Investigating effect of voltage changes on static ZIP load model in a microgrid environment

This paper presents effects of voltage changes on static polynomial (ZIP) load under three phase fault in a microgrid environment. The objective of the paper is investigating the behavior of the ZIP load model under a faulty condition. Load representation is a crucial factor on approaching power system realistically. The static characteristics of the load can be classified into constant power, constant current and constant impedance load, depending on the power relation to the voltage. For a constant impedance load (Z), the power dependence on voltage is quadratic, for a constant current (I) it is linear, and for a constant power (P) the power it is independent of changes in voltage. The ZIP model is a polynomial model that represents the sum of these three categories. Behavior of the ZIP loads connected to the Microgrid test system will be investigated and overall changes will be discussed.