Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
  • H02H3/28—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus
  • H02H3/30—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus using pilot wires or other signalling channel
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/02—Details
  • H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H1/00—Details of emergency protective circuit arrangements
  • H02H1/0061—Details of emergency protective circuit arrangements concerning transmission of signals
  • H02H1/0084—Details of emergency protective circuit arrangements concerning transmission of signals by means of pilot wires or a telephone network; watching of these wires

Definitions

• the invention relates to a method for generating an error signal indicative of a fault in the secondary circuit of a current transformer cooperating with a local differential protection device monitoring a section end of an electric power network, wherein current measurements detected by the current transformer include a current flowing through the section end be monitored by the local differential protection device and a suspect signal is generated when the amounts of successive current readings fall abruptly; the error signal is generated when the suspicion signal is present.
• the invention relates to a differential protection device for monitoring a portion end of an electric power supply network, which cooperates with at least one current transformer, by means of which the differential protection device current readings that characterize a current flowing in the section end of the power supply network, are detected.
• the differential protection device has a computation device which carries out monitoring of the end of the section based on the measured current values and at least one remote differential protection device to the local differential protection device, wherein the computation device has a monitoring unit which monitors a secondary circuit of the current transformer for errors.
• Electrical differential protection devices are used in electrical power supply networks to monitor selected cuts to mistakes, such. As short circuits or ground faults used.
• Typical sections of an electrical power supply network monitored by differential protection devices are, for example, electrical power supply lines or transformers.
• a number of differential protection devices are required according to the number of ends of each section.
• a power supply line having three section ends that is to say, for example, a main line with a branch line leaving therefrom-three differential protection devices are required, one of the differential protection devices being provided at each section end.
• the differential protection devices operate according to the following protection principle: Each differential protection device detects, for each phase conductor of the section end monitored by it, current measured values that indicate a current flowing through this phase conductor in each case. The current readings detected at all ends of the monitored section will then be lost
• the summation can be done either in a selected differential protection device or in all differential protection devices.
• current measured values simultaneously detected by the remote differential protective devices are transmitted to the local differential protection device via data transmission lines running between the differential protection devices, so that this local differential protection device can form the sum of its own detected current measured values and the transmitted current measured values of the removed differential protection devices.
• the calculated current total should approximately equal zero, that is, the one in the section of the Electric power supply network flowed into it also flows out of this section again.
• the calculated current sum must be compared with a predetermined threshold value. When the threshold value is exceeded, a triggering signal is generated by the respective local differential protection device, with the electric circuit breaker provided at the section ends of the faulty section for opening its
• Switching contacts are caused, whereby the faulty portion is separated from the rest of the electrical power grid.
• Differential protection principle needed current readings initially installed directly at each section end of the electrical energy supply network current transformer - usually inductive current transformer - tapped and transmitted via electrical lines to the respective electric differential protection device. Since the current intensity of the currents detected by these first current transformers for internal processing in the differential protection device is usually too high, the electrical differential protection device again has device-internal current transformers on the input side, with which the transmitted currents are again transformed to a lower current level. Subsequently, the currents thus detected are usually supplied to an analog-to-digital converter, which assigns corresponding digital current measured values to the analog currents. These current measured values are used in a computing device of the respective differential protection device for implementing the differential protection principle.
• the current measurements form the basis for implementing the differential protection for the monitored section of the power supply network, its path from detection to processing in the differential protection device must be continuously monitored.
• a current transformer provided for detecting the current measured values of a phase is affected on its secondary side by a fault, for example an interruption in one of the coil windings or one of the lines (a so-called wire breakage), so that the electric differential protection device measures zero apparent current readings even though currents flow through the corresponding phase conductor of the section end.
• Such erroneously detected current measured values would significantly change the current sum, so that in this case the differential protection devices would respond inadvertently and their respective circuit breakers would open. Since such an overfunction, ie a shutdown of an actually flawless section of the power grid, is associated with the network operator at a high cost, it should be avoided if possible.
