Frequency domain dielectric response measurement device and method for converter transformer valve side bushing

Abstract

The present invention provides a frequency domain dielectric response measurement system for a converter transformer valve side bushing, the measurement system comprising a temperature control module and a high voltage frequency domain dielectric response measurement module, the high voltage frequency domain dielectric response measurement module comprising a signal output and acquisition unit, a signal amplification unit and a signal monitoring and analysis unit, the high voltage frequency domain dielectric response measurement module can realize high voltage frequency domain dielectric response measurement under a wide range of variable temperatures, and is easy to carry out measurements in complex field environments, the present invention also provides a frequency domain dielectric response measurement method for a converter transformer valve side bushing, the present invention has the advantages of wide range adjustable measurement temperature and strong anti-electromagnetic interference capability, and provides an effective detection means for insulation detection of ultra-high voltage large-size converter transformer valve side bushings.

Description

Technical Field

[0001] The present invention belongs to the field of frequency domain dielectric performance analysis and insulation state evaluation of converter transformer valve side bushings, and in particular to a frequency domain dielectric response measurement device and method for converter transformer valve side bushings. Background Art

[0002] In recent years, my country's ultra-high voltage direct current transmission projects have developed rapidly. The converter transformer is the core equipment of the ultra-high voltage direct current transmission project, and it plays the role of power conversion and transmission. Among them, the converter transformer bushing, as the valve-side outlet equipment of the converter transformer, undertakes important functions such as leading the current out of the converter transformer and insulation support. During the long-term operation of the converter transformer, the valve-side bushing of the converter transformer will be affected by factors such as electrical stress, thermal stress, mechanical stress and pressure, causing its insulation to gradually deteriorate. Severe degradation may cause explosions and fires at the tail of the valve-side bushing of the converter transformer, which seriously threatens the safe and stable operation of the converter transformer and the valve hall. Therefore, timely and effective insulation status detection and evaluation of the valve-side bushing of the converter transformer is of great significance to ensure the reliable operation of the converter transformer and the power system.

[0003] Frequency domain dielectric spectroscopy is a nondestructive testing technology that reflects the insulation state of dielectrics based on the internal polarization behavior and conductivity characteristics of dielectrics. Domestic and foreign researchers have conducted a lot of research on the diagnosis and evaluation of bushing insulation state using frequency domain dielectric spectroscopy technology. Domestically: Liao Ruijin et al. of Chongqing University used frequency domain dielectric spectroscopy technology with a measured voltage effective value of 140V at room temperature to study the effect of moisture on the insulation state of 10kV oil-paper capacitor bushings. The results showed that the main insulation dielectric loss and capacitance value of the bushing increased with the increase of moisture content, and the capacitance ratio characteristic at a frequency of 10-3Hz can effectively evaluate the insulation state of the bushing. Mu Haibao et al. of Xi'an Jiaotong University used frequency domain dielectric spectroscopy technology with a measured voltage effective value of 140V at room temperature to test 110kV transformer bushings at uniform and non-uniform moisture-damaged oil-paper insulation and field ambient temperature. The study showed that non-uniform moisture-damaged oil-paper insulation had significant loss peaks, and proved that this moisture model is suitable for field transformer bushing moisture state assessment. Pan Zhicheng and others from China Southern Power Grid Company used the frequency domain dielectric spectroscopy technology with a measured voltage of 140V effective value to test the insulation state of 500kV bushings at the on-site ambient temperature. The research results show that the mid-frequency band and low-frequency band of the frequency domain dielectric spectrum can effectively diagnose the aging defects and moisture defects of the transformer bushings respectively. In foreign countries: Diego M. Robalino and others from the United States used the frequency domain dielectric spectroscopy technology with a measured voltage of 140V and 1400V effective value to test the transformer bushings at the on-site environment. The study showed that the bushing frequency domain dielectric response measurement curve under the electromagnetic noise interference of 140V measured voltage showed large fluctuations in the low frequency region, but the bushing frequency domain dielectric response curve under the measured voltage of 1400V was almost not disturbed. Sumereder C and others from Australia used the frequency domain dielectric spectroscopy technology with a measured voltage of 140V effective value to test new and aged high-voltage bushings at room temperature. The study showed that the frequency domain dielectric spectrum curves of high-voltage bushings in different aging states were quite different in the low frequency region, and moisture caused the bushing dielectric loss value to increase.

