A current transformer detection system and method

Abstract

The application discloses a current transformer detection system and method, and relates to the technical field of current transformer detection, which comprises a current collection sensor, a compensation device and a controller. The current collection sensor is arranged between a to-be-detected current transformer and a load, and is used for collecting a load current. The compensation device is connected in parallel with the to-be-detected current transformer. The controller is connected with the current collection sensor and the compensation device. The controller is used for controlling the compensation device to generate a compensation current according to the load current collected by the current collection sensor, so that the current flowing through the to-be-detected current transformer is changed between 5% and 120% of a rated current, and the performance detection of the to-be-detected current transformer at multiple current data points between 5% and 120% of the rated current is met. That is, the application can adjust the current flowing through the to-be-detected current transformer in a short time, and realizes the full-range performance detection in a short time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current transformer detection, and in particular to a current transformer detection system and method. BACKGROUND

[0002] The current transformer is a commonly used device in the power system, and plays an important role in protection and metering. The performance of the current transformer directly affects the reliability of the system. According to relevant regulations, the precision of the instrument transformer in the power grid must be checked regularly. Therefore, it is very important to detect the performance of the current transformer.

[0003] At present, the traditional on-site calibration of the transformer requires the current transformer to be taken out of operation for calibration, which greatly affects the reliability of the power distribution network operation, and the operation is complex and the detection equipment is heavy, which is very inconvenient for fault analysis and hidden danger judgment.

[0004] Chinese patent application CN201821606820.5 discloses a 10kV current transformer online detection device, which mainly avoids the contact between the host and the high voltage by using the host and the extension and the wireless communication module. The extension uses a clamp-on transformer and a high-voltage insulating rod to operate, ensuring safety during online detection and improving operation convenience.

[0005] However, the application patent can only detect the performance state of the current transformer under the current load current in practical application, and cannot realize the detection of the 5%-120% rated current range. If the detection data of multiple current points is required, a lot of time is wasted waiting for the load current to change. SUMMARY

[0006] The embodiments of the present application provide a current transformer detection system and method to solve the technical problem that the existing current transformer detection system in the related art cannot realize performance detection in the 5%-120% rated current range in a short time.

[0007] In a first aspect, a current transformer detection system is provided for online detection of a current transformer located between a power supply network and a load, comprising:

[0008] A current collection sensor is arranged between the to-be-detected current transformer and the load, and the current collection sensor is used to collect the load current.

[0009] A compensation device is connected in parallel with the to-be-detected current transformer.

[0010] A controller is connected to the current collection sensor and the compensation device.

[0011] The controller is configured to control the compensation device to generate a compensation current according to the load current collected by the current collection sensor, so that the current flowing through the current transformer under test varies between 5% and 120% of the rated current.

[0012] In some embodiments, the compensation device comprises:

[0013] a first compensator and a second compensator, the AC side of the first compensator being connected to the power grid and the current transformer under test, the AC side of the second compensator being connected to the current transformer under test and the load, and the DC side of the first compensator being connected to the DC side of the second compensator.

[0014] The controller controls the first compensator and the second compensator to generate compensation currents of the same magnitude and opposite phase, so that the current flowing through the current transformer under test varies between 5% and 120% of the rated current.

[0015] In some embodiments, if the load current is greater than the required current of the current transformer under test, the controller controls the first compensator to generate a current of the same phase as the load current, so that the current flowing through the current transformer under test increases.

[0016] If the load current is less than the required current of the current transformer under test, the controller controls the first compensator to generate a current of opposite phase to the load current, so that the current flowing through the current transformer under test decreases.

[0017] In some embodiments, a capacitor is connected in parallel to the DC side of the first compensator and the DC side of the second compensator.

[0018] In some embodiments, a first disconnecting switch is provided between the AC side of the first compensator and the power grid and the current transformer under test.

[0019] A second disconnecting switch is provided between the AC side of the second compensator and the current transformer under test and the load.

[0020] In some embodiments, a first inductor is provided between the AC side of the first compensator and the first disconnecting switch.

