CN107589330B - Live detection system and method for loss of power transformer - Google Patents
Live detection system and method for loss of power transformer Download PDFInfo
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Abstract
The invention discloses a live detection system and a live detection method for loss of a power transformer, wherein in the system, the input end of a primary side voltage transformer is respectively connected with the high-voltage side and the low-voltage side of the power transformer, and the output end of the primary side voltage transformer is connected with an isolation transformer; the input end of the primary side current transformer is connected with the ports of the high-voltage side and the low-voltage side of the power transformer through the jaw, and the output end of the primary side current transformer is connected with the secondary side current transformer; the output end of the isolation transformer is connected with the input end of the secondary side voltage transformer; the output end of the secondary side current transformer is connected with the input end of the optical coupling isolation module; the output end of the optical coupling module and the output end of the secondary side voltage transformer are connected with the input end of the signal acquisition system, and the output end of the signal acquisition system is connected with the upper computer system; the upper computer system is used for extracting and analyzing the acquired voltage and current signals and finally obtaining the no-load loss and the load loss of the power transformer. The invention can accurately judge the loss state of the power transformer, has the characteristics of real-time calculation and live test, and has high test accuracy.
Description
Technical Field
The invention relates to the technical field of power transformers, in particular to a live detection system for loss of a power transformer.
Background
The power transformer is an electric device for changing the magnitude of ac voltage, and converts ac voltage of a certain level into ac voltage of another level according to the principle of electromagnetic induction, so as to meet different requirements of various electric devices, and thus has a significant position in the electric industry. With the development of power industry, the variety of transformers is increasing, from low voltage and small capacity to current high voltage and large capacity, and nowadays, the voltage class and the capacity of the transformers even reach millions of volts and kilovolts. The power transmission and distribution equipment which is indispensable in the power system is responsible for the tasks of power transmission and voltage and current transformation in the power system, and the performance of the power transmission and distribution equipment directly influences the safe, reliable, economical and efficient operation of a power grid.
Losses of the power transformer can be divided into no-load losses and load losses. The no-load loss refers to the loss generated by the iron core of the power transformer in the no-load state of the transformer, and is mainly caused by hysteresis loss and eddy current loss, and is related to factors such as voltage, frequency, iron core material and the like. Load losses refer to losses in the power transformer caused by the internal windings under load conditions, which are mainly related to the load size. The state of losses in the transformer is an important factor in determining the operating temperature of the transformer. When the loss of the power transformer is high, the working temperature of the power transformer can be gradually increased, the reliability of the power transformer is reduced, and the normal working state and the working life of the transformer are affected. When the temperature rises, the no-load loss and the load loss of the power transformer are influenced and further increased, positive feedback is formed to promote the further increase of the temperature, the aging rate of an internal insulation structure of the transformer is accelerated, the working state of the transformer is influenced, and the service life of the transformer is finally reduced. The world energy is increasingly stressed, and energy conservation is the subject of common attention and research in the whole society, so that the research on the harmonic loss of the transformer has important significance in saving energy, optimizing the environment and assisting in realizing the loss reduction and energy conservation of the power grid.
At present, an off-line test method is generally adopted for detecting the loss of the power transformer, namely, the power transformer is cut off from the power grid side during detection, the rated voltage is added to the low-voltage side of the power transformer, the no-load loss of the power transformer is tested by opening the circuit at the high-voltage side of the power transformer, the rated current is added to the high-voltage side of the power transformer, and the load loss of the power transformer is tested by short-circuiting the low-voltage side of the power transformer. The offline testing method is complex in operation, the power transformer is required to be cut off from the operation state, and the offline testing method can only be completed under light load and the corresponding load provided by the standby power transformer, so that the offline testing method has a large limitation. Therefore, a live test method for the no-load loss and the load loss of the power transformer is provided, and the no-load loss and the load loss of the power transformer are deduced by testing the current and the voltage of the high-voltage side and the low-voltage side of the power transformer respectively. However, the measurement accuracy of the primary side and secondary side measuring equipment is limited, and the system errors caused by various electronic devices in the measuring process have certain influence on the test results of the no-load loss and the load loss of the power transformer.
Chinese patent application publication No. CN104502738A discloses a "transformer loss monitoring device" that measures internal loss of a transformer using a high-voltage meter and a low-voltage meter, and transmits a test result by means of wireless signal communication. The method is only suitable for testing low-voltage-class power transformers, and the wireless signal communication mode has the problems of poor signal quality, useless signal coupling and the like under the strong electromagnetic interference environment, so that the final test result is influenced.
Chinese patent application No. CN201410438533.8 discloses an online three-winding transformer loss measurement system that uses a voltage transformer and a current transformer to test the three-winding power transformer loss. The voltage transformer and the current transformer in the patent application are not isolated, and are easy to damage a signal acquisition system. And in signal analysis, a final loss result is obtained by adopting a Fourier transformation superposition subharmonic loss method, and subharmonic on the voltage transformer and the current transformer is easy to couple, so that the final calculation result is interfered.