[0004] At present, the existing achievements are mainly to use the frequency domain dielectric spectroscopy technology with an effective value of 140V to carry out insulation status detection and analysis of transformer bushings at ambient temperature. At present, the shortcomings of using frequency domain dielectric spectroscopy technology to carry out insulation status detection and analysis of transformer bushings are as follows: (1) When carrying out on-site operation and maintenance of converter transformer bushings, maintenance personnel need to understand the temperature, humidity and other conditions to decide when to carry out maintenance, which causes certain troubles to the staff. At the same time, the frequency domain dielectric spectroscopy results are greatly affected by factors such as the temperature difference between the inside and outside of the converter transformer bushing and the oil tank and the ambient humidity, and it is difficult to smoothly realize the effective detection and evaluation of the insulation status of the converter transformer bushing. (2) The existing frequency domain dielectric spectroscopy technology has the shortcomings of low measurement voltage and weak current signal. The test results are easily interfered by factors such as electromagnetic noise, which makes it difficult to characterize the internal defects of the converter transformer bushing, and there are great difficulties in diagnosing and evaluating its insulation status. Summary of the invention

[0005] The purpose of the present invention is to provide a method for realizing a wide temperature and humidity range of the core body and insulating sheath of the valve side bushing of a converter transformer, as well as a method for realizing a wide temperature range of the tail of the valve side bushing in insulating oil, which can simulate the temperature difference distribution and humidity adjustment of the valve side bushing during operation; and to provide a high voltage frequency domain dielectric response measurement device, which can realize the frequency domain dielectric response measurement of the converter transformer valve side bushing at a higher voltage, effectively enhance the measurement current signal, and improve the anti-electromagnetic signal interference ability of the converter transformer valve side bushing under a wide temperature, wide humidity range and high voltage frequency domain dielectric response measurement method. To overcome the shortcomings of the prior art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is

[0007] A frequency domain dielectric response measurement system for a converter transformer valve side bushing, characterized in that: the measurement system comprises a temperature control module and a high voltage frequency domain dielectric response measurement module, wherein:

[0008] The temperature control module is used to control the temperature and humidity in the system;

[0009] The high-voltage frequency-domain dielectric response measurement module includes a signal output unit, a signal amplification unit, a signal acquisition unit, and a signal monitoring and analysis unit:

[0010] The signal output unit is used to output AC voltage excitation signals of different frequencies;

[0011] The signal amplifying unit is used to amplify the AC voltage excitation signal, apply the amplified AC voltage excitation signal to the object to be tested, and send it to the signal monitoring and analyzing unit;

[0012] The signal acquisition unit is used to measure the AC response current that appears after the object to be measured is applied with the amplified AC voltage excitation signal;

[0013] The signal monitoring and analysis unit is used to collect the voltage value and voltage phase of the received amplified AC voltage excitation signal, and collect the current value and current phase generated by the object to be measured, and obtain high-voltage frequency-domain dielectric response data according to the collected voltage value and voltage phase, and current value and current phase;

[0014] The high-voltage frequency-domain dielectric response measurement module is arranged next to the valve-side bushing of the converter transformer. The high-voltage frequency-domain dielectric response measurement module outputs an AC voltage excitation signal to the valve-side bushing of the converter transformer. The valve-side bushing of the converter transformer outputs an AC response current signal that appears after high voltage excitation is applied to the high-voltage frequency-domain dielectric response measurement module. The high-voltage frequency-domain dielectric response measurement module is used to realize high-voltage frequency-domain dielectric response measurement under a wide range of variable temperatures.

[0015] The temperature control module includes a spiral tube heater, a temperature sensor, a humidity control device, a humidity sensor and a transparent temperature control cover unit.

[0016] The spiral tube heater and the temperature sensor are used to set the temperature range in the transparent temperature control cover unit within a set range;

[0017] The humidity control device and humidity sensor are used to control the humidity in the transparent temperature control cover unit within a set range;

[0018] The transparent temperature control cover unit is arranged at the body of the converter transformer valve side bushing and the oil tank, so that the core and the outside of the insulating sheath of the converter transformer valve side bushing are all covered in the transparent temperature control cover unit, and the transparent temperature control cover unit is used to control the external environmental temperature of the converter transformer valve side bushing;

[0019] A spiral tube heater is arranged inside the oil tank of the valve-side bushing of the converter transformer.

[0020] The temperature range is set at 25° C. to 80° C., and the humidity is controlled between 1% and 70%.

