PQLib- A Modelica Library for Power Quality analysis in Networks

In power supply networks, the quality of the voltage is becoming more and more of a determining factor. Non-linear loads such as diode or thyristor converters contribute to the degradation of the supply voltage quality. Non-sinusoidal currents of the non-linear loads result in the distortion of the supply voltage wave form at the point of common coupling due to the finite supply impedance. To improve the power quality of the supply voltage active filters and reactive current compensators are used. The optimal power rating and topology of these units are very important, but also the determination of the best compensation strategy for a specific application is very important as well. Different topologies and strategies can often perform related compensation functions, resulting in a situation where financial implications determine the best solution. In this situation the power quality analysis in network using simulation tools is very useful. This paper describes a Modelica library called PQLib (Power Quality Library) designed for power quality analysis in networks using simulation tools written in Modelica. The PQLib contains the following components: • Definition of connectors for three phase networks • Models for: • three phase passive electrical elements like resistor, capacitor and so on. • three phase electrical machines and transformers • three phase transmission lines • semiconductor controlled dc and ac electrical drives • power factor correction devices (passive filters) • mains active restoring devices using semiconductors (active filters) • measuring instruments: true rms voltmeter and amperemeter, digital frequency analyser • Examples 1. Building of the PQLib The PQLib is based on the package concept. The package concept was introduced into Modelica to help organize definitions of models, connectors, etc. [1, 2]. Fig.1 shows the components of the package PQLib.