Distributed Plant Control Nodes Without CPU-Based Centralization
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Solution Overview
Problem
Conventional distributed control systems for plant facilities, such as nuclear power plants, require advanced calculation processing units like CPUs, leading to complex configurations and decreased reliability, especially in small-scale systems, and increased costs.
Innovation Solution
A plant-monitoring autonomous control system is implemented using a network of nodes with different functions (input, calculation, and output nodes) connected through a control network, managed by a scheduler that transmits data and calculation results without relying on advanced processing units like CPUs, allowing for autonomous distributed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a centralized control device is used for monitoring control in plant facilities, then control logic calculation can be performed, but the system configuration becomes complicated and reliability decreases
Solution Approach 1:
The control system is divided into multiple independent control devices, each capable of performing control logic calculations autonomously. Instead of one centralized control device, the functionality is segmented across several distributed units that can operate independently, thereby reducing system configuration complexity while maintaining automation capability.
Solution Approach 2:
A relay apparatus serves as an intermediary component that connects control devices to control target apparatuses. This mediator enables simplified connections between distributed control units and their respective targets, reducing the overall system configuration complexity while preserving full control logic calculation capability across the distributed architecture.
2Extent of automation
If a centralized control device is used, then control functions can be consolidated, but the entire system is influenced by abnormalities in the centralized device, decreasing reliability
Solution Approach 1:
The control function is segmented across multiple independent control devices rather than consolidated in a single centralized device. Each control device operates autonomously, so an abnormality in one device does not affect the others, thereby maintaining control functionality while significantly improving system reliability through functional distribution.
Solution Approach 2:
The system architecture parameter changes from centralized to distributed configuration. This fundamental parameter change transforms the reliability characteristic by eliminating the single point of failure inherent in centralized systems, while still achieving control function consolidation through coordinated operation of multiple distributed control devices.
3Productivity
If advanced calculation processing units like CPUs are used in distributed control systems, then control processing capability is improved, but configuration becomes complicated and costs increase
Solution Approach 1:
Instead of using advanced CPUs, the system employs multiple inexpensive calculation processing units that replicate basic computational functionality. Each control device contains a simple calculation processing unit capable of performing control logic calculations, providing adequate processing capability through quantity rather than individual unit sophistication, thereby reducing configuration complexity and cost.
Solution Approach 2:
The system replaces expensive, complex CPUs with cheaper, simpler calculation processing units. These less sophisticated units are deployed in multiple instances across distributed control devices, achieving necessary control processing capability through cost-effective, simple components rather than relying on high-performance but complex and expensive processors.
Data Source
AI summary
To obtain a plant-monitoring autonomous control system which performs autonomous distributed control without using an advanced calculation processing unit such as a CPU. A plant-monitoring autonomous control system is provided with a control network which mutually connects: input nodes for receiving an input signal from a control target apparatus and transmitting the input signal to the control network; a calculation node having calculation circuits, and for transmitting, to the control network, a result obtained by performing calculation processing on data received from the input node; and an output node for outputting, to the control target apparatus, data received from the calculation node.