[0021] The high voltage frequency domain dielectric response measurement module comprises:

[0022] Signal output and acquisition unit: used to output stable voltage signals and acquire noise-removing current. The signal output unit outputs AC voltage excitation signals of different frequencies. The acquisition unit measures the AC response current that appears after the valve side casing is applied with high voltage excitation. The signal output and acquisition unit includes a switching power supply, a filter capacitor, a micro-current preamplifier and an ammeter.

[0023] Signal amplification unit and signal monitoring and analysis unit: the signal amplification unit utilizes a high-voltage amplifier to amplify the tiny voltage signal provided by the signal output unit, and applies the amplified voltage signal to the sample module under test and the signal monitoring and analysis unit. The amplification factor of the high-voltage amplifier is calculated according to the measured high voltage value to be applied and the small signal output voltage value. The range of the applied measured high voltage is 1kV-20kV; the signal monitoring and analysis unit: includes a voltage divider, a standard capacitor and an oscilloscope. The signal monitoring and analysis unit collects and processes the value and phase of the high-voltage excitation signal applied to the measured valve side casing and the value and phase of the response current generated by the valve side casing; the collected voltage signal and current signal are subjected to complex capacitance and dielectric loss calculation to obtain high-voltage frequency domain dielectric response data.

[0024] The present invention also provides a measurement method using the frequency domain dielectric response measurement system of the converter transformer valve side bushing, the method comprising the following steps:

[0025] The temperature control module is installed at the bushing body and the oil tank on the valve side of the converter transformer, and the temperature of the temperature control module is set to the required temperature;

[0026] The signal output unit in the high-voltage frequency-domain dielectric response measurement module outputs AC voltage excitation signals of different frequencies;

[0027] The signal amplifying unit amplifies the AC voltage excitation signal, applies the amplified AC voltage excitation signal to the object to be tested, and sends it to the signal monitoring and analyzing unit;

[0028] The signal acquisition unit measures the AC response current that occurs after the amplified AC voltage excitation signal is applied to the object to be measured;

[0029] The signal monitoring and analysis unit collects the voltage value and voltage phase of the received amplified AC voltage excitation signal, and collects the current value and current phase generated by the object to be tested, and obtains high-voltage frequency domain dielectric response data based on the collected voltage value and voltage phase, and current value and current phase.

[0030] According to the collected voltage value and voltage phase, as well as current value and current phase, high voltage frequency domain dielectric response data is obtained, including:

[0031] The complex capacitance and dielectric loss are calculated for the collected voltage value and voltage phase, as well as the current value and current phase, to obtain high-voltage frequency-domain dielectric response data.

[0032] The beneficial effects of the present invention are:

[0033] During long-term operation, the valve-side bushing of the converter transformer will be affected by factors such as electrical stress, thermal stress, and pressure, causing its insulation performance to gradually deteriorate, which may eventually lead to insulation failure of the valve-side bushing of the converter transformer, and even serious accidents such as explosion and fire. The present invention provides a system that can realize the frequency domain dielectric response measurement of the valve-side bushing of the converter transformer under a wide temperature, wide humidity range and high voltage. The measurement system can keep the temperature and humidity inside and outside the core body and the insulating sheath of the valve-side bushing of the converter transformer consistent, and can also realize the wide temperature range control of the tail of the valve-side bushing in the insulating oil. At the same time, a high-voltage frequency domain dielectric response measurement method is provided to realize the frequency domain dielectric response measurement of the valve-side bushing of the converter transformer at a higher voltage, effectively enhance the measurement current signal, improve the anti-electromagnetic signal interference capability, and facilitate the discovery of more insulation defect information inside the valve-side bushing of the converter transformer. The present invention provides a feasible technical means for realizing accurate and effective diagnosis and evaluation of the insulation state of the valve-side bushing of ultra-high voltage large-size converter transformer, and provides technical support for the safe and reliable operation of the valve-side bushing of the converter transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1It is a schematic diagram of the bushing model on the valve side of the converter transformer in the present invention;

[0035] Figure 2 This is a schematic diagram of the temperature control module of the valve side sleeve of the converter transformer in the present invention;

[0036] Figure 3 It is a schematic diagram of the high-voltage frequency-domain dielectric response measurement system of the present invention;

[0037] Figure 4 It is a system schematic diagram of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0039] The present invention provides a frequency domain dielectric response measurement system for a converter transformer valve side bushing (such as Figure 4 As shown), the present invention has the advantages of wide adjustable measuring temperature and strong anti-electromagnetic interference capability, and provides an effective detection means for insulation detection of UHV large-size converter valve-side bushings.

