As the first line of defense for ensuring the safe operation of power grids, the reliability of relay protection plays a pivotal role in the safe and stable operation of the entire power system. In the past, the setting of test state sequences relied mainly on manual calculation of various excitation quantities and manual input into test instruments, which featured low automation, inconsistent standardization and heavy manual calculation workload. This not only affects the efficiency of relay protection tests, but also fails to ensure the consistency of test results.

In response to this problem, Wuhan Haomai Electric Power has designed and developed a method and platform for generating relay protection test state sequences. Based on the imported setting parameters and configuration information, the platform automatically calculates the test data of the state sequences for each test module through test scheme instantiation, and completes the configuration of test state sequences.

Overall Platform Functional Structure

The relay protection test state sequence generation platform mainly consists of a data import module, scheme configuration module, sequence generation module, database module, human-computer interaction module and data interaction interface.

△ Overall Platform Module Structure Diagram

Data Import Module: Completes the import of setting parameters and relevant configuration information required for relay protection tests, parses the included parameter information, and saves the confirmed imported parameter information in the database module.

Scheme Configuration Module: Completes the configuration of specific test items in test scheme instances, and automatically presets the algorithms for subsequent state sequence generation for different types of relay protection test items.

Sequence Generation Module: Establishes association with test scheme instances, and generates test state sequences for specific test items by selecting the setting mode of state sequence generation. After all state sequences are generated, the confirmed test state sequence settings are saved in the database module.

Database Module: Implements integrated information management of each module, and saves imported information and generates exported data in specified formats according to the requirements of the data interaction interface.

Human-Computer Interaction Module: Performs information interaction with each application module, uniformly coordinates computing and analysis resources, and completes specific operations of relay protection function tests and corresponding visual display on the human-computer interface.

Data Interaction Interface: Performs information interaction with the database module to complete the import of original strategies or operation instructions and the export of generated data in specified formats.

Setting parameters include calculation settings required by the test object, press plate input status and control word setting status.

Configuration information includes device model, software version and manufacturer.

Key Function of Sequence Generation Module: When the automatic mode is selected to generate test state sequences, the module automatically calculates the state quantities of each test item according to the algorithms preset by the scheme configuration module, combined with the setting parameters and configuration information imported by the data import module.

Overall Platform Method Flow

△ Overall Platform Method Flow Chart

1. The human-computer interaction module calls the data import module to open an existing test scheme instance from the database module, or calls the scheme configuration module to create a new test scheme instance.
2. The human-computer interaction module calls the data import module to obtain the setting parameters and configuration information required for relay protection function tests, parses the data and saves it in the database module.
3. When creating a new test scheme instance, the scheme configuration module determines specific test items and test sequences according to test requirements and completes the scheme instance settings; when opening an existing test scheme instance, it modifies the items and sequences of the instance.
4. The scheme configuration module automatically verifies the matching between the imported information and the instance, and saves the verified scheme instance in the database module; the unverified instance will undergo manual verification through steps 1 to 3.
5. The sequence generation module retrieves the test scheme instance saved in the database module, selects the working mode to generate test state sequences for specific test items, and saves the sequences in the database module.

Field Application Case Analysis

1. Import Test Template

Add test items in the template, which are divided into different protection types for transmission lines, main transformers and busbars; one or more test items can be added customarily.

△ Transmission Line Protection Test Item Template

2. Set Line Scheme Setting Items

Select the test scheme, the system automatically matches the relevant settings for the test and the user can tick the required items. Setting values can be directly entered in the table or imported via a setting list (e.g., set the differential current setting to 5A). The state sequence module is automatically generated after clicking the setting scheme button.

△ Line Setting List

3. Set Main Transformer Scheme Setting Items

△ Main Transformer Setting List

4. Set Busbar Scheme Setting Items

△ Busbar Setting List

5. State Quantity Result Display of State Sequences

△ 0.95 Times Phase A

△ 1.05 Times Phase A

△ 0.95 Times Phase B

The platform automatically generates three states: pre-fault state, fault state and normal state. For different test items of 0.95 times, 1.05 times and three phases (A, B, C), different fault state results are generated, and the results can be manually modified.

Test Data Analysis

Different test results are generated according to the content of different test items, including action description, report generation time and action time.

1. Phase-Separated Steady-State Current Differential Protection

Test Item	Action Description	Actual Protection Action Description	Action Time (ms)
Phase-Separated Steady-State Current Differential Protection	Zone I_0.95 Times_Phase A Ground	No action	\
Phase-Separated Steady-State Current Differential Protection	Zone I_1.05 Times_Phase A Ground	Protection Start (Differential Protection)	51
Phase-Separated Steady-State Current Differential Protection	Zone I_0.95 Times_Phase B Ground	No action	\
Phase-Separated Steady-State Current Differential Protection	Zone I_1.05 Times_Phase B Ground	Protection Start (Differential Protection)	49

2. Ground Check

Test Item	Action Description	Actual Protection Action Description	Action Time (ms)
Ground Check	Zone I_0.95 Times_Phase A Ground	Protection Start (Earth Distance Zone I Operation_Phase A)	41
Ground Check	Zone I_1.05 Times_Phase A Ground	No action	\

3. Phase-to-Phase Distance Check

Test Item	Action Description	Actual Protection Action Description	Action Time (ms)
Phase-to-Phase Distance Check	Zone I_0.95 Times_Phase AB Short Circuit	Protection Start (Phase-to-Phase Distance Zone I Operation_Phase AB)	41
Phase-to-Phase Distance Check	Zone I_1.05 Times_Phase AB Short Circuit	No action	\
Phase-to-Phase Distance Check	Zone I_0.95 Times_Phase BC Short Circuit	Protection Start (Phase-to-Phase Distance Zone I Operation_Phase BC)	41
Phase-to-Phase Distance Check	Zone I_1.05 Times_Phase BC Short Circuit	No action	\
Phase-to-Phase Distance Check	Zone I_0.95 Times_Phase CA Short Circuit	Protection Start (Phase-to-Phase Distance Zone I Operation_Phase BC)	41
Phase-to-Phase Distance Check	Zone I_1.05 Times_Phase CA Short Circuit	No action	\

The application of the relay protection test state sequence generation method and platform realizes the automatic import and parsing of setting values and relevant parameter information required for power system relay protection tests. Through standard content import, parameter information parsing and consistency verification, the setting information required for tests is automatically matched with test schemes. By automatically generating standard test state sequences, the test and calibration process becomes more efficient and reliable.