Pad-Mounted Substation in Railway

Application of Pad-Mounted Substation in Railway

The characteristics of railway power supply load introduces the structure and functional characteristics of pad-mounted substation. On this basis, the construction design of the railway is described in detail.

The application of pad-mounted substation in the railway power supply and distribution system is expected to meet the current needs of railway power load growth.

Table of Contents

Overview of railway power supply

Railway is the main artery of the national economy. Electricity is one of the main driving forces for the production of railway transportation.

The railway power department is responsible for the task of supplying power to the railway command system, automation system, traction system and various railway industries.

With the development of railway transportation and the continuous improvement of automation and electrification, more and more departments need power supply, and the requirements for the reliability of railway power supply are also getting higher and higher.

Characteristics of railway load

1) The load is distributed along the railway and the capacity is small;

2) Most of the first-class loads require uninterrupted power supply. Due to the above two characteristics, the power supply radius of the 10kV and 35kV power lines is longer than that of the power system.

The power distribution facilities built earlier by the railway are traditional civil substations and pole-mounted substations. The equipment is outdated and has a small capacity and a large maintenance workload. It can no longer meet the needs of the current increase in electricity load.

Because the pad mounted substation has strong complete set, small size, less land occupation, can penetrate into the load center, improve power supply quality, reduce line loss, shorten power transmission cycle, flexible site selection, strong environmental adaptability, convenient installation, safe and reliable operation And a series of advantages such as low investment and quick results.

Therefore, the pad mounted substation is a new type of substation and distribution equipment that is worth promoting and using in the railway power supply and distribution system.

Structure and functional characteristics of pad mounted substation

Structure of pad mounted substation

The pad mounted substation is a factory-prefabricated compact substation that consists of high-voltage electrical equipment distribution transformers and low-voltage power distribution devices arranged in one according to a certain wiring scheme.

The box is generally divided into high voltage room, low voltage room and transformer room. The high-voltage chamber of the pad mounted substation is generally composed of a high-voltage load switch, a high-voltage fuse and a lightning arrester, which can perform power-off operation and has overload and short-circuit protection functions;

The low-voltage room is composed of low-voltage circuit breakers, current transformers, ammeters, voltmeters, etc.;

The transformer room generally adopts measures such as filling the surrounding walls with insulation materials, adopting a double-layer plywood structure, and adopting an air cushion on the top plate to prevent sunlight radiation, and adopting natural ventilation and mechanical forced ventilation to ensure the heat dissipation of electrical equipment.

In addition, some protection devices such as dehumidification, humidity control and anti-condensation are also installed.

Daelim Pad-Mounted Substation
Daelim Pad-Mounted Substation

Features of pad mounted substation

1) High degree of automation.

The pad mounted substation adopts an intelligent design, and the protection system adopts a substation microcomputer integrated automation device.

The pad mounted substation carries out distributed installation, which can realize remote setting of operating parameters. At the same time, the pad mounted substation can also realize remote monitoring of images as required.

2) Factory prefabrication.
All equipment is installed and qualified in the factory at one time. Realizing the factoryization of substation construction has shortened the design and manufacturing cycle.

On-site installation is simple and efficient. The entire substation from installation to commissioning only takes about 5 to 8 days, which greatly shortens the construction period.

3) Flexible combination, easy transportation and installation

The pad mounted substation has a relatively compact structure. Each box constitutes an independent system.
Pad mounted substation does not have a fixed combination mode. The unit of use can freely combine some modes according to the actual situation to meet the needs of safe operation.

4) The investment province is effective and the operation and maintenance cost is low.

Compared with the conventional substations of the same scale, the pad mounted substation reduces the investment by 40%-50%. In the pad mounted substation, the selection of advanced equipment, especially the operation of oil-free equipment, fundamentally solves the problem of equipment leakage in the conventional substation.

The substation can be subject to state overhaul to reduce maintenance workload. The overall economic benefits are very considerable.

5) Small footprint, beautiful appearance, and easy to coordinate with the environment.

