TWI598601B - Partial discharge detection method, vhf antenna, partial discharge detection system and signal processing unit - Google Patents

Description

Partial discharge detection method, UHF antenna, partial discharge detection system, and signal processing unit

The embodiments of the present invention relate to a partial discharge detection method, and more particularly to a partial discharge detection method using a UHF antenna for sensing, and a partial discharge detection method for performing frequency reduction processing, and related methods. UHF antenna, signal processing circuit and partial discharge detection system.

Due to the demand for power quality and safety in today's industry, users are increasingly demanding the insulation status of their power equipment, especially high-voltage power equipment, such as high-voltage cables or cast-model transformers, often due to design, manufacturing, installation and maintenance work. Poor and form a problem of partial discharge. Therefore, the importance of the partial discharge diagnosis method has been recognized by the public.

Ultra High Frequency (UHF) is the current mainstream partial discharge detection method. In general, the frequency range sensed by the UHF method falls within the frequency band of 300 MHz to 3 GHz, which can sense electromagnetic waves at the operating voltage to determine whether partial discharge occurs. This method can be contact/non-contact measurement, In the case of cost considerations, the effect of immediate monitoring can also be achieved.

However, partial discharges always occur in a small range, have a very fast breakdown time characteristic, and decay rapidly when propagating in the air. In addition, the ultra-high frequency band signal has good anti-interference performance, but the signal is weak and often caused by misdetection. In addition, in the case where important high-voltage equipment requires individual monitoring of partial discharges in real time, the use of ultra-high-frequency methods requires the use of expensive spectrum analyzers to extract UHF signals, and then use specialized software to analyze whether high-voltage equipment is used. Partial discharge occurs and affects the safety of the power supply, making the overall efficiency low and expensive, resulting in difficulties in implementing immediate monitoring, and increasing the risk of missed or misjudged, thereby increasing the safety of the work safety. Replacing real-time monitoring with periodic inspections often results in discrepancies, especially in many cases where partial discharges are diagnosed when the damage to the electrical equipment is severe.

In view of this, how to improve the diagnostic accuracy at the initial stage of partial discharge and the cost of overall real-time monitoring has become an urgent problem to be solved in this field.

One of the objectives of the present invention is to provide a partial discharge detection method using a UHF antenna for sensing, and a partial discharge detection method for performing frequency reduction processing, and related UHF antennas, signal processing circuits and local parts. A discharge detection system to improve the above problems.

According to a first embodiment of the present invention, a partial discharge detection method is provided, comprising: sensing an electrical device using at least one UHF antenna, and generating at least one spectral result; and determining according to the at least one spectral result Whether the electrical equipment has a partial discharge.

According to a second embodiment of the present invention, a UHF antenna for detecting partial discharge is provided, comprising: a sensor and an output unit. The sensor is configured to sense an electrical device and generate a spectral result; and the output unit is configured to output the spectral result; wherein the spectral result is used to determine whether the electrical device has a partial discharge.

According to a third embodiment of the present invention, a partial discharge detection system is provided, comprising at least one UHF antenna and an analysis unit. The at least one UHF antenna is configured to sense an electrical device and generate at least one spectral result; and the analyzing unit is coupled to the at least one UHF antenna for utilizing the at least one spectrum As a result, it is judged whether or not the electrical discharge occurs in the electrical equipment.

According to a fourth embodiment of the present invention, a partial discharge detection method includes: sensing an electrical device using at least one antenna, and generating at least one spectral result; performing frequency reduction processing on the at least one spectral result, and Generating at least one down-converted spectrum result; and determining whether the electrical device is partially discharged according to the at least one down-converted spectrum result when the at least one down-converted spectrum result meets a specific condition.

According to a fifth embodiment of the present invention, a signal processing unit is provided, including a down-converting unit and a phase-taking unit. The down-converting unit is configured to perform frequency-down processing on at least one spectrum result sensed by the at least one antenna, and generate at least one frequency-down spectrum result; and the phase-taking unit is coupled to the frequency-down unit for And determining, by the at least one down-converted spectrum result and the at least one power phase corresponding to the at least one down-converted spectrum result, whether the at least one down-converted spectrum result is interfered by crosstalk.

According to a sixth embodiment of the present invention, a partial discharge detection system is provided, comprising at least one antenna, a frequency reduction unit and a determination unit. The at least one antenna is configured to sense an electrical device and generate at least one spectral result; the down-clocking unit is configured to perform frequency-down processing on the at least one spectral result, and generate at least one frequency-down spectrum result; And the determining unit is configured to determine whether the electrical device has a partial discharge according to the at least one frequency down spectrum result.

The partial discharge detection method of the present invention replaces the conventional UHF antenna with a UHF antenna, which not only improves the accuracy of partial discharge detection, but also achieves the purpose of early detection, and the cost thereof is also greatly reduced. In addition, the present invention uses a lower-order system and a lower-resolution signal processing method to distinguish instantaneously and quickly. Whether or not electrical equipment is partially discharged, due to its low cost, can be widely used on all electrical equipment and monitored at any time.