• the object of the invention is to provide a method and a differential protection device of the type mentioned, with the even more reliable detection of errors in secondary current transformer circuits can be achieved.
• a first reset signal is generated by the local differential protection device, with respect to their amounts, at the time of generating the suspicion signal in at least one distant differential end of the electrical power supply network monitoring distant differential squirrel also fall abruptly, and the error signal is blocked when the first reset signal is present.
• the decision as to whether to make a fault in the secondary circuit of a current transformer can be made even more reliable since the likelihood of the simultaneous occurrence of errors In secondary current transformer circuits distant differential protection devices is very low.
• the current measured values detected by current transformers of all phases are monitored for sudden decay with respect to their amounts, the suspect signal is generated, if for at least one phase the amounts are consecutive Current readings of a current transformer of the local differential protection device a sudden drop is detected, and the first reset signal is generated when for each same phase in the amounts of successive comparison current measurements of a current transformer of the at least one remote differential protection device also a sudden drop is detected.
• the method according to the invention reliably detects a fault in a secondary current transformer circuit even in the case of a polyphase power supply network.
• simultaneously occurring faults in secondary current transformer circuits are detected in several phases; even in the secondary current transformer circuits of all phases simultaneously occurring errors are reliably detected.
• a further advantageous embodiment is seen in that in the local differential protection device, the secondary circuits of the current transformer of all phases are monitored for current flow, a second reset signal is generated, if in at least one current transformer with existing current flow, the amounts of successive current measurement values abruptly len, and the error signal is also blocked when at least the second reset signal is present.
• a third reset signal is generated if at the time of generating the suspect signal, the course of successive sums - or Erdstrommesshong has a sudden change, and the error signal is also blocked when at least the third reset signal is present.
• an overfunction of the differential protection device can be prevented even more reliably, since a jump in the sum or ground current indicates an actual fault in the section of the electrical power supply network.
• the amounts of the current measured values of all phases are monitored for exceeding a predetermined threshold value and a fourth reset signal is generated the magnitude of the current readings of at least one phase exceeds the threshold value. increases, and the error signal is also blocked if at least the fourth reset signal is present.
• a further advantageous embodiment of the inventive method also provides that a circuit breaker controllable by the local differential protection device is checked for the position of its switching contacts and a fifth reset signal is generated when the switching contacts of the circuit breaker are open, and also blocks the error signal when at least the fifth reset signal is present.
• a further advantageous embodiment of the method according to the invention also provides that, as comparison current measured values of the at least one remote differential protection device, such current measured values are used, which are also transmitted from the at least one remote differential protection device to the local differential protection device for carrying out the differential protection function.
• the differential protection functions of the local differential protection device and the at least one remote differential protection device are blocked with respect to the phase affected by the fault in the secondary circuit of the corresponding current transformer.
• the presence of the fault signal from the local differential protection device and / or or the at least one remote differential protection device and / or a control room computer is displayed optically.
• differential protection device the above object is achieved by a differential protection device of the type specified, in which the monitoring unit for implementing a method according to one of claims 1 to 11 is set up.
• FIG. 1 shows a schematic view of a differential protection system for protecting a section of a power supply network having two section ends
• FIG. 2 shows a schematic view of a differential protection system for protecting a three-section end section of a power supply network
• FIG. 3 shows a block diagram with a differential protection device arranged at a section end
• Figure 4 is a logic flow diagram for explaining a first embodiment of a method for
• FIG. 5 shows a further logical flow diagram for explaining a second exemplary embodiment of a method for generating an error signal
• FIG. 6 shows a further logical flow diagram for explaining a third exemplary embodiment of a method for generating an error signal.
• FIG. 1 shows a section 10 of an otherwise not further illustrated electrical energy supply network.
• Section 10 is shown in FIG. 1 as part of a power transmission line.
• the section 10 of the energy supply network can also be a transformer or another component of an electrical energy supply network to be protected.
• a differential protection device is provided at each end of section 10.
• a first differential protection device 12a is disposed at a first section end IIa and a second differential protection device 12b at a second section end IIb.
