CSUV

Duplex automatic control system for rotating machine exciters

Purpose

Digital control system for rotating machine exciters is intended for work within the system of brushless synchronous generator initiation with power up to 25 MW. Control for drive is implemented on the basis of digital analysis of sinusoidal signals proceeding from the generator"s instrument transformers. The outflow for the system is the current of the generator exciter.

Basic functions

• receiving and transforming voltage and currents from instrument transformers of phase voltage and phase currents.
  
• measuring voltage and current of each phase of a generator, frequency, power factor.
  
• control for quality of sinusoidal signals voltages and currents (high harmonic presence and constant component tests)
  
• computing active and reactive power of the generator.
  
• forming current of the generator exciter according to the set mode of the generator.
  
• realization of exciter current governor function, automatic regulation of generator"s voltage, regulating active power of the generator, limiting minimal drive value, forcing drive.
  
• in manual mode forming exciter current by commands from buttons MORE and LESSВ.
  
• control for isolation winding of generator"s drive.
  
• all necessary information of the current working mode about is displayed on the alphanumeric display.
  
• control for up-state of the microcontroller and the other system"s elements
  
• maintenance of bumpless transition from main to auxiliary control channel in case of main channel critical units malfunction.
  
• receiving commands from control panel unit, events registering.
  

Control system structure

The panel of digital control system for synchronous generator includes: Micro PC controllers, secondary phase current and generator voltage, transistor commutators for output current forming, auxiliary units, power supplies.

The responsibility of the system"s exploitation makes for the necessity to reserve the basic units. This system has two identical hardware-based channels: basic and reserve. Each control channel includes secondary converters, controller, commutator.

Realization of reserving

The control in the normal mode is implemented by the basic channel. Reserve channel is set into "hot standby" mode. Simultaneously the reserve channel free from control executes monitoring functions, checks the up-state of the basic control channel and its ability to maintain efficient control for the drive. Having found the critical failure of main control channel the reserving channel intercepts the control.

Backswitch to the main channel is done only manually, after finding out the reason of switching to reserve channel. The channels" control exchange information vie the Ethernet network, thus maintaining the bumpless switch from one channel to another (without the leap of the regulated parameter).

The commutator is developed using IGBD-transistors maintaining device"s high safety and compactness.

Transistor commutators works in the pulse-duration mode of voltage which forms the constant IBB value current on the exciter drive winding. The channel"s processor implements commutator"s temperature control.

Basic tasks of the control program

• registering the signal of secondary measuring converters each 100 ms
• In-circuit drive current regulation algorithm, execution cycle - 2 ms.
• secondary regulators algorithm, execution cycle - 10 ms.

Integrity test

Promautomation developed a special hardware-mathematics model of synchronous generator for checking and debugging the control algorithms.

The system of equations of the mathematic model is a simplified type of Park-Gorev equations.

This model switched to the digital control system for synchronous generator drive inputs helped to test the algorithms of initial drive, idling, isolated work, infinite cardinality, bumpless transition under load. This model is also used for integrity test of the digital control system for synchronous generator drive, during which the technical and program realizations are checked as well as, eventually, the systems serviceability.