At present, protection devices in smart substations mainly achieve sampling loop digitization through electronic transformers, collectors, and merging units, or traditional transformers and merging units. Tripping loops are digitized using protection devices and intelligent terminals. However, the technical level of existing electronic transformers, collectors, and merging units cannot fully meet requirements for high-precision and synchronized data, often leading to abnormal sampling data that is difficult to locate, resulting in certain defects in practical use.

To address the shortcomings of digital sampling and leverage the advantages of GOOSE tripping, the power grid system has proposed a new mode—conventional sampling GOOSE tripping mode—in accordance with standardized relay protection design specifications. Conventional sampling means the protection device directly samples analog data, while GOOSE tripping means the protection device sends tripping commands directly to intelligent terminals via optical fibers. For this mode, neither conventional relay protection testers nor digital relay protection testers can independently complete protection tests; a digital-analog integrated relay protection tester is required. This paper demonstrates a differential protection test on the NR Electric PCS-931A5-DG-N EHV Line Protection Device using the Relaystar-7000A Integrated Digital Relay Protection Test System.

1. Introduction to Conventional Sampling GOOSE Tripping Protection Devices

△ Front Panel of PCS-931 Protection Device

△ Back Panel of PCS-931 Conventional Sampling GOOSE Tripping Protection Device

The NR1181 is a DSP plug-in for conventional sampling and digital tripping, consisting of a high-performance digital signal processor, 16-bit high-precision ADC for synchronous sampling, and other peripherals. This plug-in performs analog data acquisition, exchanges sampling data with the opposite side, executes protection logic calculations, and manages tripping outputs. Dual redundant sampling channels and digital signal processors effectively enhance device reliability. The DSP and MONI plug-ins occupy two slots (slot numbers 04 and 05) and support GOOSE functionality and the IEC61850-9-1/2 protocol, enabling the protection device to receive data from merging units and send GOOSE commands to intelligent operation boxes.

2. Introduction to Test Equipment

△ Relaystar-7000A Integrated Digital Relay Protection Test System

The Relaystar-7000A Integrated Digital Relay Protection Test System can output analog current and voltage signals, while subscribing to or publishing GOOSE signals. It simulates CT/PT secondary quantities for protection devices, receives GOOSE tripping signals from protection devices, and completes functional verification of conventional sampling GOOSE tripping protection devices.

3. Test Example

A protection device in a smart substation uses analog sampling and GOOSE tripping. The line optical differential setting for Line 1A (NR Electric PCS-931A5-DG-N) is 1.0A. The Relaystar-7000A is used to verify the differential protection action and measure its operating time.

1) Wiring Method

Analog Output Current Wiring: As shown in the diagram, connect the tester’s current outputs to the protection device’s current input terminals.

Analog Output Voltage Wiring: Connect the tester’s ABCN outputs to the protection device’s UA, UB, UC, UN input terminals.

GOOSE Tripping Output Wiring: As shown in the diagram, connect the protection device’s GOOSE tripping outputs to the tester’s GOOSE ports.

△ Analog Output Wiring Diagram

△ GOOSE Wiring Diagram

2) Software Configuration

Enter the State Sequence Test interface, click the IEC61850 Parameter Settings interface, select "Power Amplifier Output" in the lower-left corner and disable it to enable analog current and voltage output.

△ IEC61850 Parameter Settings

Go to the GOOSE Parameter Settings interface and import the protection’s tripping control block. The tester simulates an intelligent terminal to receive tripping signals from the protection device, with the GOOSE port set to "Subscribe" and the channel selected as "Optical Fiber 1". Map the corresponding tripping outputs to inputs ABC, and if reclosing is included, map the closing output to input R. Close the interface to complete configuration.

△ GOOSE Parameter Settings

3) Test Method

Launch the "Relaystar" software from the desktop shortcut and click the "State Sequence" icon to enter the test module.

△ State Sequence Test Interface

Before testing, set the Channel 1 Differential Soft Pressure Plate to 1, enable the corresponding differential protection and reclosing control words, set Channel 1 optical fiber to "Self-Transmit and Self-Receive", and ensure the local and remote identification codes are identical. To simulate a Phase A fault with a differential current of 1.2Id, follow these steps:

1. Add/delete states using the "+"/"-" buttons on the toolbar to ensure exactly 2 states.
2. Set voltages and currents for each state as follows:

Parameter	State 1 (Pre-Fault)	State 2 (Fault)
UA/V	57.735∠0°	10∠0°
UB/V	57.735∠-120°	57.735∠-120°
UC/V	57.735∠120°	57.735∠120°
IA/A	0	0.6∠-78°
IB/A	0	0
IC/A	0	0
Trigger Condition	Key Trigger	Time Trigger
Test Time/ms	-	100
Post-Trigger Delay/ms	0	0

The Phase A current amplitude is calculated as I=m×Id​/2, where m=1.2.

3. Click "▶" on the toolbar or press the "run" key to start the test. Wait until the "PT Disconnection" indicator turns off and the "Charging Complete" indicator turns on, then click "▶▶" or press the "TAB" key to switch to the fault state.
4. Observe the protection action results. The tester records the operating time of Input A as 34ms in State 2. Complete the test and print the action report.

Serial No.	Start Time	Relative Time	Action Phase	Action Element
0146	2019-11-23 16:26:22:327	0000ms	—	Protection Start
		0030ms	A	Pilot Protection Operated
		0837ms	—	Reclosing Action
Fault Phase Voltage	—	—	—	9.98 V
Fault Phase Current	—	—	—	0.60 A
Maximum Zero-Sequence Current	—	—	—	0.60 A
Maximum Differential Current	—	—	—	1.21 A
Fault Distance	—	—	—	20.40 km
Fault Phase	—	—	—	A

 

△ Differential Protection Action Report