JP5063282B2 - Transformer protection relay - Google Patents

Description

  The present invention relates to a transformer protection relay for protecting a transformer arranged in a power system by a current differential method.

  Although there are three-winding transformers having primary, secondary, and tertiary windings in the transformer arranged in the power system, in this specification, the primary and secondary transformers are simplified. A two-winding transformer having windings will be described as an example.

  Transformer protection relays are the primary currents of the transformer and the currents taken from the secondary side of each CT (instrument current transformer) placed on the line connected to the primary side and secondary side of the transformer. When the vector combined current (difference current) with the secondary current becomes an abnormal value, the circuit breakers placed on the primary and secondary sides of the transformer are opened, assuming that an internal failure has occurred in the transformer. The transformer is protected by disconnecting the transformer from the system.

  Therefore, conventionally, the connection of the secondary cable of each CT arranged on the line connected to the primary side and the secondary side of the transformer is such that a difference current does not occur depending on the connection method. It was necessary to make the connection so that there was no difference in the phase of the input current to the protective relay.

  In addition, when it is difficult to match the phases by selecting the connection of the secondary side cable of each CT, an auxiliary CT or the like may be installed on the secondary side of each CT for phase correction.

  Furthermore, since the transformer internal connection method, that is, the winding method of the transformer is not fixed to one type, and multiple types of methods are mixed, the connection on the secondary side of each CT is also the same as that of the transformer. It was necessary to change for each type, that is, for each winding method of the transformer, which could cause incorrect wiring.

  In order to solve such a problem, for example, in Patent Document 1, the phase of two input currents having different phases can be automatically adjusted to the same phase inside the relay, thereby enabling internal connection (that is, winding method). The phase difference is measured so that the CT connections on the primary and secondary sides of the transformer can be determined regardless of the winding method of the transformer, If so, a technique has been proposed in which one input current is compensated for by the phase difference so as to match the phases.

Japanese Patent Laid-Open No. 10-313531

  However, the phase correction method for the input current from each CT on the primary side and the secondary side of the transformer disclosed in Patent Document 1 described above unifies the connection of each CT into a Y connection, and in a rated load state. The phase difference between the primary side current and the secondary side current of the transformer is measured, and phase compensation is performed to match one of the current phases based on the phase difference. For example, the winding method is Yd1 or Phase correction ignoring the effects of primary side Δ connection and secondary side Y connection used as a countermeasure for ground fault in CT connection with a transformer with Yd11 (that is, primary side is Y connection, secondary side is Δ connection) There is a problem of becoming.

  Therefore, in the phase correction method disclosed in the above-mentioned Patent Document 1, it is difficult to perform phase correction corresponding to all of the plurality of winding methods (internal connection methods) defined in the international standard (IEC 60076-1).

  The present invention has been made in view of the above, and can perform phase correction for all of the plurality of winding methods (internal connection methods) of the transformer even if the connection of each CT is unified to Y connection. The purpose is to obtain a protective relay.

  In order to achieve the above-described object, the present invention is for each instrument on the system upstream side and system downstream side installed on the line connected to the system upstream side and the system downstream side of the transformer arranged in the power system. An input processing unit that digitally processes the system current captured from the current transformer, and an input system current from each of the current transformers on the upstream side and the downstream side of the system, using digital data from the input processing unit. A current correction unit that corrects the differential current to be zero, and a ratio differential calculation using each current data of the system upstream side and system downstream side corrected by the current correction unit, and the transformer In the transformer protection relay comprising a ratio differential operation unit for determining the presence or absence of internal faults, the current transformers on the upstream side and the downstream side of the grid are respectively connected to the system current of the transformer by Y connection. take out The current correction unit that is configured to output and corresponds to either the system upstream side or the system downstream side corresponds to either the system upstream side or the system downstream side that is input from the input processing unit. Current conversion processing is performed according to whether the type of the internal winding on either the system upstream side or the system downstream side of the set transformer is Δ connection or other than Δ connection A first current conversion unit; and a first gain correction unit that applies a gain correction to the current data output from the first current conversion unit and applies the gain correction to the ratio differential operation unit. The current correction unit corresponding to any one of the downstream side is configured to change the set change for the digital data corresponding to the other of the system upstream side and the system downstream side input from the input processing unit. A second current conversion unit for performing a current conversion process according to whether the type of the internal winding on the other side of the system upstream side and system downstream side of the vessel is Δ connection or other than Δ connection; and Whether the type of internal winding on the other side of the system upstream side and system downstream side of the set transformer is Δ connection or other than Δ connection in the current data output by the current converter 2 A phase correction unit that performs a phase correction process using a phase correction value that is determined in accordance with the phase correction value, and a second gain correction unit that applies gain correction to the current data output from the phase correction unit and supplies the current data to the differential ratio calculation unit. It is characterized by having.

