Estimating the margin to voltage collapse in a dwindling electric power network
For more than a decade, Nigeria National Grid (NNG) has encountered an average of 24 times per year of total incidences of voltage collapse in the system. Nigerian manufacturers, small scale businesses, families including private households have been unable to break even in their businesses owing to this ugly trend. The main focus of the work is to estimate the limit and margin of active power transmission across a certain defined boundary prio to voltage collapse. This will help to alert the power systems operators and planners about the dangers that lie ahead in case of any voltage collapse scenario. The paper made an exploit of Continuation Power Flow to determine the Margin to Voltage Collapse (MVC) of NNG. The effectiveness of the approach was tested in the 10Bus NNG and 30Bus NNG. For the 10Bus NNG, the results show that at 15th iteration the corrector solution (4.3698pu) was found to be too far from the predictor value (1.7454pu). However, the maximum loading Parameter 4.3698pu with a mismatch of 0.00324pu converged at 40th iteration search in 1.5016 seconds. To enable quicker convergence of the solutions and the computation speed, the step size was reduced to 0.04. The MVC for the 10Bus NNG and 30Bus NNG are estimated to be 4.1698 p.u and 3.5 p.u respectively.
Keywords: CPF, MVC, Voltage Collapse, Voltage Stability, Saddle Node Bifurcation Point, Current Operating Point