In view of the foregoing, there is no method for realizing high-precision online measurement of no-load loss and load loss of a power transformer, and a novel testing means and a novel detection method are needed.
Disclosure of Invention
The invention aims to provide a live detection system for loss of a power transformer, so as to solve the technical problems. The invention is suitable for the live detection of the no-load loss and the load loss of the high-voltage-class power transformer, can accurately judge the loss state of the power transformer, has the characteristics of real-time calculation and live test, and has higher test accuracy.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the live detection system for the loss of the power transformer comprises a primary side voltage transformer, a primary side current transformer, an isolation transformer, a secondary side current transformer, a secondary side voltage transformer, an optical coupler isolation module, a signal acquisition system and an upper computer system; the input end of the primary side voltage transformer is respectively connected with the high-voltage side and the low-voltage side of the power transformer, and the output end of the primary side voltage transformer is connected with the isolation transformer; the input end of the primary side current transformer is connected with the ports of the high-voltage side and the low-voltage side of the power transformer through the jaw, and the output end of the primary side current transformer is connected with the secondary side current transformer; the output end of the isolation transformer is connected with the input end of the secondary side voltage transformer; the output end of the secondary side current transformer is connected with the input end of the optical coupling isolation module; the output end of the optical coupling module and the output end of the secondary side voltage transformer are connected with the input end of the signal acquisition system, and the output end of the signal acquisition system is connected with the upper computer system; the upper computer system is used for extracting and analyzing the acquired voltage and current signals and finally obtaining the no-load loss and the load loss of the power transformer.
Further, the primary side voltage transformer comprises a voltage transformer PT A Potential transformer PT B Potential transformer PT C Potential transformer PT X Potential transformer PT Y Potential transformer PT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the potential transformer PT A Input end is connected with high-voltage side A of power transformer, and voltage transformer PT B Input terminal and power transformer heightThe B phase of the pressure side is connected, the potential transformer PT C Input end is connected with high-voltage side C of power transformer, voltage transformer PT X Input end is connected with low-voltage side A of power transformer, and voltage transformer PT Y Input end is connected with low-voltage side B of power transformer, voltage transformer PT Z The input end is connected with a low-voltage side C of the power transformer;
the isolation transformer includes an isolation transformer IT A Isolation transformer IT B Isolation transformer IT C Isolation transformer IT X Isolation transformer IT Y Isolation transformer IT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein the isolation transformer IT A Input terminal and voltage transformer PT A The output end is connected with the isolation transformer IT B Input terminal and voltage transformer PT B The output end is connected with the isolation transformer IT C Input terminal and voltage transformer PT C The output end is connected with the isolation transformer IT X Input terminal and voltage transformer PT X The output end is connected with the isolation transformer IT Y Input terminal and voltage transformer PT Y The output end is connected with the isolation transformer IT Z Input terminal and voltage transformer PT Z The output end is connected;
the secondary side voltage transformer comprises a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the potential transformer PT a Input terminal and isolation transformer IT A The output end is connected with a voltage transformer PT b Input terminal and isolation transformer IT B The output end is connected with a voltage transformer PT c Input terminal and isolation transformer IT C The output end is connected with a voltage transformer PT x Input terminal and isolation transformer IT X The output end is connected with a voltage transformer PT y Input terminal and isolation transformer IT Y The output end is connected with a voltage transformer PT z Input terminal and isolation transformer IT Z The output end is connected.
Further, the primary side current transformer comprises a current transformer CT A Current transformer CT B Current transformer CT C Current transformer CT X The current transformer comprises CT Y The current transformer comprises CT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the current transformer CT A Input end is connected with high-voltage side A of power transformer, current transformer CT B Input end is connected with high-voltage side B phase of power transformer, current transformer CT C Input end is connected with high-voltage side C of power transformer, current transformer CT X The input end is connected with the low-voltage side A of the power transformer, and the current transformer CT Y Input end is connected with low-voltage side B phase of power transformer, current transformer CT Z The input end is connected with a low-voltage side C of the power transformer;
the secondary side current transformer comprises a current transformer CT a Current transformer CT b Current transformer CT c Current transformer CT x The current transformer comprises CT y Current transformer CT z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the current transformer CT a Input end and current transformer CT A The output ends are connected, and the current transformer CT b Input end and current transformer CT B The output ends are connected, and the current transformer CT c Input end and current transformer CT C The output ends are connected, and the current transformer CT x Input end and current transformer CT X The output ends are connected, and the current transformer CT y Input end and current transformer CT Y The output ends are connected, and the current transformer CT z Input end and current transformer CT Z The output end is connected;
the optocoupler isolation module comprises an optocoupler isolation module OC a Optical coupling module OC b Optical coupling module OC c Optical coupling module OC x Optical coupling module OC y Optical coupling module OC z The method comprises the steps of carrying out a first treatment on the surface of the Wherein the optical coupling module OC a Input end and current transformer CT a The output end is connected with the optical coupling module OC b Input end and current transformer CT b The output end is connected with the optical coupling module OC c Input end and current transformer CT c The output end is connected with the optical coupling module OC x Input end and current transformer CT x The output end is connected with the optical coupling module OC y Input end and current transformer CT y The output end is connected with the optical coupling module OC z Input end and current transformer CT z The output end is connected.