  According to the present invention, the first current correction unit in one of the two current correction units provided between the system upstream side and system downstream side of the transformer and both input ends of the ratio differential operation unit, and the other The phase of the system upstream current and system downstream current input from the transformer for the instrument whose connection is Y-connected by the second current correction unit and the phase correction unit in FIG. , There is an effect that can be matched.

  First, in order to facilitate understanding of the present invention, the problem of the phase correction method disclosed in Patent Document 1 will be described with reference to FIGS. In addition, FIG. 10 is a figure explaining the current distribution at the time of the external ground fault in the conventional phase correction method. FIG. 11 is a diagram for explaining a current distribution at the time of an external ground fault when a correct CT connection is made.

FIG. 10 shows a case where the transformer 30 to be protected has a winding method of Yd11. However, in the phase correction method disclosed in Patent Document 1 above, the Y connection side (primary side) of the transformer 30 is shown. Side) and the connection method of CT31, 32 respectively arranged on the line connected to the Δ connection side (secondary side) is unified to Y connection, and each secondary cable of these CT31, 32 is a transformer protection relay. 33.

  The method of phase correction is as described above. However, when a one-phase ground fault occurs outside the CT 31 arranged on the Y-connection side of the transformer 30, as shown in FIG. In the secondary Y connection, a fault current flows through each winding. Therefore, the CT 31 arranged on the Y connection side detects the fault current that flows and inputs it to the transformer protection relay 33.

  On the other hand, in the secondary side Δ connection of the transformer 30, since the fault current flows back through the Δ connection, no fault current flows through the CT 32, and no current is sent out to the transformer protection relay 33. That is, in the transformer protection relay 33, since there is no current input from the Δ connection side of the transformer 30, regardless of the phase compensation related to Patent Document 1, a malfunction occurs because a difference current is generated at the time of an external ground fault. There is a possibility.

  However, as shown in FIG. 11, when CT31 arranged on the Y-connection side of the transformer 30 is Δ-connected, the fault current flowing through CT31 flows back through the Δcircuit of CT31, so that the transformer protection relay 33 The current corresponding to each of the Δ-connection side and the Y-connection side of the transformer 30 is not input to the transformer 30, and as a result, no difference current is generated.

  In short, each CT on the primary side and secondary side of the transformer is Y-connected, and the phase difference between the primary and secondary measurement phase differences (theoretical 30 degrees) at the rated load current is simply shifted. A phase correction method that only compensates can prevent changes in the load current and the occurrence of a difference current when an external short-circuit fault occurs. There is a problem.

  In addition, it measures the phase difference due to the rated load current, and because it is a phase correction method based on the measured phase difference, it complicates the phase even in the case of CT connection errors as well as the disadvantage of a heavy computational processing burden. This is a reliability problem.

  Therefore, in the present invention, from the viewpoint of preventing CT misconnection, the connection method of each CT is unified to Y connection in the same manner as in the above-mentioned Patent Document 1, but various types of standards defined in the international standard (IEC6000076-1) are used. The configuration is such that phase correction corresponding to all of the plurality of winding methods including the winding method (internal connection method) can be performed. Exemplary embodiments of a transformer protection relay according to the present invention will be described below in detail with reference to the drawings.

Embodiment 1 FIG.
1 is a block diagram showing a configuration of a transformer protection relay according to Embodiment 1 of the present invention. In FIG. 1, a transformer 1 to be protected is, for example, a Yd1 transformer having a winding system in which a primary side that is upstream of the system is Y-connected and a secondary side that is downstream of the system is Δ-connected.

