CN114924209A - Transformer winding deformation monitoring system and method - Google Patents

Abstract

The embodiment of the invention discloses a transformer winding deformation monitoring system. The system includes: a voltage source, a secondary side capacitance sensor, a phase splitting switch, a secondary current monitoring device, and a winding deformation diagnosis unit; The phase switch and the secondary side capacitance sensor inject a voltage signal into each phase of the secondary side of the transformer; the secondary current monitoring device is used to measure the current signal of each phase on the secondary side of the transformer; the winding deformation diagnosis unit is also used to utilize each phase of the transformer. The voltage signal and current signal under the phase injection determine the loss tangent value of each phase of the transformer under different output frequencies, and use the loss angle tangent value of each phase to determine whether the transformer winding is deformed. Using the above transformer winding deformation monitoring system, the capacitance sensor is installed on the secondary side, which is easy to install and inexpensive. Since the transformer winding deformation mostly occurs on the secondary side, injecting a voltage signal on the secondary side to measure the winding deformation is helpful for finding minor windings. Deformation failure.

Description

Transformer winding deformation monitoring system and method

technical field

The invention relates to the technical field of power system monitoring, in particular to a transformer winding deformation monitoring system and method.

Background technique

Transformer is the key equipment in the power system. The sudden failure of the transformer during operation seriously affects the safety and stability of the power system, which can cause major asset losses and large-scale power outages. Transformer-related accidents show that winding deformation is one of the main causes of accidents. During operation, transformers are inevitably subjected to short-circuit current shocks, and the windings will be subjected to huge and uneven axial and radial electrodynamic forces. When there is a weak link in the internal mechanical structure of the winding, the winding deformation will inevitably occur due to the cumulative effect of the short-circuit power shock. Including axial and radial dimensional changes, body displacement, inter-turn short circuit and winding twist, bulge, etc. After the transformer winding is deformed, if it cannot be found in time, continued operation may cause sudden damage, insulation breakdown and other accidents.

In order to ensure the safe operation of the transformer, the offline detection method is generally used. In recent years, some scholars and research institutions have proposed the online frequency response method. Sweep signal. However, the end screen of the transformer bushing in online operation must be grounded. For a transformer running online, it is almost impossible to inject a sweeping signal from the end screen of the bushing; injecting a signal from the grounded neutral line of the transformer high-voltage winding requires a large power supply and operating noise. Large, difficult to inject and measure, difficult to implement on-site, and has not been used in practical applications after years of development.

In order to ensure the safe operation of the transformer, a convenient, economical and effective on-line monitoring system and method for transformer winding deformation is urgently needed, so as to realize on-line monitoring of the transformer winding state.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a transformer winding deformation monitoring system and method, which can solve the risks brought by the injection signal from the high voltage side to the operation of the transformer and the large error of the neutral point measurement current signal in the existing transformer winding deformation online monitoring technology. The problem.

In order to achieve the above object, a first aspect of the present invention provides a transformer winding deformation monitoring system, the transformer winding deformation monitoring system includes: a voltage source, a secondary side capacitance sensor, a phase split switch, a secondary current monitoring device, and a winding deformation diagnosis unit; wherein the voltage source is electrically connected to one end of the secondary side capacitive sensor via the phase split switch, and the other end of the secondary side capacitive sensor is electrically connected to the secondary side of the transformer; the The secondary current monitoring device is electrically connected to the secondary side of the transformer; the winding deformation diagnosis unit is electrically connected to the secondary current monitoring device and the voltage source, respectively;

The winding deformation diagnosis unit is configured to control the voltage source to inject a voltage signal into each phase of the secondary side of the transformer through the phase split switch and the secondary side capacitance sensor at different output frequencies;

The secondary current monitoring device is used to measure the current signal of each phase on the secondary side of the transformer, and transmit the current signal to the winding deformation diagnosis unit;

The winding deformation diagnosis unit is further configured to use the voltage signal and the current signal injected by each phase to determine the loss tangent value of each phase of the transformer under different output frequencies, and use the loss of the transformer in each phase. The tangent value determines whether the winding of the transformer is deformed.

In a feasible implementation manner, determining the loss tangent value of each phase of the transformer under different output frequencies by using the voltage signal and the current signal injected by each phase, including:

为注入电压信号；

为电流信号，tanδ_i为损耗角正切值，i表示所述电压源的不同输出频率。In the formula,

is the injection voltage signal;

is the current signal, tanδ _i is the loss tangent value, and i represents the different output frequencies of the voltage source.

In a feasible implementation manner, the judging whether the winding of the transformer is deformed by using the loss tangent value of the transformer of each phase includes:

Using the voltage source to inject the voltage signal into the total number of points of each phase of the transformer and the loss tangent value, determine the correlation coefficient of the loss tangent value between the corresponding phases of the transformer;

According to the correlation coefficient of the loss tangent value between the phases, it is determined whether the winding of the transformer is deformed.

