JP5030686B2 - Transformer load state detection device, load state detection method of transformer load state detection device, and program - Google Patents

Description

  The present invention relates to a load state detection device for a transformer, a load state detection method for the device, and a load state detection for a computer in the device, for detecting the load state of the transformer in order to protect the transformer in the power system, for example. The present invention relates to a program for executing a method.

  In a power system, for example, a three-winding transformer that transforms the voltage of a high-voltage side bus to two low-voltage side buses is known. In general, in order to supply high-quality power with a stable power system to a load, it is necessary to take measures and measures when a problem occurs in this transformer. Therefore, an overload protection facility is usually added to the transformer. That is, when the overload operation exceeding the rating of the transformer continues, this is detected and an alarm is issued or the load is interrupted automatically (see, for example, Patent Document 1). . The rating means a usage limit guaranteed for the transformer, defines a usage limit for the capacity, and specifies a voltage, a current, a frequency, a power factor, and the like.

  A configuration example of the load state detection apparatus 900 that detects the load state in order to determine the presence or absence of the overload described above will be described with reference to FIG. The figure is a schematic diagram showing a configuration example of a three-winding transformer 10 and a control device 920 thereof. The primary winding 11 of the transformer 10 is connected to the high-voltage side bus 1, while the secondary winding 12 and the tertiary winding 13 of the transformer 10 are connected to the two low-voltage side buses 2 and 3, respectively. Has been. The primary winding 11, the secondary winding 12, and the tertiary winding 13 include bushing current transformers (hereinafter simply referred to as “current transformers”) 901, 902, and 903 that detect respective currents. Each is provided. Based on the current value detected by each of the current transformers 901, 902, 903, the control device 920 issues a warning according to the function of determining the presence or absence of an overload on the transformer 10, and the determination result. Or it has the function etc. which interrupts | blocks between the load (not shown) of the transformer 10 and the buses 2 and 3. In this case, the load state detection device 900 is configured to include three current transformers 901, 902, and 903 and a portion that performs the above-described determination function in the control device 920.

The transformer is not limited to three windings, and may be, for example, two windings including a primary winding on the high voltage side and a secondary winding on the low voltage side.
JP 2004-170093 A

  However, in general, the current transformer 901 provided in the primary winding 11 is considered to be more expensive than the current transformers 902 and 903 provided in the secondary winding 12 and the tertiary winding 13. Along with this, the load state detection device 900 is also more expensive, and eventually there is a risk that the equipment cost of the overload protection facility of the transformer 10 will increase.

  On the other hand, if the presence / absence of overload is determined based on only the current values of the secondary winding 12 and the tertiary winding 13 without considering the current value of the primary winding 11, for example, the determination accuracy decreases. Therefore, the overload protection of the transformer 10 may be insufficient.

  As described above, the above is a problem that may occur even with a transformer other than three windings (for example, two windings). Further, the above is not limited to the determination of the presence or absence of an overload on the transformer 10, but generally a problem that may also occur when the load state of the transformer 10 is detected.

  This invention is made | formed in view of this subject, The place made into the objective is providing the low-cost load state detection apparatus which can detect the load state of a transformer accurately.

The invention for solving the above-mentioned problems is to detect a load state of a transformer having an input winding to which power is supplied from a first power line connected to a power system and an output winding for supplying power to a second power line. A device that detects a current flowing through the output winding; a first voltage detector that detects a voltage of the first power line; and a second voltage detector that detects a voltage of the second power line. And the input winding based on the detection current of the current detection unit and the turns ratio of the input winding and the output winding determined from the detection voltages of the first voltage detection unit and the second voltage detection unit. Whether or not the current calculation unit for calculating the current flowing through the line, the detection current of the current detection unit, and the calculation current of the current calculation unit are within a range of current values for determining whether or not there is an overload. in response to detecting the state of loading of the transformer load state detection And, it made with a.

