CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119 and the Paris Convention Treaty, this application claims foreign priority to Chinese Patent Application No. 202010450544.3 filed May 25, 2020, the contents of which, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl P. C., Attn.: Dr. Matthias Scholl Esq., 245 First Street, 18th Floor, Cambridge, Mass. 02142.

BACKGROUND

The disclosure belongs to the field of communication technology for smart substation, and in particular, to a priority scheme of communication services in smart substation, a queue scheduling method for the priority scheme, a sending module, and a forwarding module.

The further development of the smart grid puts forward the requirement of unified networking for all communication services in the smart substation. That is, the structure of the communication network in the smart substation develops towards the mode that all intelligent electronic devices (IED) in the station are connected to the same network. This networking construction maximizes information sharing and improves network efficiency, but increases the uncertainty of network load and network delay at the same time. When the smart substation meets system disturbance or network attacks, the burst traffic may cause network congestion, thus making switches become the bottleneck of the network, and the network quality of service (QoS) decreases. Burst traffic will lead to the communication delay of key service increases, affect the action behavior of sensitive equipment, and eventually affect the safe and stable operation of the power grid. Therefore, how to ensure the real-time and reliability of key services under network congestion is a problem that must be solved when there is just one network in the smart substation.

IEC61850 gives preliminary suggestions that messages within the station use IEEE802.1Q priority tags to give different priority levels, while in the current actual project, two-level priority is adopted by default. The services carried by Generic Object Oriented Substation Event (GOOSE) messages and Sampled Value (SV) messages are set as high priority 4. And the remaining services are set as low priority 1. Switches use Strict Priority Queue (SPQ) algorithm to schedule messages. However, in the smart substation, different types of services have different real-time requirements, and service failure also causes varying degree damage to a primary power system. The two-level priority and SPQ scheduling strategy lack more detailed research on distinguishing services according to their different characteristics, and thus are difficult to guarantee the real-time and reliability of key services in case of network congestion.

SUMMARY

In view of the above-described problems, the disclosure provides a priority scheme of communication services in the smart substation, a queue scheduling method for the priority scheme, a sending module, and a forwarding module. The sending module can be integrated into the terminal equipment of the smart substation, such as breaker IED, P&C IED, MU IED, station PC, etc., and the forwarding module can be integrated into the switches used in smart substation.

In the first aspect, a method for dividing communication services in smart substation into different priorities comprises:

(a1) determining the priority of a message to be sent according to the service type and its priority definition; the communication services comprise 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

(a2) filling the user priority field of IEEE802.1Q label in a message header with a binary value corresponding to its priority.

In the second aspect, the queue scheduling method for the priority scheme comprises:

(b1) initializing each queue, and setting a buffer size for each queue;

(b2) reading a packet from the receive buffer of switch, and putting the packet into the corresponding queue according to its priority; and

(b3) scheduling and outputting the packet according to HDWRR scheduling rule.

In the third aspect, the sending module comprises a processing unit and a sending unit, wherein

the processing unit is configured to determine the priority of message to be sent according to the service type and its priority definition; and

the sending unit is configured to fill the user priority field of IEEE802.1Q label in the message header with a binary value corresponding to its priority, and send the message.

In the fourth aspect, the forwarding module comprises a configuration unit, a receiving unit, and a scheduling unit:

the configuration unit is configured to initialize each queue, and set a buffer size for each queue;

the receiving unit is configured to receive a packet p, and put the packet p into the corresponding queue according to its priority; and

the scheduling unit is configured to schedule and output packets according to HDWRR scheduling rule.

The disclosure has the following advantages and benefits:

(1) By using a fine-grained priority scheme based on services, the switches allocate network resources more reasonably according to the real-time and reliability requirements of all kinds of services in the communication network of the smart substation.

(2) HDWRR queue scheduling method is a combination of SPQ and Deficit Weight Round Robin (DWRR), which improves the ability to resist traffic attacks in the communication network, and ensures the Quality of Service (QoS) requirements of key service.

(3) The HDWRR queue scheduling method is universality. Users set the queue weight as a constant value according to the actual needs of users or a dynamic value according to different network conditions. The HDWRR queue scheduling method is suitable for the industrial network, which carries both real-time and non-real-time services. And the real-time services have different QoS requirements.