In a feasible implementation manner, the voltage source is used to inject the voltage signal into the total number of points of each phase of the transformer and the loss tangent value, so as to determine the phase-to-phase relationship between the corresponding phases of the transformer. Correlation coefficients for loss tangent values, including:

r_xy为所述电压源的输出频率i下x相与y相注入时的损耗角正切值tanδ_i的曲线的相关系数，n为所述电压源的不同输出频率的总点数；x_i为x相第i频率点的损耗角正切值，y_i为y相第i频率点的损耗角正切值tanδ_i。in,

r _xy is the correlation coefficient of the curve of the loss tangent value tanδ _i when the x-phase and y-phase are injected at the output frequency i of the voltage source, n is the total number of points of different output frequencies of the voltage source; x _i is x The loss tangent value of the i-th frequency point of the phase, y _i is the loss tangent value tanδ _i of the i-th frequency point of the y-phase.

In a feasible implementation manner, the determining whether there is deformation in the winding of the transformer according to the correlation coefficient of the loss tangent value between the phases includes:

If the difference between the absolute values of the correlation coefficients of the loss tangent values between the phases is greater than a preset difference threshold, it is determined that the winding of the transformer is deformed;

If the difference between the absolute values of the correlation coefficients of the loss tangent values between the phases is less than or equal to a preset difference threshold, it is determined that the winding of the transformer is normal.

In a feasible implementation manner, the phase-splitting switch is composed of at least six switching elements, the winding deformation diagnosis unit is further electrically connected to the phase-splitting switch, and the winding deformation diagnosis unit is further configured to determine the voltage according to the voltage The target injection phase of the signal controls the opening and closing states of each switching element in the phase splitting switch.

In a feasible implementation manner, the transformer includes A-phase, B-phase and C-phase, and the control of the switching state of each switching element in the phase-splitting switch according to the target injection phase of the voltage signal, including :

When the target injection phase is phase A, the control switching elements Ka and K2 are in a closed state, and the control switching elements Kb, Kc, K1 and K3 are in an open state;

When the target injection phase is the B phase, the control switching elements Kb and K3 are in a closed state, and the control switching elements Ka, Kc, K1 and K2 are in an open state;

When the target injection phase is the C phase, the switching elements Kc and K1 are controlled to be in a closed state, and the switching elements Ka, Kb, K2 and K3 are controlled to be in an open state.

In a feasible implementation manner, the secondary side capacitive sensor has the load-bearing function of the pillar insulator, the capacitance value of the secondary side capacitive sensor of each phase of the transformer is equal, and the maximum capacitance is calculated by the following formula:

In the formula, I is the human body to get rid of the current, U _φ is the relative ground voltage of the system, and ω is the angular frequency at the power frequency.

In a feasible implementation manner, the secondary current monitoring device includes a Rogowski coil or a broadband current sensor for measuring broadband current, and the voltage source emits a power frequency with an amplitude of 0-500V and a frequency of 0.01Hz-10GHz sine wave.

In order to achieve the above object, a second aspect of the present invention provides a transformer winding deformation monitoring method, the transformer winding deformation monitoring method comprising:

When it is determined that the secondary side outlet of the transformer has no ground fault and the zero-sequence voltage offset is normal, the control voltage source injects voltage signals into each phase of the secondary side of the transformer at different output frequencies;

Using the voltage signal injected by each phase and the current signal of each phase on the secondary side of the transformer measured by the secondary current monitoring device, determine the loss tangent value of each phase of the transformer under different output frequencies;

Whether the winding of the transformer is deformed is judged by using the loss tangent value of the transformer of each phase.

Adopting the embodiment of the present invention has the following beneficial effects:

The invention provides a transformer winding deformation monitoring system. The transformer winding deformation monitoring system includes: a voltage source, a secondary side capacitance sensor, a phase split switch, a secondary current monitoring device, and a winding deformation diagnosis unit; The switch is electrically connected to one end of the secondary side capacitive sensor, and the other end of the secondary side capacitive sensor is electrically connected to the secondary side of the transformer; the secondary current monitoring device is electrically connected to the secondary side of the transformer; the winding deformation diagnosis unit is respectively connected to the secondary side of the transformer. The secondary current monitoring device and the voltage source are electrically connected; the winding deformation diagnosis unit is used to control the voltage source to inject voltage signals into each phase of the secondary side of the transformer through the phase splitting switch and the secondary side capacitance sensor at different output frequencies; the secondary current The monitoring device is used to measure the current signal of each phase on the secondary side of the transformer, and transmit the current signal to the winding deformation diagnosis unit; the winding deformation diagnosis unit is also used to use the voltage signal and current signal injected by each phase to determine different outputs The tangent value of the loss angle of each phase of the transformer under the frequency, and the tangent value of the loss angle of each phase is used to judge whether the winding of the transformer is deformed. The above transformer winding deformation monitoring system is adopted, and its capacitive sensor is installed on the secondary side of the transformer, which can be used instead of any insulator on the low-voltage side, and can also be installed next to the electromagnetic voltage transformer PT on the low-voltage side of the transformer, without the need for the installation of bus power failure, and its operating life Consistent with insulators, and the price is low. Since the deformation of transformer windings mostly occurs on the low-voltage side, injecting voltage signals on the low-voltage side to measure the winding deformation is conducive to finding minor winding deformation faults; the line voltage on the low-voltage side of the transformer is usually below 66kV, and the voltage level is low, which is extremely high. Partially ungrounded systems, the sensors are easy to install and operate with low risk.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

in:

1 is a schematic structural diagram of a transformer winding deformation monitoring system in an embodiment of the present invention;

2 is a flowchart of a method for monitoring transformer winding deformation in an embodiment of the present invention;

3 is another schematic structural diagram of a transformer winding deformation monitoring system in an embodiment of the present invention;

4 is a schematic diagram of injecting a voltage signal into each phase of a transformer in an embodiment of the present invention;

FIG. 5 is a loss tangent curve of each phase of a transformer under different output frequencies in an embodiment of the present invention, wherein FIG. 5a is a loss tangent curve of phase A of the transformer under different output frequencies, and FIG. 5b is a The loss tangent curve of phase B of the transformer under different output frequencies, Figure 5c is the loss tangent curve of phase C of the transformer at different output frequencies, and Figure 5d is the A, B and C of the transformer at different output frequencies The combined schematic diagram of the three-phase loss tangent curve;

FIG. 6 is another flowchart of a method for monitoring transformer winding deformation in an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to FIG. 1. FIG. 1 is a schematic structural diagram of a transformer winding deformation monitoring system according to an embodiment of the present invention. As shown in FIG. 1, the transformer winding deformation monitoring system includes: a secondary side capacitance sensor 10, a phase split switch 20, a voltage source 30. A winding deformation diagnosis unit 40, and a secondary current monitoring device 50; wherein, the voltage source 30 is electrically connected to one end of the secondary side capacitive sensor 10 through the phase split switch 20, and the other end of the secondary side capacitive sensor 10 is connected to the transformer 00. The secondary side is electrically connected; the secondary current monitoring device 50 is electrically connected to the secondary side of the transformer 00; the winding deformation diagnosis unit 40 is electrically connected to the secondary current monitoring device 50 and the voltage source 30 respectively;

Further, the winding deformation diagnosis unit 40 is used to control the voltage source 30 to inject a voltage signal into each phase of the secondary side of the transformer 00 through the phase split switch 20 and the secondary side capacitive sensor 10 at different output frequencies, wherein the voltage signal It is a frequency sweep signal, the voltage source 30 can generate an amplitude within 0-500V, and the output frequency can be a power-frequency sine voltage wave of 0.01Hz-10GHz; the secondary current monitoring device 50 is used to measure the secondary side of the transformer 00 The current signal of each phase is transmitted to the winding deformation diagnosis unit 40; for example, the primary side of the transformer can be the high voltage side of the transformer, and the secondary side of the transformer can be the medium voltage side of the transformer or the lowest voltage level. On the low voltage side, the secondary side capacitive sensor 10 may be a ceramic capacitive sensor.

The winding deformation diagnosis unit 40 is also used to determine the loss tangent value of each phase of the transformer 00 under different output frequencies by using the voltage signal and the current signal injected by each phase, and use the loss tangent value of the transformer 00 of each phase to determine the loss angle of the transformer 00. Whether the winding is deformed. Exemplarily, the winding deformation diagnosis unit 40 judges online whether there is a winding in the transformer winding by comparing the three-phase voltage injected by the voltage source 30 into the transformer 00 and the relative change of the loss tangent value of the same frequency current monitored by the secondary current monitoring device 50. Deformation, that is, by comparing the relative change of the three-phase dielectric loss tangent value, it is judged online whether there is winding deformation in the transformer winding.

It should be noted that if the frequency sweep signal is injected from the grounding neutral line of the high-voltage winding of the transformer or from the lead-out line of the high-voltage side bushing of the transformer, the sweep-frequency signal is capacitively coupled, so that the end of the bushing of the transformer must be grounded in online operation. Therefore, for the transformer running online, It is almost impossible to inject the sweeping signal from the end screen of the bushing; and if the signal is injected from the grounded neutral line of the high-voltage winding of the transformer, it requires a large power supply, large operating noise, difficult injection and measurement, and is difficult to implement on site. The invention overcomes the deficiency of injecting signals from the grounded neutral line of the transformer high-voltage winding or from the capacitive coupling at the end of the bushing on the high-voltage side of the transformer. The invention installs the ceramic capacitive sensor 10 on the low-voltage side of the transformer with the lowest voltage level, and the voltage source 30 passes through the divider. The phase switch 20 injects voltage signals of sine waves of different frequencies, the secondary current monitoring device 50 measures the current signals of each phase, and judges online whether there is winding deformation in the transformer winding through the relative change of the loss tangent value between the voltage signal and the current signal. . Since the voltage source 30 injects the voltage signal through the ceramic capacitive sensor 10, before the winding is deformed, the distribution parameters of each winding are almost the same. Therefore, the curves of the loss tangent value tanδ _i of each phase detected from the high-voltage side are consistent, and once the winding deformation occurs, due to the change of the distribution parameters, the loss angle tangent value tanδ _i curve of each phase will no longer be consistent. The loss tangent value _tanδi can judge whether the transformer winding deformation occurs.