[0021] A second inductor is provided between the AC side of the second compensator and the second disconnecting switch.

[0022] In some embodiments, a first step-up transformer is provided between the AC side of the first compensator and the first inductor.

[0023] A second step-up transformer is provided between the AC side of the second compensator and the second inductor.

[0024] In some embodiments, the first compensator and the second compensator are both static synchronous compensators.

[0025] In some embodiments, the current transformer detection system further comprises:

[0026] a standard transformer connected in series between the current transformer to be detected and a power supply network, the standard transformer being connected to the controller, the controller being configured to determine whether the current transformer to be detected is accurately measured according to an amplitude ratio difference between the standard transformer and the current transformer to be detected.

[0027] In a second aspect, a current transformer detection method is provided, comprising the following steps:

[0028] collecting a load current;

[0029] controlling the compensating device to generate a compensating current according to the collected load current, so that the current flowing through the current transformer to be detected varies between 5% and 120% of the rated current.

[0030] The technical solutions provided by the present application have the following beneficial effects:

[0031] The current transformer detection system and method provided by the embodiments of the present application are provided with a current collection sensor, a compensating device and a controller, the current collection sensor is configured to collect a load current, the compensating device is connected in parallel with the current transformer to be detected, and the controller is configured to control the compensating device to generate a compensating current according to the load current collected by the current collection sensor, so that the current flowing through the current transformer to be detected varies between 5% and 120% of the rated current, and the performance detection of the current transformer to be detected at multiple current data points between 5% and 120% of the rated current is satisfied. That is, the present application can adjust the current flowing through the current transformer to be detected in a short time, and realize the full-range performance detection in a short time. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 A structural schematic diagram of a current transformer detection system provided by the embodiments of the present application is shown in the figure.

[0034] Figure 2 A current phasor diagram provided by the embodiments of the present application is shown in the figure.

[0035] Figure 3Another current phasor diagram provided for the embodiments of the present application. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0037] The embodiments of the present application provide a current transformer detection system, which can solve the technical problem that the current transformer detection system is difficult to realize performance detection in a short time in a range of 5% to 120% rated current.

[0038] Referring to Figure 1 The embodiments of the present application provide a current transformer detection system for online detection of a current transformer between a power supply network and a load, which comprises a current collection sensor, a compensation device and a controller.

[0039] The current collection sensor is arranged between a to-be-detected current transformer (to-be-detected CT) and the load, and is used to collect a load current. Optionally, the current collection sensor can adopt an auxiliary current transformer. The compensation device is connected in parallel with the to-be-detected current transformer, and the controller is connected with the current collection sensor and the compensation device.

[0040] The controller is used to control the compensation device to generate a compensation current according to the load current collected by the current collection sensor, so that the current flowing through the to-be-detected current transformer changes between 5% to 120% rated current.

[0041] Specifically, the controller is usually provided with an analog-to-digital conversion module, and the load current collected by the current collection sensor is input into a control module of the controller for processing after analog-to-digital conversion. In general, the load current is the same as the current flowing through the to-be-detected current transformer. However, the controller controls the compensation device to generate a compensation current, which is superimposed with the load current, so that the current flowing through the to-be-detected current transformer changes between 5% to 120% rated current, thereby realizing performance detection of multiple current data points.

[0042] The current transformer detection system in the embodiment of the application is provided with a current collection sensor, a compensation device and a controller, the current collection sensor is used for collecting load current, the compensation device is connected in parallel with the current transformer to be detected, and the controller controls the compensation device to generate compensation current according to the load current collected by the current collection sensor, so that the current flowing through the current transformer to be detected is changed between 5% and 120% of the rated current, and the performance detection of the current transformer to be detected at multiple current data points between 5% and 120% of the rated current is met, that is, the current flowing through the current transformer to be detected can be adjusted in a short time, and full-range performance detection in a short time is realized.