  The secondary cables of CT (instrument current transformers) 2 and 3 respectively disposed on the lines connected to the primary side (Y connection side) and the secondary side (Δ connection side) of the transformer 1 It is connected to the transformer protection relay 4a. As shown in FIG. 5 described later, CT2 and CT3 both detect the primary side current and the secondary side current of the transformer 1 by Y connection. With the configuration shown in FIG. 1, the transformer protection relay 4 a is configured such that CT <b> 2 and CT <b> 3 are based on the respective grid currents taken from the secondary cables of CT <b> 2 and CT <b> 3 in the state where the grid current flows through the transformer 1. System faults that occur on the line between them are detected.

  On the input side of the transformer protection relay 4a, a current input unit 11 that takes in a system current from CT2 on the transformer primary side and a current input unit 21 that takes in a system current from CT3 on the transformer secondary side are arranged. . The current input units 11 and 21 correspond to the input processing units, respectively, and respectively digitize the system current received from the filter processing unit and the filter processing unit for removing harmonic current components contained in the system current. An AD conversion processing unit is provided.

  And the ratio differential calculating part 5 and the output part 6 are arrange | positioned at the output side. The ratio differential calculation unit 5 performs ratio differential calculation using the current data applied to the transformer primary side input terminal and the current data applied to the transformer secondary side input terminal. Determine if there is an internal failure. When the ratio differential operation unit 5 detects an internal failure, the output unit 6 outputs a control signal from the output end to a circuit breaker (not shown) installed on the primary side and the secondary side of the transformer 1. The transformer 1 is disconnected from the system.

  In this embodiment, a current conversion unit 12 and a gain correction unit 14 are connected in series as one current correction unit between the current input unit 11 and the transformer primary side input terminal of the ratio differential calculation unit 5. Between the current input unit 21 and the transformer secondary side input terminal of the ratio differential operation unit 5, a current conversion unit 22, a phase correction unit 23, and a gain correction unit 24 are provided as the other current correction unit. They are arranged in series.

  A current conversion setter 7 is connected to the current conversion units 12 and 22, and a fixed phase correction value setting unit 8 is connected to the phase correction unit 23. The current conversion setter 7 and the fixed phase correction value setter 8 are so-called interface circuits used when the user performs relay settling.

  In addition, the structure of both said current correction | amendment parts is a structure on the basis of the primary side of the transformer 1. FIG. In other words, the above configuration may be replaced and a configuration based on the secondary side of the transformer 1 may be used, but in this embodiment, a configuration based on the primary side of the transformer 1 will be described.

  The gain correction unit 14 receives the output of the current conversion unit 12, and the gain correction unit 24 receives the output of the phase correction unit 23, depending on the turns ratio of the transformer 1 and the primary and secondary CT ratios, respectively. Gain correction for making the difference current zero is performed and given to the ratio differential operation unit 5.

  FIG. 2 is a diagram illustrating a configuration of a current conversion table provided in the current conversion unit illustrated in FIG. The current converters 12 and 22 perform an operation simulating Δ connection on the system current input from the CT 2 and 3 on the digital data input from the current input units 11 and 21, that is, differential processing of the three-phase current (Δ conversion ) Is executed based on the current conversion table shown in FIG. FIG. 2 shows the relationship between twelve “current conversion setting numbers” and “current conversion processing” performed thereon. At the right end, supplemental explanation of the conversion contents is shown for easy understanding.

  The user sets the “current conversion setting number” for the primary side of the transformer 1 and the “current conversion setting number” for the secondary side in the current conversion setter 7 as relay settling values. As shown in FIG. 2, when “current conversion setting number” = 0, the a phase current Ia is in the A phase, the b phase current Ib is in the B phase, and the c phase current Ic is in the C phase. Since each is selected, the current conversion process is substantially non-converted. This is a calculation that simulates the connection of CT to the Y connection with respect to the system current input from CT2 and CT3.

  On the other hand, when “current conversion setting number” = 1 to B, the current phases assigned to the A phase, the B phase, and the C phase are different from the above, and the current conversion processing causes a phase shift. For example, when “current conversion setting number” = 1, the difference current Ia−Ic between the a phase and the c phase in the A phase, the difference current Ib−Ia between the b phase and the a phase in the B phase, Since the c-phase and b-phase difference currents Ic-Ib are respectively selected, the current conversion process causes a phase shift of -30 degrees. This is a simulation that simulates the connection of CT to Δ connection with respect to the system current input from CT2 and CT3. When setting the “current conversion setting number” = 1 to B, the user selects and specifies the current phase to be assigned to the A phase, the B phase, and the C phase.