  According to this load state detection device, the current calculation unit does not detect the current A flowing through the input winding by, for example, a current transformer, and the current calculation unit detects the current B and the winding detected by the current detection unit on the output winding side. Based on the ratio C, the current A can be obtained by calculation. Thereby, the load state detection part can detect the state of the load of a transformer based on the electric current A and the electric current B. FIG. That is, this load state detection device can keep the cost low because there is no current detector on the input winding side. In addition, since the load state is detected based on both the currents A and B, the detection accuracy is higher than that in the case where the load state is detected based only on the current B, for example, This may be sufficient for overload protection of the vessel. From the above, a low-cost load state detection device capable of accurately detecting the load state of the transformer is provided.

  According to this transformer load state detection device, the winding ratio C between the input winding and the output winding corresponds to, for example, the ratio between the voltage D of the first power line and the voltage E of the second power line. . For example, if the means (first voltage detection unit, second voltage detection unit) for detecting the voltages D and E in the power system is equipped as standard, the existing means is used for winding. The ratio C can be easily obtained.

  In the transformer load state detection device, the input winding of the transformer is a primary winding, the output winding of the transformer is a secondary winding and a tertiary winding, and the current detection is performed. The unit detects each current flowing through the secondary winding and the tertiary winding, and the current calculation unit determines the detected current of the secondary winding of the current detection unit as the primary winding and the 2 According to the winding ratio of the secondary winding, it is converted into the first converted current on the primary winding side, and the detected current of the tertiary winding of the current detection unit is set to the primary winding and the tertiary winding. It is good also as converting into the 2nd conversion current by the side of the above-mentioned primary winding by winding ratio, and obtaining the current which flows through the above-mentioned primary winding based on the above-mentioned 1st conversion current and the 2nd conversion current. .

  When this load state detection device of a transformer is applied to a so-called three-winding transformer, the current calculation unit is detected by the current detection unit without detecting the current A flowing through the primary winding by, for example, a current transformer. Based on the detected current B ′ on the secondary winding side and current B ″ on the tertiary winding side and winding ratios C ′ and C ″, the current A can be obtained by calculation. Thereby, the load state detection unit can detect the state of the load of the transformer based on the currents A, B ′, B ″. That is, the load state detection device can detect the current on the primary winding side. The cost can be reduced to the extent that there is no detection unit. Further, since the load state is detected based on the three currents A, B ′, B ″, the detection accuracy is, for example, two currents B ′. , B ″ alone, which is higher than the case where the load state is detected, and may be sufficient for, for example, the overload protection of the transformer. By multiplying the winding ratio C ′ or its reciprocal, the current B ′ is converted to the primary winding side, and by multiplying the current B ″ by, for example, the winding ratio C ″ or its reciprocal, the current B ′ "Is converted to the primary winding side, for example the real part of the two converted currents By summing fine imaginary part each other, it is possible to obtain the current A.

In the transformer load state detection apparatus, it is preferable that the first power line is a higher-voltage power line than the second power line.
According to this transformer load state detection device, it is possible to accurately detect the load state of the transformer without providing a current detector on the high voltage side. In general, a current detection unit (for example, a bushing current transformer) to be provided on the high voltage side is considered to be more expensive than a current detection unit provided on the low voltage side, and thus the cost of the load state detection device is more effective. Can be kept low.

Moreover, the invention for solving the above-mentioned problems is a load of a transformer having an input winding to which power is supplied from a first power line connected to a power system and an output winding for supplying power to the second power line. A load state detection method for a state detection device, comprising: a current detection step for detecting a current flowing through the output winding; a first voltage detection step for detecting a voltage of the first power line; and a voltage of the second power line. A second voltage detection step to detect, a detection current of the current detection step, a winding ratio of the input winding and the output winding determined from the detection voltages of the first voltage detection step and the second voltage detection step ; based on a current calculating step of calculating the current flowing through the input winding, and a detection current of the current detection step, and calculating the current of the current calculating step, but for determining the presence or absence of overload Depending on whether it is within the range of current values, comprising and a load state detection step for detecting the state of loading of the transformer.
According to the load state detection method of the load state detection device for a transformer, the load state of the transformer can be detected with high accuracy while suppressing the load state detection device at low cost.

