Equivalent operational impedance: A new approach to calculate technical and non-technical losses in electric distribution systems

This paper presents the definition of Equivalent Operational Impedance, which is a new concept established for distribution grids analysis with potential application in calculating technical and non-technical losses in Medium Voltage and Low Voltage distribution feeders. Considering a specified distribution network topology, the main feature of Equivalent Operational Impedance for this grid is that it is fairly constant even under varying load scenarios, once these scenarios present similar voltage solutions. This way, a load flow solution is used to obtain the Equivalent Operational Impedance of a specified grid topology and then the calculated Equivalent Operational Impedance can be used to obtain total technical and nontechnical losses for other load scenarios using only the calculated Equivalent Operational Impedance and the respective measurement of injected current at the Medium Voltage or Low Voltage distribution feeder. The use of this methodology by electric utilities allows the calculation of technical losses more accurately, as well as the inclusion of non-technical losses in the distribution networks operation planning. Results using the IEEE 13-bus test system are presented to demonstrate the effectiveness of the proposed methodology.