Protective device for a circuit with remote diagnostic equipment

Description

[0001] The invention relates to a protective device for an electrical circuit, which has a triggering unit with a signal input for signal data sets of analog / digitally converted signals corresponding to operating quantities and a control output for a protective actuator which is supplied with a control signal by the triggering unit depending on the signal data sets.

[0002] To test the correct function of protective devices such as protective relays, it is common practice to connect protective test equipment to the respective signal inputs of the device on-site, thereby simulating signals from both fault-free and faulty operating states. However, a disadvantage is that an operator must always be present on-site to prepare, execute, and monitor the test procedure, making such testing methods extremely time-consuming. Furthermore, the monitored parts of the circuit must be disconnected from the protective device for testing purposes, both to apply the test signals and to prevent the activation of a protective actuator by these signals.

[0003] Due to increasing digitalization, it is common practice to convert signals from measuring points for operational parameters from analog to digital and make them available to protective devices via a common process bus. Data streams generated by a test device, representing various current and voltage values ​​in digital form, can be transmitted to the protective device via the process bus. Based on the transmitted data stream, the protective device is checked for correct function according to the current and voltage values ​​representing the respective operating state.However, even with such testing procedures, an operator is required on-site to connect a digital test device to the process bus of the protective device, while normal process operation is interrupted. This is because the reproduction of the correct timing of the signals and their analog-to-digital conversion is affected by any fluctuations in signal propagation time. Reproducible test results are therefore only achievable with considerable effort.

[0004] From WO2007079702 A1, a method for testing a protection device that processes digital sample data is known. In this method, a stored disturbance value recording (DU, DI) of at least one transducer is loaded into a test device (50). Digital samples are generated from the disturbance value recording data, corresponding to the transducer data recorded by the transducer during the disturbance value recording. The generated digital samples are embedded in digital network-compatible data packets (Dtest). The network-compatible data packets (Dtest) are transmitted to a network-compatible interface (D60) of the protection device (60), and the protection device's response to the transmitted digital samples is evaluated.

[0005] The invention is therefore based on the objective of designing a protective device of the type described above in such a way that reliable and time-efficient remote testing of the protective device is enabled without interrupting the process operation.

[0006] The invention solves the stated problem in that the protective device has a test interface connected to a test unit for inputting test signal packets and outputting protocol data packets, that the test unit is connected to the trigger unit for inputting test signal data sets, and that the test unit includes a recording module connected to the trigger unit for storing the protocol data sets in protocol data packets.

[0007] By transmitting test signal packets independently of the signal input—that is, multiple test signal data sets combined into a single packet—it is possible to avoid isolating the protective device from the source of the analog-to-digitally converted operating variables. Furthermore, the transmission of the test signal data sets from the test signal packet from the test unit to the tripping unit can occur at a predefined clock rate within the protective device, so that any propagation delays during the transmission of the test signal packets have no impact on the test. Conversely, by recording the protocol data sets output by the tripping unit within the protective device, the external connection to protective actuators can generally remain active even if the control output is deactivated or the output of a control signal is interrupted in a test mode of the tripping unit.If the recording of the protocol data records for a protocol data packet also occurs at the specified clock rate, the test signal data records from the test signal packet can be directly assigned to the protocol data records of the protocol data packet, thus creating repeatable test conditions. The analog-to-digital conversion of the operating parameters can take place either within the protective device itself or outside of it using an external analog-to-digital converter, with the transmission of the signal data records to the tripping unit occurring, for example, via a process bus. Thanks to the separate test interface and the independence from any propagation delays, remote testing can also be performed according to the invention, without requiring an operator to be present. The simultaneous testing of multiple protective devices is thus also easily enabled.

[0008] Although the trip unit can, in principle, only have one switchable signal input, which is connected either to the signal input of the protective device or to the test signal output of the test unit, and / or only one switchable control output, which is connected either to the control output of the protective device or to the protocol signal input of the test unit, particularly favorable testing conditions arise if the trip unit has a test signal input separate from the signal input for inputting test signal data sets and / or a protocol signal output separate from the control output for outputting protocol data sets. As a result of these measures, a test completely independent of normal operation can be carried out via the separate test signal inputs or protocol signal outputs, as long as it is ensured that both the signal input for normal operation and the test signal input are fed to the same trip logic.With a separate protocol signal output, on the one hand the test signal input can only influence the protocol signal output, while the signal input for normal operation can only influence the control output, and on the other hand additional test information, for example in case of fault, can be output via the protocol signal output, which facilitates diagnosis.

[0009] To accurately represent the highly dynamic signal waveforms that occur, especially during transient operating conditions, the test unit can be connected to a system clock for the synchronized transmission of test signal data sets from a test signal packet to the triggering unit. This system clock can, for example, be powered by a system clock signal specified via the process bus.