[0043] As an optional implementation, in one embodiment of the application, the compensation device comprises a first compensator and a second compensator, the AC side of the first compensator is connected with the power supply network and the current transformer to be detected, the AC side of the second compensator is connected with the current transformer to be detected and the load, and the DC side of the first compensator is connected with the DC side of the second compensator. The controller controls the first compensator and the second compensator to generate compensation current with the same size and opposite phase, so that the current flowing through the current transformer to be detected is changed between 5% and 120% of the rated current.

[0044] Specifically, the actual current flowing through the current transformer to be detected can be represented as: i CT =i L +i STATCOM1 。 Wherein, i CT is the actual current flowing through the current transformer to be detected, i L is the load current, and i STATCOM1 is the compensation current generated by the first compensator.

[0045] Further, the first compensator and the second compensator generate compensation current with the same size and opposite phase, and the compensation current only flows in the loop of “the first compensator-current transformer to be detected-the second compensator”, without affecting other parts of the system, that is, i STATCOM2 =-i STATCOM1 , wherein i STATCOM2 is the compensation current generated by the second compensator, and by changing the current size generated by the first compensator and the second compensator, the current size flowing through the current transformer to be detected can be changed between 5% and 120% of the rated current I N , so as to complete full-measurement-range detection of the current transformer to be detected.

[0046] Still further, referring to Figure 2As shown, if the load current is greater than the required current of the current transformer to be tested, the controller controls the first compensator to generate a current of the same phase as the load current, so that the current flowing through the current transformer to be tested is increased.

[0047] Referring to Figure 3 As shown, if the load current is less than the required current of the current transformer to be tested, the controller controls the first compensator to generate a current of the opposite phase of the load current, so that the current flowing through the current transformer to be tested is reduced.

[0048] Optionally, the first compensator and the second compensator are both static synchronous compensators. The static synchronous compensator has the advantages of continuous adjustment, small harmonic, low loss, wide operating range, high reliability, fast adjustment speed, etc.

[0049] As an optional implementation, in one embodiment of the application, a capacitor U is connected in parallel between the DC side of the first compensator and the DC side of the second compensator. dc The capacitor U dc ensures that the voltage does not change during detection, and provides the active component necessary for tracking the load current.

[0050] As an optional implementation, in one embodiment of the application, a first disconnecting switch is arranged between the AC side of the first compensator and the power grid and the current transformer to be tested, and a second disconnecting switch is arranged between the AC side of the second compensator and the current transformer to be tested and the load. The first disconnecting switch and the second disconnecting switch facilitate the first compensator and the second compensator to access the power grid-load circuit.

[0051] As an optional implementation, in one embodiment of the application, a first inductor is arranged between the AC side of the first compensator and the first disconnecting switch, and a second inductor is arranged between the AC side of the second compensator and the second disconnecting switch. The first inductor and the second inductor can reduce the impact during the process of the first compensator and the second compensator being electrified to access the power grid-load circuit.

[0052] As an optional implementation, in one embodiment of the application, a first step-up transformer is arranged between the AC side of the first compensator and the first inductor, and a second step-up transformer is arranged between the AC side of the second compensator and the second inductor. The first step-up transformer and the second step-up transformer facilitate the output voltage of the first compensator and the second compensator to match the voltage of the power grid-load circuit.

[0053] As an optional implementation, in one embodiment of the application, the current transformer detection system further comprises a standard transformer connected in series between the current transformer to be detected and the power supply network, the standard transformer being connected to the controller, and the controller being configured to determine whether the current transformer to be detected is accurate in measurement according to the amplitude ratio difference between the standard transformer and the current transformer to be detected.

[0054] During detection, the data collected by the standard current transformer and the current transformer to be detected are converted into digital quantities after A / D conversion, and the data in multiple cycles are continuously read under the same time reference after the output signals of the standard current transformer and the current transformer to be detected are stable, so as to obtain the amplitudes of the signals of the two current transformers, and the amplitude ratio difference is:

[0055]

[0056] wherein K n is the standard transformation ratio, I CT1 is the amplitude of the standard current transformer, and I CT2 is the amplitude of the current transformer to be detected. If the amplitude ratio difference f is within the preset ratio difference range, it is determined that the current transformer to be detected is accurate in measurement; otherwise, it is determined that the current transformer to be detected is inaccurate in measurement.