Further, the signal acquisition system comprises a voltage acquisition card and a current acquisition card; the input end of the voltage acquisition card is respectively connected with a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z The output end is connected; the input end of the current acquisition card is respectively isolated from the optical coupler isolation module OC a Optical coupling isolation module OC b Optical coupling isolation module OC c Optical coupling isolation module OC x Optical coupling isolation module OC y Optical coupling isolation module OC z The output end is connected; the signal acquisition system is used for acquiring output results of the installed secondary side voltage transformer and the secondary side current transformer in a time-sharing manner, acquiring continuously-transformed voltage and current signals in a real-time discrete manner, and sending the acquisition results to the upper computer system.
Further, the upper computer system calculates the no-load loss and the load loss of the power transformer in real time according to a preset no-load loss and load loss calculation method according to the acquired discrete voltage and current signals;
the preset no-load loss and load loss calculation method comprises the following steps:
before the live detection system for loss of the power transformer is used for testing no-load loss and load loss of the power transformer, a standard instrument is used for calibrating voltage and current test results of the live detection system for loss of the power transformer and a voltage calibration curve f is drawn u And a current calibration curve f i ;
If the voltage signal sequences obtained by the live detection system testing the loss of the power transformer are respectively U a ,U b ,U c ,U x ,U y ,U z The current signal sequence is I a ,I b ,I c ,I x ,I y ,I z The method comprises the steps of carrying out a first treatment on the surface of the Then the voltage signal sequence is changed to f by using the calibration curve u (U a ),f u (U b ),f u (U c ),f u (U x ),f u (U y ),f u (U z ) The method comprises the steps of carrying out a first treatment on the surface of the The current signal sequence is changed to f i (Ia),f i (I b ),f i (I c ),f i (I x ),f i (I y ),f i (I z ) The method comprises the steps of carrying out a first treatment on the surface of the Firstly, converting voltage and current signals into voltage and current of a Yy0 type power transformer according to standards, and then directly converting voltage and current sequences into per unit value according to the grade of the power transformer; if the signal acquisition system acquires 12n points in 0.02s, the voltage signal sequence f of the A phase per unit value of the high-voltage side of the power transformer after conversion u ’(U a ) Expressed as:
f u '(U a )=[f u '(U a0 ),f u '(U a1 ),f u '(U a2 ),…,f u '(U ai ),…,f u '(U an )]
the power transformer high side a-phase current signal sequence is expressed as:
f i '(I a )=[f i '(I a0 ),f i '(I a1 ),f i '(I a2 ),…,f i '(I ai ),…,f i '(I an )]
the power at the high-voltage side of the a-phase of the power transformer is expressed as:
the power of the B phase, the C phase and the Z phase of the high-voltage side of the power transformer and the power of the X phase, the Y phase and the Z phase of the low-voltage side of the power transformer are calculated according to the above formula respectively; the power loss of the power transformer is expressed as:
P total (S) =P A +P B +P C -P X -P Y -P Z
The no-load loss of the power transformer is expressed as:
the load loss of the power transformer is expressed as:
a live detection method of power transformer loss is based on a live detection system of power transformer loss; the live detection system for the loss of the power transformer comprises a primary side voltage transformer, a primary side current transformer, an isolation transformer, a secondary side current transformer, a secondary side voltage transformer, an optical coupling isolation module, a signal acquisition system and an upper computer system; the input end of the primary side voltage transformer is respectively connected with the high-voltage side and the low-voltage side of the power transformer, and the output end of the primary side voltage transformer is connected with the isolation transformer; the input end of the primary side current transformer is connected with the ports of the high-voltage side and the low-voltage side of the power transformer through the jaw, and the output end of the primary side current transformer is connected with the secondary side current transformer; the output end of the isolation transformer is connected with the input end of the secondary side voltage transformer; the output end of the secondary side current transformer is connected with the input end of the optical coupling isolation module; the output end of the optical coupling module and the output end of the secondary side voltage transformer are connected with the input end of the signal acquisition system, and the output end of the signal acquisition system is connected with the upper computer system; the upper computer system is used for extracting and analyzing the acquired voltage and current signals and finally obtaining the no-load loss and the load loss of the power transformer;
the live detection method for the loss of the power transformer comprises the following steps: the upper computer system calculates the no-load loss and the load loss of the power transformer in real time according to a preset no-load loss and load loss calculation method according to the acquired discrete voltage and current signals;
the preset no-load loss and load loss calculation method comprises the following steps:
before the live detection system for loss of the power transformer is used for testing no-load loss and load loss of the power transformer, a standard instrument is used for testing the voltage and current of the live detection system for loss of the power transformerThe result is calibrated and a voltage calibration curve f is drawn u And a current calibration curve f i ;
