Current providing device, power equipment vector testing device and system

Abstract

The present invention provides a current providing device, a power equipment vector testing device and a system. The existing parallel-connected compensation capacitors are changed into series-connected compensation capacitors in the current providing device. Since the resistance of the transformer is very small, the impedance shown is mainly reactance. After the capacitor is connected in series in the test loop, the reactance of the test loop can be reduced, so that the purpose of obtaining a larger test current by applying the same test voltage during the test can be achieved. In addition, the impedance of the compensation capacitor is different from the impedance of the tested power equipment, thereby avoiding resonance caused by the same impedance when connected in series. Furthermore, through the ingenious combination of the above means, it can be suitable for high-impedance transformer vector testing.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment vector testing, and more specifically, to a current providing device, a power equipment vector testing device and a system. Background Art

[0002] When the relay protection phasor inspection test technology before commissioning, which only uses the principle of voltage regulator and step-up transformer, is used on site, it is greatly affected by the on-site power supply, and the output current and voltage are relatively limited. Under the condition of unchanged power supply capacity, outputting high voltage and outputting large current are contradictory. The construction power supply capacity of general substations is less than 200kVA. Unlimited increase in the capacity of test equipment is also unbearable for on-site test power supply, and the increase in the capacity of test equipment also brings difficulties to the transportation of test equipment.

[0003] When the simulated load of the test is inductive, the parallel capacitor compensation method can effectively increase the output current of the test system, and also significantly reduce the capacity requirements of the test power supply on site. This technology has been verified in the field test of 500kV substation. However, for high-impedance power equipment, such as high-impedance transformers (determined according to the voltage level and ct ratio, for example, for 500kV transformers, transformers with impedance greater than 500 ohms can be considered as high-impedance transformers), this test method is difficult to meet the voltage and current required for phasor testing.

[0004] In order to solve the problem of vector testing of high-impedance power equipment, the present invention provides a current providing device, a power equipment vector testing device and a system. Summary of the invention

[0005] In order to solve at least one of the above problems, the present invention provides a current providing device for vector testing of power equipment, comprising:

[0006] A voltage regulator, an input terminal of the voltage regulator is coupled to an output terminal of a test power supply;

[0007] A booster, an input end of the booster coupled to an output end of the voltage regulator;

[0008] A compensation capacitor, wherein the input end of the compensation capacitor is coupled to the output end of the booster; wherein,

[0009] The output end of the compensation capacitor is coupled to one end of a tested electrical device, and a short-circuit point is set at the other end of the tested electrical device, and at least one end of the tested electrical device is coupled to at least one secondary device for detecting the tested electrical device;

[0010] The impedance of the compensation capacitor is different from the impedance of the measured electrical device.

[0011] In some embodiments, the impedance of the compensation capacitor is smaller than the impedance of the electrical device under test.

[0012] In some embodiments, the current providing device further comprises:

[0013] A controller is used to adjust the voltage value output by the voltage regulator.

[0014] In some embodiments, the current providing device further comprises:

[0015] A current transformer is coupled to one end of the controller, and the other end of the controller is coupled to the voltage regulator.

[0016] In some embodiments, the output end of the compensation capacitor is coupled to the high voltage end of the electrical device under test, and a short-circuit point is set at the low voltage end of the electrical device under test.

[0017] A second aspect of the present invention provides a power equipment vector testing device, comprising:

[0018] A voltage regulator, an input terminal of the voltage regulator is coupled to an output terminal of a test power supply;

[0019] A booster, an input end of the booster coupled to an output end of the voltage regulator;

[0020] a compensation capacitor, wherein an input end of the compensation capacitor is coupled to an output end of the booster, and an output end of the compensation capacitor is coupled to one end of a tested electrical device; and

[0021] At least one secondary device is coupled to at least one end of the tested electrical device and is used to detect the tested electrical device; wherein,

[0022] A short-circuit point is arranged at the other end of the measured electrical equipment, and the impedance of the compensation capacitor is different from the impedance of the measured electrical equipment.