  FIG. 3 is a diagram showing an international standard table used by a user who performs relay settling on the current conversion setter and the fixed phase correction value setter shown in FIG. Symbols shown in “Transformer winding system” shown in FIG. 3 are those used in the international standard (IEC 60076-1). The winding method of “Yd1” and “Yd11” described above is also included. Thus, in the international standard (IEC6000076-1), three types of Y, D (Δ), and Z are defined as the types of transformer windings (internal connections), and the time in the counterclockwise direction is set as the phase shift. Are used to define the phase delay times of 0, 1, 2, 4, 5, 6, 7, 8, 10, 10 and 11 o'clock. The table can handle all these combinations.

  In the standard table shown in FIG. 3, a “transformer winding system” column, a “primary side setting” column, and a “secondary side setting” column are provided. Since the transformer protection relay 4a is configured with the primary side of the transformer 1 as a reference, in the “primary side setting” column, the “current conversion setting number” shown in FIG. Is described. In the “secondary side setting” column, “current conversion setting number” shown in FIG. 2 given to the current conversion setter 7 and “phase correction selection value” given to the fixed phase correction value setter 8 are described. Has been. In addition, the supplementary explanation of the contents of current conversion and phase correction is shown at the right end for easy understanding.

  As the “phase correction selection value” given to the fixed phase correction value setting unit 8 will be described later, how to use the “current conversion setting number” shown in FIG. 2 given to the current conversion setter 7 will be described. According to the winding method of the transformer 1, when the user provides the current conversion setter 7 with “current conversion setting numbers” for the primary side and the secondary side of the transformer 1 as relay set values, the “current” The current conversion units 12 and 22 execute the above-described “current conversion process” corresponding to the “conversion setting number”.

  As shown in FIG. 3, in the setting of “current conversion setting number” on the primary side, when the primary winding is Y-connected, “current conversion setting number” = 1 is set to simulate Δ connection When the primary winding is in D connection (that is, Δ connection), “current conversion setting number” = 0 is set to instruct the operation simulating Y connection.

  On the other hand, in the setting of “current conversion setting number” on the secondary side, when the transformer is “Dd0” winding method and “Yd1” winding method, “current conversion setting number” = 0 is set and Y is set. Instruct the calculation simulating the connection, and in other winding methods, set any of the “current conversion setting number” = 1 to B to indicate the calculation simulating the Y connection or Δ connection. ing.

This will be specifically described. When the transformer 1 is an international standard Dy11 system, for example, the primary side is Δ- connected and the secondary side is Y- connected, and the secondary phase is a position 30 degrees counterclockwise with respect to the primary phase. Therefore, it is necessary to convert the secondary side to a Δ connection (d1 connection) that has the same phase as the Y connection on the primary side. Therefore, in the current conversion setter 7, “current conversion setting number” = 0 is set for the primary side setting of the transformer 1, and “current conversion setting number” = 1 is set for the secondary side setting of the transformer 1. Set the designation of the selected phase. The designation of the selected phase is to select and designate the current phase “Ia-Ic” assigned to the A phase, the current phase “Ib-Ia” assigned to the B phase, and the current phase “Ic-Ib” assigned to the C phase. That is. In FIG. 1, one arrow line is shown from the current conversion setter 7 to the current converter 12, whereas two arrow lines are shown from the current conversion setter 7 to the current converter 22. This indicates the above contents.

  Then, since there is no designation of the phase in the current conversion unit 12, the a phase current Ia is selected for the A phase, the b phase current Ib is selected for the B phase, and the c phase current Ic is selected for the C phase. Then, a current conversion process without substantial conversion is performed.

  On the other hand, in the current conversion unit 22, an instruction to assign “Ia-Ic” to the A phase, “Ib-Ia” to the B phase, and “Ic-Ib” to the C phase is input. Therefore, on the current data from the current input unit 21, current conversion is performed for the phase difference of “Ia-Ic” for the A phase, “Ib-Ia” for the B phase, and “Ic-Ib” for the C phase. Therefore, the 30-degree phase shift designated by “d1” and the Δ conversion are simultaneously performed.