The invention provides a transformer winding deformation monitoring system. The transformer winding deformation monitoring system includes: a voltage source, a secondary side capacitance sensor, a phase split switch, a secondary current monitoring device, and a winding deformation diagnosis unit; The switch is electrically connected to one end of the secondary side capacitive sensor, and the other end of the secondary side capacitive sensor is electrically connected to the secondary side of the transformer; the secondary current monitoring device is electrically connected to the secondary side of the transformer; the winding deformation diagnosis unit is respectively connected to the secondary side of the transformer. The secondary current monitoring device and the voltage source are electrically connected; the winding deformation diagnosis unit is used to control the voltage source to inject voltage signals into each phase of the secondary side of the transformer through the phase splitting switch and the secondary side capacitance sensor at different output frequencies; the secondary current The monitoring device is used to measure the current signal of each phase on the secondary side of the transformer, and transmit the current signal to the winding deformation diagnosis unit; the winding deformation diagnosis unit is also used to use the voltage signal and current signal injected by each phase to determine different outputs The tangent value of the loss angle of each phase of the transformer under the frequency, and the tangent value of the loss angle of each phase is used to judge whether the winding of the transformer is deformed. The above transformer winding deformation monitoring system is adopted, and its capacitive sensor is installed on the secondary side of the transformer, which can be used instead of any insulator on the low-voltage side, and can also be installed next to the electromagnetic voltage transformer PT on the low-voltage side of the transformer, without the need for the installation of bus power failure, and its operating life Consistent with insulators, and the price is low. Since the deformation of transformer windings mostly occurs on the low-voltage side, injecting voltage signals on the low-voltage side to measure the winding deformation is conducive to finding minor winding deformation faults; the line voltage on the low-voltage side of the transformer is usually below 66kV, and the voltage level is low, which is extremely high. Partially ungrounded systems, the sensors are easy to install and operate with low risk.

Please refer to FIG. 2. FIG. 2 is a flowchart of a transformer winding deformation monitoring method according to an embodiment of the present invention. As shown in FIG. 2, the transformer winding deformation monitoring method includes:

201. When it is determined that the secondary side outlet of the transformer has no ground fault and the zero-sequence voltage offset is normal, control the voltage source to inject voltage signals into each phase of the secondary side of the transformer with different output frequencies;

202. Determine the loss tangent of each phase of the transformer under different output frequencies by using the voltage signal injected by each phase and the current signal of each phase on the secondary side of the transformer measured by a secondary current monitoring device value;

203. Determine whether the winding of the transformer is deformed by using the loss tangent value of the transformer of each phase.

It should be noted that the content of each step shown in FIG. 2 is similar to the content of the transformer winding deformation monitoring system shown in FIG. 1. To avoid repetition, it will not be repeated here. For details, refer to the above-mentioned transformer winding deformation monitoring system shown in FIG. content.

The invention provides a transformer winding deformation monitoring method. The method includes: when it is determined that the secondary side outlet of the transformer has no grounding fault and the zero-sequence voltage offset is normal, controlling the voltage source with different output frequencies, to the secondary side of the transformer. Each phase injects a voltage signal; using the voltage signal injected by each phase and the current signal of each phase on the secondary side of the transformer measured by the secondary current monitoring device, determine the loss tangent value of each phase of the transformer under different output frequencies; Use the loss tangent value of each phase transformer to judge whether the winding of the transformer is deformed. Using the above method, the capacitive sensor is installed on the secondary side of the transformer, which can be used instead of any insulator on the low-voltage side, and can also be installed next to the electromagnetic voltage transformer PT on the low-voltage side of the transformer, without the need for installation of bus power failure, and its operating life is the same as that of the insulator. And the price is low. Because the deformation of transformer windings mostly occurs on the low-voltage side, injecting a voltage signal on the low-voltage side to measure the winding deformation is conducive to finding minor winding deformation faults; the line voltage on the low-voltage side of the transformer is usually below 66kV, the voltage level is low, and most of them are not grounded. System, sensors are easy to install and operate with low risk.

Please refer to FIG. 3. FIG. 3 is another schematic structural diagram of a transformer winding deformation monitoring system according to an embodiment of the present invention. As shown in FIG. 3, the transformer winding deformation monitoring system includes: a secondary side capacitance sensor 10, a phase split switch 20, A voltage source 30, a winding deformation diagnosis unit 40, and a secondary current monitoring device 50; wherein, the voltage source 30 is electrically connected to one end of the secondary side capacitive sensor 10 via the phase split switch 20, and the other end of the secondary side capacitive sensor 10 is connected to the transformer The secondary side of the transformer 00 is electrically connected; the secondary current monitoring device 50 is electrically connected to the secondary side of the transformer 00; the winding deformation diagnosis unit 40 is electrically connected to the secondary current monitoring device 50 and the voltage source 30 respectively;

The winding deformation diagnosis unit 40 is used to control the voltage source 30 to inject a voltage signal into each phase of the secondary side of the transformer 00 through the phase split switch 20 and the secondary side capacitive sensor 10 at different output frequencies;

The secondary current monitoring device 50 is used to measure the current signal of each phase on the secondary side of the transformer 00, and transmit the current signal to the winding deformation diagnosis unit 40;

The winding deformation diagnosis unit 40 is also used to determine the loss tangent value of each phase of the transformer 00 under different output frequencies by using the voltage signal and the current signal injected by each phase, and use the loss tangent value of the transformer 00 of each phase to determine the loss angle of the transformer 00. Whether the winding is deformed.