[0057] The embodiment of the application further provides a current transformer detection method, comprising the following steps:

[0058] Collecting a load current;

[0059] Controlling a compensation device to generate a compensation current according to the collected load current, so that the current flowing through the current transformer to be detected is changed between 5% and 120% of the rated current.

[0060] The current transformer detection method in the embodiment of the application collects a load current, and controls a compensation device to generate a compensation current according to the collected load current, so that the current flowing through the current transformer to be detected is changed between 5% and 120% of the rated current, thereby meeting the performance detection of the current transformer to be detected at multiple current data points between 5% and 120% of the rated current, i.e., the application can adjust the current flowing through the current transformer to be detected in a short time, and realize the full-range performance detection in a short time.

[0061] In the description of the present application, it should be noted that the terms "upper", "lower", and the like are used for indicating the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0062] It should be noted that in the present application, relational terms such as "first" and "second", and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or other elements inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus including the element.

[0063] The above is only a specific embodiment of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features of the present application.

Claims

1. A current transformer detection system for online detection of a current transformer located between a power supply network and a load, characterized in that The current acquisition sensor is arranged between the to-be-tested current transformer and a load, and is configured to acquire a load current. The compensation device is connected in parallel with the to-be-tested current transformer. The controller is connected with the current acquisition sensor and the compensation device. The controller is configured to control the compensation device to generate a compensation current according to the load current acquired by the current acquisition sensor, so that the current flowing through the to-be-tested current transformer changes between 5% and 120% of the rated current. The compensation device comprises: The first compensator and the second compensator, the AC side of the first compensator is connected with the power supply network and the to-be-tested current transformer, the AC side of the second compensator is connected with the to-be-tested current transformer and the load, and the DC side of the first compensator is connected with the DC side of the second compensator. The controller controls the first compensator and the second compensator to generate compensation currents of the same size and opposite phases, so that the current flowing through the to-be-tested current transformer changes between 5% and 120% of the rated current.

2. The current transformer detection system according to claim 1, wherein: If the load current is greater than the required current of the to-be-tested current transformer, the controller controls the first compensator to generate a current of the same phase as the load current, so that the current flowing through the to-be-tested current transformer increases. If the load current is less than the required current of the to-be-tested current transformer, the controller controls the first compensator to generate a current of the opposite phase to the load current, so that the current flowing through the to-be-tested current transformer decreases.

3. The current transformer detection system according to claim 1, wherein: The DC side of the first compensator is connected in parallel with the DC side of the second compensator.

4. The current transformer detection system according to claim 1, wherein: The AC side of the first compensator is provided with a first disconnecting switch between the power supply network and the to-be-tested current transformer. The AC side of the second compensator is provided with a second disconnecting switch between the to-be-tested current transformer and the load.

5. The current transformer detection system according to claim 4, wherein: The AC side of the first compensator is provided with a first inductor between the first disconnecting switch. The AC side of the second compensator is provided with a second inductor between the second disconnecting switch.

6. The current transformer detection system according to claim 5, wherein: The AC side of the first compensator is provided with a first step-up transformer between the first inductor. The AC side of the second compensator is provided with a second step-up transformer between the second inductor. The first compensator and the second compensator are both static synchronous compensators.

7. The current transformer detection system of claim 1, wherein: Further comprising:

8. The current transformer detection system of claim 1, wherein, A standard transformer is connected in series between the to-be-tested current transformer and the power supply network, the standard transformer is connected with the controller, and the controller is configured to determine whether the to-be-tested current transformer is accurately measured according to the amplitude ratio difference between the standard transformer and the to-be-tested current transformer. The steps comprise:

9. A current transformer detection method using the current transformer detection system of claim 1, characterized by, Acquiring a load current; ​ The compensation device generates a compensation current according to the collected load current, so that the current flowing through the current transformer to be tested varies between 5% and 120% of the rated current.

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