**9. References**


**Part 3** 

**Software Tools** 

182 Electrical Generation and Distribution Systems and Power Quality Disturbances

feeder schemes are deployed one next to other and have even direct electrical contact between them. Electrical systems in DC and AC railway systems are designed separately, especially considering earthing, and this leads to new problems that weren't faced when old

Disturbances are a common issue that an engineer has to face while designing a new facility or system. Disturbances can also appear when the system is already in operation. These systems need to be protected from the effects of the disturbances in the most effective ways. These ways are usually the replacement of equipments (or at least part of them) and the

In the above sections it has been explained the effects that disturbances from high speed lines can cause on conventional DC lines. A measurement methodology has been proposed. This methodology was used in on site measuring campaigns and their results have been used as a validation of the protecting works carried out before the high speed line comes into operation. The determination of the boundaries between what needs to be changed and what does not need to be changed is a complex problem that must be solved in a cost

The different ways of disturbance have been presented and explained so a global vision of

Arturi, C. M. (2008). Campi elettrici, magnetici e di conduzione – introduzione ai metodi computazionali, Maggioli Editore, ISBN: 978-88387-4248-4. Milano, Italy. Carson, J. R. (1926). Wave propagation in overhead wires with earth return, *Bell systems* 

Dommel, H. W. et al (1992). Electro – Magnetic Transient Program (EMTP). Theory Book. González Fernández, F. J. & Fuentes Losa. (2010) (2nd edition). *J. Ingeniería Ferroviaria* (2nd

Koopal, R. & Evertz, E. P. (2008). 50 Hz Track Circuits Parallel to a 25 kV 50 Hz Railway Line, *proceedings of World Congress on Railway Research*, ISBN, Seoul, May 2008. Perticaroli, F. (2001). Sistemi elettrici per i transporti. Trazione Elettrica (2nd edition), Casa

edition), UNED Editorial, ISBN: 978-84-362-6074-8. Madrid, Spain.

*technical journal*, Vol. 5, No. 4, (Oct. 1926), pp 539 – 554.

Editrice Ambrosiana, ISBN: 88-408-1035-8. Milano, Italy.

DC lines were design, deployed and operated.

shielding against those electrical disturbances.

effective way, but without reducing safety issues.

the problem can be easily achieved.

**9. References** 

**8** 

*Portugal* 

**Design of a Virtual Lab to Evaluate and Mitigate** 

The technological advances of the last decades favored a widespread of power electronics converters in the majority of household appliances, industrial equipment connected to the Low Voltage (LV) grid and, more recently, in distributed power generation, near the

Most of this electronic equipment is a strong producer of current harmonics, polluting the LV network and generating sensitivity to dips, unbalances and harmonics, being also more sensitive to Power Quality issues. In the future, the massive use of renewable and decentralized sources of energy will probably worsen the problem, increasing Total Harmonic Distortion (THD), RMS voltage values, increasing unbalances and decreasing

In these and in other Power Quality related issues, power electronics became, to a certain extent, the cause of the problem. However, due to the continuous development of power semiconductors characteristics, less demanding drive circuits, integration in dedicated modules, microelectronic control circuits improvement, allowing their operation at higher frequencies and with higher performance modulation and control methods, power electronics converters also have the potential to become the solution for the problem. Still, even the non polluting grid connected converters are not usually exploited to their full

The smart exploitation of μG systems may become very attractive, using power electronics converters and adequate control strategies to allow the local mitigation of some power quality problems, minimizing the LV grid harmonics pollution (near unitary power factor)

Based on these new challenges, the main aim of this work is to create a virtual LV grid laboratory to evaluate some power quality indicators, including power electronics based models to guarantee a more realistic representation of the most significant loads connected to the LV grid. The simulated microgenerators are represented as Voltage Source Inverters (VSI) and may be controlled to guarantee: a) near unity power factor (conventional μG); b)

capability as, in general, they are not used to mitigate Power Quality problems.

and guaranteeing their operation as active power filters (APF).

local compensation of reactive power and harmonics (active μG).

**1. Introduction** 

consumer – microgeneration (μG).

Power Factor in Low Voltage Networks.

**Power Quality Problems** 

*DEEC; Instituto Superior Técnico, TULisbon,* 

**Introduced by Microgeneration** 

Sonia Pinto, J. Fernando Silva, Filipe Silva and Pedro Frade

*Cie3 – Centre for Innovation in Electrical and Energy Engineering* 
