Network design and simulation

 Brochure

In the field of DC transport systems more than anywhere else, to provide an adapted, efficient and safe product has become a key factor. With millions of every day users, installations must be at the head of reliability and security. Due to its long experience in the DC traction domain, Sécheron has developed an excellent know-how for the DC system design. Today, Sécheron can offer a large panel of services for DC traction network design and simulation in order to ensure a correct design and protection of the system. It is indeed essential to understand all the subsystems of a traction network like AC network, DC power supply substation, DC network and vehicles, and our engineering team does this successfully!

Available to clients looking to establish or to improve existing equipments or services, Sécheron applies its executive experience to a variety of situations. Our offer includes a wide range of services from dynamic network simulation to harmonics calculation and measurement, through various calculations and tests about transformer-rectifiers sets or short-circuits. We offer consulting expertise and answer to any questions you may have about DC traction network design and calculation.

Dynamic DC network simulation

For the DC Railway applications, the good knowledge of the whole system behaviour is highly important. To take into account the huge number of parameters and the complexity of the interaction between all parts of the system, Sécheron has developed a DC network simulation software.

Studies we are providing can, among other things, answer the following questions:

• Where to implement the substations and how many?
• What power and which overload capability are required for the rectifier set?
• What rating shall be provided at each level of the feeding system (DC circuit breakers, disconnecting switch, cables and ...catenary feeder...)?
• What will be the voltage drop along the line?
• What happens in case of failure of one substation?
• What is the efficiency of the system and how to increase it?

The picture shows the result of a simulation of traffic in a 1500VDC LRT network including 9 substations.
This case shows an alternative where the substation number 7 would be out of service.
The diagram allows the reading of minimum, maximum and rms current values at each DC output feeder in the entire network and these results serve as guide for the most suitable setting of high speed circuit breakers.

Dynamic simulation results exemple : speed and acceleration of a vehicle running along the line

Short-circuit calculation and tests

Sécheron, as a supplier of DC high-speed circuit breakers, has acquired a strong experience in the domain of short circuits. Theoritical knowledge and calculations complemented by on-site or laboratory testing (IPH Berlin or CESI Milano) satisfy the demands, in term of protection solutions and of major transit authorities worldwide.
We are able to provide our partner with different services as:

• On-site short circuit measuring in order to check the protection and their appropriate adjustment.
• Short circuit calculation in order to select the components in the electric distribution chain.
• A complete study for the design of protections like line fault DDL, Imax, thermal etc...

Field short-circuit test - measurement of the voltage and the current during a short-circuit test

Harmonics calculation and measurement

Nowadays, more and more regulations concern the harmonics content generated by the power converters into AC or DC networks.
We are able to deliver several services in this domain:

• AC and DC harmonics calculation
• On-site measurement of harmonics in the network.
• Improvement solutions like harmonic filters, 12 or 24 pulse operation.

On site measurement of AC harmonics : AC current and FFT of a 6 pulse rectifier of 1.2MW - 600V

Design and protection coordination for the transformer-rectifier set

Sécheron has built transformer-rectifier sets for ages. Our long experience in this domain led us up to develop particular software for the design of the transformer and rectifier in a more accurate and optimal way.
We are also able to provide answer to any particular questions regarding transformer-rectifier set and its operation within the traction system.
We have also a strong experience in combined tests, according to the EN50328 or IEC60146 standards, including for instance short circuit, warm up and off-load operating tests.

Digital simulation on a transformer-rectifier set