[0010] For protective devices, in addition to the proper functioning of the tripping logic, correct configuration of the operating parameters is crucial for reliable operation. For example, with protective relays, the correct specification of primary and secondary-side transformation ratios of the measuring transformers is required. To also be able to consider such operating parameters during testing, it is proposed that both the tripping unit and the test unit be connected to a parameter memory. In this way, a corresponding parameter set can be written to the parameter memory before the test signal data sets are applied to the tripping unit, or the plausibility of the parameter set already present in the parameter memory can be checked.

[0011] In order to be able to test several protective devices according to the invention together, or to coordinate and automate such tests in a circuit, it is proposed that the test interface be connected to a test bus. In contrast to the process bus, this test bus can meet less stringent real-time requirements and, with suitable safety measures, can also be connected to other transmission media.

[0012] The invention also relates to a method for testing a protective device according to the invention, wherein a test signal packet is transmitted via the test interface to the test unit, which passes individual test signal data records of the test signal packet to the triggering unit and records the protocol data records output by the triggering unit into a protocol data packet, wherein the transmission of the test signal data records and the recording of the protocol data records occur in sync with the system clock of the triggering unit. After the test has been carried out, the protocol data packet can either be automatically output via the test interface or retrieved via the test interface.

[0013] The invention is illustrated in the drawing, for example, in a schematic block diagram.

[0014] A protective device 1 according to the invention for a circuit 2 has a signal input 3, via which signals corresponding to operating parameters from measuring points 4, such as current or voltage, which have been converted into signal data sets via analog-to-digital converters 5, are transmitted to a tripping unit 6. According to a tripping logic, the tripping unit 6 outputs a control signal, which is fed to a protective actuator 8, such as a relay, via a control output 7. The protective device 1 also includes a test unit 9, which is connected to a test interface 10. Test signal packets can be transmitted to the test unit 9 or protocol data packets can be retrieved from the test unit 9 via this test interface 10.

[0015] To verify the correct function of the triggering unit 6, it is connected via a test signal input 11 to a test signal output of the test unit 9. Individual test signal data records of a test signal packet transmitted via the test interface 10 are transmitted via this output at a predefined clock rate, preferably the clock rate of the triggering unit 6 itself or the clock rate of the signal data records transmitted via the signal input 3. Simultaneously, the triggering unit 6 has a protocol signal output 12 for outputting protocol data records. This protocol signal output 12 is connected to a recording module 13 of the test unit 9, which combines the individual protocol data records into a protocol data packet and stores them.

[0016] In a particularly preferred embodiment, the result of the evaluation of the test signal data sets transmitted via the test signal input 11 is output exclusively via the protocol signal output 12, while the result of the evaluation of the signal data sets transmitted via the signal input 3 is output exclusively via the control output 7. In an alternative embodiment not shown in detail, the signal input 3 and the test signal input 11 and / or the control output 7 and the protocol signal output 12 can be switched or alternately deactivated.

[0017] A common system clock generator 14 can be provided for the triggering unit 6 and the test unit 9, which is connected to a process bus 16 via a clock signal input 15, via which, for example, the signal data sets from the analog / digital converters 5 are also transmitted to the signal input 3.

[0018] A parameter memory 17 can be provided for specifying and verifying parameter sets; this memory is connected to both the trigger unit 6 and the test unit 9. Such parameter sets can, for example, include the transformation ratio of a transducer 18.

[0019] For remote testing of one or more protective devices, the test interface 10 can be connected to a test bus 19.

Claims

1. Protective device (1) for a circuit (2), which has a trigger unit (6) with a signal input (3) for signal data sets of analog / digitally converted signals corresponding to operating variables, and a control output (7) for a protective actuator (8), which control output (7) is applied with a control signal by the trigger unit (6) in dependence of the signal data sets, wherein the protective device (1) has a test unit (9) and a test interface (10) connected to the test unit (9) for the input of test signal packets and for the output of protocol data packets and wherein the test unit (9) is connected to the trigger unit (6) for inputting test signal data sets, characterized in that the test unit (9) comprises a recording module (13) connected to the trigger unit (6) for storing protocol data sets in protocol data packets.

2. Protective device according to claim 1, characterized in that the trigger unit (6) has a test signal input (11), which is separate from the signal input (3), for inputting test signal data sets and / or a protocol signal output (12), which is separate from the control output (7), for outputting protocol data sets.

3. Protective device according to claim 1 or 2, characterized in that the test unit (9) is connected to a system clock (14) for synchronized transmission of test signal data sets of a test signal packet to the trigger unit (6).

4. Protective device according to one of claims 1 to 3, characterized in that both the trigger unit (6) and the test unit (9) are connected to a parameter memory (17).

5. Protective device according to one of claims 1 to 4, characterized in that the test interface (10) is connected to a test bus (19).

6. Method for testing a protective device (1) according to one of the preceding claims, characterized in that a test signal packet is transmitted to the test unit (9) via the test interface (10), which transmits individual test signal data sets of the test signal packet to the trigger unit (6) and records the protocol data sets output by the trigger unit (6) to form a protocol data packet, wherein the transmission of the test signal data sets and the recording of the protocol data sets is done according to the system clock of the trigger unit (6).