Metal-clad rectifier semiconductor substations KVPP

Power diodes

The rectifiers are based on 2500 A class 25 power tab diodes manufactured by VISHAY (or ABB). Two diodes are connected in series in each rectifier arm for more reliability and lifetime prolongation. Forced current division in parallel paths is carried out due to the efficient magnetic dividers providing current division between parallel paths no less than 5 %.

Overvoltage protection

Diodes are protected against internal switching surges with RC-circuits and against external switching surges combined with RC- circuits and varistors.

Galvanic isolation boards

Galvanic isolation boards provide protection against overvoltage with RC- circuits, supply information for diagnostics system controller analysis.

The following transformers are applied in KVPP:

• RESIBLOC® (600, 800, 1250, 1600) kVA,
• TSZPU-(1000, 2000) /10 GT.

Transformer with RESIBLOC® windings has the following advantages:

• fail-safe (reliable) operation under conditions of increased pollution, high humidity (in highly contaminated and humid environment), at low temperatures;
• dynamical stability of windings to mechanical loads is 650-750 N/mm²;
• conformance to the basic transformer equipment standards IEC 60076-11 and VDE 0532;
• low noise level;
• fire safety and environmental compatibility, self-damping in case of influence of external flame or electric arc, with no emission of toxic gases. All materials are non-flammable and flame-resistant;
• availability of vibration damping devices;
• winding and magnetic core temperature monitoring;
• «cold» start with maximum load;
• minimum maintenance requirements;
• enhanced resistance to dynamic loads in case of overloading (under overloads) or short-circuit failures.

Rectifiers are equipped with microprocessor control and diagnostics system. This system issues the following criteria information about state of each diode on visualization panel: “normal operation”, “parameters derating”, “breakdown”, as well as diodes temperature Control system is based on SOTA® controller, that meets IEC 61131 series of standards for PLC, and provides support of IEC 61850 protocol.

Due to application of Weintek visualization panel, the required information is displayed in convenient intuitive form and control is provided by tapping the touch screen. Each diode parameters are monitored dynamically, during rectifier operation. Diagnostics according to the mentioned criteria allows to significantly increase the period of rectifier troublefree operation.

The system also provides:

• control of diode heating temperature;
• protection against rectifier and transformer overheating;
• event logging;
• communication with the upper level (SCADA system);
• visualization of all necessary information on the color touch-screen display
  - power single-line diagram and status of rectifier (on/off);
  - diode status;
  - rectified current, voltage, temperature, diode parameter value;
  - warning and emergency messages.

Cabinets with automatic equipment are designed for power supply and protection of 230 V DC circuits at iron and steel works crane substations.

Configuration:

• SHLA – linear switching cabinet;
• SHVA – incoming switching cabinet;
• SHSA – sectionalizing switch cabinet;
• SHSR - sectionalizing disconnector cabinet.

Cabinets with automatic equipment include automatic circuit breakers of the leading European manufacturers (ABB, Schneider Electric) having the following advantages:

• withdrawable or fixed design;
• high switching capacity, up to 65 kA;
• electronic or thermomagnetic tripping device.