BCS – BEMU Charging Station

The charging substation does without frequency conversion and is designed for 

• AC 15 kV 50 Hz and
• AC 25 kV 50 Hz

supply voltages. In the design of the prTS 50729, the AC 15 kV 50 Hz system voltage has been additionally specified for charging BEMU by means of current collectors at a standstill or at low speeds.

Electric vehicles for AC 15 kV 16,7 Hz can be converted in principle for operation with 50 Hz. In general, it is necessary to merely adapt the software in the vehicle’s traction control system. No hardware adjustments are necessary. The voltage level of 15 kV was selected for the reason that not all vehicles can be converted to 25 kV for insulation reasons and due to the electrical technical equipment. 

A higher voltage for the charging power is a fundamental advantage, because the current at the contact point between the current collector contact strip / contact wire is the limiting quantity (80 A in accordance with EN 50367). 

The charging substation for 50 Hz can be configured in two series in output ratings for 1,2 MVA (one one feeding section), 2,4 MVA (two feeding sections) or 3,6 MVA (three feeding sections) or 2,0 MVA, 4,0 MVA or 6,0 MVA. One feeding section can be loaded up to 1,2 MVA or 2,0 MVA.

• Charging vehicles with accumulators at a standstill at platforms and/or storage sidingsaden
• Supply of spatially limited overhead contact line installations
• Charging station for electrical shunters on tracks not equipped with an overhead contact line

• Internal transport

• Connecting railways

• Dock railways

The balancing converter ensures symmetrical loading of the supply network, regardless of the amount of power. The balancing converter counter-acts any existing asymmetries in the supply network.

The power at each feeding section (contact line section) is variable and arbitrary. A 1,2 MVA or 2 MVA can be used for each contact line section, depending on the style. The sections do not have to be loaded evenly. Several vehicles can be charged in one section if their total output does not exceed the maximum output per feeding section. However, it is also possible to operate one contact line section alone at its maximum power.

Charging substations are set up at locations where one cannot always assume there is a particularly powerful power supply network. The network can be supported at the withdrawal point by the provision of reactive power, for example. The voltage quality can be actively improved by the converter control.

The use of power electronic components on traction units can result in circuit reactions such as harmonics and distortion reactive power. The active balancing converter can counteract this with its filter.

The balancing converter does not only ensure a symmetric power from the supply network, it can also actively reduce existing asymmetries.

The charging substation is pre-configured to meet the requirements of the operating company and delivered and installed fully equipped. Only the cables of the medium-voltage supply network and the feeding and return cables must be connected and tested, the low-voltage connection established, the container connected to earth and the protective functions tested on site. About three days are sufficient for this purpose.
Furthermore, the overhead contact line (overhead conductor rail) must be set up. Technologies like the ground shield foundation method are available for this purpose in suitable ground conditions. They allow the contact line to be set up just as quickly. The overhead contact line can be set up in the same time in parallel to the charging substation.

Railway operations are impaired only slightly or not at all during the setup due to the short set-up time.
Due to its compact style, the charging substation can be dismounted just as fast and set up elsewhere if necessary. An overhead contact line with ground shield foundation method can be dismounted completely and also reused if necessary.

Due to the prefabrication of the charging substation, merely the cable inlets and the foundations for the charging substation including an earthing system must be implemented by the customer. A level, load-bearing floor is sufficient for temporary usage.

The overhead contact line is limited, for example to the platform length, due to its style as overhead conductor rail system. Due to the rigid conductor rail, no overhead contact line area has to be assumed, which is why additional earthing measures at metal constructions are not required in this area (EN 50122-1).

Due to the overhead contact line expanding only slightly, the influence on neighbouring electrical systems such as signalling and telecommunication equipment is low and additional measures may therefore not be required. This issue must be checked and verified in individual cases.

Due to its structure, the charging power is transferred merely by the transformer. The balancing converter connected to the third winding merely has to provide the reactive balancing power, which is always lower than the charging power. The balancing converter is used less for solutions with more than one feeding sections, because these feeding sections compensate each other. The load without active intervention of the balancing converter is symmetric if three feeding sections are loaded evenly. This means that the energy efficiency increases together with the load in solutions with more than one feeding section.
In charging breaks, the balancing converter is switched off and does not cause any no-load losses itself. 

The installation does not require any planning approval due to its limited size.