What are the applications of smart grid IoT? What factors affect smart grid relay protection?

Leveraging existing network infrastructure, such as fault detectors, energy operators can cost-effectively build smart grids

Connecting legacy devices to smart grid IoT applications allows utilities to:

1) Push data in real time – Relying on centralized data polling results in significant latency and limited scalability. Many IIoT gateways poll data locally and create data models that can communicate with legacy SCADA systems as well as cloud-based platforms to leverage modern web services.

2) Leverage cellular infrastructure – IIoT gateways allow grid monitoring devices to leverage cellular connectivity, forming secure connections with multiple backend or cloud systems.

3) Through low power consumption

4) Leverage the cloud – As distributed grids become more complex with more devices to manage, IIoT gateways are able to connect to cloud-based infrastructure and share real-time data and analytics with users through cloud-managed dashboards.

5) Enhanced grid security – Traditional grid monitoring systems (when connected via IP networks) are vulnerable to cyberattacks. They lack strong cybersecurity capabilities because legacy protocols were not designed with modern threats in mind. IIoT gateways can use the latest security methods to minimize security risks and update and patch security features to adapt to evolving cybersecurity threats.

Smart grid relay protection is not much different from conventional microcomputer protection in principle, and its main development lies in the change of protection secondary circuit. The protection secondary circuit uses a series of key technologies and factors that affect smart grid relay protection, such as the application of IEC61850 standard and electronic transformer, the emergence of intelligent primary equipment, the application of network communication technology and the overall architecture of automation system. These factors are actually interrelated and cannot be separated. The following is a detailed introduction.

1. IEC 61850 standard

IEC
61850 standard itself is not a professional technical standard for relay protection, but because the standard brings huge changes and wide influence on the functional architecture, communication system and automation system of substations, relay protection is inevitably deeply affected by it.

2. Electronic transformer

Electronic transformer is a general term for various new unconventional or semi-conventional current transformers or voltage transformers based on photoelectric conversion principle or electromagnetic induction principle by the International Electrotechnical Commission. Its impact on relay protection is mainly reflected in the following aspects: a)
The improvement of the transformer transmission performance is mainly the improvement of anti-saturation ability, which improves the working conditions of relay protection; b) The digitization of the transformer output signal causes changes in the sampling method of the protection device; c)
The removal of the sampling link makes it impossible for the protection device itself to control the sampling time, and the measurement frequency tracking method can only use software algorithms.

From the implementation of smart grid relay protection, the latter two aspects have a more obvious impact on relay protection.

3. Intelligent primary equipment

Among the intelligent primary equipment, the most influential on relay protection is the intelligent circuit breaker. At present, the intelligent implementation method of circuit breakers is: traditional circuit breakers + intelligent terminals. The emergence of intelligent terminals brings the following changes: a)
The circuit breaker operation mode has been changed, the circuit breaker operation box circuit and relays are digitized and intelligent, and the functions are realized through software logic; b)
The tripping and closing output mode of the protection device and the input mode of the locking and starting signals are changed from conventional hard contacts and cable connections to digital signals, connected through optical fibers and Ethernet switches.

4. Network communication technology

Smart substations introduce network technology into the automation system, resulting in station control layer/interval layer network and process layer network. Among them, the process layer network includes GOOSE network and SV network. GOOSE network is mainly used for interlocking information interaction between protection devices, transmission of tripping and closing commands between protection devices and intelligent terminals, and acquisition of switch position information; SV network is used to transmit electrical quantity sampling values. It is not difficult to see that the operation of the process layer network has an important impact on the realization of the protection function of the protection device.

5. Automation architecture

As a component of the automation architecture, relay protection is greatly affected by the architecture design. The architecture design not only affects the interface requirements of the protection device, but more importantly, it affects the configuration of the protection device, the function implementation method, the operation and maintenance method, and the safety and reliability of the operation.