T&D World Magazine

MPRT Now Capable of Testing IEC 61850 Relays and Substations

IEC 61850 is the new international communication standard for substations. The main goal of 61850 is to obtain interoperability between different protective devices from different vendors. IEC 61850 has many benefits and one of these is replacing the traditional copper wiring with Ethernet/Fiber cables. This means no more binary inputs and outputs for control and protection functions. The traditional method of tripping a breaker via a contact will be replaced by a GOOSE (Generic Object Oriented Substation Events) messages sent via Ethernet or fiber optic cables. One of the major challenges currently facing 61850 is defining testing procedures. How is a 61850 device supposed to be tested? What is required in order to test these devices?

New Features and Capabilities

Traditional testing methods can still be used to test 61850 devices with the Megger's MPRT. Voltage and current signals must be applied to the device in order for it to trip. The difference is in the way the tripping signal is monitored. Traditionally the user would connect a test lead from a binary input of the test set to a binary output of the protective device. When the protective device would trip, the output would close and this would cause the input on the test set to activate and stop either test injections or a timer.

With 61850 devices, a physical output is no longer monitored by the test set. The test set will have to be able to detect and “read” a GOOSE message from the relay under test. Once the GOOSE message is detected the test set must either stop injections and/or stop the timer very quickly. This would require the test system to be able to interrogate the network, acquire the right GOOSE message, and stop injections or timer in less than 2 milliseconds. Also the test system would have to be able to read SCL (Substation Configuration Language) files and map inputs of the relay test set to the various GOOSE messages available in the SCL file. If an SCL file is not available then the test system would have to be able to interrogate the network, and display all available GOOSE messages on the network, to allow the user to be able to map these messages to binary inputs on the test system.

The MPRT with the IEC 61850 option and the MGC, Megger GOOSE Configurator, software now has this test capability.

Megger MPRT and GOOSE Configurator Test Solution

The MGC provides easy-to-use tools for testing relays and substations using the IEC 61850 protocol. The configurator allows relay test engineers and technicians to import parameters from configuration files in the SCL format and use it to configure the MPRT to subscribe to preselected GOOSE messages by assigning the data attributes from received GOOSE messages to the appropriate binary inputs. This provides both manual and automatic testing of the relay using either the Touch View Interface or AVTS software. Use the MGC to assign the appropriate binary outputs of the MPRT to publish GOOSE messages simulating circuit breaker status. Use the MPRT TVI in the dynamic enabled mode to perform high speed trip and reclose timing tests, or use test files created in AVTS to perform fully automatic tests. Perform high speed timing tests manually using the TVI or automatic mode using the AVTS software (the MPRT meets the IEC 61850-5 standard, Type 1A, Class P 2/3, for high speed trip and reclose simulations).

For example, a user needing to test a reclosing scheme using 61850 would perform the following: First, the user would connect the test system to the network to determine what GOOSE messages are available. This can also be done via an SCL file. After all GOOSE messages of interest are found, these would be "mapped" internally to the binary inputs and outputs of the MPRT (similar to connecting the binary inputs and outputs of the relay using test leads to the binary outputs and inputs of the MPRT). The test values would be injected and the relay would trip sending a trip GOOSE message to the network. The MPRT will detect the message and record the trip time. After a few cycles of delay used to simulate breaker opening the MPRT will send a GOOSE message to the network simulating a breaker opening (52A) condition. The relay receives the message and initiates reclosing. Once the reclosing time expires; the relay will send another GOOSE message to reclose the breaker. The MPRT will read the GOOSE message to reclose and sends another GOOSE message simulating breaker closing. This continues until the last reclosing cycle is performed by the relay.

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