Devices in smart substations communicate through digital signals, and the logical circuits (also called virtual circuits) between devices are described by SCD files. The correctness of these circuits is directly related to whether the relay protection devices can operate properly. At present, the compilation and management of configuration files for smart substations have gradually become mature. However, as they rely on manual compilation, and virtual circuits are different from the hard-wired circuits in conventional substations, the invisibility of virtual circuits greatly increases the difficulty of fault and defect handling. Some potential safety hazards such as incorrect communication parameter configurations and wrong communication relationship (virtual circuit) configurations cannot be effectively inspected and controlled. To ensure that hidden dangers such as incorrect connection, redundant connection and missing connection of virtual circuits in newly-built, reconstructed and expanded smart substations are identified and eliminated in a timely manner, it is necessary to further strengthen the virtual circuit verification work during the debugging, acceptance, operation and maintenance of smart substations.

Currently, the verification of virtual circuits in smart substations generally adopts integrated configuration tools or single-device-centric visualization tools for manual verification. Such methods cannot display the panorama of the secondary system from the perspective of relay protection professionals, and are complicated to operate, requiring high technical levels of users. Usually, a 220kV smart substation has about 2,000–3,000 virtual circuits, resulting in heavy verification workload, low efficiency and high possibility of missing inspections.

△ Relaystar-Z70 Handheld Digital-analog Integrated Relay Protection Tester

On the basis of retaining all the relay protection test functions, the Relaystar-Z70 Handheld Digital-analog Integrated Relay Protection Tester adds an SCD file visual comparison and verification tool for relay protection professionals from the perspective of bay protection function configuration.

△ SCD Visualization

It is compatible with the virtual circuit verification of smart substations with typical and non-typical designs, non-"Nine Unifications", "Nine Unifications", the latest device standards, as well as those with coexisting non-"Six Unifications", "Six Unifications", "Nine Unifications" and the latest device standards in the station.It features stable and reliable performance, free from the influence of voltage levels, wiring modes, different design standards, different device standards and other factors, and is simple to operate and easy to master.From the perspective of bay protection function configuration, it conducts verification and result display according to protection configuration and protection circuits.

Relaystar-Z70 has a built-in empirical model that conforms to the substation design mode and supports learning and training. During verification, it identifies the protection configuration features obtained from SCD model conversion, performs intelligent parsing of SCD files through a software algorithm based on graph theory association search, combines fuzzy matching of virtual terminal self-check principles, quickly realizes the legality check of virtual terminals in the SCD file configured for the entire station, visually displays the network connections between various IEDs in the model file, and automatically generates the logical connection diagram of virtual secondary circuits between IEDs.

△ SCD Visual Comparison

By parsing the SCD file, it converts the SCD communication model into a relay protection business model, verifies the correctness of the business model based on the typical empirical model, identifies potential hazards in virtual circuits, and ensures the correct operation of relay protection devices.

Main Functions: SCD parsing and model conversion, intelligent device type identification, bay protection configuration model data construction, bay protection configuration and circuit verification, verification result inquiry, report output, manual verification and empirical learning, etc.

△ Network Analysis

SCD Parsing and Model Conversion

Convert the SCD communication model into a relay protection business model.

Intelligent Device Type Identification

Identify the type of intelligent device according to the ICD model characteristics, IED name and description of the IED in the SCD.The type of intelligent device of an IED is determined according to its ICD model characteristics. Usually, the relevant models of devices such as main transformer protection, busbar protection, line protection and circuit breaker protection can uniquely determine their device types.For intelligent terminals, merging units, integrated smart terminal and merging unit devices, etc., whose device types cannot be uniquely determined (they can be used for line, busbar and other bays), their device types are determined with the assistance of IED names and descriptions.

Bay Protection Configuration Model Data Construction

The interconnected intelligent devices and their relationships in the entire station are decomposed according to bay types (line bay, main transformer bay, bus coupler bay, section bay, busbar PT bay) into the protection configuration model data of each bay.

Bay Protection Configuration and Circuit Verification

Verify the bay protection configuration based on the typical empirical model, and check the correctness of the bay protection configuration and the correctness of the circuits between devices under the bay protection configuration.

1. Correctness of bay protection configuration: Check whether there are redundant or missing device connections in the bay, and whether the connections between devices are redundant or missing.

△ Virtual Terminal Check Diagram

2. Correctness of inter-device circuits under bay protection configuration: Check whether there are redundant, missing or misplaced virtual circuits, etc.

△ Virtual Terminal Check Report