If the voltage signal sequences obtained by the live detection system testing the loss of the power transformer are respectively U a ,U b ,U c ,U x ,U y ,U z The current signal sequence is I a ,I b ,I c ,I x ,I y ,I z The method comprises the steps of carrying out a first treatment on the surface of the Then the voltage signal sequence is changed to f by using the calibration curve u (U a ),f u (U b ),f u (U c ),f u (U x ),f u (U y ),f u (U z ) The method comprises the steps of carrying out a first treatment on the surface of the The current signal sequence is changed to f i (Ia),f i (I b ),f i (I c ),f i (I x ),f i (I y ),f i (I z ) The method comprises the steps of carrying out a first treatment on the surface of the Firstly, converting voltage and current signals into voltage and current of a Yy0 type power transformer according to standards, and then directly converting voltage and current sequences into per unit value according to the grade of the power transformer; if the signal acquisition system acquires 12n points in 0.02s, the voltage signal sequence f of the A phase per unit value of the high-voltage side of the power transformer after conversion u ’(U a ) Expressed as:
f u '(U a )=[f u '(U a0 ),f u '(U a1 ),f u '(U a2 ),…,f u '(U ai ),…,f u '(U an )]
the power transformer high side a-phase current signal sequence is expressed as:
f i '(I a )=[f i '(I a0 ),f i '(I a1 ),f i '(I a2 ),…,f i '(I ai ),…,f i '(I an )]
the power at the high-voltage side of the a-phase of the power transformer is expressed as:
the power of the B phase, the C phase and the Z phase of the high-voltage side of the power transformer and the power of the X phase, the Y phase and the Z phase of the low-voltage side of the power transformer are calculated according to the above formula respectively; the power loss of the power transformer is expressed as:
P total (S) =P A +P B +P C -P X -P Y -P Z
The no-load loss of the power transformer is expressed as:
the load loss of the power transformer is expressed as:
further, the primary side voltage transformer comprises a voltage transformer PT A Potential transformer PT B Potential transformer PT C Potential transformer PT X Potential transformer PT Y Potential transformer PT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the potential transformer PT A Input end is connected with high-voltage side A of power transformer, and voltage transformer PT B Input end is connected with high-voltage side B of power transformer, voltage transformer PT C Input end is connected with high-voltage side C of power transformer, voltage transformer PT X Input end is connected with low-voltage side A of power transformer, and voltage transformer PT Y Input end is connected with low-voltage side B of power transformer, voltage transformer PT Z The input end is connected with a low-voltage side C of the power transformer;
the isolation transformer includes an isolation transformer IT A Isolation transformer IT B Isolation transformer IT C Isolation transformer IT X Isolation transformer IT Y Isolation transformer IT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein the isolation transformer IT A Input terminal and voltage transformer PT A The output end is connected with the isolation transformer IT B Input terminal and voltage transformer PT B The output end is connected with the isolation transformer IT C Input terminal and voltage transformer PT C The output end is connected with the isolation transformer IT X Input terminal and voltage transformer PT X The output end is connected with the isolation transformer IT Y Input terminal and voltage transformer PT Y The output end is connected with the isolation transformer IT Z Input terminal and voltage transformer PT Z The output end is connected;
the secondary side voltage transformer comprises a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the potential transformer PT a Input terminal and isolation transformer IT A The output end is connected with a voltage transformer PT b Input terminal and isolation transformer IT B The output end is connected with a voltage transformer PT c Input terminal and isolation transformer IT C The output end is connected with a voltage transformer PT x Input terminal and isolation transformer IT X The output end is connected with a voltage transformer PT y Input terminal and isolation transformer IT Y The output end is connected with a voltage transformer PT z Input terminal and isolation transformer IT Z The output end is connected.
Further, the primary side current transformer comprises a current transformer CT A Current transformer CT B Current transformer CT C Current transformer CT X The current transformer comprises CT Y The current transformer comprises CT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the current transformer CT A Input end is connected with high-voltage side A of power transformer, current transformer CT B Input end is connected with high-voltage side B phase of power transformer, current transformer CT C Input end is connected with high-voltage side C of power transformer, current transformer CT X The input end is connected with the low-voltage side A of the power transformer, and the current transformer CT Y Input end is connected with low-voltage side B phase of power transformer, current transformer CT Z The input end is connected with a low-voltage side C of the power transformer;
the secondary side current transformer comprises a current transformer CT a Current transformer CT b Current transformer CT c Current transformer CT x The current transformer comprises CT y Current transformer CT z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the current transformer CT a Input end and current transformer CT A The output ends are connected, and the current transformer CT b Input end and current transformer CT B The output ends are connected, and the current transformer CT c Input end and current transformer CT C The output ends are connected, and the current transformer CT x Input end and current transformer CT X The output ends are connected, and the current transformer CT y Input end and current transformer CT Y The output ends are connected, and the current transformer CT z Input end and current transformer CT Z The output end is connected;
the optocoupler isolation module comprises an optocoupler isolation module OC a Optical coupling module OC b Optical coupling module OC c Optical coupling module OC x Optical coupling module OC y Optical coupling module OC z The method comprises the steps of carrying out a first treatment on the surface of the Wherein the optical coupling module OC a Input end and current transformer CT a The output end is connected with the optical coupling module OC b Input end and current transformer CT b The output end is connected with the optical coupling module OC c Input end and current transformer CT c The output end is connected with the optical coupling module OC x Input end and current transformer CT x The output end is connected with the optical coupling module OC y Input end and current transformer CT y The output end is connected with the optical coupling module OC z Input end and current transformer CT z The output end is connected.
