The TOSMAP-DS^TM Automatic Control System (ACS) is specifically designed to control the entire power plant, which enables complete integration of boiler, turbine, generator, balance of plant and switchyard control into a DCS. Operation and maintenance work, as well as the number of spare parts, can be reduced by using unified control system architecture. Toshiba's highly sophisticated surface mount technology (SMT) and semiconductor technology utilized for high-density Gate Arrays (GA) minimizes the printed circuit board size and enables high-density mounting and superior reliability. Due to proper design of heat radiation, the ACS standard cabinet is naturally ventilated, so that cooling fans, which require periodic replacement, are not necessary.

ACS overview

Standard-type controller
The standard-type ACS controller uses an advanced 32-bit microprocessor that provides high performance and large capacity, which enables versatile application to plant control. Up to 128 control loops can be configured in a single controller and individually maintained on-line, while other task loops are operating. The compact PCI backplane used for the CPU bus provides open system connectivity to industrial standard.
One of the ACS's distinguishing features is flexible I/O configuration. Two types of I/O configurations are applicable to the ACS:

• The DeviceNet^TM interface, which is an industrial standard based on CAN (Controller Area Network) ISO11898, can be used for universal process I/O. Any type of I/O module that conforms to the standard, DeviceNet^TM can be connected to the ACS.
• Toshiba's proprietary I/O is used for special purposes, such as high-speed pulse input, remote process I/O, or where large numbers of inputs/outputs are required.

The ACS supports more than 130 Function Block Diagrams (FBD). These Macro instructions are most suitable for power plant control application. Around forty of the function blocks named TAG Macro instructions automatically link the ACS control logic inputs/outputs to the HMI data with just the TAG No. configured in the IES, so that engineering work for linking between display data and logic data is dramatically reduced.
Any kind of control system, redundant controllers, redundant I/Os, combination of DeviceNet^TM I/O and Toshiba proprietary I/O, etc. can be configured by means of the versatile ACS.

High-speed controller
Primary control, such as governor control and generator control, requires extra-high speed execution. For this purpose, Toshiba developed the high-speed controller, capable of a minimum 1 ms control cycle, for use in the TOSMAP-DS^TM system, which enables direct control of turbine governor and generator excitation. The high-speed controller features:

• Dual and triple redundant configurations for each.
• Special input cards such as speed input, 3-phase current and voltage input, etc.
• Recording of high resolution transients in CPU memory

The high-speed controller is also applicable to protection logic, such as turbine trip logic, MFT logic, etc., which require high-speed execution. For customers who prefer hard-wired circuits rather than software logic, Toshiba can also provide a Programmable Logic Device (PLD) card that is programmable but solid state.
SOE (Sequence Of Events) which has 1ms resolution is essential for power plant control to analyze trip causes in case of plant trip. The high-speed controller can be diverted into an intelligent SOE, which has not only a trip analysis function but also high-speed control functions.