[0023] In some embodiments, the impedance of the compensation capacitor is smaller than the impedance of the electrical device under test.

[0024] In some embodiments, the power equipment vector testing device further includes:

[0025] A controller is used to adjust the voltage value output by the voltage regulator.

[0026] In some embodiments, the power equipment vector testing device further includes: a current transformer, wherein the current transformer is coupled to one end of the controller, and the other end of the controller is coupled to the voltage regulator.

[0027] In some embodiments, the output end of the compensation capacitor is coupled to the high voltage end of the electrical device under test, and a short-circuit point is set at the low voltage end of the electrical device under test.

[0028] In some embodiments, the secondary device includes at least one of the following:

[0029] A voltage transformer, detecting the voltage of the branch where the tested electric power equipment is located;

[0030] A current transformer, for detecting the current of the branch where the tested electric power equipment is located;

[0031] A relay protection device, which uses the voltage and current of the branch where the tested electric equipment is located to determine the fault state;

[0032] A metering device for counting the power consumption of the measured power equipment;

[0033] The fault recording device records the voltage and current of the branch where the tested power equipment is located when a power grid fault occurs.

[0034] A third aspect of the present invention provides a power equipment vector testing system, including: a tested power equipment and the above-mentioned power equipment vector testing device.

[0035] A fourth aspect of the present invention provides a power equipment vector testing system, comprising: a test power supply, a tested power equipment and the above-mentioned power equipment vector testing device, wherein the test power supply is coupled to the power equipment vector testing device.

[0036] The beneficial effects of the present invention are as follows:

[0037] The present invention provides a current providing device, a power equipment vector testing device and a system. By changing the existing parallel-connected compensation capacitor into a series-connected compensation capacitor in the current providing device, since the resistance of the transformer is very small, the impedance shown is mainly reactance. After the capacitor is connected in series in the test loop, the reactance of the test loop can be reduced, so that the purpose of obtaining a larger test current by applying the same test voltage during the test can be achieved. In addition, the impedance of the compensation capacitor is different from the impedance of the tested power equipment, thereby avoiding resonance caused by the same impedance when connected in series. Furthermore, through the ingenious combination of the above means, it can be applied to high-impedance transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 One of the structural schematic diagrams of the power equipment vector test system in the prior art is shown.

[0040] Figure 2 The second structural schematic diagram of the power equipment vector test system in the prior art is shown.

[0041] Figure 3 A schematic diagram of the structure of a power equipment vector test system in an embodiment of the present invention is shown.

[0042] Figure 4 A schematic diagram of the structure of a test power supply in a specific scenario in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Figure 1 One of the current mainstream vector test system structure diagrams is shown in FIG. Figure 1 As shown, the system directly adds voltage to both ends of the tested device, which specifically includes a voltage regulator and a booster. The test power supply of the general voltage regulator is taken from the substation site with a 220V maintenance voltage, and the power is generally about 40kV; after the voltage regulator outputs, the voltage is increased by the booster and applied to the transformer under test. When the voltage transformer and current transformer collect the voltage and current values, they are transmitted to the protection device, measurement and control device, metering device, etc. This method has great drawbacks. If the impedance of the tested device is small, when the voltage rises to a relatively high level, the current will be very large, which will cause the test voltage power to be very large, and it is difficult to meet the requirements on site. For example, for a 500kV transformer with a 5Ω impedance, when a single-phase voltage of 500V is applied on the high-voltage side, the current is 100A, and the total power of the three phases reaches 150kVA. Such a large power supply cannot be provided on site. In this scheme, if a large voltage is applied, the power of the power supply will be too large, burning the cables or equipment. If a small voltage is applied, the voltage and current will be too small, and the test cannot be completed.