• the differential protection Devices 12a and 12b receive, via current transformers 13a, 13b arranged at the respective section ends IIa, IIb, current measured values which indicate the current flowing through the respective section end IIa, IIb. If the electrical energy supply network is a polyphase, for example a three-phase, electrical energy supply network, appropriate current measured values are recorded at the section ends IIa, IIb for each phase of the section 10 and supplied to the respective differential protection device 12a, 12b.
• the differential protection devices 12a, 12b calculate from the own current measured values and simultaneously measured current measured values of the respective remote differential protection device, taking into account the respective signs, a current sum.
• the current measured values between the individual differential protection devices 12a, 12b can be exchanged via a communication line 14.
• the calculated current sum should assume a value of approximately zero.
• an error such as a ground fault on the section 10
• the calculation of the current sum can take place in two differential protection devices 12a, 12b or only one of the two.
• FIG. 2 shows a further differential protection system.
• the illustration according to FIG. 2 corresponds essentially to that of FIG. Only with the differential protection system according to Figure 2, a portion 20 of an electrical power supply network is monitored, which now has three section ends 21a to 21c.
• the number of section ends is not limited to three, but a section with any number of section ends can be monitored.
• the number of differential protection devices used for this corresponds to the number of section ends.
• an electrical differential protection device 22a to 22c is provided at each section end 21a to 21c, with which current measured values are detected via correspondingly connected current transformers 23a to 23c.
• the current measured values are exchanged between the differential protection devices 22a to 22c and can thus be used to form a current sum taking into account all three section ends 21a to 21c.
• the calculation of the current sum can also take place in each case in all differential protection devices 22a to 22c or in a selected differential protection device.
• the differential protection devices 22a to 22c generate a respective trigger signal
• the trip signals A are generated when the calculated current sum exceeds a preset threshold.
• the trip signals A cause circuit breakers 25a to 25c at the respective section ends 21a to 21c to open their switching circuits. contacts, whereby the faulty portion 20 is separated from the rest of the power grid.
• FIG. 3 shows a section end 30 of a section of a three-phase energy supply network which is otherwise not shown.
• the section end 30 also has three phase conductors L1, L2 and L3.
• first current transformer 31a, 31b, 31c are arranged, which may be, for example, conventional inductive current transformers.
• the first current transformers 31 a to 31 c emit at their secondary side the currents of lower current intensity which are proportional to the currents flowing in the individual phase conductors L 1, L 2 and L 3, which are transmitted to measuring inputs of a differential protection device 33 via measuring lines of a respective secondary current transformer circuit 32 a, 32 b, 32 c.
• the differential protection device 33 has device-internal (second) current transformers 34a, 34b, 34c at its measuring inputs, which again transform the currents transmitted via the secondary current transformer circuits of the first current transformers 31a, 31b, 31c to a lower level so that they can be connected to the sensitive electronic circuits of the Differential protection device 33 can be processed.
• the current transformers 34a to 34c are also, for example, inductive current transformers. On their secondary side, they in turn deliver the currents proportional to the differential protection device 33 via the secondary current transformer circuits 32a to 32c of the first current transformers 31a to 31c.
• the device-internal current transformers 34a to 34c also have secondary current transformer circuits 35a, 35b, 35c.
• the currents flowing in these secondary current transformer circuits 35a to 35c of the device-internal current transformers 34a to 34c are supplied within the differential protection device 33 to analog-to-digital converters 36a, 36b, 36c, which convert the analog currents into digital current measurements.
• the current measured values generated in each case are supplied to a computing device 37 of the differential protection device 33.
• the arithmetic unit 37 of the differential protection device 33 leads at the same time for the individual phase conductors L1, L2, L3 on the basis of the individual current measured values acquired with respect to the individual phase conductors L1, L2, L3 on the one hand and of at least one remote differential protection device
• the computing device 37 has a communication unit COM, which is connected to a data transmission line 38. Comparative current measured values from at least one other remote differential protection device can be transmitted to the local differential protection device 33 via the data transmission line 38 and the communication unit COM.