It should be noted that the contents of the secondary side capacitance sensor 10, the phase split switch 20, the voltage source 30, the winding deformation diagnosis unit 40, and the secondary current monitoring device 50 shown in FIG. 3 are the same as those of the secondary side capacitance shown in FIG. 1. The contents of the sensor 10, the phase-separating switch 20, the voltage source 30, the winding deformation diagnosis unit 40, and the secondary current monitoring device 50 are similar. To avoid repetition, they will not be repeated here. For details, please refer to the secondary capacitor shown in FIG. 1. Contents of the sensor 10 , the phase-separating switch 20 , the voltage source 30 , the winding deformation diagnosis unit 40 , and the secondary current monitoring device 50 .

Further, the above-mentioned secondary current monitoring device 50 may include a Rogowski coil or a broadband current sensor for measuring broadband current, or may be other dedicated broadband current sensors, wherein the voltage source 30 can emit an amplitude within 0-500V, and a frequency of 0.01Hz ~ 10GHz power frequency sine wave.

The secondary side capacitive sensor 10 can be a secondary ceramic capacitor, and the secondary side capacitive sensor 10 is a transmission sensor, which is encapsulated in epoxy resin or other resins using ceramic capacitors, and has the function of a pillar insulator. The capacitance values of the transmission sensors are equal, that is, the secondary side capacitance sensor 10 has the load-bearing function of the pillar insulator, and the capacitance value of the secondary side capacitance sensor 10 is the same for each phase of the transformer 00. Further, the capacitance value should be greater than 40pF, the maximum capacitance should satisfy the human body to get rid of the current 10mA, which can be calculated by the following formula:

In the formula, I is the human body to get rid of the current, U _φ is the relative ground voltage of the system, and ω is the angular frequency at the power frequency.

Further, the split-phase switch 20 is composed of at least six switching elements, the rated voltage of the split-phase switch should be configured according to the maximum output voltage of the voltage source 30, and the rated current can be selected as 10mA, which is a switch with split-phase control function. Further, the winding deformation diagnosis unit 40 is also electrically connected to the phase split switch 20 , and the winding deformation diagnosis unit 40 is also used to control the opening and closing states of each switching element in the phase split switch 20 according to the target injection phase of the voltage signal. Exemplarily, as shown in FIG. 3 , the transformer 00 includes A-phase, B-phase and C-phase, and the split-phase switch 20 includes six switching elements, which are respectively the switching elements Ka, Kb, Kc, K1, K2 and K3. The target injection phase of the voltage signal controls the opening and closing states of each switching element in the phase split switch 20, including: when the target injection phase is phase A, controlling the switching elements Ka and K2 to be in a closed state, and controlling the switching elements Kb, Kc, K1 and K3 are in an off state; when the target injection phase is B phase, the control switching elements Kb and K3 are in a closed state, and the control switching elements Ka, Kc, K1 and K2 are in an open state; when the target injection phase is C phase, The control switching elements Kc and K1 are in a closed state, and the control switching elements Ka, Kb, K2 and K3 are in an open state.

Please refer to FIG. 4 . FIG. 4 is a schematic diagram of injecting a voltage signal into each phase of the transformer 00 according to an embodiment of the present invention, wherein the A-phase, B-phase and C-phase are the three phases of the primary side of the transformer, and the a-phase and the b-phase are the three phases of the primary side of the transformer. And the c-phase is the three-phase of the secondary side of the transformer. Before and after the transformer winding is deformed, the parameters such as distributed capacitance and distributed inductance of the transformer winding will inevitably change, and they will be reflected on the port side. The voltage source 30 injects a voltage signal through the ceramic capacitive sensor 10, and before the winding is deformed, the distribution parameters of each winding are almost the same. Therefore, the tanδ _i curves of each phase detected from the high-voltage side are consistent, and once the winding deformation occurs, due to the change of the distribution parameters, the tanδ _i curves of each phase will no longer be consistent _. Determine whether the transformer winding deformation occurs. It should be noted that the winding deformation diagnosis unit 40 can control the output voltage signal and output frequency of the voltage source 30 , control the switching of the phase split switch 20 , monitor the current signal of the high voltage side of the transformer, and determine the winding deformation of the transformer 00 according to the setting.