[0045] Figure 2 The second schematic diagram of the mainstream vector test system structure is shown in FIG. Figure 2As shown in the figure, the technical principle of capacitor compensation is to connect a three-phase capacitor in parallel to the output side of the original test system, and regard the system after the capacitor is connected as the test system. Therefore, the output current of the test system is the sum of the output current of the test boost transformer and the capacitor compensation current. The output voltage of the test system is still the output voltage of the test boost transformer. The current passing through the simulated load is the output current of the test system, and the simulated load is still a three-phase inductor. The capacitor compensation is based on the characteristics that the phase difference between the capacitive current and the inductive current in the circuit is 180°. The simulated load is a pure inductive reactor (or transformer reactor). After the pure capacitive capacitor is connected in parallel in the loop, the output current IT of the test boost transformer is IL-IC, and the output current of the test system is IL. Therefore, the output current of the test boost transformer is significantly reduced, thereby significantly reducing the power supply current. However, this scheme has a disadvantage. When the transformer impedance is too high, the current flowing through the transformer is too small, which will cause the secondary current to be too small to be monitored and the test cannot be completed. For high-impedance transformers, vector testing cannot be effectively performed.

[0046] Figure 3 A current providing device for vector testing of electric power equipment in an embodiment of the present invention is shown, comprising: a voltage regulator 2, wherein the input end of the voltage regulator 2 (the end on the left side of the voltage regulator 2 in the figure) is coupled to the output end of the test power supply 1; a booster 3, wherein the input end of the booster 3 (the end on the left side of the booster 3 in the figure) is coupled to the output end of the voltage regulator 2 (the end on the right side of the voltage regulator in the figure); a compensation capacitor 4, wherein the input end of the compensation capacitor 4 (the end on the left side of the compensation capacitor in the figure) is coupled to the output end of the booster 3 (the end on the right side of the booster 3 in the figure); wherein the output end of the compensation capacitor 4 (a section on the right side of the compensation capacitor 4 in the figure) is coupled to one end of a tested electric power equipment 5, wherein at least one end of the two ends of the tested electric power equipment 5 is coupled to at least one secondary device for detecting the tested electric power equipment 9, and a short-circuit point 8 is provided at the other end of the tested electric power equipment 5; the impedance of the compensation capacitor 4 is different from the impedance of the tested electric power equipment 5.

[0047] The current providing device of the present invention changes the existing parallel-connected compensation capacitor into a series-connected compensation capacitor in the current providing device. Since the resistance of the transformer is very small, the impedance shown is mainly reactance. After the capacitor is connected in series in the test loop, the reactance of the test loop can be reduced, so that the purpose of obtaining a larger test current by applying the same test voltage during the test can be achieved. In addition, the impedance of the compensation capacitor is different from the impedance of the tested power equipment, which avoids resonance caused by the same impedance when connected in series. Furthermore, through the ingenious combination of the above-mentioned means, it can be suitable for high-impedance transformers.

[0048] The coupling in the present invention may be a direct electrical connection, such as an electronic component A and an electronic component B being electrically connected via a wire, or A and B being co-located at a node. The coupling may also be an indirect electrical connection, such as an electronic component C being connected between A and B, as long as the electronic component C does not affect the functional relationship between A and B.

[0049] During specific use, the current providing device is electrically connected to the subsequently connected power device under test, and at least one of the two ends of the power device under test is coupled to at least one secondary device, which is used to perform vector testing on the power device under test.

[0050] It can be understood that the secondary device can be one or more and can be coupled to one end of the power device under test, for example, a current transformer can be connected to one end thereof, and the secondary device can also be coupled to both ends of the power device under test at the same time, for example, a voltage transformer can be coupled to both ends of the power device under test, that is, whether the secondary device is coupled to one end or both ends of the power device under test can be determined according to specific detection needs, and the number of secondary devices can also be determined according to detection needs, which will not be elaborated here.

[0051] In the present invention, the impedance of the compensation capacitor may be higher or lower than the impedance of the measured power device, as long as the impedance of the compensation capacitor is not consistent with that of the measured power device.

[0052] The transformer impedance is mainly manifested as inductive reactance, and the capacitor is manifested as capacitive reactance. If the capacitive reactance of the series compensation capacitor is greater than the inductive reactance of the tested transformer, the impedance of the entire test loop will change from inductive reactance characteristics to capacitive reactance characteristics, and the current direction will be reversed, resulting in a complex circuit. Therefore, in a preferred embodiment, the impedance of the series compensation capacitor should generally be less than the impedance of the tested power equipment.