• the local differential protection device 33 can also be connected to the at least one remote differential protection device via the communication unit COM and the data transmission line 38 transmit its own current readings.
• the differential protection device 33 checks with its computing device 37 whether the calculated current sum exceeds a preset current threshold value, and generates a trigger signal A at a command output if a threshold violation exists.
• the trigger signal A is used to cause an electrical circuit breaker 39 to open its switch contacts. If the fault on the section of the electrical energy supply network is a single-phase fault, for example a ground fault of the phase conductor L1, then it is sufficient for the power switch 39 to open only those switching contacts which are assigned to the phase conductor L1.
• the respective switching contacts of the affected phase conductors L1, L2, L3 of the circuit breaker 39 are opened accordingly. This takes place both at the section end 30 and at the at least one further section end of the section of the electrical power supply network.
• an earth current or a total current is detected for the individual phase conductors Ll, L2, L3 of the section 30 of the electrical energy supply network.
• An earth current can be tapped at a grounded three-phase section of an electrical energy supply network, for example, at the connection between neutral point and earth.
• a total current can, for example, as indicated in FIG. 3, be detected via a summation current transformer, which is designed as conversion converter 31c and encompasses all phase conductors L1 to L3 of section 30 of the electrical energy supply network become.
• the detected summation current is in turn fed via a secondary current transformer circuit 32d of the conversion converter 31c, a device-internal current transformer 34d and a device-internal secondary current transformer circuit 35d to another analog / digital converter 36d, which converts the analog sum current into digital summation current measurements and to the computing device 37 of the Differential protection device 33 outputs.
• the arithmetic means 37 of the differential - Protective device 33 transmitted faulty current measured values.
• faults in secondary CT circuits are so-called wire breaks, i. E. H. an interruption, for example, of the secondary winding of the respective current transformer or the measuring lines of the secondary current transformer circuit.
• interruptions of the power converter circuits 32a to 32c of the first power converters 31a to 31c which may be unintentionally caused by construction machinery due to building activities near the end of the section.
• the arithmetic unit 37 of the differential protection device 33 will not be supplied with correct current transformer measured values, which will result in erroneous calculation of the total current and thus in unwanted tripping of the electrical circuit breaker 39.
• the computing device 37 of the differential protection device 33 has a monitoring unit 40 which monitors the secondary current transformer circuits 32a, 32b, 32c of the first current transformers 31a, 31b, 31c and / or the device-internal secondary current transformer circuits 35a to 35c for interruptions and in the event of a detected interruption emits an error signal.
• the arithmetic unit 37 is caused to block the differential protection functions for the phase conductors L1, L2, L3 correspondingly affected by the fault in the secondary current transformer circuit. In this way, the delivery of a trigger signal A based on a current sum calculated with erroneous current measurements is avoided and the circuit breaker contacts remain closed.
• the method performed by the monitoring unit 40 will be explained in more detail below with reference to FIGS. 4 to 6.
• the monitoring unit 40a of this exemplary embodiment is supplied at a first input 41a to the current measured value IL recorded by a phase conductor.
• the monitoring unit 40a monitors - as per
• Block 42a indicated - these current readings to determine whether the time course of their amounts has a sudden drop.
• Such an abrupt drop in the amounts of the current measured values can be due to an interruption of a secondary current-carrying circuit, but also to an actual current
• the control unit 40a uses compare current measurements IaL, IbL which have been acquired for the phase conductor with differential protection devices removed at other section ends of the monitored section. As mentioned, these comparison current measurements are communicated to the local differential protection device by the remote differential protection devices via data transmission lines. The comparative current measurements are applied to the monitor at second inputs 41b, 41c, which are highlighted in Figure 4 by a dashed frame 41b.