以及所述电流信号

确定不同输出频率下所述变压器00的每相的损耗角正切值tanδ_i，包括：Exemplarily, using the voltage signal injected under each phase

and the current signal

Determine the loss tangent value tanδ _i of each phase of the transformer 00 under different output frequencies, including:

为注入电压信号；

为电流信号，tanδ_i为损耗角正切值，i表示所述电压源30的不同输出频率，进一步的，该电流信号

为注入电压源后宽频电流传感器测量得到的电流，其中，损耗角正切值tanδ_i用于反映变压器每一相的损耗情况。In the formula,

is the injection voltage signal;

is the current signal, tanδ _i is the loss tangent value, i represents the different output frequencies of the voltage source 30, further, the current signal

It is the current measured by the broadband current sensor after the voltage source is injected, and the loss tangent value _tanδi is used to reflect the loss of each phase of the transformer.

Please refer to FIG. 5. FIG. 5 is a loss angle tangent curve of each phase of the transformer 00 at different output frequencies according to an embodiment of the present invention, wherein, FIG. 5a is the loss angle of the A phase of the transformer 00 at different output frequencies. The tangent value curve, Figure 5b is the loss angle tangent value curve of the B phase of the transformer 00 under different output frequencies, Figure 5c is the loss angle tangent value curve of the C phase of the transformer 00 at different output frequencies, and Figure 5d is the different output frequency The combined schematic diagram of the loss tangent value curves of the three phases A, B and C of the transformer 00 below; wherein, tgδ represents the loss tangent value. The figure shows the change curve of the loss tangent value of each phase under different output frequencies.

In a feasible implementation manner, the determining whether the winding of the transformer 00 is deformed by using the loss tangent value of the transformer 00 of each phase includes: using the voltage source 30 to inject the voltage signal into the transformer The total number of points of each phase of 00 and the loss tangent value, determine the correlation coefficient of the loss tangent value between the corresponding phases of the transformer 00; according to the correlation coefficient of the loss tangent value between the phases, determine Whether the windings of the transformer 00 are deformed.

Further, determine the correlation coefficient of the loss tangent value between the corresponding phases of the transformer 00, including:

r_xy为所述电压源30的输出频率i下x相与y相注入时的损耗角正切值tanδ_i的曲线的相关系数，n为所述电压源30的不同输出频率的总点数；x_i为x相第i频率点的损耗角正切值，y_i为y相第i频率点的损耗角正切值tanδ_i，x相与y相可以基于A、B及C相进行任意组合。示例性的，如果输出频率包括0.1Hz、0.5Hz及10Hz，那么总点数n则为3，输出频率包括0.1Hz、0.5Hz、0.7Hz及10Hz，那么总点数n则为4。在此举例不做限定。也即，n为0.01Hz～10GHz之间注入电流信号的输出频率的总点数。示例性的，计算出每相注入下，n个频率点tanδ曲线的相关系数，依据r_ab、r_bc、r_ca相关系数大小判断绕组状态，其中，相间的损耗角正切值的相关系数用于反映变压器任意两相之间的n个频率点tanδ曲线的相关程度，若两条曲线完全相关则相关系数就是1，若完全不相关相关系数就是0。in,

r _xy is the correlation coefficient of the curve of the loss tangent value tanδ _i when the x-phase and y-phase are injected at the output frequency i of the voltage source 30, n is the total number of points of the different output frequencies of the voltage source 30; x _i is the loss tangent value of the ith frequency point of the x-phase, y _i is the loss tangent value tanδ _i of the ith frequency point of the y-phase phase, and the x-phase and the y-phase can be arbitrarily combined based on the A, B and C phases. Exemplarily, if the output frequency includes 0.1 Hz, 0.5 Hz and 10 Hz, then the total number of points n is 3, and if the output frequency includes 0.1 Hz, 0.5 Hz, 0.7 Hz and 10 Hz, then the total number of points n is 4. This example is not limited. That is, n is the total number of points of the output frequency of the injection current signal between 0.01 Hz and 10 GHz. Exemplarily, the correlation coefficients of the tanδ curves of n frequency points under the injection of each phase are calculated, and the winding state is judged according to the correlation coefficients of r _ab , r _bc , and r _ca , wherein the correlation coefficient of the tangent value of the loss angle between phases is used for It reflects the correlation degree of the tanδ curves of n frequency points between any two phases of the transformer. If the two curves are completely correlated, the correlation coefficient is 1, and if there is no correlation at all, the correlation coefficient is 0.

In a feasible implementation manner, determining whether the winding of the transformer 00 is deformed according to the correlation coefficient of the tangent value of the loss angle between the phases includes: if the difference between the absolute values of the correlation coefficient of the tangent value of the loss angle between the phases is greater than a preset difference value threshold γ, it is determined that the windings of the transformer 00 are deformed; if the difference between the absolute values of the correlation coefficients of the loss angle tangents between phases is less than or equal to the preset difference threshold γ, it is determined that the windings of the transformer 00 are normal, exemplarily, preset The difference threshold γ can be a basic set value, which can be γ=0.2, so as to determine whether the transformer winding is deformed.

The advantages of the present invention are: (1) The transformer winding deformation mostly occurs on the low-voltage side, and the winding deformation is measured by injecting a voltage signal on the low-voltage side, which is conducive to finding minor winding deformation faults; (2) The ceramic capacitive sensor has high dielectric strength, which can be used as a It is used as an insulator, installed on the low-voltage side of the transformer, and can be used instead of any insulator on the low-voltage side, or can be installed next to the electromagnetic voltage transformer PT of the busbar on the low-voltage side of the transformer, without the need to install the busbar power failure, the operating life of the sensor is the same as that of the insulator, and the price is low; (3 ) The line voltage of the low-voltage side of the transformer is usually below 66kV, and the voltage level is low. Most of the sensors in the ungrounded system are easy to install and have low operating risks.