  Next, the phase correction unit 23 performs a 30-degree delayed phase shift process and a process that does not perform the phase shift process on the current data from the current conversion unit 22 in accordance with an instruction from the fixed phase correction value setting unit 8. The relay set value to the fixed phase correction value setter 8 is the “phase correction selection value” in the “secondary side setting” column of the standard table shown in FIG. The “phase correction selection value” is either a value 0 or a value 1. The fixed phase correction value setting unit 8 gives the set “phase correction selection value” to the phase correction unit 23. The phase correction unit 23 does not perform the phase shift process when “phase correction selection value” = 0, and performs the 30-degree delayed phase shift process when “phase correction selection value” = 1. In the above example, since the output phases of the current converters 12 and 22 are the same, “phase correction selection value” = 0 is set in the standard table, and the phase correction unit 23 performs a phase shift of 30 degrees. Do not process.

  In short, on the primary side of the transformer 1, when the transformer primary winding is Y-connected, “current conversion setting number” = 1 and the applied phase of the application phase in order to calculate as if the CT connection is Δ-connected. When the transformer primary winding is Δ-connected, “current conversion setting number” = 0 is set to make the CT connection Y-connect.

  On the secondary side of the transformer 1, when the transformer secondary winding is Y-connected or Z-connected, and Δ connection other than “d0” and “d1”, “current conversion setting number” = 1 to B Either one is set, and “phase correction selection value” = 1 is set. When the transformer secondary winding is “d0” and “d1” with Δ connection, “current conversion setting number” = 0 is set and “phase correction selection value” = 0 is selected and set.

  Thereby, in the primary side current converter 12, the secondary current converter 22 and the phase corrector 23, the phase between the primary side and the secondary side with respect to various transformer winding methods. The operation of matching is performed.

  Next, with reference to FIG. 4, the operation | movement which the phase correction | amendment part 23 carries out a 30 degree delay phase shift, and the operation | movement which does not perform the shift operation are demonstrated. FIG. 4 is a diagram for explaining the operation of the phase correction unit shown in FIG. The 30 ° sampling data string shown in FIG. 4 is a data string obtained by sampling the sampling data obtained by the AD conversion process in the current input unit 21 at the timing of every electrical angle 30 °.

  In this 30 ° sampled data string, when “phase correction selection value” = 0 where no 30 degree delayed phase shift is performed, the current data I (t) is used and an operation of performing a 30 degree delayed phase shift is performed. In the case of “selected value” = 1, data I ′ (t) 30 degrees before is used. In this way, two independent phase corrections can be realized with a simple selection process.

  Next, the operation | movement at the time of the external ground fault in the transformer protection relay 4a comprised as mentioned above is demonstrated. FIG. 5 is a diagram for explaining a protection operation when an external ground fault occurs. As shown in FIG. 5, CT2 and CT3 both detect the primary side current and the secondary side current of the transformer 1 by Y connection.

  As shown in FIG. 5, when a one-phase ground fault occurs outside the CT 2 arranged on the Y connection side (primary side) of the transformer 1, each winding in the primary Y connection of the transformer 1 Therefore, CT2 arranged on the Y-connection side detects the flowing fault current and inputs it to the transformer protection relay 4a. On the other hand, in the secondary side Δ connection of the transformer 1, since the fault current flows back through the Δ connection, no fault current flows through CT3 and no current is sent to the transformer protection relay 4a.

  In this case, on the Y winding input side of the transformer protection relay 4a, a configuration in which YΔ conversion is performed by the input transformer is shown. However, the transformer protection relay 4a is applied to the input current to the Y winding input side. , On the digital data subjected to AD conversion processing at the current input unit 11, an operation simulating Δ connection, that is, phase difference processing of three-phase current, is performed to cancel the input current to the Y winding input side Since the current is generated, the difference current as in the conventional example does not flow.

