symbolic dynamic models for highly varying power system loads

3
Static load model: Most of the loads in a power system respond very rapidly to the
change in voltage and frequency. The steady state of the load response is achieved
quickly. Such cases can be analyzed by using static models. In a static model, the active
power component P and the reactive power component Q are the functions of the bus
voltage magnitude and frequency.
Dynamic load model: There are many loads which cannot be analyzed in the above
manner. In such cases, it is important to account for the dynamics of the load component.
In a dynamic load model, the active and reactive power components at any instant of time
are functions of the bus voltage magnitude at past and present instants of time.
Power engineers need various power system mathematical models for studying
the performance and control of the power system. Conventional power system modeling
demands parameters and characteristics of system components. In many cases, what
exists in the field may be uncertain because of system complexity, age and other
inaccuracies.
Power engineers can circumvent this uncertainty through the use of measurements
to formulate a mathematical model that is consistent with the measurements. The process
of power system modeling involves physical analysis, mathematical deductions,
modeling induction and the utilization of measurements.
1.4 Literature search on power system load modeling
Many papers have been published on load modeling using different techniques.
The literature of this area spans about 100 years. Recent efforts focus on accuracy, highly