block.PIController that you might use. For example, You can replace PIController with PIAWHardLimit in the definition of VSGOuterPIModel as below. Here I skipped the detailed parameters input, you might need to pay attention.

class VSGOuterPIModel:
    """
    Outer PI controllers for REGCV1
    """

    def __init__(self, vderr: str = 'vd-vref2', vqerr: str = 'vq'):
        self.PIvd = PIAWHardLimit(u=vderr,
                                 kp=self.Kpvd,
                                 ki=self.Kivd,
                                 x0='Id0',
                                 )
        self.PIvq = PIAWHardLimit(u=vqerr,
                                 kp=self.Kpvq,
                                 ki=self.Kivq,
                                 x0='Iq0',
                                 )

        self.Idref = AliasAlgeb(self.PIvd_y)
        self.Iqref = AliasAlgeb(self.PIvq_y)

I would suggest referencing some industry-grade models and following their design. WECC Approved Dynamic Model Library can be a good reference. Further, Examples and Model development workflow might be helpful for model development.

[xiaoheimai95]

Thank you for your answer!
The equation of Idref, Iqref and Pe under current limitation are as below:


So actually, I would like to add judgment statements in the code. And it is a little difficult for me to find a proper place.

[jinningwang]

In the discrete module, there are LessThan and IsEqual can be used in your function. You can do a search and take a look at any models that have these elements.