[0053] The electrical equipment under test can be a device with higher impedance, such as a high-impedance transformer. Of course, the present invention can also be used for electrical equipment with lower impedance. Different from the prior art, the present invention can be applied to high-impedance equipment at the same time, while the prior art cannot be used for devices with higher impedance (generally speaking, the definition of high impedance is determined according to the voltage level and ct ratio. For example, for a 500kV transformer, a transformer with an impedance greater than 500 ohms can be considered as a high-impedance transformer), which is insufficient.

[0054] The voltage regulator is used to adjust the voltage value of the test power supply output. Its input is 380V three-phase power supply and its output is 0~380V three-phase power.

[0055] The booster is needed to increase the voltage to the voltage value required for testing the power equipment under test. Its input is the output of the voltage regulator. The compensation capacitor is connected in series to the booster and the power equipment under test. The booster connects the output high voltage to the 5 tested transformer through 4 series compensation capacitors.

[0056] Generally speaking, the compensation capacitor is connected to the high-voltage side of the power equipment under test, and the power equipment under test generally has a short-circuit point on the low-voltage side to short-circuit the three phases of the three-phase electricity. In this way, a current loop can be formed when the test voltage is applied to the high-voltage side of the power equipment under test.

[0057] The voltage regulator can be manually adjusted to a suitable output pressure value, or can be automatically adjusted, and the present invention does not impose any limitation thereto.

[0058] During manual adjustment, it is necessary to manually preset a set output pressure value and then operate the entire current providing device.

[0059] In a preferred embodiment, the present invention can automatically adjust the voltage regulator, and the current providing device of the present invention also includes a controller for adjusting the voltage value output by the voltage regulator. The controller is coupled to the voltage regulator, and then outputs a control signal to the voltage regulator to adjust the output parameters. When used specifically, the test personnel can input the size of the required output test current in the controller, and the controller controls the output current to reach the target value. The control signal can be preset according to certain conditions, such as certain conditions that match the time parameters, or certain conditions that match the state parameters of the current providing device itself.

[0060] In a more preferred embodiment, the current providing device of the present invention further includes: a current transformer, the current transformer is coupled to one end of the controller, and the other end of the controller is coupled to the voltage regulator. In this embodiment, the controller is coupled to the current transformer, and the current transformer can detect the current value of the line in real time, and then output the current value to the controller, so that the controller outputs the control signal of the voltage regulator in real time or regularly according to the current value, so that the current output by the current providing device is always stable within a target value range, thereby improving the stability of the current providing device, or the voltage regulator is adjusted by the detected current until the current is stable at the target value, and the voltage regulator stops adjusting, thereby realizing the function of automatic voltage regulation.

[0061] It can be known from the above description that the current providing device provided by the present invention changes the existing parallel-connected compensation capacitor into a series-connected compensation capacitor in the current providing device. Since the resistance of the transformer is very small, the impedance exhibited is mainly reactance. After the capacitor is connected in series in the test loop, the reactance of the test loop can be reduced, thereby achieving the purpose of obtaining a larger test current by applying the same test voltage during the test. In addition, the impedance of the compensation capacitor is different from the impedance of the tested electrical equipment, thereby avoiding resonance caused by the same impedance when connected in series. Furthermore, through the ingenious combination of the above means, it can be applied to high-impedance transformers.

[0062] A second aspect of the present invention provides a power equipment vector testing device, such as Figure 3 As shown, it includes the above-mentioned current providing device and at least one secondary device 9, at least one secondary device 9 is coupled to both ends of the measured power device 5, and is used to detect the measured power device 5; a short-circuit point 8 is set at the other end of the measured power device 5, and the impedance of the compensation capacitor 4 is different from the impedance of the measured power device 5.

[0063] It can be understood that the current providing device in the power equipment vector testing device in the present invention is the same as that in the above-mentioned embodiment, and will not be described in detail here.

