Unbalanced load flow implementation in pandapower- an open source software

Student name: Mr Shankho Ghosh
Guide: Dr Atul Kumar
Year of completion: 2018
Host Organisation: Fraunhofer IEE, Kassel, Germany
Supervisor (Host Organisation): Ms Friederike Meier

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Abstract: Power flow analysis in classical education has always used single phase power flow analysis and extrapolated it to three phases. This works perfectly for a High Voltage transmission system, where three phases are balanced. Distribution system planning, however, requires a detailed analysis of three-phase power flow, since most of the distribution systems in the world are unbalanced, especially in the low voltage side. This unbalance, combined with radial systems, leads to voltage sags in a few phases for consumers furthest from the distribution sub-stations.

With a higher penetration of renewables and micro-sources like CHP, fuel cells and electric vehicles in distribution grids, which are generally single phase, an opensource tool to plan and calculate three-phase power flow in distribution grids is quite valuable.

This project takes this into account and considers the different approaches and algorithms developed over the years. The objective is to analyze three-phase power flow, model network components and calculate power values, losses, voltages and currents flowing through the network.

The algorithm uses a hybrid of Newton-Raphson and Current Injection methods and the elements are modeled with sequence components. This algorithm has been implemented in pandapower software. This is an open source software built using python language.

Finally, the results have been verified with DigSilent Power Factory for a 2 bus and 4 bus system connected via a transmission line.

Keywords: Three Phase Load Flow, Unbalanced load flow, pandapower, open source software