• the monitoring unit 40a In correspondence with the monitoring of the own current measured values, the monitoring unit 40a also examines the amounts of the comparison current measured value for sudden dropping, as indicated by blocks 42b and 42c. If the amounts of the comparative current measurements fall abruptly at the same time as their own current measurement values, this indicates an actual error in the monitored section of the electrical energy supply network, since the probability of a simultaneous occurring error in the secondary current transformer circuits at different section ends is highly unlikely , If, however, no abrupt drop in the amounts can be detected in the comparison current measured values, this indicates an error in the secondary current transformer circuit of a current transformer cooperating with the local differential protection device.
• a first reset signal R1 is generated when coincident with the sudden drop in the amounts of the own current measured values also with respect to the amounts of the comparative current measured values an occurring abrupt drop is recognized.
• This first reset signal R1 is applied to a blocking input of the block 44 for generating the error signal F and blocks the output of the error signal F.
• an error signal F is consequently generated by the block 44 if a sudden drop in the amounts of the own current measured values has been recognized, but in the comparison current measured values of the remote differential protection devices no abrupt drop has been recognized. If, on the other hand, an abrupt drop also occurs at the same time in the comparison current measurement values, this indicates an actual fault on the section of the electrical power supply network and correspondingly no error signal F is output by the monitoring unit 40a, which blocks the differential protection functions of the differential protection device.
• FIG. 5 shows a monitoring unit 40b, to which the measured current values IL1, IL2, IL3 of the three phase conductors detected at the local differential protection device are supplied at a first input 51a. These are then checked to determine whether the course of their amounts shows a sudden drop. If such an abrupt drop is detected in at least one phase of the current measured values, the first suspect signal V is generated at block 53a. If the suspicion signal is present in block 53a, this becomes active passed a block 54 to generate an error signal.
• the monitoring unit 40b is also supplied with the comparison current measured values IaL1 to IaL3 and IbL1 to IbL3 of all three phases of the remote differential protection devices at inputs 51b and 51c.
• blocks 52b and 52c it is checked in accordance with the procedure in the single-phase system according to FIG. 4 whether the amounts of the comparison current measured values of the removed differential protection devices have a sudden, sudden drop.
• a first reset signal R1 is generated correspondingly precisely when a sudden drop in at least one course of the other comparison current measured values is detected based on the same phase conductor in which the jump has occurred at its own current measured values.
• Block 53b requires the information about which phase conductor the sudden drop in its own current measured values has occurred. The transmission of this information is indicated by a dashed line 56 in FIG.
• the first reset signal R 1 is also present with respect to the same phase in which the suspicion signal V was generated, this is transmitted to the blocking input of the block 54 for generating the error signal F and blocks the output of the error signal F, because in this case the signal F 1 is blocked actual error is detected in the section of the power grid.
• FIG. 6 shows a further exemplary embodiment of a monitoring unit.
• the monitoring unit 40c according to FIG. 6 carries out some additional checks, by means of which a decision can more reliably be made as to whether a fault has occurred in a secondary current transformer circuit or whether there is an actual fault on the section of the electrical power supply network.
• the individual current measured values are detected at the input 61a with respect to all phase conductors and tested for sudden decay at blocks 62a.
• a suspect signal V is generated at block 62a when such a jump has been detected in the current readings of at least one phase.
• the suspected signal V is forwarded to block 64 for generating the error signal F.
• the comparison current measured values which are present at inputs 61b and 61c in blocks 62b and 62c are recorded simultaneously at the same time. supervised by a sudden drop in their amounts. If, in the comparison current measured values of at least one remote differential protection device with respect to the same phase, a sudden drop can be detected, the first reset signal R1 is generated in block 63b.
• the first reset signal Rl is supplied to an input of an OR module 65, whose output side is connected to the blocking input of the block 64 for error signal generation.
• the secondary current transformer circuits are also monitored for current flow.
• a current flow can be detected, for example, by current sensors used in accordance with the secondary current transformer circuits, for example Hall sensors.
• This information is fed to input 61d of the monitoring unit 40c.
• blocks 62d it is checked whether there is a corresponding current flow and a second reset signal R2 is generated if there is a current flow in a secondary current transformer circuit with respect to the phase to which the suspect signal V has been generated, since a current flow indicates that the secondary current transformer circuit is not interrupted.