Moreover, the invention for solving the above-mentioned problems is a load of a transformer having an input winding to which power is supplied from a first power line connected to a power system and an output winding for supplying power to the second power line. A computer for controlling a load state detection operation in the state detection device includes: a current detection procedure for detecting a current flowing through the output winding; a first voltage detection procedure for detecting a voltage of the first power line; A second voltage detection procedure for detecting a voltage; a detection current of the current detection procedure; a winding of the input winding and the output winding determined from the detection voltages of the first voltage detection procedure and the second voltage detection procedure A current calculation procedure for calculating a current flowing through the input winding based on the ratio, a detection current of the current detection procedure, and a calculation current of the current calculation procedure for determining whether or not there is an overload. Within the range of values Depending on whether there is a program for executing a load state detection step of detecting the state of loading of the transformer.
According to this program, for example, by installing this program in a computer, it is possible to accurately detect the load state of the transformer while suppressing the load state detection device at low cost.

  It is possible to provide a low-cost load state detection device that can accurately detect the load state of a transformer.

=== First Embodiment ===
<<< Load state detection device >>>
A configuration example of the load state detection apparatus 100 according to the present embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating a configuration example of a three-winding transformer 10 and its control device 200 according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration example of the load state detection apparatus 100 according to the first embodiment. FIG. 3 is a graph that visualizes an example of the allowable load sharing curve data 104b according to the first embodiment.

  As illustrated in FIG. 1, the primary winding (input winding) 11 of the transformer 10 is connected to the high-voltage side bus (first power line) 1, while the secondary winding ( The output winding) 12 and the tertiary winding (output winding) 13 are connected to the low-voltage side bus (second power line) 2 and the bus (second power line) 3, respectively. In FIG. 1 and FIG. 8 described above, the same numbers are assigned to the same devices. The primary winding 11 is provided with a plurality of switchable taps (not shown). By switching the tap position and changing the tap ratio (winding ratio), the voltages of the secondary winding 12 and the tertiary winding 13 can be adjusted. The secondary winding 12 and the tertiary winding 13 are provided with bushing current transformers (hereinafter simply referred to as “current transformers”) 102 and 103 for detecting respective currents, while the primary winding The winding 11 is not provided with a current transformer. As will be described later, the control device 200 has a function of determining whether or not there is an overload on the transformer 10 based on the current value detected by each of the current transformers 102 and 103 and the tap position of the primary winding 11. In addition, according to the determination result, it has a function of issuing an alarm or blocking between the transformer 10 and the load (not shown) of the buses 2 and 3.

  As illustrated in FIG. 2, the load state detection apparatus 100 mainly includes a control unit (current calculation unit, load state detection unit) 101, two current transformers (current detection units) 102 and 103, and a RAM 104. The counter 105 and the ROM 106 are provided. In addition, the load state detection apparatus 100 of this Embodiment comprises the control apparatus 200 of the transformer 10 with the alternating current overcurrent relay 110, the on-load tap switch 120, and the alarm part 130 which are mentioned later.

  The control unit 101 has a function of performing overall control of the control device 200 to determine whether or not there is an overload on the transformer 10, and to perform an alarm or a load interruption according to the determination result. The current transformer 102 is a known bushing current transformer that detects a current flowing through the secondary winding 12, and the current transformer 103 is a known bushing current transformer that detects a current flowing through the tertiary winding 13. The RAM 104 stores tap position data 104a indicating the tap position of the primary winding 104a and allowable load sharing curve data 104b indicating a current value range for determining whether or not the transformer 10 is overloaded. It is. When a tap switching signal instructing raising / lowering of the tap of the primary winding 11 is transmitted from a predetermined voltage adjusting unit (not shown), the counter 105 separately counts the raising and lowering taps indicated by this signal. Is. This voltage adjusting unit is a well-known device having a function of detecting a voltage at the bus 2 or the bus 3 by a predetermined voltage detecting means and a function of transmitting a tap switching signal for compensating this voltage, for example. It is provided inside or outside the control device 200 of the form. The ROM 106 stores a program or the like that defines a procedure of processing to be described later of the control unit 101.

