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Development of Digital Valve PCC Intelligent Governor
**Abstract:**
This paper presents a novel turbine governor known as the Digital Valve PCC Programmable Intelligent Governor, developed by Tianjin KeYin Automatic Control Equipment Co., Ltd. The system is centered around a PCC (Programmable Computer Controller) as the main control unit, utilizing electromagnetic ball valves for electro-hydraulic conversion and two-way cartridge valves for mechanical amplification. It eliminates the need for traditional lever structures and pipeline-based systems. Field applications in power stations have demonstrated that this governor surpasses national standards in performance, offers simple commissioning, easy maintenance, and high reliability. Key terms include: Intelligent Governor, PCC, Digital Valve, Cartridge Valve.
**Preface:**
Currently, most turbine governors rely on PLCs as their core components. However, the Digital Valve PCC Programmable Intelligent Governor introduces a new control concept, using the PCC as the central controller. This system integrates solenoid and cartridge valves to replace conventional electro-hydraulic converters and main pressure valves. As the core of the governor, the controller handles signal acquisition, data processing, control logic execution, status switching, and output control. Choosing an appropriate controller is critical for the development of a reliable governor. After evaluating various options like microcontrollers, PLCs, and PCCs, the PCC from B&R in Austria was selected due to its industrial suitability, strong anti-interference capability, and high reliability.
PCC combines the features of a PLC with those of an industrial computer, offering scalability, high computing power, and ease of programming. Its modular hardware and software allow flexible system expansion. With a 32-bit TPU processor, it achieves microsecond response times and supports fieldbus technology, aligning with modern industrial trends.
The Digital Valve PCC Intelligent Governor comes in both single and dual adjustment models. This document focuses on the dual adjustment version, detailing its key features, functions, and structure.
**Main Features of the Digital Valve PCC Intelligent Governor:**
1. **Innovative Control Concept:** Utilizes PCC, a next-generation programmable controller, allowing high-level language programming and efficient multitasking.
2. **High Reliability:** Achieves a mean time between failures (MTBF) of up to 500,000 hours.
3. **Multitasking Capability:** Prioritizes tasks based on urgency, improving system responsiveness.
4. **Intelligent Control:** Uses adaptive PID algorithms and self-diagnosis to ensure stable operation under varying grid conditions.
5. **High-Speed Frequency Measurement:** Leverages the PCC’s HSC module for precise frequency detection.
6. **Digital Adjustment:** Allows field modifications to curves, ensuring optimal performance.
7. **Large Memory Capacity:** Provides 1.5 MB of user memory for complex operations.
8. **Digital Valves:** Replaces traditional electro-hydraulic components, eliminating oil leakage issues.
9. **Fault Lock Function:** Ensures hydraulic locking even during power loss.
10. **No Lever Structure:** Enhances speed control accuracy and simplifies design.
11. **User-Friendly Interface:** Features a touch screen with full Chinese display and intuitive controls.
12. **Easy Maintenance:** High integration reduces the need for specialized technical staff.
**Key Functions of the Digital Valve PCC Intelligent Governor:**
- Supports automatic, electric manual, and manual modes with bumpless switching.
- Offers no-load frequency tracking, power regulation, and AGC functionality.
- Includes robust self-diagnosis, fault tolerance, and alarm systems.
- Enables communication with host computers and remote monitoring.
- Features intelligent shutdown, auxiliary testing, and water level control.
- Implements multi-level password protection and polyline shut-off functions.
**System Composition:**
The governor consists of a PCC CPU module, high-speed DI modules, pulse output modules, A/D converters, digital I/O modules, and communication interfaces. The frequency measurement process uses the PCC’s TPU for high precision and reliability. Digital valve control is managed via PWM signals, driving electromagnetic ball valves efficiently.
**Electro-Hydraulic Servo System:**
The system replaces traditional components with standard solenoid and cartridge valves, offering improved reliability and simplified maintenance. The use of cone valves ensures zero leakage at 31.5MPa, while the absence of mechanical feedback enhances system stability.
**Working Process:**
Upon startup, the governor follows pre-set rules, selecting frequency or opening adjustment modes based on input. It adjusts guide vane openings automatically, enabling smooth grid connection and load regulation. In case of faults, the system initiates safe shutdown procedures.
**Applications and Results:**
Several units have been successfully deployed in hydropower stations, exceeding the GB9652.1-1997 standard. For example, the Yangtou Hydropower Station in Guizhou achieved a speed dead zone of 0.015%, excellent dynamic performance, and reliable operation without failures.
**Conclusion:**
The Digital Valve PCC Intelligent Governor not only overcomes the limitations of traditional systems but also meets modern industrial demands, paving the way for unattended hydropower operations. It has passed national testing and received recognition from the Ministry of Science and Technology, marking a significant advancement in turbine control technology.