[0064] Secondary equipment is an auxiliary device that monitors, measures, controls, protects and regulates the primary equipment in the power system, that is, equipment that is not directly connected to electric energy. Specifically, secondary equipment may include voltage transformers, current transformers, relay protection devices, metering devices (or electric energy metering devices), fault recording devices, and measurement and control devices (also known as control and signal devices).

[0065] More specifically, the voltage transformer detects the voltage of the branch where the tested power equipment is located; the current transformer detects the current of the branch where the tested power equipment is located; the relay protection device uses the voltage and current of the branch where the tested power equipment is located to determine the fault state; the metering device counts the power consumption of the tested power equipment; the fault recording device records the voltage and current of the branch where the tested power equipment is located when the power grid fails. The measurement and control device is used for signal input and control of circuit devices.

[0066] It can be understood that based on the inventive concept of the above-mentioned embodiment, the power equipment vector testing device provided by the present invention changes the existing parallel-connected compensation capacitor into a series-connected compensation capacitor in the current providing device. Since the resistance of the transformer is very small, the impedance exhibited is mainly reactance. After the capacitor is connected in series in the test loop, the reactance of the test loop can be reduced, thereby achieving the purpose of obtaining a larger test current by applying the same test voltage during the test. Moreover, the impedance of the compensation capacitor is different from the impedance of the power equipment under test, thereby avoiding resonance caused by the same impedance when connected in series. Furthermore, through the ingenious combination of the above-mentioned means, it can be suitable for high-impedance transformers.

[0067] The third aspect of the present invention provides a power equipment vector test system, please continue to refer to Figure 3 , including: the power equipment under test, 5 and the above-mentioned power equipment vector test device. The system includes the power equipment under test, that is, the power equipment under test and the vector test device are integrated together, which can be used for test research, performance testing, etc.

[0068] Based on the same inventive concept as the above embodiments, it can be understood that the power equipment vector test system provided by the present invention changes the existing parallel-connected compensation capacitor into a series-connected compensation capacitor in the current providing device. Since the resistance of the transformer is very small, the impedance exhibited is mainly reactance. After the capacitor is connected in series in the test loop, the reactance of the test loop can be reduced, thereby achieving the purpose of obtaining a larger test current by applying the same test voltage during the test. Moreover, the impedance of the compensation capacitor is different from the impedance of the power equipment under test, thereby avoiding resonance caused by the same impedance when connected in series. Furthermore, through the ingenious combination of the above means, it can be suitable for high-impedance transformers.

[0069] The fourth aspect of the present invention provides a power equipment vector test system, please continue to refer to Figure 3 , including: a test power supply 1, a tested power equipment 5 and the above-mentioned power equipment vector testing device, the test power supply 1 is coupled to the power equipment vector testing device.

[0070] This embodiment integrates the test power supply, the vector test device and the tested electrical equipment together, and changes the existing parallel-connected compensation capacitor into a series-connected compensation capacitor in the current providing device. Since the resistance of the transformer is very small, the impedance exhibited is mainly reactance. After the capacitor is connected in series in the test loop, the reactance of the test loop can be reduced, so that the purpose of obtaining a larger test current by applying the same test voltage during the test can be achieved. In addition, the impedance of the compensation capacitor is different from the impedance of the tested electrical equipment, avoiding resonance caused by the same impedance when connected in series. Through the clever combination of the above means, it can be applied to high-impedance transformers.

[0071] In some embodiments, the test power supply is a three-phase power grid. In some embodiments, the test power supply is a 380V three-phase power supply. The test power supply is generally taken from an on-site maintenance power box of a substation.

[0072] The following uses the high-impedance transformer as an example of the tested power equipment to illustrate the use of the present invention.

