220kV地區(qū)變電所電氣一次系統(tǒng)設(shè)計(jì)01,kv,地區(qū),變電所,電氣,一次,系統(tǒng),設(shè)計(jì),01 2PB02 Active Shielding Design for a MVLV Distribution Transformer Substation Concettina Buccella Mauro Feliziani A lberlo Prudenzi Dept of Electrical Engineering University of L Aquila Poggio di Roio 67040 CAquila Italy prudenzi ing univaq it Tel 39 0862434437 Fax 39 0862 434403 Email c buccella ieee org felizian ing univaq it Abstract The shielding of the low frequency magnetic field is obtained by using a system of fed active coils that produce a magnetic field opposite to the incident one reducing the total magnetic field In this paper the design of a real active shield system is proposed to mitigate the magnetic field in the MVLV distribution transformer substation located at the Engineering Building of the University of L Aquila The design of the active shield system is developed starting from the experimental data obtained by the measurement of the magnetic field inside the MVLV substation INTRODUCTION The recent exposure limits of human body to electric and magnetic fields at low frequency demands for a reduction of the extremely low frequency ELF fields I 9 The general public basbecome increasingly aware of possible effects fiom exposure to ELF magnetic fields Recently in a WHOOARC study the ELF magnetic fields have been classified as Group 2B Possible Carcinogenic on the basis on epidemiologic studies of childhood leukemia I The traditional passive shielding technique is not always convenient to mitigate the ELF magnetic fields in some practical applications since a large quantity of material can be often required to build a shield adequate to mitigate low frequency magnetic fields A better solution is to design a system of low frequency current coils i e active shield which produce a magnetic field opposite to the disturbing one in order to reduce the total magnetic field 6 7 By this way it is possible to obtain good shielding performances often at a lower cost in comparison to the passive shielding technique 8 9 In this paper the development of an active shielding configuration is presented for the medium voltage MV low voltage LV distribution transformer substation located at the Engineering Building of the University of CAquila A scheme of the substation is shown in Fig 2 where the MV and LV panels and the transformer cubicles are represented Y Fig 1 Sketch of the MVLV distribution transformer substation located inside the Engineering Building of the University of L Aquila ttttt MEDIUM VOLTAGELOW VOLTAGE DISTRIBUTION TRANSFORMER SUBSTATION The configuration of the examined MVLV substation with the layout of the power cables and bars is represented in Fig 1 In the substation it is possible to identify the medium voltage bars at 20 kV the transformer 20 kVl0 4 kV and the low voltage 0 4 kV bus bars of a switch board panel allocating four LV rising mains Fig 2 Map of the MVLV substation with the measuring points inside the substation The magnetic field has been measured by using the Wandel Aug 2 L29 199 Ps7 20i y 1988 353