Smart Substation Queue Scheduling for Network Delay Reduction
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Solution Overview
Problem
The current priority and scheduling strategies in smart substations, relying on two-level priority and Strict Priority Queue algorithms, fail to adequately distinguish between different communication services' real-time requirements, leading to network congestion and decreased Quality of Service (QoS) during burst traffic, which can impact the safe and stable operation of the power grid.
Innovation Solution
A fine-grained priority scheme is introduced, where communication services are categorized with specific priority levels (trip message: 7, state change message: 6, sampled value message: 5, device status message: 4, time synchronization message: 3, and file transfer message: 1), and the HDWRR queue scheduling method is implemented, combining SPQ and DWRR, to allocate network resources based on service requirements, ensuring QoS through appropriate queue management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a unified network structure is adopted for all communication services in smart substation, then information sharing and network efficiency are improved, but network load uncertainty and network delay increase
Solution Approach 1:
The patent segments the unified communication network into multiple priority queues (at least two queues: high-priority queue and low-priority queue) based on service types. Critical services such as GOOSE and SV messages are assigned to the high-priority queue, while non-critical services are assigned to the low-priority queue. This segmentation allows differential handling of traffic streams, ensuring that time-sensitive services receive preferential treatment during network congestion, thereby reducing network delay for critical operations while maintaining overall network efficiency.
2Device complexity
If two-level priority and SPQ scheduling strategy are used, then implementation is simple, but real-time and reliability of key services cannot be guaranteed under network congestion
Solution Approach 1:
The patent further segments the high-priority queue into multiple sub-queues based on service types (e.g., GOOSE queue, SV queue, other high-priority queue). Each sub-queue is dedicated to specific service types with different real-time requirements. This fine-grained segmentation enables precise control over service quality, ensuring that key services with stringent real-time requirements are guaranteed bandwidth and low latency even during network congestion, while maintaining manageable system complexity through structured queue organization.
3Device complexity
If all services are treated equally in network scheduling, then scheduling is simple, but communication delay of key services increases during burst traffic
Solution Approach 1:
The patent applies local quality by assigning different service levels and scheduling policies to different service types within the network. Critical services (GOOSE, SV) receive high-priority treatment with guaranteed bandwidth allocation, while non-critical services (file transfer, configuration) receive lower priority. This differentiated quality of service approach ensures that key services maintain low communication delay during burst traffic conditions, while the overall scheduling mechanism remains relatively simple through the use of priority queues and weighted round-robin scheduling.
Data Source
AI summary
A method for dividing communication services in smart substation into different priorities, the method including: determining the priority of a message to be sent according to the service type and its priority definition; the communication services includes trip message, state change message, sampled value message, device status message, time synchronization message, and file transfer message; the corresponding priority is respectively defined as 7, 6, 5, 4, 3, 1; and filling the user priority field of IEEE802.1Q label in a message header with a binary value corresponding to its priority.