Because the pad mounted substation arranges most of the power distribution device in a closed box, the area and space are greatly reduced by optimizing the design and reasonable combination of the insulation distance between the parts.

The outer shell of the box adopts aluminum-zinc steel plate and container manufacturing technology, and the appearance is beautiful.

Under the premise of ensuring the reliability of power supply, by choosing the color of the shell of the pad mounted substation, it is very easy to coordinate with the surrounding environment.

Application of pad mounted substation in railway power supply and distribution system

Application of pad mounted substation in station power supply

The primary and secondary loads such as station signals and communications are powered by dual power supplies, which are designed as independent pad mounted substations.

The pad mounted substation two-way power supply is designed to be connected to the railway power through power supply and the railway power self-closing power supply. The pad mounted substation is dedicated to the 10kV railway signal power system.

It combines high-voltage ring network switch cabinets, transformers, low-voltage switch cabinets, dual power supply monitoring devices, and automatic power line fault removal systems.

Installing near the railway line can effectively avoid interference, and can monitor the power supply in real time and segment the fault of the high-voltage line.

The signal power of the station and the parameters of the outdoor vacuum switch are monitored through the remote terminal “RTU” integrated in the pad mounted substation and connected to the remote control system.

Using 2 M dedicated Tietong optical cable as the communication data channel, the communication between the dispatching station and the controlled station adopts the “loop lead” method to transmit the main switch status, current, voltage, power and other parameter values ​​of the signal load of each power distribution station and each station The main control station to the dispatcher is uniformly dispatched and monitored by the power supply section dispatcher.

The transformer capacity of the integrated pad mounted substation of the station is about 100kVA, which is used as the power supply for the three-level load such as the lighting of the station production house, the power supply of various equipment and the lighting of the night freight operation of the station.

The high-voltage side connection is derived from the railway power through power supply; the high-voltage system schemes of integrated pad mounted substation and signal dedicated pad mounted substation are the same.

Application of pad mounted substation in interval power supply

According to regulations, if the length of straight tunnel exceeds 1km, and the length of curved tunnel exceeds 500m, there should be fixed tunnel lighting, and maintenance socket boxes should be installed to maintain the line and tunnel;

Mechanical majors need to set up a mechanical forced exhaust system in the tunnel. Most of the above load points are located in the tunnel. A pad mounted substation is installed at the opening of the tunnel wall, which is designed as a compact pad mounted substation dedicated to power supply in the tunnel.

It combines high-voltage ring network switch cabinets, transformers, low-voltage switch cabinets, dual power supply monitoring devices and power line fault automatic removal systems. Install in the shelter in the tunnel.

All high-voltage equipment of the substation is concentrated in four sets of containers, arranged in a “one” shape, 35kV switches from left to right
35kV and 10kV high-voltage circuit breakers use handcart-type vacuum circuit breakers, the main transformers, transformers, and voltage transformers are all dry-type equipment, which fully realizes oil-free operation. Fundamentally avoid power outage maintenance caused by equipment leakage.

The cabinet is equipped with a smoke alarm system and a remote image monitoring system to upload alarm signals and images to the dispatching station for 24h monitoring to prevent the occurrence and spread of accidents such as fires and explosions. There are also five prevention measures.

The secondary equipment adopts the DSA microcomputer protection and control system, which is distributed and arranged to integrate the functions of protection and “four remotes”.

The protection current and the measurement and control current are input separately, and the device chassis is molded from the whole board, which has the characteristics of compact structure, good sealing, anti-interference, and strong anti-vibration ability.

The selection of the above equipment greatly improves the degree of power supply automation, while also reducing operation and maintenance costs, which meets the needs of railway power development.

Concluding remarks

The widespread use of pad mounted substations in the railway power supply system is an inevitable result of modern development. The advantages of pad mounted substations are incomparable to civil substations and pole-type substations.

It is believed that the pad mounted substation will continue to play a significant role in the transformation of the railway power supply system and the new railway power supply system.

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