• the second reset signal is also supplied to the OR block 65 on the input side.
• the monitoring unit 40c additionally detects at a further input 6Ie the sum current or ground current which has been detected at the respective section end with a corresponding converter (see FIG. According to FIG. 6, the sum current Isum is to be detected by way of example.
• a block 62e it is checked whether at the same time as the sudden drop in the amounts of the own current measured values, a jump occurs in the course of the cumulative or ground current. is If so, a third reset signal is generated because a jump in the course of the sum or earth current measurements indicates an actual fault on the portion of the electrical power grid.
• the third reset signal R3 is also supplied to the OR block 65.
• the locally detected current measured values are also checked as to whether they exceed a predefined threshold. If this is the case, then a fourth reset signal R4 is generated, which is supplied to the OR block 65. This is to prevent blocking of the differential protection functions in the case of very high currents on the section of the power supply network. In such a case, it may in fact be, for example, short-circuit currents flowing in the section of the electrical energy supply network, so that the differential protection functions must not be blocked for safety reasons in any case.
• the monitoring unit 40c receives information about the state (open / closed) of the switching contacts of the circuit breaker associated with the local differential protection device.
• block 62g it is checked whether the switching contacts are in the open position, ie whether the monitored section is already disconnected from the power supply network.
• a fifth reset signal R5 is generated when the switch contacts of the circuit breaker are in the open state.
• This fifth reset signal R5 is also supplied to the OR block 65. This is to ensure that the differential protection functions are not interrupted when the section of the power supply network is switched off. This could in fact lead to an unwanted blocking of the differential protection when restarting the section of the power supply network.
• the monitoring unit 40c receives voltage measured values with respect to all phases of the section of the energy supply network. For the sake of simplicity, however, only one voltage value input is shown in FIG. this is representative of voltage value fairings of all three phases.
• the course of the voltage measurement values is checked in block 62h as to whether it has a sudden change and a sixth reset signal R6 is generated in block 63h if a sudden change in the course of the voltage measurement values occurs simultaneously with the generation of the suspicion signal V. Indeed, such an erratic course of the voltage readings would also indicate an error on the section of the electrical power grid, rather than a fault in the secondary CT circuit.
• a seventh reset signal R7 is generated in block 63i if the monotony condition is not met, ie if the current measurement values following the generation of the suspect signal V do not approach zero.
• the seventh reset signal R7 is supplied to the OR block 65.
• the OR module outputs at its output a signal to the blocking input of the block 64 for generating the error signal F, if at least one of the reset signals Rl to R7 is present. In such a case, the generation of the error signal F should be blocked, so that the differential protection functions of the differential protection device are not impaired.
• the differential contactor functions for the affected phase of the electrical power grid in the local differential protection device and the remote differential protection devices are blocked.
• the blocking is canceled as soon as the error signal F is no longer generated, i. H. if the fault in the secondary CT circuit is eliminated.
• the local and / or the remote differential protection devices can visually be used to indicate that a fault has occurred in a secondary current transformer. Circuit has been detected. This error can be specified by specifying the appropriate phase and location of the CT. Such a display may alternatively or additionally also be displayed to the operating personnel of the electrical energy supply network in a control room via a host computer. In this way, operators can promptly initiate actions to correct the fault in the secondary CT circuit.
• the comparison current measured values measured at the respective remote differential protection devices were checked for abrupt changes.
• the course of the current sum or a current subtotal or the course of so-called stabilization current values that can be used to stabilize the differential protection system can be used.
• the type of information used about the current measured values recorded at the remote differential protection devices should advantageously be selected such that values exchanged between the differential protection devices in any case are used in the course of the differential protection procedure for the function of the monitoring unit. As a result, no additional transmission bandwidth on the data transmission line between the differential protection is required for the transmission of additional information.

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• 2006
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  • 2006-09-22 CN CN200680055898.6A patent/CN101512861B/zh not_active Expired - Fee Related
  • 2006-09-22 WO PCT/DE2006/001707 patent/WO2008034400A1/de active Application Filing

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