Please refer to FIG. 6. FIG. 6 is another flowchart of a transformer winding deformation monitoring method according to an embodiment of the present invention. As shown in FIG. 6, the transformer winding deformation monitoring method includes:

601. When it is determined that the secondary side outlet of the transformer has no ground fault and the zero-sequence voltage offset is normal, control the voltage source to inject voltage signals into each phase of the secondary side of the transformer with different output frequencies;

602. Determine the loss tangent of each phase of the transformer under different output frequencies by using the voltage signal injected by each phase and the current signal of each phase on the secondary side of the transformer measured by a secondary current monitoring device value;

Exemplarily, step 602 may include:

为注入电压信号；

为电流信号，tanδ_i为损耗角正切值，i表示所述电压源的不同输出频率。In the formula,

is the injection voltage signal;

is the current signal, tanδ _i is the loss tangent value, and i represents the different output frequencies of the voltage source.

603. Using the voltage source to inject the voltage signal into the total number of points of each phase of the transformer and the loss tangent value, determine a correlation coefficient of the loss tangent value between the corresponding phases of the transformer;

In a feasible implementation manner, step 603 may include:

r_xy为所述电压源的输出频率i下x相与y相注入时的损耗角正切值tanδ_i的曲线的相关系数，n为所述电压源的不同输出频率的总点数；x_i为x相第i频率点的损耗角正切值，y_i为y相第i频率点的损耗角正切值tanδ_i。in,

r _xy is the correlation coefficient of the curve of the loss tangent value tanδ _i when the x-phase and y-phase are injected at the output frequency i of the voltage source, n is the total number of points of different output frequencies of the voltage source; x _i is x The loss tangent value of the i-th frequency point of the phase, y _i is the loss tangent value tanδ _i of the i-th frequency point of the y-phase.

604. Determine whether the winding of the transformer is deformed according to the correlation coefficient of the tangent value of the loss angle between the phases.

In a feasible implementation manner, step 604 may include steps a1 and a2:

a1. If the difference between the absolute values of the correlation coefficients of the loss tangent values between the phases is greater than a preset difference threshold, it is determined that the winding of the transformer is deformed;

a2. If the difference between the absolute values of the correlation coefficients of the loss tangent values between the phases is less than or equal to a preset difference threshold, it is determined that the winding of the transformer is normal.

It should be noted that the content of each step of the method shown in FIG. 6 is similar to the content of the transformer winding deformation monitoring system shown in FIG. 3 . In order to avoid repetition, it will not be repeated here. For details, please refer to the transformer winding deformation monitoring system shown in FIG. 3 above. Content.

The invention provides a transformer winding deformation monitoring method. The method includes: when it is determined that the secondary side outlet of the transformer has no grounding fault and the zero-sequence voltage offset is normal, controlling the voltage source with different output frequencies, to the secondary side of the transformer. Each phase injects a voltage signal; using the voltage signal injected by each phase and the current signal of each phase on the secondary side of the transformer measured by the secondary current monitoring device, determine the loss tangent value of each phase of the transformer under different output frequencies; Use the voltage source to inject the voltage signal into the total number of points of each phase of the transformer and the loss tangent value to determine the correlation coefficient of the loss tangent value between the corresponding phases of the transformer; Whether the windings of the transformer are deformed. Using the above method, the capacitive sensor is installed on the secondary side of the transformer, which can be used instead of any insulator on the low-voltage side, and can also be installed next to the electromagnetic voltage transformer PT on the low-voltage side of the transformer, without the need for installation of bus power failure, and its operating life is the same as that of the insulator. And the price is low. Because the deformation of transformer windings mostly occurs on the low-voltage side, injecting a voltage signal on the low-voltage side to measure the winding deformation is conducive to finding minor winding deformation faults; the line voltage on the low-voltage side of the transformer is usually below 66kV, the voltage level is low, and most of them are not grounded. System, sensors are easy to install and operate with low risk.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium , when the program is executed, it may include the flow of the above-mentioned method embodiments. Wherein, any reference to memory, storage, database or other medium used in the various embodiments provided in this application may include non-volatile and/or volatile memory. Nonvolatile memory may include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous chain Road (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features It is considered to be the range described in this specification.

The above-mentioned embodiments only represent several embodiments of the present application, and the descriptions thereof are relatively specific and detailed, but should not be construed as a limitation on the scope of the patent of the present application. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the appended claims.