  As described above, according to the first embodiment, on the transformer primary side, the current converter 12 performs the three-phase current difference process (process for simulating the Δ connection) according to the winding type of the transformer. In the transformer secondary side, three-phase current difference processing (processing for simulating Δ connection) is performed on the transformer secondary side according to the type of winding of the transformer. ) To select whether or not to implement and only to specify the conversion phase, the current conversion units 12 and 22 and the phase correction unit 23 can perform the primary current and the secondary current by simple processing. Current phases can be matched.

  In addition, phase correction for a plurality of transformer winding systems (internal connection systems) defined in the international standard (IEC 60076-1) can be performed without increasing the processing load. In addition, it is possible to prevent a difference current from being generated even when an external ground fault has been difficult in the conventional example.

  Furthermore, since the wiring is simplified by unifying the connection of each CT to the Y connection, erroneous wiring can be reduced. Even if there is an incorrect wiring, the Δ connection and the Y connection are simulated according to the type of winding, so that the incorrect wiring can be found and the reliability can be improved.

Embodiment 2. FIG.
6 is a block diagram showing a configuration of a transformer protection relay according to Embodiment 2 of the present invention. In FIG. 6, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are assigned the same reference numerals. Here, the description will be focused on the portion related to the second embodiment.

  In the transformer according to the international standard (IEC60076-1), as described in the first embodiment, when the phase correction is performed, the phase shift process of 30 degrees may be performed. However, the international standard (IEC60076- A special transformer not specified in 1) may not be able to cope with the phase shift process of 30 degrees.

  Therefore, as shown in FIG. 6, the transformer protection relay 4 b according to the second embodiment has a variable phase correction in place of the fixed phase correction value setting unit 8 in the configuration shown in FIG. 1 (the first embodiment). A value setter 9 is provided, and a phase correction unit 23b is provided instead of the phase correction unit 23a. The variable phase correction value setting unit 9 can variably set the phase correction value within a range from −30 degrees to +30 degrees as a relay settling value.

FIG. 7 is a diagram for explaining the operation of the phase correction unit shown in FIG. As shown in FIG. 7, in order to shorten the data length used for calculation at the time of phase correction, the phase correction unit 23b uses the current data I (t) and 1 sampling in the data of the calculation sampling period of the transformer protection relay 4b. Using the previous data I (t−1), for example, the data of phase 0 degree is used as the current data I (t), and this is the data at phase correction value = 0 degree without phase correction. For example, using the current data I (t) and the data I (t−1) 30 degrees before, the set angle I ′ (t) within the range from −30 degrees to +30 degrees as the phase correction value. The
I ′ (t) = k1 · I (t) + k2 · I (t−1) (1)
Calculate by

For example, if the set angle as the phase correction value is φ, equation (1) is
I ′ (t) = cosφ · I (t) + sinφ · (2 · 1 (t−1) −√3 · I (t))
= (Cosφ-√3 · sinφ) · I (t)
+ 2 · sinφ · I (t-1) (2)
Therefore, the coefficients k1 and k2 in equation (1) are
k1 = cosφ−√3 · sinφ, k2 = 2 · sinφ (3)
It can be expressed.

  FIG. 8 shows an example of a special winding type transformer not in the international standard, where (a) is a phase diagram of a Yz11 (1/4) transformer, and (b) is a Yz10 (3/4) transformer. FIG. The Yz11 (1/4) transformer (a) is a transformer that requires a phase shift of -7.5 degrees. The Yz10 (3/4) transformer (b) is a transformer that requires a phase shift of +7.5 degrees.

  For such a special transformer, the user can use the Yz11 (1/4) transformer (a) as the relay settling for the current conversion setter 7 and the variable phase correction value setter 9 in the primary side. Then, the value 1 is set as the current conversion setting number, and the value 1 is set as the current conversion setting number and -7.5 degrees is set as the phase correction value on the secondary side. In the case of the Yz11 (3/4) transformer (b), the primary side sets the value 1 to the current conversion setting number, and the secondary side sets the value 1 to the current conversion setting number and the phase correction. Set +7.5 degrees for each value.

  Then, the phase correction unit 23b sets the set angle ± 7.5 within the range from the 30 degree phase advance to the 30 degree phase lag, and the type of the set transformer internal winding is Δ connection as described above. Or the current data and the data 30 degrees before the current data, selected according to whether it is other than the Δ connection.

