1. Project Name: Chongqing Dahekou Hydropower Station Monitoring System
2. Country / region: Chongqing, China
3. Industry: Water Conservancy & Hydropower
4. Number of I/O signals:
5. CPU model: CPU401-0501

Parameters: redundant CPU, high-performance CPU, built-in 2 * RS232 (standard MODBUS), 1 * Ethernet port (standard MODBUS/TCP), program space: 32M.

6. Technical Description:

Dahekou Hydropower Station contains two unit LCU, a common LCU, a switch station LCU and two computers, the specific network structure diagram is shown in the following figure:

The NA400 programmable controller provides three system configurations, including single CPU single Ethernet mode, single CPU dual Ethernet redundancy mode, dual CPU redundancy mode, and multiple flexible system configuration modes can be better adapted to a variety of different practical applications. NA400 provides a variety of types of modules including power supply modules, three different types of CPU modules, serial communication modules (providing 4 standard RS232/RS485), switching input modules, SOE modules, switching output modules, analog input modules (current and voltage), temperature mode, etc.

The CPU module integrates 10M/100M Ethernet port, supports Modbus/TCP protocol, and supports dual Ethernet redundancy configuration. The NA400 programmable controller provides serial communication modules and can freely configure the number of modules. Each serial communication module provides 4 serial ports, each serial port supports RS-232/RS-485 interface standard, and all support C language programming. NA400 programmable controller adopts fieldbus network, with fast communication rate, strong anti-interference ability, low cost, simple structure, good real-time and other characteristics, and has good expandability, easily achieving flexible configuration of modules, and for the field environment and installation requirements are not very high, while providing convenience for system expansion and remote control. The NA400 programmable controller supports different types of fieldbus interfaces such as ProfiBus-DP, CANOpen, ModBus, etc., and can be easily connected to other systems.

The system adopts dual CPU hot standby redundancy scheme to achieve CPU redundancy and network redundancy so as to meet the requirements for PLC system redundancy function of medium and large hydropower stations. Hot standby redundant CPU in a rack can solve the control cabinet space problem and reduce system costs. The time-to-peer mode of PPM split pulse and MODBUS TCP network is adopted. The auxiliary system adopts a stand-alone CPU with Ethernet interface to realize the interconnection and interoperability of the whole plant system.