Further, the signal acquisition system comprises a voltage acquisition card and a current acquisition card; the input end of the voltage acquisition card is respectively connected with a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z The output end is connected; the input end of the current acquisition card is respectively isolated from the optical coupler isolation module OC a Optical coupling isolation module OC b Optical coupling isolation module OC c Optical coupling isolation module OC x Optical coupling isolation module OC y Optical coupling isolation module OC z An output terminalAre connected; the signal acquisition system is used for acquiring output results of the installed secondary side voltage transformer and the secondary side current transformer in a time-sharing manner, acquiring continuously-transformed voltage and current signals in a real-time discrete manner, and sending the acquisition results to the upper computer system.
Compared with the prior art, the invention has the following advantages:
1. the real-time measurement is strong. The system can detect the no-load loss and the load loss of the power transformer in real time in a live manner, achieves the purpose of detecting the loss state of the power transformer in real time, and provides corresponding basis for determining the internal temperature, the working state and the life prediction of the power transformer.
2. The measuring object range is wide. The system can change primary side and secondary side voltage transformers and current transformers according to power transformers with different voltage levels, and can complete loss detection on power transformers with different power levels, different models and capacities under the condition that calibration is only needed, so that the system is wide in application range.
3. The detection system has high safety. The primary side voltage transformer and the secondary side voltage transformer of the system are isolated by adopting the isolation transformer, the secondary side current transformer and the signal acquisition system are isolated by adopting the optocoupler isolation module, the signal acquisition system, the upper computer and the operating personnel are always isolated from primary side voltage and current, and the safety performance of the measurement system is improved.
4. And using the per unit value to measure the no-load loss and the load loss. The no-load loss and the load loss of the power transformer are obtained by adopting per unit value calculation, so that the power transformers of different types are easy to compare with each other, the working state of the power transformer is easier to determine, and the operability of the system is improved.
Drawings
Fig. 1 is a schematic block diagram of a live detection system for loss of a power transformer according to the present invention.
Fig. 2 is an installation mode and a connection diagram of a live detection system for loss of a power transformer according to the present invention.
Fig. 3 is an equivalent schematic diagram of the no-load loss and load loss tests.
FIG. 4 is a flow chart of the detection method.
Detailed Description
The invention is further described with reference to the accompanying drawings:
referring to fig. 1 to 2, the power transformer loss live detection system of the invention comprises a primary side voltage transformer, a primary side current transformer, an isolation transformer, a secondary side current transformer, a secondary side voltage transformer, an optical coupling isolation module, a signal acquisition system and an upper computer system.
The input end of the primary side voltage transformer is respectively connected with the high-voltage side and the low-voltage side of the power transformer, and the output end of the primary side voltage transformer is connected with the isolation transformer; the input end of the primary side current transformer is connected with the ports of the high-voltage side and the low-voltage side of the power transformer through the jaw, and the output end of the primary side current transformer is connected with the secondary side current transformer; the output end of the isolation transformer is connected with the input end of the secondary side voltage transformer; the output end of the secondary side current transformer is connected with the input end of the optical coupling isolation module; the output end of the optical coupling module and the output end of the secondary side voltage transformer are connected with the input end of the signal acquisition system, the output end of the signal acquisition system inputs the acquired result into the upper computer system, and the acquired voltage and current signals are extracted and analyzed to finally obtain the no-load loss and the load loss of the power transformer.
The primary side voltage transformer comprises a voltage transformer PT A Potential transformer PT B Potential transformer PT C Potential transformer PT X Potential transformer PT Y Potential transformer PT Z . Wherein, the potential transformer PT A Input end is connected with high-voltage side A of power transformer, and voltage transformer PT B Input end is connected with high-voltage side B of power transformer, voltage transformer PT C Input end is connected with high-voltage side C of power transformer, voltage transformer PT X Input end is connected with low-voltage side A of power transformer, and voltage transformer PT Y Input end is connected with low-voltage side B of power transformer, voltage transformer PT Z The input end is connected with the low-voltage side C of the power transformer. The function of the transformer is to ensure that the voltage of the high-voltage side and the low-voltage side of the power transformer does not exceed the range of the primary-side voltage transformer, and the transformer is converted into the transformer in proportionAnd (3) voltage exceeding the range of the secondary side voltage transformer, and inputting the voltage into the isolation transformer.