  When the control unit 101 determines that the AC overcurrent relay 110 has an overload with respect to the transformer 10, for example, depending on the degree of the overload, the AC overcurrent relay 110 is connected between the load of the transformer 10 and the buses 2 and 3. This is a known relay having a function of interrupting.

  The on-load tap changer 120 does not interrupt between the transformer 10 and the load of the buses 2 and 3 (that is, in a state in which the load is always connected). This is a known device having a function of switching from one tap to another. In order to move from one tap to another without interrupting the load, a state that spans both taps in the middle of switching is required. At this time, the circuit of the on-load tap changer 120 includes a current limiting resistor and a reactor so that the voltage between the taps is not short-circuited and the primary winding 11 is not damaged. The on-load tap changer 120 has a function of raising or lowering the tap based on the tap change signal transmitted from the voltage adjusting unit described above.

  The alarm unit 130 is a well-known notification unit for notifying the operator of this fact, for example, when the control unit 101 determines that the transformer 10 is overloaded.

  In the illustration of FIG. 2, the AC overcurrent relay 110, the on-load tap switch 120, and the alarm unit 130 are assumed to be outside the load state detection device 100 of the present embodiment, but are not limited thereto. It is not something. For example, the load state detection apparatus 100 may further include an AC overcurrent relay 110, a load tap changer 120, and an alarm unit 130. Alternatively, for example, the AC overcurrent relay 110 may have the function of the load state detection device 100 of the present embodiment.

  As illustrated in FIG. 3, whether or not there is an overload on the transformer 10 is that each current value in the primary winding 11, the secondary winding 12, and the tertiary winding 13 is the allowable load sharing curve data 104 b. It is determined by whether or not the current value is within the range. Since the primary winding 11 of the present embodiment is not provided with a current transformer, the tap ratio and each current in the secondary winding 12 and the tertiary winding 13 are determined prior to determination, as will be described later. The current value of the primary winding 11 is obtained based on the value. In the example of FIG. 3, for example, the power of a secondary load (not shown) connected to the secondary winding 12 and the power of a tertiary load (not shown) connected to the tertiary winding 13 are represented by a curve D. The range of each current value from the left side to the lower left side of the drawing corresponds to a range where there is no overload on the transformer 10. In addition, the area | region enclosed with the curve D is an example of the range of the allowable load with respect to the transformer 10, and is not limited to this.

<<< Load status detection method >>>
The load state detection method of the load state detection apparatus 100 described above will be described with reference to FIG. FIG. 3 is a flowchart for explaining a processing procedure of the control unit 101 when the load state detection apparatus 100 according to the first embodiment performs the load state detection method.

  First, the control unit 101 receives information on the detected current value from the current transformer 102 connected to the secondary winding 12 (S100) and the current transformer 103 connected to the tertiary winding 13. The information of the detected current value is received from (S101). In the present embodiment, the control unit 101 stores the current value acquired in steps S100 and S101 in, for example, the RAM 104.

  By the way, the control unit 101 uses the counter 105 to count the tap increase or decrease indicated by the tap switching signal received by the on-load tap changer 120 from the voltage adjustment unit (not shown). On the other hand, the initial tap position in the transformer 10 is stored in advance in the RAM 104 as tap position data 104a. Therefore, each time the counter 105 counts the increment or decrement, the control unit 101 obtains the current tap position based on the count result and the initial tap position, and updates the tap position data 104a in the RAM 104. .

  Based on the tap position data 104 a stored in the RAM 104, the control unit 101 has a tap ratio of the secondary winding 12 to the primary winding 11 (hereinafter referred to as “secondary / primary tap ratio”), 1 A tap ratio of the tertiary winding 13 to the secondary winding 11 (hereinafter referred to as “tertiary / primary tap ratio”) is obtained (S102).