[0073] like Figure 3As shown, the test power supply 1 is generally taken from the local maintenance power supply box of the substation, which is 380V three-phase electricity; the test system is composed of a voltage regulator 2, a booster 3, and a series compensation capacitor 4, where the input of the voltage regulator 1 is a 380V three-phase power supply and the output is a 0-380V three-phase electricity; the input of the booster 2 is the output of the voltage regulator, and the booster connects the output high voltage to the tested transformer 5 through the series compensation capacitor 4, usually connected to the high-voltage side of the tested high-impedance transformer; the tested transformer is generally provided with a short-circuit point on the low-voltage side, and the A phase, B phase, and C phase are short-circuited, so that a current loop can be formed when the test voltage is applied to the high-voltage side of the transformer. Secondary equipment such as relay protection devices, measurement and control devices, metering devices, and fault recording devices collect the voltage applied to the primary circuit through a voltage transformer, and collect the current through the tested high-impedance transformer through a current transformer. Vector testing is to test whether the secondary current loop through these secondary devices is correct and whether it meets the commissioning requirements, including phase relationship, amplitude, and transformation ratio. During the test, the controller is used to control the output voltage of the voltage regulator, and then control the test current. The tester can input the output test current into the controller, and the controller will control the output current to reach the target value. The controller collects the primary loop current through the current transformer, and adjusts the output voltage of the voltage regulator according to the collected current. When the output current stabilizes at the target value, the voltage regulator stops outputting. Since the resistance of the transformer is very small, the impedance shown is mainly reactance. After connecting the capacitor in series in the test loop, the reactance of the test loop can be reduced, so that the purpose of applying the same test voltage during the test can be achieved to obtain a larger test current.

[0074] The effects of the present invention are described below in conjunction with specific test scenarios.

[0075] Figure 4 A schematic diagram of the structure of a test power supply is shown, and the corresponding circuit breaker opening and closing positions are shown in the figure. The unmarked circuit breakers are open positions. In the figure, 500kVI A, 500kVI B, 500kVII A, and 500kVII B are 500kV busbars, and 5011, 5012, 5013, 511, 522, and 5021 are circuit breakers. The station transformer parameters are 525kV / 10.5kV; 40MVA, YN, d11; Uk = 11.83%, and the calculated impedance is Xd = 815.2Ω.

[0076] Based on the test power supply, three different schemes are shown below:

[0077] 1. Solution 1: 3kV step-up transformer without compensation solution

[0078] 1) High voltage side current

[0079] If a 3000V line voltage is applied to the high-voltage side of the station transformer, the primary phase current on the high-voltage side is

[0080] 3000 / (815.2×1.73)=2.12A

[0081] CT ratio:

[0082] a) The CT ratio of the high-voltage side bushing is: 300-600 / 1, 2000-4000 / 1, 150-300 / 1.

[0083] b) The CT ratio of 500kV circuit breaker is 800 / 1, 150-300 / 1, 2500-4000 / 1, 200 / 1.

[0084] When the CT ratio on the high-voltage side is 2000 / 1, the secondary current is 1.06mA; when the CT ratio on the high-voltage side is 2500 / 1, the secondary current is 0.85mA.

[0085] 2) Low voltage side current

[0086] The primary value of the low voltage side current is:

[0087] 2.12A×525 / 10.5=106A

[0088] CT ratio:

[0089] a) The CT ratio of the low-voltage side bushing is: 800 / 1.

[0090] b) The CT transformation ratio of 10kV circuit breaker is: 2500 / 1, 800 / 1.

[0091] When the CT ratio on the low voltage side is 800 / 1, the secondary current is 133mA. When the CT ratio is 2500 / 1, the secondary current is 42.5mA. Table 1 shows the calculation data of the 3kV step-up transformer without compensation solution.

[0092] Table 1 Calculation data of 3kV step-up transformer without compensation solution

[0093] Transformer impedance 815.2Ω Primary line voltage / phase voltage 3000V / 1732V Phase voltage secondary value 330mV Primary value of high voltage side phase current 2.12A High voltage side phase current secondary value 800 / 1 2.6mA High voltage side phase current secondary value 2000 / 1 1.06mA High voltage side phase current secondary value 2500 / 1 0.85mA Primary value of low voltage side phase current 106A Low voltage side phase current secondary value 800 / 1 133mA Low voltage side phase current secondary value 2500 / 1 42.5mA 220V power supply power (phase) 3.67kW 220V power supply current (phase) 16.7A