The primary side current transformer comprises a current transformer CT A Current transformer CT B Current transformer CT C Current transformer CT X The current transformer comprises CT Y The current transformer comprises CT Z . Wherein, the current transformer CT A Input end is connected with high-voltage side A of power transformer, current transformer CT B Input end is connected with high-voltage side B phase of power transformer, current transformer CT C Input end is connected with high-voltage side C of power transformer, current transformer CT X The input end is connected with the low-voltage side A of the power transformer, and the current transformer CT Y Input end is connected with low-voltage side B phase of power transformer, current transformer CT Z The input end is connected with the low-voltage side C of the power transformer. The function of the power transformer is to ensure that the high-voltage side current and the low-voltage side current of the power transformer do not exceed the range of the primary side current transformer, to convert the power transformer into the current which does not exceed the range of the secondary side current transformer in proportion, and to input the current into the secondary side current transformer.
The isolation transformer includes an isolation transformer IT A Isolation transformer IT B Isolation transformer IT C Isolation transformer IT X Isolation transformer IT Y Isolation transformer IT Z . Wherein the isolation transformer IT A Input terminal and voltage transformer PT A The output end is connected with the isolation transformer IT B Input terminal and voltage transformer PT B The output end is connected with the isolation transformer IT C Input terminal and voltage transformer PT C The output end is connected with the isolation transformer IT X Input terminal and voltage transformer PT X The output end is connected with the isolation transformer IT Y Input terminal and voltage transformer PT Y The output end is connected with the isolation transformer IT Z Input terminal and voltage transformer PT Z The output end is connected. The high-voltage output side of the power transformer is isolated from the secondary side voltage transformer and the secondary side current transformer, so that the secondary side voltage transformer and the secondary side current transformer are prevented from being damaged.
The secondary side voltage transformer comprises a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z . Wherein, the potential transformer PT a Input terminal and isolation transformer IT A The output end is connected with a voltage transformer PT b Input terminal and isolation transformer IT B The output end is connected with a voltage transformer PT c Input terminal and isolation transformer IT C The output end is connected with a voltage transformer PT x Input terminal and isolation transformer IT X The output end is connected with a voltage transformer PT y Input terminal and isolation transformer IT Y The output end is connected with a voltage transformer PT z Input terminal and isolation transformer IT Z The output end is connected. The primary side voltage transformer has the function of converting the voltage output by the primary side voltage transformer so that the voltage can be collected by the signal collection system.
The secondary side current transformer comprises a current transformer CT a Current transformer CT b Current transformer CT c Current transformer CT x The current transformer comprises CT y Current transformer CT z . Wherein, the current transformer CT a Input end and current transformer CT A The output ends are connected, and the current transformer CT b Input end and current transformer CT B The output ends are connected, and the current transformer CT c Input end and current transformer CT C The output ends are connected, and the current transformer CT x Input end and current transformer CT X The output ends are connected, and the current transformer CT y Input end and current transformer CT Y The output ends are connected, and the current transformer CT z Input end and current transformer CT Z The output end is connected. The function of the current transformer is to transform the current output by the primary side current transformer, so that the current signal can be subjected to signal A/D acquisition conversion by the signal acquisition system.
The optocoupler isolation module comprises an optocoupler isolation module OC a Optical coupling module OC b Optical coupling module OC c Optical coupling moduleOC x Optical coupling module OC y Optical coupling module OC z . Wherein the optical coupling module OC a Input end and current transformer CT a The output end is connected with the optical coupling module OC b Input end and current transformer CT b The output end is connected with the optical coupling module OC c Input end and current transformer CT c The output end is connected with the optical coupling module OC x Input end and current transformer CT x The output end is connected with the optical coupling module OC y Input end and current transformer CT y The output end is connected with the optical coupling module OC z Input end and current transformer CT z The output end is connected. The function of the system is to isolate the output current of the secondary side current transformer from the signal acquisition system, so that the suddenly transformed large-current signal is prevented from being coupled to the signal acquisition system, and the acquisition board card is prevented from being damaged.
The signal acquisition system comprises a voltage acquisition card and a current acquisition card. The input end of the voltage acquisition card is respectively connected with a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z The output end is connected; the input end of the current acquisition card is respectively isolated from the optical coupler isolation module OC a Optical coupling isolation module OC b Optical coupling isolation module OC c Optical coupling isolation module OC x Optical coupling isolation module OC y Optical coupling isolation module OC z The output end is connected. The function of the system is to collect output results of the installed secondary side voltage transformer and the secondary side current transformer in a time-sharing way, collect continuously-transformed voltage and current signals in a real-time discrete manner, and send the collection results to an upper computer system.
And the upper computer system calculates the no-load loss and the load loss of the power transformer in real time according to a preset no-load loss and load loss calculation method according to the acquired discrete voltage and current signals.
