Cross-Border Synchrophasors Integration: Smart Grid Cooperation between two countries

The above figure is extracted from the article "Synchrophasor Applications in the Croatian Power System" written by Zdeslav Čerina, Ivan Šturlić, and Renata Matica from HEP-TSO (Croatian Transmission System Operator), and Veselin Skendžić. This diagram illustrates the synchrophasors network topology, showing the communication architecture between Swissgrid (Switzerland) and HEP-TSO (Croatia) for the exchange of PMU data.

1. Architecture Objective

This network ensures the real-time transmission of synchrophasor data between the PMUs (Phasor Measurement Units) located in Switzerland and those in Croatia, as part of a Wide Area Monitoring System (WAMS).

2. Main Components

Swissgrid Side:

• PMU Bassecourt: Measures voltage and frequency phasors in compliance with IEEE 1344-1995.
• WAMS Server: Collects PMU measurement data.
• EH Firewall + EH Routers (SLO and BIH): Ensure secure access to the Electronic Highway (EH) network.

HEP (Croatia) Side:

• EH Routers (SRB, HUN, etc.): Provide geographical redundancy in IP routing via multiple entry points (e.g., Serbia, Hungary).
• EH Switches 1 and 2: Offer local redundancy by interconnecting routers, firewalls, and servers.
• EH Firewalls 1 and 2: Secure the entry into HEP’s internal infrastructure.
• HEP WAMS Server: Aggregates both local and remote PMU data, functioning as a Phasor Data Concentrator (PDC).
• PMU Ernestinovo: Local PMU in Croatia, compliant with IEEE C37.118.
• WAMS Network: Internal HEP network for monitoring, processing, and visualizing PMU data.

 3. Data Flow

• Upstream data from Swissgrid: The PMU at Bassecourt sends measurements to its WAMS Server. The data passes through a firewall, traverses the EH infrastructure, and reaches HEP via the EH HUN Router.
• Downstream data at HEP: HEP can process and combine incoming data from Swissgrid with local data from the Ernestinovo PMU, within its own WAMS Server.

The red dashed line represents the main PMU data flow between Swissgrid and HEP, including both physical and virtual PMUs.

4. Redundancy and Security

The EH network is a private communication network with an availability exceeding 99.8%, ensuring high operational resilience. The use of two firewalls at HEP’s perimeter, along with redundant switches, provides:

• Fault tolerance,
• Strict separation between critical PMU data traffic and other types of network traffic.

5. Synchronization and Standards

The standards applied:

• IEEE 1344-1995 on the Swissgrid side,
• IEEE C37.118 on the HEP side, ensure both temporal and semantic compatibility between the devices.

This enables HEP to build a virtual PMU based on Swissgrid data, supporting regional disturbance analysis and situational awareness.

Conclusion

This architecture is an excellent example of the implementation of a secure transnational WAMS, based on:

• Open IEEE standards,
• A highly reliable communication infrastructure (EH),
• And effective topological redundancy.

It significantly contributes to the stability and resilience of the European interconnected power system.

If you are interested in discussing PMU network architectures and topologies for your own projects, I would be glad to exchange ideas with you. Feel free to connect with me on LinkedIn.

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