[0094] 2. Solution 2: 3kV boost transformer series compensation capacitor solution

[0095] 1) Calculation of series compensation capacitor

[0096] The capacitance value of 8 groups of 40uF capacitors connected in series is 5uF, and the impedance value is:

[0097] 1 / (2π×5uF)=637Ω

[0098] After being connected in series with the station transformer, the comprehensive impedance is:

[0099] 815.2-637≈177.2Ω

[0100] 2) Calculation of high voltage side current

[0101] If a 3000V line voltage is applied to the high-voltage side of the station transformer, the primary phase current on the high-voltage side is

[0102] 3000 / (177.2×1.73)=9.77A

[0103] When the CT ratio on the high-voltage side is 2000 / 1, the secondary current is 4.9mA; when the CT ratio on the high-voltage side is 2500 / 1, the secondary current is 3.9mA.

[0104] 3) Low voltage side current

[0105] The primary value of the low voltage side current is:

[0106] 9.11A×525 / 10.5=488.7A

[0107] When the CT ratio on the low voltage side is 800 / 1, the secondary current is 611mA. When the CT ratio is 2500 / 1, the secondary current is 195mA. Table 2 shows the calculation data of the series compensation capacitor scheme for the 3kV step-up transformer.

[0108] Table 2 Calculation data of 3kV step-up transformer series compensation capacitor solution

[0109] Transformer impedance 815.2Ω Primary line voltage / phase voltage 3000V / 1732V Phase voltage secondary value 330mV Primary value of high voltage side phase current 9.77A High voltage side phase current secondary value 800 / 1 12.2mA High voltage side phase current secondary value 2000 / 1 4.9mA High voltage side phase current secondary value 2500 / 1 3.9mA Primary value of low voltage side phase current 488.7A Low voltage side phase current secondary value 800 / 1 611mA Low voltage side phase current secondary value 2500 / 1 195mA 220V power supply power (phase) 16.9kW 220V power supply current (phase) 76.9A

[0110] 3. Scheme 3: 10kV step-up transformer series compensation capacitor scheme

[0111] 1) Calculation of high voltage side current

[0112] If a 10kV line voltage is applied to the high-voltage side of the station transformer, the primary phase current on the high-voltage side is:

[0113] 10000 / (826.875×1.73)=7.08A

[0114] At this time, the 220V power supply power (phase) is: 7.08×10000 / 1.732=40.9kVA

[0115] At this time, the 220V power supply current (phase) is: 40.3kVA÷0.22kV=186A>120A

[0116] 186A exceeds the power cable limit of 120A, and capacitor compensation should be used or the voltage should be reduced.

[0117] a) If the parallel compensation capacitor method is used, the capacitor that needs to be compensated is:

[0118]

[0119] In the above formula, “*” represents the multiplication operator.

[0120] Calculated C = 3.13 ~ 3.71uF

[0121] When 8 groups of 40uF capacitors and 2 groups of 75uF capacitors are connected in series:

[0122] C=4.41uF, still does not meet the conditions.

[0123] When 8 groups of 40uF capacitors and 9 groups of 90uF capacitors are connected in series:

[0124] C=3.33uF, which meets the requirements, but all capacitors are only enough for one phase compensation.

[0125] Therefore, the solution of parallel capacitors does not meet the requirements.

[0126] b) Solution to reduce the boost voltage, when the power supply current is 110A:

[0127]

[0128] In the above formula, “*” represents the multiplication operator.

[0129] The transformer impedance is 815.2Ω, so the maximum phase voltage applied is U=4442V

[0130] The primary phase current at this time is 4442÷815.2=5.45A

[0131] When the CT ratio on the high-voltage side is 2000 / 1, the secondary current is 2.7mA; when the CT ratio on the high-voltage side is 2500 / 1, the secondary current is 2.12mA.

[0132] The primary value of the low voltage side current is:

[0133] 5.45A×525 / 10.5=272.4A

[0134] When the CT ratio on the low voltage side is 800 / 1, the secondary current is 340mA. When the CT ratio is 2500 / 1, the secondary current is 109mA. Table 3 shows the calculation data of the 10kV step-up transformer without compensation solution.

