Chittagong - BPDB

4.3.5 Excitation System
A continuous fast acting automatic excitation control system of a proven design
shall be provided to control the generator voltage without hunting/instability over
the entire operating range of the generator.
The excitation system shall be provided with a fast-acting MVAr limiter so as to
prevent the generator output falling below its safe limit. A power system
stabilizer shall be incorporated in the excitation system of each generator. The
Automatic Voltage Regulator (AVR) shall also be provided with but not be
limited to Quadrature Droop Compensation, and Cross Current Compounding.
Protection features as part of the system shall include over-voltage, overcurrent,
VT fuse failure, diode failure, overfluxing, and AVR power supply failure. A
field shorting or discharge switch feature shall also be included in the system as
protection against overstressing the generator insulation in the event of a fault.
Manual excitation control facilities shall be provided as a backup to the
automatic control, and shall have an adequate range to allow for control of
excitation for testing purposes. A true null balance shall be provided to allow for
smooth excitation transfer between manual and automatic control.
4.3.6 Power and Auxiliary Transformers
The Company shall provide generator step-up, start-up, and auxiliary
transformers for Facility service, including all protection, busbars, and disconnect
switches as required, and transformers for all auxiliaries. The power transformer
shall be equipped with on-load tap changer.
4.3.7 Control and Supervision
Supervision/control, monitoring and information systems shall comply with
BPDB’s system control concepts and procedures and shall be subject to the
approval of BPDB.
Automatic and manual synchronizing facilities, with such check facilities as may
be required shall be provided as a minimum for all circuits associated with
generators.
The Facility shall be provided with a central on-Site control room (CCR) so that
operators can control the generators and perform switching and load dispatch
duties. A Distributed Control System (DCS) shall be provided to coordinate the
control and supervision of the generator control, Facility auxiliary systems, and
generator step-up transformer breakers.
Request for Proposal (Chittagong 50±10% MW HFO Fired Project) Page 63