  As described above, according to the second embodiment, the phase correction value can be variably set within a range of −30 degrees to +30 degrees. Therefore, even for a special transformer that is not defined in the international standard (IEC60076-1). Can respond.

  In addition, since the angle that can be set within the range of -30 degrees to +30 degrees is obtained by using the current data and the data 30 degrees before, the data length used for the calculation can be shortened, and an error due to transient response can be caused. The output can be reduced.

Embodiment 3 FIG.
FIG. 9 is a block diagram showing a configuration of a transformer protection relay according to Embodiment 3 of the present invention. In FIG. 9, the same reference numerals are given to components that are the same as or equivalent to those shown in FIG. 1 (Embodiment 1). Here, the description will be focused on the portion related to the third embodiment.

  As shown in FIG. 9, in the transformer protection relay 4c according to the third embodiment, a standard table 10 is added to the configuration shown in FIG. 1 (first embodiment). The standard table 10 is a table in which the standard table shown in FIG. 3 is set in the storage device. When the user gives a symbol of the transformer winding as a relay set value, the primary side corresponding to the symbol is read from the standard table 10. A current conversion setting number for setting and a current conversion setting number for secondary side setting are output to the current conversion setter 7, and a phase correction selection value of value 0 or value 1 is input to the fixed phase correction value setting device 8. It is output.

  In the first embodiment, the user needs to set the current conversion settling device 7 and the fixed phase correction value setting device 8 in consideration of the coincidence of phases. Since it is sufficient to set a standard symbol indicating the internal wiring of the transformer to be applied, it is possible to reduce mistakes in relay setting.

  In the embodiment described above, a two-winding transformer having primary and secondary windings has been shown as a transformer. However, the present invention provides primary, secondary, and tertiary windings. The present invention can be similarly applied to a three-winding transformer having the same.

  As described above, the transformer protective relay according to the present invention prevents a CT erroneous connection, and includes a plurality of windings including various winding methods (internal connection methods) defined in the international standard (IEC60076-1). This is useful for performing phase correction corresponding to all of the methods.

It is a block diagram which shows the structure of the transformer protection relay by Embodiment 1 of this invention. It is a figure which shows the structure of the current conversion table with which the current converter shown in FIG. 1 is provided. It is a figure which shows the international specification table | surface used by the user who performs relay settling to the current conversion setter and fixed phase correction value setter shown in FIG. It is a figure explaining operation | movement of the phase correction part shown in FIG. It is a figure explaining the protection operation at the time of an external ground fault. It is a block diagram which shows the structure of the transformer protection relay by Embodiment 2 of this invention. It is a figure explaining operation | movement of the phase correction part shown in FIG. An example of a special winding type transformer not in the international standard is shown, (a) is a phase diagram of a Yz11 (1/4) transformer, (b) is a phase diagram of a Yz10 (3/4) transformer. It is. It is a block diagram which shows the structure of the transformer protection relay by Embodiment 3 of this invention. It is a figure explaining the current distribution at the time of the external ground fault in the conventional phase correction method. It is a figure explaining the current distribution at the time of the external ground fault at the time of setting it as correct CT connection.

Explanation of symbols

1 Transformer to be protected 2 CT (instrument current transformer) installed on the primary side of the transformer
3 CT (instrument current transformer) installed on the secondary side of the transformer
4a, 4b, 4c Transformer protection relay 5 Ratio differential operation unit 6 Output unit 7 Current conversion setter 8 Fixed phase correction value setting unit 9 Variable phase correction value setting unit 10 Standard table 11 Current input unit on transformer primary side 12 Transformer primary-side current conversion unit 14 Transformer primary-side gain correction unit 21 Transformer secondary-side current input unit 22 Transformer secondary-side current conversion unit 23a, 23b Transformer secondary-side phase Correction unit 24 Gain correction unit on transformer secondary side

Claims (4)

