**4. Conclusions**

LV L1

L2

In this paper a virtual lab was designed to evaluate and mitigate some power quality problems introduced by μG. The virtual lab includes the Medium/Low voltage (MV/LV) transformer, the distribution lines, linear and non-linear loads, conventional μG and active μG. To validate the designed models, the current waveforms and distortion obtained for each one of the virtual lab loads were compared to those measured with the most used electric and electronic equipment, showing that the obtained results are similar.

The μG model is simulated based on its final stage converter, a single phase inverter, while the active μG also includes high order harmonics compensation, to perform as an active power filter.

**9** 

*Algeria* 

**Matlab Package** 

Belkacem Mahdad and K. Srairi

**Understanding Power Quality Based FACTS** 

The electricity is invisible and the complexity of mathematical models deviate the graduate students attention from well understanding the underlying main concepts. Interactive educational power system software has become a fundamental teaching tool because it helps in particular the undergraduate students to assimilate theoretical issues and complex models analysis through flexible graphic visualization of data inputs and the results (Abur et al., 2000), (Milano, F., 2005). From the educational point of view software developed for educational purposes should be flexible and interactive, easy to use and reliable. In particular, software for power system education should contain a user interface not only to allow graduate student to analyse and understand the physical phenomena, but also to

Flexible AC Transmission Systems (FACTS) philosophy was first introduced by Hingorani (Hingorani N. G., and Gyugyi L, 1999) from the Electric power research institute (EPRI) in the USA in 1988, although the power electronic controlled devices had been used in the transmission network for many years before that. The objective of FACTS devices is to bring a system under control and to transmit power as ordered by the control centers, it also allows increasing the usable transmission capacity to its thermal limits. With FACTS devices we can control the phase angle, the voltage magnitude at chosen buses and/or line

The avantages of the graphical user interface tool proposed lie in the quick and the dynamic interpretation of the results and the interactive visual communication between users and computer solution processes. The physical and technical phenomena and data of the power flow, and the impact of different FACTS devices installed in a practical network can be easily understood if the results are displayed in the graphic windows rather than numerical

The application programs in this tool include power flow calculation based Newton-Raphson algorithm, integration and control of different FACTS devices, the economic dispatch based conventional methods and global optimization methods like Parallel Genetic Algorithm (PGA), and Particle Swarm Optimization (PSO). In the literature many educational Graphical tools for power system study and analysis developed for the purpose

improve the existing models and algorithms (Mahdad, B., 2010 ).

of the power system education and training (Milano et al., 2005).

**1. Introduction** 

impedances.

tabular forms (Mahdad, 2010).

**Using Interactive Educational GUI** 

 *Department of Electrical Engineering, Biskra University* 

Using the proposed models a small low voltage grid model with six clusters of loads is designed to evaluate the impact of conventional μG and active μG on Power Quality for a no-load and a full load scenario.

From the results obtained with the virtual lab LV grid, it was possible to conclude that conventional μG slightly increases voltage THD, while active μG reduces voltage THD (up to 30% when compared to voltage THD values obtained with conventional μG), guaranteeing an overall Power Quality improvement (Power Factor increase).

Even though the μG total power never exceeds 25% of the transformer rated power SN, with a high percentage of non linear loads, as the one considered in the proposed virtual lab LV grid model (85% of the transformer rated power), the active μG presents promising results and it can be concluded that it may be a solution to mitigate some power quality problems.