[0135] Table 3 Calculation data of 10kV step-up transformer without compensation solution

[0136]

[0137]

[0138] In summary, Scheme 2 or Scheme 3 can be adopted. However, generally, 10kV power transformers are large in size, heavy in weight, and inconvenient to transport, so under the same conditions, Scheme 2 (i.e., the present invention) is better.

[0139] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. In the description of this specification, the description of the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. In addition, in the absence of mutual contradiction, a person skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples. The above is only an embodiment of the embodiment of this specification and is not intended to limit the embodiment of this specification. For those skilled in the art, the embodiment of this specification may have various changes and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the embodiment of this specification should be included in the claims of the embodiment of this specification.

Claims

1. A current providing device for vector testing of power equipment, characterized in that: include: A voltage regulator, an input terminal of the voltage regulator is coupled to an output terminal of a test power supply; A booster, an input end of the booster coupled to an output end of the voltage regulator; A compensation capacitor, wherein the input end of the compensation capacitor is coupled to the output end of the booster; wherein, The output end of the compensation capacitor is coupled to one end of a tested electrical device, and a short-circuit point is set at the other end of the tested electrical device, and at least one end of the tested electrical device is coupled to at least one secondary device for detecting the tested electrical device; The impedance of the compensation capacitor is different from the impedance of the measured electrical equipment; The impedance of the compensation capacitor is smaller than the impedance of the measured electrical equipment; The current providing device also includes: A controller is used to adjust the voltage value output by the voltage regulator.

2. The current providing device according to claim 1, characterized in that: The current providing device also includes: A current transformer is coupled to one end of the controller, and the other end of the controller is coupled to the voltage regulator.

3. The current providing device according to claim 1, characterized in that: The output end of the compensation capacitor is coupled to the high voltage end of the measured electrical equipment, and a short-circuit point is set at the low voltage end of the measured electrical equipment.

4. A power equipment vector test device, characterized in that: include: A voltage regulator, an input terminal of the voltage regulator is coupled to an output terminal of a test power supply; A booster, an input end of the booster coupled to an output end of the voltage regulator; A compensation capacitor, wherein an input end of the compensation capacitor is coupled to an output end of the booster, and an output end of the compensation capacitor is coupled to one end of a tested electrical device; as well as, At least one secondary device is coupled to at least one end of the tested electrical device and is used to detect the tested electrical device; wherein, A short-circuit point is provided at the other end of the measured electrical equipment, and the impedance of the compensation capacitor is different from the impedance of the measured electrical equipment; The impedance of the compensation capacitor is smaller than the impedance of the measured electrical equipment; The power equipment vector testing device also includes: A controller is used to adjust the voltage value output by the voltage regulator.

5. The power equipment vector testing device according to claim 4, characterized in that: The power equipment vector testing device further includes: a current transformer, wherein the current transformer is coupled to one end of the controller, and the other end of the controller is coupled to the voltage regulator.

6. The power equipment vector testing device according to claim 4, characterized in that: The output end of the compensation capacitor is coupled to the high voltage end of the measured electrical equipment, and a short-circuit point is set at the low voltage end of the measured electrical equipment.

7. The power equipment vector testing device according to claim 4, characterized in that: The secondary device includes at least one of the following: A voltage transformer, detecting the voltage of the branch where the tested electric power equipment is located; A current transformer, for detecting the current of the branch where the tested electric power equipment is located; A relay protection device, which uses the voltage and current of the branch where the tested electric equipment is located to determine the fault state; A metering device for counting the power consumption of the measured power equipment; The fault recording device records the voltage and current of the branch where the tested power equipment is located when a power grid fault occurs.

8. A power equipment vector test system, characterized in that: include: An electric power device under test and an electric power device vector testing device as described in any one of claims 4 to 7.

9. A power equipment vector test system, characterized in that: include: A test power supply, a tested power device, and a power device vector test device as described in any one of claims 4 to 7, wherein the test power supply is coupled to the power device vector test device.

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