Hi Danula, an important issue is the network model you select. For example, you can use a full nonlinear multi-phase power flow model, a second order cone model, or a linear power flow model. These will each be more or less appropriate depending on the voltage level and type of network topology you are interested in. Each type of model will require particular constraints to implement them within an optimisation problem.

Standard network constraints are:

- Power balance (real and reactive) at each node.

- Max and min voltage magnitude limits

- Max line current magnitude limits

Additionally, you may have constraints associated with particular resources:

- max and min power limits (real, reactive and/or apparent)

- max ramp rate

- max and min energy limits for batteries

- max and min temperature for flexible heating/cooling

Some potentially useful references:

A. Bernstein and E. Dall’Anese, “Linear Power-Flow Models in Multiphase Distribution Networks,” in 2017 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe), 2017, no. May, pp. 1–6.

L. Gan, N. Li, U. Topcu, and S. H. Low, “Exact Convex Relaxation of Optimal Power Flow in Radial Networks,” IEEE Transactions on Automatic Control, vol. 60, no. 1, pp. 72–87, 2015.

T. Morstyn, B. Hredzak, R. P. Aguilera, and V. G. Agelidis, “Model Predictive Control for Distributed Microgrid Battery Energy Storage Systems,” IEEE Transactions on Control Systems Technology, 2017.

Thomas Morstyn Thank you for your information , it is really useful

Two constraints such as Equality and Inequality. Equal constraints should be Real and reactive power generation should be equal to Apparent power load / demand plus power losses. Inequality constraints should be Voltage within the limits, Real and reactive power injection should not be more than the demand. Minimum and maximum real and reactive power injection should be within the specified limits.

Rest of the things depends upon your objective function

Dear Danula Balasooriya

Please take a look at these sites

Best regards

https://ieeexplore.ieee.org/iel7/6287639/7859429/08066438.pdf

https://ieeexplore.ieee.org/abstract/document/486711

https://pastel.archives-ouvertes.fr/tel-01899752/document

https://s3.amazonaws.com/academia.edu.documents/52787763/tpwrs.2011.216134920170424-5108-wyml43.pdf?response-content-disposition=inline%3B%20filename%3DImposing_Radiality_Constraints_in_Distri.pdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWOWYYGZ2Y53UL3A%2F20191130%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20191130T144935Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=9c29979f9ad81aab14fc30f00aab92aa2cc8748cb194adff56cc4806a6be7ba6

Real and Reactive power generation and demand should be equal. Voltage should be between 0.95 and 1.05. DG real power generation and Capacitor values should be between minimum and maximum values. Real and Reactive power injection should not be more than the real and reactive power demand. Network Power factor should be within the acceptable range. Branch current / Branch MVA limit should be within the maximum allowable / permissible value.