  The control unit 101 converts the current value of the secondary winding 12 to the primary winding 11 side based on the secondary / primary tap ratio and the current value of the secondary winding 12 acquired in step S100. To obtain the first conversion value. Specifically, the first converted value (first converted current) is obtained by multiplying the values of the effective current and reactive current of the secondary winding 12 by, for example, the reciprocal of the secondary / primary tap ratio. The first converted value is also a value composed of a real part and an imaginary part. Similarly, the control unit 101 converts the current value of the tertiary winding 13 to the primary winding based on the tertiary / primary tap ratio and the current value of the tertiary winding 13 acquired in step S101. The second converted value (second converted current) is obtained by converting to the 11th side. Specifically, the second converted value is obtained by multiplying the values of the effective current and reactive current of the tertiary winding 13 by, for example, the reciprocal of the tertiary / primary tap ratio. The second converted value is also a value composed of a real part and an imaginary part. Based on the first converted value and the second converted value obtained above, the control unit 101 obtains the current value of the primary winding 11 (S103). Specifically, the sum of the real part and the imaginary part of the first converted value and the second converted value is obtained. In the present embodiment, it is assumed that the control unit 101 stores the current value obtained in step S103 in, for example, the RAM 104.

  The control unit 101 obtains the current value of the primary winding 11 obtained in step S103, the current value of the secondary winding 12 acquired in step S100, and the current value of the tertiary winding 13 acquired in step S101. Then, it is determined whether the current value is within the range of the current value indicated by the allowable load sharing curve data 104b stored in the RAM 104 (S104).

  When it is determined that the three current values are within the range of the current value indicated by the allowable load sharing curve data 104b (S105: YES), it can be assumed that there is no overload on the transformer 10, so that the control unit 101 executes the process of step S100 again.

  When it is determined that the three current values are not within the range of the current value indicated by the allowable load sharing curve data 104b (S105: NO), the control unit 101 determines that the overload is applied to the transformer 10 and the control unit 101 The current relay 110 or the alarm unit 130 is operated (S106). In this case, for example, if the range of the unacceptable current value in the allowable load sharing curve data 104b is further classified and determined in advance in a more detailed range indicating the degree of overload, the degree of overload is set. The response can be changed accordingly. For example, if the degree of overload is relatively small, only an alarm is issued through the alarm unit 130. On the other hand, if the degree of overload is relatively large, load interruption is performed by the AC overcurrent relay 110.

  In addition, the process of step S100-S102 mentioned above is not limited to this procedure, For example, the order may be changed and it may process simultaneously.

=== Second Embodiment ===
<<< Load state detection device >>>
A configuration example of the load state detection apparatus 100 ′ of the second embodiment will be described with reference to FIGS. FIG. 5 is a schematic diagram illustrating a configuration example of the three-winding transformer 10 and the control device 200 ′ thereof according to the second embodiment. FIG. 6 is a block diagram illustrating a configuration example of the load state detection device 100 ′ according to the second embodiment.

  In FIG. 5, the same devices as those in FIG. As in the case of the first embodiment described above, the primary winding 11 is not provided with a current transformer. On the other hand, instrument transformers 107, 108, and 109 are provided in the primary winding 11, the secondary winding 12, and the tertiary winding, respectively. As will be described later, the control device 200 ′ uses the current value detected by each of the current transformers 102 and 103 and the voltage value detected by each of the instrument transformers 107, 108, and 109 to Has a function to determine the presence or absence of overload, and a function to issue an alarm or to cut off the load between the transformer 10 and the buses 2 and 3 (not shown). is doing.