[0040] The frequency domain dielectric response measurement system of the valve side bushing of the converter transformer of the present invention comprises a sample module to be measured, a temperature control module, and a high-voltage frequency domain dielectric response measurement module. Among them, the high-voltage frequency domain dielectric response measurement module comprises a signal output and acquisition unit, a signal amplification unit, and a signal monitoring and analysis unit, which can realize high-voltage frequency domain dielectric response measurement under a wide range of variable temperatures and is easy to carry out measurements in complex field environments.

[0041] In the above technical solution, the sample module under test is the valve-side bushing of the converter transformer, such as Figure 1 shown.

[0042] In the above technical solution, the temperature control module includes a spiral tube heater, a temperature sensor, a humidity control device, a humidity sensor and a transparent temperature control cover unit, such as Figure 2 As shown. The function of the spiral tube heater and temperature sensor is to set the temperature control range between 25℃ and 80℃. The function of the humidity control device and humidity sensor is to control the humidity of the valve side casing core and the external insulation sheath between 1% and 70%. The transparent temperature control cover is used to control the external ambient temperature of the valve side casing of the converter transformer. The spiral tube heater is directly set inside the oil tank to realize the temperature change function of the tail of the valve side casing in the insulating oil.

[0043] In the above technical solution, the high voltage frequency domain dielectric response measurement system is shown in the figure Figure 3 As shown: the high voltage frequency domain dielectric response measurement system comprises:

[0044] 1) Signal output and acquisition unit: This unit consists of a switching power supply, a filter capacitor, a micro-current preamplifier, an ammeter, etc. This unit can output stable voltage signals, collect noise-removing currents, etc. It has the advantages of high measurement accuracy and strong anti-interference ability. The signal output unit is used to output AC voltage excitation signals of different frequencies. The acquisition unit is used to measure the AC response current that appears after the valve side casing is excited by high voltage.

[0045] 2) Signal amplification unit: The system uses a high-voltage amplifier to amplify the tiny voltage signal provided by the signal output unit, and applies the amplified voltage signal to the sample module under test and the signal monitoring and analysis unit. The amplification factor of the high-voltage amplifier is calculated according to the measured high voltage value to be applied and the small signal output voltage value. The recommended range of the applied measured high voltage is 1kV-20kV;

[0046] 3) Signal monitoring and analysis unit: It consists of a voltage divider, a standard capacitor and an oscilloscope. It collects and processes the value and phase of the high voltage excitation signal applied to the tested valve side casing and the value and phase of the response current generated by the valve side casing; it calculates the complex capacitance and dielectric loss of the collected voltage and current signals to obtain the high voltage frequency domain dielectric response data.

[0047] The measurement method using the frequency domain dielectric response measurement system of the converter transformer valve side bushing is:

[0048] The first step is to place the temperature control module at the bushing body and oil tank on the valve side of the converter transformer, set the temperature of the temperature control module to the required temperature, and when the temperature and humidity reach the requirements, let it stand for 30 minutes to stabilize the temperature and humidity of the bushing body and oil tank on the valve side of the converter transformer.

[0049] The second step is to assemble the signal output and acquisition unit, the signal amplification unit and the signal detection and analysis unit into a high-voltage frequency-domain dielectric response measurement system.

[0050] In the third step, a high-voltage frequency-domain dielectric response measurement system was used to perform a frequency-domain dielectric response test on the valve-side bushing of the converter transformer with stable temperature and humidity. The measurement voltage was set to 10 kV and the measurement frequency range was 10 -3 -10 2 Hz, and obtain the high-voltage frequency domain dielectric response data of the valve-side bushing of the converter transformer.

[0051] If it is necessary to obtain the frequency domain dielectric response characteristics of the valve-side bushing of the converter transformer under different temperatures and humidities, repeat the above steps.