Referring to fig. 3 and 4, the loss calculation method is as follows:
the detection system is respectively connected with the primary side voltage transformer, the primary side current transformer and the secondary side voltage transformer in the detection processThe secondary side voltage transformer and the secondary side current transformer respectively transform the voltage and the current, so that a certain deviation exists between the voltage value and the current value of the final input signal acquisition system. For this purpose, the invention adopts a calibration curve method to reduce the influence caused by the error. Before the detection system is used for testing the no-load loss and the load loss of the power transformer, the voltage and current test results of the detection system are calibrated by a standard instrument, and a voltage calibration curve f is drawn u And a current calibration curve f i . If the voltage signal sequence obtained by the system test is set as U a ,U b ,U c ,U x ,U y ,U z The current signal sequence is I a ,I b ,I c ,I x ,I y ,I z . Then the voltage signal sequence is changed to f by using the calibration curve u (U a ),f u (U b ),f u (U c ),f u (U x ),f u (U y ),f u (U z ) The method comprises the steps of carrying out a first treatment on the surface of the The current signal sequence is changed to f i (Ia),f i (I b ),f i (I c ),f i (I x ),f i (I y ),f i (I z ). For the convenience of calculation, the voltage and current signals are firstly converted into the voltage and current of the Yy0 type power transformer according to the standard, and then the voltage and current sequence is directly converted into a per unit value according to the grade of the power transformer. If the signal acquisition system acquires 12n points in 0.02s, the voltage signal sequence f of the A phase per unit value of the high-voltage side of the power transformer after conversion u ’(U a ) Expressed as:
f u '(U a )=[f u '(U a0 ),f u '(U a1 ),f u '(U a2 ),…,f u '(U ai ),…,f u '(U an )]
the power transformer high side a-phase current signal sequence is expressed as:
f i '(I a )=[f i '(I a0 ),f i '(I a1 ),f i '(I a2 ),…,f i '(I ai ),…,f i '(I an )]
the power at the high-voltage side of the a-phase of the power transformer is expressed as:
the power of the B phase, the C phase and the Z phase of the high-voltage side of the power transformer and the X phase, the Y phase and the Z phase of the low-voltage side of the power transformer can be calculated according to the above formula respectively. The power loss of the power transformer can be expressed as:
P total (S) =P A +P B +P C -P X -P Y -P Z
The no-load loss of the power transformer is expressed as:
the load loss of the power transformer is expressed as:
。
Claims (4)
1. the live detection method for the loss of the power transformer is characterized by comprising a live detection system based on the loss of the power transformer; the live detection system for the loss of the power transformer comprises a primary side voltage transformer, a primary side current transformer, an isolation transformer, a secondary side current transformer, a secondary side voltage transformer, an optical coupling isolation module, a signal acquisition system and an upper computer system; the input end of the primary side voltage transformer is respectively connected with the high-voltage side and the low-voltage side of the power transformer, and the output end of the primary side voltage transformer is connected with the isolation transformer; the input end of the primary side current transformer is connected with the ports of the high-voltage side and the low-voltage side of the power transformer through the jaw, and the output end of the primary side current transformer is connected with the secondary side current transformer; the output end of the isolation transformer is connected with the input end of the secondary side voltage transformer; the output end of the secondary side current transformer is connected with the input end of the optical coupling isolation module; the output end of the optical coupling module and the output end of the secondary side voltage transformer are connected with the input end of the signal acquisition system, and the output end of the signal acquisition system is connected with the upper computer system; the upper computer system is used for extracting and analyzing the acquired voltage and current signals and finally obtaining the no-load loss and the load loss of the power transformer;
the live detection method for the loss of the power transformer comprises the following steps: the upper computer system calculates the no-load loss and the load loss of the power transformer in real time according to a preset no-load loss and load loss calculation method according to the acquired discrete voltage and current signals;
the preset no-load loss and load loss calculation method comprises the following steps:
before the live detection system for loss of the power transformer is used for testing no-load loss and load loss of the power transformer, a standard instrument is used for calibrating voltage and current test results of the live detection system for loss of the power transformer and a voltage calibration curve f is drawn u And a current calibration curve f i ;
If the voltage signal sequences obtained by the live detection system testing the loss of the power transformer are respectively U a ,U b ,U c ,U x ,U y ,U z The current signal sequence is I a ,I b ,I c ,I x ,I y ,I z The method comprises the steps of carrying out a first treatment on the surface of the Then the voltage signal sequence is changed to f by using the calibration curve u (U a ),f u (U b ),f u (U c ),f u (U x ),f u (U y ),f u (U z ) The method comprises the steps of carrying out a first treatment on the surface of the The current signal sequence is changed to f i (Ia),f i (I b ),f i (I c ),f i (I x ),f i (I y ),f i (I z ) The method comprises the steps of carrying out a first treatment on the surface of the Firstly, converting voltage and current signals into voltage and current of a Yy0 type power transformer according to standards, and then directly converting voltage and current sequences into per unit value according to the grade of the power transformer; if the signal acquisition system acquires 12n points in 0.02s, the voltage signal sequence f of the A phase per unit value of the high-voltage side of the power transformer after conversion u ’(U a ) Expressed as:
f u '(U a )=[f u '(U a0 ),f u '(U a1 ),f u '(U a2 ),…,f u '(U ai ),…,f u '(U an )]
the power transformer high side a-phase current signal sequence is expressed as:
f i '(I a )=[f i '(I a0 ),f i '(I a1 ),f i '(I a2 ),…,f i '(I ai ),…,f i '(I an )]
the power at the high-voltage side of the a-phase of the power transformer is expressed as:
the power of the B phase, the C phase and the Z phase of the high-voltage side of the power transformer and the power of the X phase, the Y phase and the Z phase of the low-voltage side of the power transformer are calculated according to the above formula respectively; the power loss of the power transformer is expressed as:
P total (S) =P A +P B +P C -P X -P Y -P Z
The no-load loss of the power transformer is expressed as:
the load loss of the power transformer is expressed as:
2. the method for live detection of power transformer loss according to claim 1, wherein the primary side voltage transformer comprises a voltage transformer PT A Potential transformer PT B Potential transformer PT C Electric powerPotential transformer PT X Potential transformer PT Y Potential transformer PT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the potential transformer PT A Input end is connected with high-voltage side A of power transformer, and voltage transformer PT B Input end is connected with high-voltage side B of power transformer, voltage transformer PT C Input end is connected with high-voltage side C of power transformer, voltage transformer PT X Input end is connected with low-voltage side A of power transformer, and voltage transformer PT Y Input end is connected with low-voltage side B of power transformer, voltage transformer PT Z The input end is connected with a low-voltage side C of the power transformer;
the isolation transformer includes an isolation transformer IT A Isolation transformer IT B Isolation transformer IT C Isolation transformer IT X Isolation transformer IT Y Isolation transformer IT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein the isolation transformer IT A Input terminal and voltage transformer PT A The output end is connected with the isolation transformer IT B Input terminal and voltage transformer PT B The output end is connected with the isolation transformer IT C Input terminal and voltage transformer PT C The output end is connected with the isolation transformer IT X Input terminal and voltage transformer PT X The output end is connected with the isolation transformer IT Y Input terminal and voltage transformer PT Y The output end is connected with the isolation transformer IT Z Input terminal and voltage transformer PT Z The output end is connected;
the secondary side voltage transformer comprises a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the potential transformer PT a Input terminal and isolation transformer IT A The output end is connected with a voltage transformer PT b Input terminal and isolation transformer IT B The output end is connected with a voltage transformer PT c Input terminal and isolation transformer IT C The output end is connected with a voltage transformer PT x Input terminal and isolation transformer IT X The output end is connected with a voltage transformer PT y Input and isolationTransformer IT Y The output end is connected with a voltage transformer PT z Input terminal and isolation transformer IT Z The output end is connected.
3. The method for live detection of power transformer loss according to claim 2, wherein the primary side current transformer comprises a current transformer CT A Current transformer CT B Current transformer CT C Current transformer CT X The current transformer comprises CT Y The current transformer comprises CT Z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the current transformer CT A Input end is connected with high-voltage side A of power transformer, current transformer CT B Input end is connected with high-voltage side B phase of power transformer, current transformer CT C Input end is connected with high-voltage side C of power transformer, current transformer CT X The input end is connected with the low-voltage side A of the power transformer, and the current transformer CT Y Input end is connected with low-voltage side B phase of power transformer, current transformer CT Z The input end is connected with a low-voltage side C of the power transformer;
the secondary side current transformer comprises a current transformer CT a Current transformer CT b Current transformer CT c Current transformer CT x The current transformer comprises CT y Current transformer CT z The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the current transformer CT a Input end and current transformer CT A The output ends are connected, and the current transformer CT b Input end and current transformer CT B The output ends are connected, and the current transformer CT c Input end and current transformer CT C The output ends are connected, and the current transformer CT x Input end and current transformer CT X The output ends are connected, and the current transformer CT y Input end and current transformer CT Y The output ends are connected, and the current transformer CT z Input end and current transformer CT Z The output end is connected;
the optocoupler isolation module comprises an optocoupler isolation module OC a Optical coupling module OC b Optical coupling module OC c Optical coupling module OC x Optically coupled toModule OC y Optical coupling module OC z The method comprises the steps of carrying out a first treatment on the surface of the Wherein the optical coupling module OC a Input end and current transformer CT a The output end is connected with the optical coupling module OC b Input end and current transformer CT b The output end is connected with the optical coupling module OC c Input end and current transformer CT c The output end is connected with the optical coupling module OC x Input end and current transformer CT x The output end is connected with the optical coupling module OC y Input end and current transformer CT y The output end is connected with the optical coupling module OC z Input end and current transformer CT z The output end is connected.
4. A method for detecting the loss of a power transformer according to claim 3, wherein the signal acquisition system comprises a voltage acquisition card and a current acquisition card; the input end of the voltage acquisition card is respectively connected with a voltage transformer PT a Potential transformer PT b Potential transformer PT c Potential transformer PT x Potential transformer PT y Potential transformer PT z The output end is connected; the input end of the current acquisition card is respectively isolated from the optical coupler isolation module OC a Optical coupling isolation module OC b Optical coupling isolation module OC c Optical coupling isolation module OC x Optical coupling isolation module OC y Optical coupling isolation module OC z The output end is connected; the signal acquisition system is used for acquiring output results of the installed secondary side voltage transformer and the secondary side current transformer in a time-sharing manner, acquiring continuously-transformed voltage and current signals in a real-time discrete manner, and sending the acquisition results to the upper computer system.
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