Digitally process the grid currents taken from the current transformers on the upstream and downstream sides of the transformer installed in the power system upstream and downstream of the system. Using the input processing unit and digital data from the input processing unit, a current for correcting the input system current from each of the current transformers upstream and downstream of the system so that the differential current becomes zero A correction unit, a ratio differential calculation unit that performs ratio differential calculation using each current data of the system upstream side and system downstream side corrected by the current correction unit, and determines the presence or absence of an internal failure of the transformer; In a transformer protection relay comprising:
The system current transformers on the upstream side and the downstream side of the system are each configured to take out and output the system current of the transformer with a Y connection,
The current correction unit corresponding to either the system upstream side or the system downstream side,
Wherein the Lud digital data to correspond to either one of the system upstream and systems downstream, the system upstream and internal winding in one of the lines downstream of said transformer is set to enter from the input processing unit A first current conversion unit that performs current conversion processing according to whether the type of line is Δ connection or other than Δ connection, and gain correction is applied to the current data output from the first current conversion unit A first gain correction unit to be provided to the ratio differential operation unit,
The current correction unit corresponding to the other of the system upstream side and the system downstream side,
For the digital data corresponding to either the system upstream side or the system downstream side input from the input processing unit, the internal windings in the other of the system upstream side and system downstream side of the set transformer A second current conversion unit that performs current conversion processing according to whether the type is Δ connection or other than Δ connection, and the current data output from the second current conversion unit is set to A phase correction unit that performs a phase correction process using a phase correction value determined according to whether the type of the internal winding on the other side of the system upstream side and the system downstream side is a Δ connection or other than a Δ connection; Rutotomoni and a second gain correction section that gives the ratio differential calculation unit adding the gain correction to the current data the phase correction section outputs,
First information for instructing whether to simulate Y connection or Δ connection as the connection of the current transformer is connected to the system current input by the input processing unit from each of the current transformers. A current conversion setter that is set and second information that is current phase designation information is set when the first information simulates a Δ connection;
The current conversion setter provides the first information to a current correction unit corresponding to the one and the other, and also applies the second information to a current correction unit corresponding to the one or the other. Transformer protection relay.   The phase correction value used by the phase correction unit is selected according to whether the set type of the internal winding is Δ connection or other than Δ connection, and is 30 degrees before the current data and the current data. The transformer protection relay according to claim 1, wherein the transformer protection relay is any one of data and data.   The phase correction value used by the phase correction unit is selected according to whether the set type of the internal winding is Δ connection or other than Δ connection, and is 30 degrees before the current data and the current data. The transformer protection relay according to claim 1, wherein the transformer protection relay is a predetermined value within a range from a 30 degree phase advance to a 30 degree phase lag calculated using data. Digitally process the grid currents taken from the current transformers on the upstream and downstream sides of the transformer installed in the power system upstream and downstream of the system. Using the input processing unit and digital data from the input processing unit, a current for correcting the input system current from each of the current transformers upstream and downstream of the system so that the differential current becomes zero A correction unit, a ratio differential calculation unit that performs ratio differential calculation using each current data of the system upstream side and system downstream side corrected by the current correction unit, and determines the presence or absence of an internal failure of the transformer; In a transformer protection relay comprising:
The transformer is a transformer having an internal winding defined by international standards, and the current transformers on the upstream side and the downstream side of the system take out the system current of the transformer by Y connection, respectively. Configured to output,
From the set symbol indicating the internal winding of the transformer in the international standard, the type of the internal winding on either the upstream side or the downstream side of the system of the transformer is Δ connection or other than Δ connection First current conversion information according to whether there is, second current conversion information according to whether the type of internal winding in either one is Δ connection or other than Δ connection, and the internal in either one A standard table that outputs a phase correction selection value according to whether the type of winding is Δ connection or other than Δ connection, and
The current correction unit corresponding to either the system upstream side or the system downstream side,
Based on the first current conversion information, a first current conversion unit that performs current conversion processing on digital data corresponding to one of the system upstream side and system downstream side input from the input processing unit; A first gain correction unit that applies a gain correction to the current data output by one current conversion unit and gives the current data to the ratio differential calculation unit,
The current correction unit corresponding to the other of the system upstream side and the system downstream side,
Based on the second current conversion information, a second current conversion unit that performs a current conversion process on digital data corresponding to the other of the system upstream side and the system downstream side input from the input processing unit; A phase correction unit for performing phase correction processing based on the phase correction value on the current data output from the current conversion unit, and applying the gain correction to the current data output from the phase correction unit to provide to the ratio differential calculation unit A transformer protection relay, comprising: a second gain correction unit.

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