[0052] In summary, during long-term operation, the valve-side bushing of the converter transformer will be affected by factors such as electrical stress, thermal stress, and pressure, causing its insulation performance to gradually deteriorate, which may eventually lead to insulation failure of the valve-side bushing of the converter transformer, and even serious accidents such as explosion and fire. The present invention provides a system that can realize the frequency domain dielectric response measurement of the valve-side bushing of the converter transformer under a wide temperature, wide humidity range and high voltage. The measurement system can keep the temperature and humidity inside and outside the core body and the insulating sheath of the valve-side bushing of the converter transformer consistent, and can also realize the wide temperature range control of the tail of the valve-side bushing in the insulating oil. At the same time, a high-voltage frequency domain dielectric response measurement method is provided to realize the frequency domain dielectric response measurement of the valve-side bushing of the converter transformer at a higher voltage, effectively enhance the measurement current signal, improve the anti-electromagnetic signal interference capability, and facilitate the discovery of more insulation defect information inside the valve-side bushing of the converter transformer. The present invention provides a feasible technical means for realizing accurate and effective diagnosis and evaluation of the insulation state of the valve-side bushing of ultra-high voltage large-size converter transformer, and provides technical support for the safe and reliable operation of the valve-side bushing of the converter transformer.

[0053] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A frequency domain dielectric response measurement system for a converter transformer valve side bushing, the measurement system comprising a temperature control module and a high voltage frequency domain dielectric response measurement module, The temperature control module includes a spiral tube heater, a temperature sensor, a humidity control device, a humidity sensor and a transparent temperature control cover unit. The high-voltage frequency domain dielectric response measurement module is arranged beside the valve-side bushing of the converter transformer. The high-voltage frequency domain dielectric response measurement module outputs an AC voltage excitation signal to the valve-side bushing of the converter transformer. The valve-side bushing of the converter transformer outputs an AC response current signal generated after high voltage excitation is applied to the high-voltage frequency domain dielectric response measurement module. The high-voltage frequency domain dielectric response measurement module is used to realize high-voltage frequency domain dielectric response measurement under a wide range of variable temperatures. The spiral tube heater and the temperature sensor are used to set the temperature range in the transparent temperature control cover unit within a set range; The humidity control device and humidity sensor are used to control the humidity in the transparent temperature control cover unit within a set range; The transparent temperature control cover unit is arranged at the body of the converter transformer valve side bushing and the oil tank, so that the core and the outside of the insulating sheath of the converter transformer valve side bushing are all covered in the transparent temperature control cover unit, and the transparent temperature control cover unit is used to control the external environmental temperature of the converter transformer valve side bushing; A spiral tube heater is arranged inside the oil tank of the valve side bushing of the converter transformer. It is characterized in that The high voltage frequency domain dielectric response measurement module comprises: Signal output and acquisition unit: used to output stable voltage signals and acquire noise-removing current. The signal output unit outputs AC voltage excitation signals of different frequencies. The acquisition unit measures the AC response current that appears after the valve side casing is applied with high voltage excitation. The signal output and acquisition unit includes a switching power supply, a filter capacitor, a micro-current preamplifier and an ammeter. Signal amplification unit and signal monitoring and analysis unit: the signal amplification unit utilizes a high-voltage amplifier to amplify the tiny voltage signal provided by the signal output unit, and applies the amplified voltage signal to the sample module under test and the signal monitoring and analysis unit. The amplification factor of the high-voltage amplifier is calculated according to the measured high voltage value to be applied and the small signal output voltage value. The range of the applied measured high voltage is 1kV-20kV; the signal monitoring and analysis unit: comprises a voltage divider, a standard capacitor and an oscilloscope. The signal monitoring and analysis unit collects and processes the value and phase of the high-voltage excitation signal applied to the measured valve side casing and the value and phase of the response current generated by the valve side casing; the collected voltage signal and current signal are subjected to complex capacitance and dielectric loss calculation to obtain high-voltage frequency domain dielectric response data.

2. A measurement method using the frequency domain dielectric response measurement system of the converter transformer valve side bushing according to claim 1, the measurement method comprising the following steps: The temperature control module is installed at the bushing body and the oil tank on the valve side of the converter transformer, and the temperature of the temperature control module is set to the required temperature; The signal output unit in the high-voltage frequency-domain dielectric response measurement module outputs AC voltage excitation signals of different frequencies; The signal amplifying unit amplifies the AC voltage excitation signal, applies the amplified AC voltage excitation signal to the object to be tested, and sends it to the signal monitoring and analyzing unit; The signal acquisition unit measures the AC response current that occurs after the amplified AC voltage excitation signal is applied to the object to be measured; The signal monitoring and analysis unit collects the voltage value and voltage phase of the received amplified AC voltage excitation signal, and collects the current value and current phase generated by the object to be tested, and obtains high-voltage frequency domain dielectric response data based on the collected voltage value and voltage phase, and current value and current phase.

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