  In FIG. 6, the same devices as those in FIG. 2 are given the same numbers. As illustrated in FIG. 6, the load state detection device 100 ′ mainly includes a control unit (current calculation unit, load state detection unit) 101, two current transformers (current detection units) 102 and 103, and a RAM 104. And three instrument transformers 107, 108, 109 and a ROM 106. Note that the load state detection device 100 ′ of the second embodiment is similar to the load state detection device 100 of the first embodiment in that the AC overcurrent relay 110, the on-load tap switch 120, and the alarm unit 130 are used. At the same time, the control device 200 ′ of the transformer 10 is configured.

  The functions of the control unit 101, current transformers 102 and 103, and ROM 106 are the same as the functions of the first embodiment. The RAM 104 stores the allowable load sharing curve data 104b similar to that in the first embodiment. An instrument transformer (first voltage detector) 107 is a known transformer that detects the voltage of the primary winding 11, and an instrument transformer (second voltage detector) 108 is the voltage of the secondary winding 12. The instrument transformer (second voltage detector) 109 is a known transformer that detects the voltage of the tertiary winding 13.

  The AC overcurrent relay 110, the on-load tap changer 120, and the alarm unit 130 may be provided either inside or outside the load state detection device 100 '. Alternatively, for example, the AC overcurrent relay 110 may have the function of the load state detection device 100 ′.

  Further, the transformer 10 of the second embodiment does not need to be a tapped transformer. If the transformer 10 is not a tapped transformer, the control device 200 ′ need not include the on-load tap changer 120.

<<< Load status detection method >>>
The load state detection method of the load state detection device 100 ′ described above will be described with reference to FIG. FIG. 9 is a flowchart for explaining a processing procedure of the control unit 101 when the load state detection device 100 ′ of the second embodiment performs the load state detection method.

  First, the control unit 101 receives information on the detected current value from the current transformer 102 connected to the secondary winding 12 (S200) and the current transformer 103 connected to the tertiary winding 13. The information of the detected current value is received from (S201). In the second embodiment, the control unit 101 stores the current value acquired in steps S200 and S201 in, for example, the RAM 104.

  Further, the control unit 101 obtains the ratio of the voltage value detected by the instrument transformer 108 to the voltage value detected by the instrument transformer 107 to obtain the winding of the secondary winding 12 with respect to the primary winding 11. The ratio (hereinafter referred to as “secondary / primary winding ratio”), and the ratio of the voltage value detected by the instrument transformer 109 to the voltage value detected by the instrument transformer 107, The winding ratio of the tertiary winding 13 to the primary winding 11 (hereinafter referred to as “tertiary / primary winding ratio”) is set (S202).

  The controller 101 converts the current value of the secondary winding 12 to the primary winding 11 side based on the secondary / primary winding ratio and the current value of the secondary winding 12 acquired in step S200. Thus, the first converted value (first converted current) is obtained. Specifically, the first converted value is obtained by multiplying the values of the effective current and reactive current of the secondary winding 12 by, for example, the reciprocal of the secondary / primary winding ratio. The first converted value is also a value composed of a real part and an imaginary part. Similarly, the control unit 101 changes the current value of the tertiary winding 13 to the primary winding based on the tertiary / primary winding ratio and the current value of the tertiary winding 13 acquired in step S201. A second converted value (second converted current) is obtained by converting to the line 11 side. Specifically, the second converted value is obtained by multiplying the values of the effective current and reactive current of the tertiary winding 13 by, for example, the reciprocal of the tertiary / primary winding ratio. The second converted value is also a value composed of a real part and an imaginary part. Based on the first converted value and the second converted value obtained above, the control unit 101 obtains the current value of the primary winding 11 (S203). Specifically, the sum of the real part and the imaginary part of the first converted value and the second converted value is obtained. In the second embodiment, the control unit 101 stores the current value obtained in step S203 in, for example, the RAM 104.

  The control unit 101 obtains the current value of the primary winding 11 obtained in step S203, the current value of the secondary winding 12 obtained in step S200, and the current value of the tertiary winding 13 obtained in step S201. Then, it is determined whether the current value is within the range of the current value indicated by the allowable load sharing curve data 104b stored in the RAM 104 (S204).

