With the gradual popularization and application of smart substations, their maintenance and overhaul work has increased accordingly. The networking mode of smart substations is different from that of traditional integrated automation substations: the process layer adopts outdoor intelligent component cabinets, and all voltage and current data in the substation are collected, converted and transmitted by merging units inside the intelligent component cabinets.

Polarity testing of traditional integrated automation substations uses a volt-ampere meter, with one interface collecting voltage and the other collecting current for polarity testing. Analog quantities of AC voltage and AC current can be obtained directly at the protection panel. However, in smart substations, analog quantities such as voltage and current are converted into digital quantities after analog-to-digital conversion and then transmitted to protection devices, making it impossible to collect dual-channel analog quantities of voltage and current at the protection panel. Usually, the voltage collection points and current collection points are far apart, which brings great inconvenience to the polarity testing of current.

At present, secondary operation and maintenance personnel mainly adopt the long-distance wiring method for phase checking: collect the analog voltage of the bus at PT terminal boxes at two different locations respectively, and connect them to a traditional phase meter through long cables. This method involves heavy workload and complicated procedures, and may have potential safety hazards.

To solve the above problems, in accordance with the secondary testing requirements of power system substations, especially the distributed measurement requirements of secondary analog quantities in smart substations, Wuhan Haomai Electric Power has independently developed the YD-300E Intelligent Wireless Telemetry Voltmeter-Ammeter Phase Meter. The device enables two phase checking meters located at different positions to perform synchronous sampling through wireless communication, and aggregates the data of the two meters to the same location for comparison. In practical on-site applications, it can greatly reduce the workload of testing personnel, avoid errors in the testing process caused by a large number of wiring work, and solve the practical problems in substation sites. It is applicable to both smart substations and integrated automation substations.

As an advanced intelligent multi-functional tester, the YD-300E consists of a master unit and slave units. The master unit is equipped with a 7-inch capacitive touch screen, runs on the Android system and has a built-in large-capacity lithium battery. Data can be imported and exported via a USB flash drive. Its functions include:

Basic Testing: Three-phase testing, multi-unit telemetry, current testing;

Automatic Testing: One-click testing;

Intelligent Diagnosis: Voltage testing, total power summation, line testing, bus tie testing, main transformer testing, bus differential protection testing;

Slave Unit Mode Testing: Slave units have no display screens and are mainly used for data collection and upload. They are equipped with a microUSB interface for external display screens, and all functions of the master unit can be realized through the APP on the external display screens.

△ Schematic Diagram of Multi-Unit Telemetry

The YD-300E Intelligent Wireless Telemetry Voltmeter-Ammeter Phase Meter has the function of three-phase synchronous testing, which can measure the amplitude, phase, active power, reactive power, vector diagram, frequency and phase of three-phase voltage and current. It supports multi-unit wireless telemetry to realize long-distance wireless synchronous measurement with a phase error of ≤0.5°. Multiple YD-300E devices can measure the amplitude and phase of multiple channels of voltage and multiple channels of current at the same time. Meanwhile, the device is equipped with intelligent diagnosis and automatic testing functions, which can accurately measure the amplitude and phase of voltage and current from the analysis of wrong wiring in AC secondary circuits, whether the secondary voltage and current circuits share a common grounding point or not.

Corresponding functional modules can be selected for testing according to different test items, such as voltage testing, total power summation, line testing, bus tie testing, main transformer testing, bus differential protection testing, etc. It can comprehensively detect the PT and CT secondary circuits, intelligently judge the correctness of the AC secondary circuits, and automatically generate test reports.

△ Master Unit Interface

The automatic testing function supports the configuration of test items, performs automatic testing according to the configured and selected test items, automatically calculates data such as vector analysis and power factor, and draws vector analysis diagrams and power factor diagrams synchronously.

On the main interface, click the intelligent diagnosis module, select report generation, and check the corresponding test data to generate a report. Taking voltage testing as an example, select three sets of test data and click "View Report" to generate and view the report.