Thyristor Controlled Rectifiers (withdrawable)

Withdrawable thyristor rectifier is based on standard arrangement of separate compartments common for many switchgear units:

• automation and control compartment - low-voltage compartment with control and diagnostic system components;
• withdrawable unit compartment - power part of thyristor rectifier;
• busbar compartment - includes AC and DC busbars. The compartment is divided into several isolated compartments, allowing safe access for power cables maintenance even under voltage on power busbars.

Division into compartments also allows safe maintenance of high-voltage measuring circuits and standby disconnector, located in busbar compartment.

Withdrawable unit has three positions:

• operating;
• control;
• maintenance.

Withdrawable rectifiers are equipped with microprocessor control and diagnostic system based on SOTA® controller and MC-POWER module. HMI is provided by an operator panel in the form of 7-inch TFT touchscreen display, allowing the user to exchange data with the control system.

Operator's panel provides:

• output of operation mode messages;
• output of warning and emergency messages;
• selection of rectifier control mode;
• setting, change and saving of parameters settings;
• rectifier event logging;
• testing of separate rectifier units;
• connection of rectifier with telecontrol system.

Similar to traditional switchgear, withdrawable thyristor rectifiers protect traction network by continuous monitoring and analysis of current and voltage variations dynamics in traction network and issuing rectifier tripping commands in case protective functions set parameters are exceeded.

SOTA^® control system generates and saves two types of fault waveforms (current and voltage waveforms) each time one of protections trips:

• “Fast track” (time coverage depth is 100 ms);
• “Slow track” (time coverage depth is 100 s).

Types of electronic protection (ANSI code):

• instantaneous overcurrent (50);
• time overcurrent protection (76);
• current rate of rise protection;
• current increment directional protection;
• overvoltage protection (59);
• undervoltage protection (27);
• time/current protection (49);
• rectifier failure;
• DDL protection;
• impedance protection.

The substation power equipment includes:

Converter transformer for rectifiers (if necessary to connect more than one transformer, it is possible to sectionalize AC busbar);

Line rectifiers - the main devices providing power and protection for a traction network section;

Standby rectifier - provides reliable load power supply via a system of disconnectors in case of one of the line rectifiers failure or can be connected in parallel to the most loaded rectifier (optional);

Recuperator - designed to transfer rolling stock braking energy to AC network and consists of inverter with switching device and matching converter transformer.

Thus, a new approach in organizing the equipment during construction or global reconstruction of traction substations is proposed.