  When it is determined that the three current values are within the range of the current value indicated by the allowable load sharing curve data 104b (S205: YES), it can be assumed that there is no overload on the transformer 10, and therefore the control unit 101 executes the process of step S200 again.

  If it is determined that the three current values are not within the range of the current value indicated by the allowable load sharing curve data 104b (S205: NO), the control unit 101 causes the transformer 10 to overload because there is an overload on the transformer 10. The current relay 110 or the alarm unit 130 is operated (S206). In this case, for example, if the range of the unacceptable current value in the allowable load sharing curve data 104b is further classified and determined in advance in a more detailed range indicating the degree of overload, the degree of overload is set. The response can be changed accordingly. For example, if the degree of overload is relatively small, only an alarm is issued through the alarm unit 130. On the other hand, if the degree of overload is relatively large, load interruption is performed by the AC overcurrent relay 110.

  In addition, the process of step S200-S202 mentioned above is not limited to this procedure, For example, the order may be changed and it may process simultaneously.

=== High detection accuracy and low cost ===
According to the load state detection devices 100 and 100 ′ of the above-described embodiment, the current value of the primary winding 11 is obtained without providing a current transformer in the primary winding 11, and this current value and the secondary Based on the current values of the winding 12 and the tertiary winding 13, it is possible to determine whether or not there is an overload on the transformer 10. In general, the current transformer to be provided in the primary winding 11 is considered to be more expensive than the current transformers 102 and 103 provided in the secondary winding 12 and the tertiary winding 13, so that the load state The detection devices 100 and 100 ′ can reduce the cost to the extent that there is no current transformer for the primary winding 11. In the above-described embodiment, since the presence / absence of overload is determined based on all the current values of the primary winding 11, the secondary winding 12, and the tertiary winding 13, the determination accuracy is For example, it is sufficient for overload protection of the transformer 10. From the above, low-cost load state detection devices 100 and 100 ′ that can accurately determine whether or not the transformer 10 is overloaded are provided.

  In the above-described embodiment, the program stored in the ROM 106 causes the control unit 101 to execute the processing of steps S100 to S106 (FIG. 4) or the processing of steps S200 to S206. For example, by installing this program in a computer including the control unit 101, it is possible to accurately detect the load state of the transformer 10 while suppressing the load state detection devices 100 and 100 'at low cost.

  In the above-described embodiment, the bus 1 is on the high voltage side and the buses 2 and 3 are on the low voltage side. However, the present invention is not limited to this. According to the load state detection devices 100 and 100 ′ of the above-described embodiments, the current transformer on the other side is not provided on either side of the bus 1 side or the buses 2 and 3 side. Based on the winding ratio, the current on both sides can be determined. Thereby, the cost of the apparatus can be kept low.

  In the above-described embodiment, as an example of the process of the load state detection unit, the process of determining whether or not there is an overload on the transformer 10 has been described. However, the present invention is not limited to this, and in general, the transformer Any process may be used as long as it can detect 10 load states.

=== Other Embodiments ===
The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention is changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  In the first embodiment described above, the tap position data 104a is generated by adding or subtracting the increment or decrement counted by the counter 105 with respect to the initial tap position of the transformer 10. However, the present invention is not limited to this. In short, any detection means for detecting the current tap position of the transformer 10 may be used.

  The transformer 10 of the first and second embodiments described above is a three-winding transformer, but is not limited to this, and is a transformer other than three windings (for example, two windings). There may be. Even in cases other than three windings, the current on the primary winding side is changed to the tap ratio or turns ratio of the primary winding and the N-order winding (N is an integer of 2 or more) and the current of the N-order winding. Can be based on.

