Solution

Atekon Technology Co., Ltd.

Application Case of the Computer Monitoring System at Dali Liuhe Hydropower Station in Yunnan

Release date:

2020-03-27

　

Project Overview:

The Heqing County Liuhe Hydropower Station project is located in the lower canyon section of the Yanggong River, near Changwei Village, Liuhe Township, southeast of Heqing County. The station is the fourth in a planned cascade of six hydropower plants along the lower Yanggong River canyon stretch from Shimenkang to Hekou. Power generation primarily occurs from June to October, making it a seasonal power plant that harnesses time-varying river resources; it operates as a run-of-river type facility. The station is equipped with two generators, each with an installed capacity of 2 × 15,000 kW. Its design head stands at 235 meters, while the designed flow rate for power generation is 14.48 m³/s. The annual electricity output is expected to reach 148 million kWh, and the water diversion tunnel spans 5,933.285 meters in length.

This computer monitoring system utilizes our company's NA400 PLC, which features a professional SOE event recording module with time accuracy better than 1 ms. It also includes a customizable, programmable serial communication module, the CMM401-0411, equipped with four RS485 interfaces. Each CPU unit can expand to accommodate up to four additional modules, providing a total of 16 serial ports—perfectly meeting the power station's need for multiple automation communication interfaces.

 

Solution: Application of the NA400 PLC System

Aoto Technology has built a comprehensive station-wide computer monitoring system centered around the NA400 PLC, with implementation details as follows:

1. Multiple CPUs provide a plant-wide automation solution

The NA400 PLC offers a variety of CPU models, ranging from cost-effective to hot-standby redundant types, meeting the requirements of unit monitoring systems in medium-to-large-scale hydropower stations.

 

2. Integrated RS485 Multi-Port Communication Module

① Independently implement the communication protocol, enabling data exchange either via CAN network with the NA400 CPU or through a serial port with external serial devices.

② 4 extended RS485 serial ports, supporting both internal Modbus master communication and custom protocol communication; they can also be used for communication with devices such as debugging tools, excitation systems, and microcomputer-based protection equipment.

③ One RJ45 Ethernet port, which can be configured, monitored, and debugged using NAComm software;

④ Divide inputs and outputs, supporting up to 1024 digital inputs, 1024 digital outputs, 512 analog inputs, and 512 analog outputs.

 

3. Professional SOE Event Logging Module

The SOE event recording module directly receives GPS second pulse signals for time synchronization, ensuring higher precision. At the same time, it performs asynchronous time synchronization with the CPU. SOE events are generated by the event recording module and transmitted to the CPU via communication. Internally, the module stores these events, capable of logging up to 2048 events in total—preventing time loss even if communication with the CPU is interrupted.

 

4. Professional Satellite Time-Sync Network

The NA400 PLC supports multiple time synchronization methods, including NTP and B-code, and also features PPM fractional pulse synchronization, ensuring that the SOE system maintains a time accuracy error of less than 1 ms.

 

Aoto

Image 8 GPS Time-Synchronization Network

 

5. Intuitive Flowchart Editing Language

Our company has developed a sequential control programming language tailored to the unique features of hydropower station sequence control. It enables fast programming, easy modifications, and intuitive debugging, significantly reducing the programming time for field service personnel.

 

Aoto

Image 9 Sequential Control Chart Programming Interface

 

The PLC operates stably and reliably on-site, earning unanimous praise from both the owner and the system integration vendor!!! Thanks to the customer for sharing the on-site photos!

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