Claims (10)

1. A transformer winding deformation monitoring system, characterized in that, transformer winding deformation monitoring system includes: the device comprises a voltage source, a secondary side capacitance sensor, a split-phase switch, a secondary current monitoring device and a winding deformation diagnosis unit; the voltage source is electrically connected with one end of the secondary side capacitance sensor through the split-phase switch, and the other end of the secondary side capacitance sensor is electrically connected with the secondary side of the transformer; the secondary current monitoring device is electrically connected with the secondary side of the transformer; the winding deformation diagnosis unit is electrically connected with the secondary current monitoring device and the voltage source respectively;

the winding deformation diagnosis unit is used for controlling the voltage source to inject voltage signals into each phase of the secondary side of the transformer through the split-phase switch and the secondary side capacitance sensor at different output frequencies;

the secondary current monitoring device is used for measuring current signals of all phases on the secondary side of the transformer and transmitting the current signals to the winding deformation diagnosis unit;

the winding deformation diagnosis unit is further used for determining the loss tangent value of each phase of the transformer under different output frequencies by using the voltage signal and the current signal injected into each phase, and judging whether the winding of the transformer is deformed or not by using the loss tangent value of each phase of the transformer.

2. The system for monitoring deformation of a winding of a transformer according to claim 1, wherein said determining the tangent loss value of each phase of said transformer at different output frequencies by using said voltage signal and said current signal injected at each phase comprises:

in the formula,

is an injection voltage signal;

tan delta as current signal _i For the loss tangent values, i represents the different output frequencies of the voltage source.

3. The system for monitoring deformation of a winding of a transformer according to claim 1, wherein said determining whether deformation of the winding of the transformer exists by using the loss tangent of each phase of the transformer comprises:

determining a correlation coefficient of loss tangent values of the phases of the transformer corresponding to the voltage source by using the total points of the voltage signal injected into each phase of the transformer by the voltage source and the loss tangent values;

and determining whether the winding of the transformer is deformed or not according to the correlation coefficient of the loss tangent values of the phases.

4. The system for monitoring deformation of a winding of a transformer according to claim 3, wherein said determining the correlation coefficient of the loss tangent value of each phase of the transformer by using the total number of points of the voltage signal injected from the voltage source into each phase of the transformer and the loss tangent value comprises:

wherein,

r _xy the loss tangent tan delta of the x phase and the y phase under the output frequency i of the voltage source _i N is the total number of points of different output frequencies of the voltage source; x is the number of _i Is the loss tangent value, y, of the i-th frequency point of the x phase _i Tan delta of loss tangent at i-th frequency point of y-phase _i 。

5. The method according to any one of claims 3-4, wherein the determining whether the winding of the transformer is deformed according to the correlation coefficient of the loss tangent values of the phase-to-phase comprises:

if the difference of the absolute values of the correlation coefficients of the loss tangent values between the phases is larger than a preset difference threshold value, determining that the winding of the transformer is deformed;

and if the difference of the absolute values of the correlation coefficients of the loss tangent values between the phases is less than or equal to a preset difference threshold value, determining that the winding of the transformer is normal.

6. The transformer winding deformation monitoring system according to claim 1, wherein the phase-splitting switch is composed of at least six switch elements, the winding deformation diagnosis unit is further electrically connected to the phase-splitting switch, and the winding deformation diagnosis unit is further configured to control an on-off state of each switch element in the phase-splitting switch according to a target injection phase of the voltage signal.

7. The system for monitoring deformation of a winding of a transformer according to claim 7, wherein the transformer comprises a phase A, a phase B and a phase C, and the controlling of the on-off state of each switching element in the split-phase switch according to the target injection phase of the voltage signal comprises:

when the target injection phase is an A phase, controlling the switching elements Ka and K2 to be in a closed state, and controlling the switching elements Kb, Kc, K1 and K3 to be in an open state;

when the target injection phase is a B phase, controlling the switching elements Kb and K3 to be in a closed state, and controlling the switching elements Ka, Kc, K1 and K2 to be in an open state;

when the target injection phase is the C phase, the switching elements Kc and K1 are controlled to be in a closed state, and the switching elements Ka, Kb, K2 and K3 are controlled to be in an open state.

8. The system for monitoring deformation of a winding of a transformer according to claim 1, wherein the secondary side capacitive sensor has a force-bearing function of a post insulator, the capacitance values of the secondary side capacitive sensors of each phase of the transformer are equal, and the maximum capacitance is calculated by using the following formula:

in the formula, I is the body's free from current, U _φ And omega is the angular frequency under the power frequency, which is the voltage of the system relative to the ground.

9. The device as claimed in claim 1, wherein the secondary current monitoring device comprises a rogowski coil or a broadband current sensor for measuring broadband current, and the voltage source emits a power frequency sine wave with an amplitude within 0-500V and a frequency within 0.01 Hz-10 GHz.

10. The method for monitoring the deformation of the transformer winding is characterized by comprising the following steps:

when the condition that the outgoing line of the secondary side of the transformer has no ground fault and the zero sequence voltage is deviated normally is determined, controlling a voltage source to inject voltage signals into each phase of the secondary side of the transformer at different output frequencies;

determining the loss tangent value of each phase of the transformer under different output frequencies by using the voltage signal injected by each phase and the current signal of each phase of the secondary side of the transformer measured by a secondary current monitoring device;

and judging whether the winding of the transformer is deformed or not by using the loss tangent value of each phase of the transformer.

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