It is a schematic diagram which shows the structural example of the transformer of 3 windings of 1st Embodiment, and its control apparatus. It is a block diagram which shows the structural example of the load condition detection apparatus of 1st Embodiment. It is the graph which visualized an example of the allowable load sharing curve data of 1st Embodiment. It is a flowchart for demonstrating the procedure of the process of the control part when the load condition detection apparatus of 1st Embodiment implements a load condition detection method. It is a schematic diagram which shows the structural example of the transformer of 3 windings of 2nd Embodiment, and its control apparatus. It is a block diagram which shows the structural example of the load condition detection apparatus of 2nd Embodiment. It is a flowchart for demonstrating the process sequence of the control part when the load condition detection apparatus of 2nd Embodiment implements the load condition detection method. It is a schematic diagram which shows the structural example of a 3 winding transformer and its control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High voltage side buses 2 and 3 Low voltage side bus lines 10 Transformer 11 Primary winding 12 Secondary winding 13 Tertiary windings 100, 100 ', 900 Load state detection device 101 Control units 102, 103, 901, 902 , 903 Current transformer 104 RAM
104a Tap position data 104b Allowable load sharing curve data 105 Counter 106 ROM
107, 108, 109 Instrument transformer 110 AC overcurrent relay 120 Load tap changer 130 Alarm unit 200, 200 ′, 920 Control device

Claims (5)

A transformer load state detection device having an input winding to which power is supplied from a first power line connected to a power system and an output winding for supplying power to a second power line,
A current detector for detecting a current flowing through the output winding;
A first voltage detector for detecting a voltage of the first power line;
A second voltage detector for detecting a voltage of the second power line;
Based on the detection current of the current detection unit and the turns ratio of the input winding and the output winding determined from the detection voltage of the first voltage detection unit and the second voltage detection unit, the input winding A current calculation unit for calculating a flowing current ;
The state of the load of the transformer is detected depending on whether or not the detection current of the current detection unit and the calculation current of the current calculation unit are within a range of current values for determining whether or not there is an overload. A load state detection unit to perform,
A transformer load state detection device comprising: The input winding of the transformer is a primary winding,
The output winding of the transformer is a secondary winding and a tertiary winding,
The current detection unit detects each current flowing through the secondary winding and the tertiary winding,
The current calculator is
The detected current of the secondary winding of the current detection unit is converted into the first converted current on the primary winding side by the winding ratio of the primary winding and the secondary winding,
The detected current of the tertiary winding of the current detector is converted into a second converted current on the primary winding side by the winding ratio of the primary winding and the tertiary winding,
2. The transformer load state detection device according to claim 1, wherein a current flowing through the primary winding is obtained based on the first converted current and the second converted current. 3. The load state detection device according to claim 1, wherein the first power line is a higher-voltage power line than the second power line. 4. A load state detection method for a load state detection device for a transformer having an input winding to which power is supplied from a first power line connected to a power system and an output winding for supplying power to a second power line,
A current detection step of detecting a current flowing through the output winding;
A first voltage detecting step of detecting a voltage of the first power line;
A second voltage detecting step of detecting a voltage of the second power line;
Based on the detection current of the current detection step and the turns ratio of the input winding and the output winding determined from the detection voltage of the first voltage detection step and the second voltage detection step , the input winding A current calculation step for calculating a flowing current;
Depending on whether the detection current of the current detection step and the calculation current of the current calculation step are within the range of current values for determining whether or not there is an overload, the load state of the transformer is determined. A load state detection step to detect;
A load state detecting method for a transformer load state detecting device. A computer for controlling a load state detection operation in a load state detection device for a transformer having an input winding for supplying power from a first power line connected to the power system and an output winding for supplying power to the second power line In addition,
A current detection procedure for detecting a current flowing through the output winding;
A first voltage detection procedure for detecting a voltage of the first power line;
A second voltage detection procedure for detecting the voltage of the second power line;
Based on the detection current of the current detection procedure and the turns ratio of the input winding and the output winding determined from the detection voltages of the first voltage detection procedure and the second voltage detection procedure , A current calculation procedure for calculating a flowing current;
Depending on whether or not the detection current of the current detection procedure and the calculation current of the current calculation procedure are within the range of current values for determining whether or not there is an overload, the state of the load of the transformer is determined. A load state detection procedure to be detected;
A program for running

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