A Power Transfer Distribution Factor Model for Sensitivity Analysis of Time Flows on Power System Bus Injections

Abstract

Power transfer distribution factor, (PTDF) is a useful factor for sensitivity analysis of line flows. It shows the linear and impact of a transfer of power.

This research paper presents a PTDF model to evaluate the sensitivity of line flows using a 12-bus system as a case study. It is a polynomial model of order 6 whose order increases as more buses are injected into the system.

A source and a sink were specified for each transaction for the flows of active powers from source to sink in a direction. PTDF provides a linear and approximation of how the flow on the transmission lines and interface changes in response to the transaction between the seller and buyer. The PTDFs are operating point dependent.

Appropriate correction actions were taken to bring back the MW on the lines to within its operational limit to ensure that the MVA limit of the lines and all line flows are within operational limits.

When the generation at bus 10 was reduced to 130MW and shedding the load at busses 2 and 5 to 65MW, bus 7 to 60MW and at bus 8 to 10MW, at bus 3 and 8 to 40MW, the MW on the lines came back to within its operational limit. The MVA limit of the lines and all the line flows were within the operational limit.

The polynomial model developed will help the busy power system operators or engineers in formulating appropriate policies.

Keywords: LODFs, PTDF, Voltage Stability, Contingency, Source, Sink, Change in transactions, Disturbance.