T1‧‧‧ boundary

L1‧‧‧Background spectral line

P201~P206‧‧‧ partial discharge pulse

P301~P311‧‧‧ partial discharge pulse

400, 500‧‧‧ partial discharge detection system

402‧‧‧First UHF Antenna

4022‧‧‧first sensor

4024‧‧‧First output unit

404‧‧‧Second UHF antenna

4042‧‧‧Second sensor

4044‧‧‧second output unit

406‧‧‧Third UHF antenna

4062‧‧‧ third sensor

4064‧‧‧ third output unit

408, 508‧‧‧ analysis unit

4082, 5084‧‧‧ judgment unit

410, 510‧‧‧ electrical equipment

502‧‧‧First UHF Antenna

504‧‧‧Second UHF antenna

506‧‧‧ Third UHF Antenna

5082‧‧‧Signal Processing Unit

50822‧‧‧down frequency unit

50824‧‧‧Sampling unit

50826‧‧‧ phase taking unit

The following illustrations are included to form a part of the description of the present invention in order to explain the various embodiments of the present disclosure.

In order to make the description of the present disclosure more detailed and complete, the following description is taken in conjunction with the following drawings, wherein like reference numerals represent like elements. The following description of the embodiments is only intended to illustrate the technical content of the disclosure, and is not intended to limit the scope of the disclosure.

1 is a frequency waveform diagram of a background spectrum sensed by a measurement environment of the present invention; FIG. 2 is a partial discharge frequency waveform diagram sensed for a faulty high voltage cable; and FIG. 3 is sensed for a faulty cast model transformer. FIG. 4 is a schematic diagram of an exemplary embodiment of a partial discharge detection system of the present invention; FIG. 5 is a schematic diagram of another exemplary embodiment of a partial discharge detection system of the present invention; A schematic diagram of an embodiment of a signal processing unit in a partial discharge detection system of the present invention.

In the related drawings, reference symbols may be repeated throughout the embodiments, but the features of one embodiment are not necessarily applicable to another embodiment, even if the features share the same reference symbols. The drawings are provided for reference purposes only, but are not necessarily drawn to scale, and in some cases, the drawings may be enlarged and/or simplified. Those of ordinary skill in the art to which the disclosure pertains may be described in this embodiment. Any changes and modifications in mind, as well as any further principles applied in this document.

One of the spirits of the present invention is to use a frequency band of Very High Frequency (VHF) instead of the frequency band used by the conventional UHF method. In general, UHF refers to the frequency band of 30 MHz to 300 MHz, while UHF refers to the frequency band of 300 MHz to 3 GHz, which are different in range from each other and do not overlap. Compared with UHF signals, UHF signals have a longer transmission distance and are easier to detect. The following is a detailed description.

To illustrate the principle of operation, the measurement method and measurement results of the present invention will first be described in order to describe the difference in the distribution of the sensed partial discharge spectrum at UHF and UHF. 1 is a frequency waveform diagram of a background spectrum sensed by a measurement environment of the present invention. The measurement environment of the present invention is carried out in the 1966 ElectroMagnetic Interference (EMI) laboratory of Intertek Group plc, which complies with the European Standard for Environmentally Applicable (CE) Heavy Industrial Zone Environmental Use Standard (Class A). The size specification is 9M*6M*6M, which is equipped with a 50KV pressurization device that meets the partial discharge measurement standard (IEC60270).

Before the spectrum analysis of the measured object is formally carried out, the background spectrum needs to be measured. The process is as follows: in the state without the test object, the pressurizing device is pressurized to 50KV, at this time, a full-frequency receiving antenna is used to sense the signal intensity of 30 MHz to 1 GHz, and it is confirmed that there is no discharge on a spectrum analyzer. The situation, as well as the spectrum of 30MHz to 1GHz is recorded as the background electromagnetic spectrum of the measurement environment, and the strength is confirmed to be less than the boundary T1 specified by the CE CLASS A standard.

After the background spectrum is determined, the faulty electrical equipment that has partially discharged can be operated according to the pressurization procedure specified in IEC60270. First, in the first stage, the voltage is increased to 1.8 times normal and maintained for 30 seconds. : then in the second order In the segment, the voltage is reduced to 1.5 times normal and maintained for 150 seconds. During the second phase, the full-frequency receiving antenna is used to sense electromagnetic waves in the space of 30 MHz to 1 GHz, and the discharge spectrum thereof is recorded for subsequent analysis.

2 is a waveform diagram of a partial discharge frequency sensed for a faulty high voltage cable. One of the background spectral lines L1 is the background spectrum recorded in FIG. It can be seen from Fig. 2 that after the full-frequency analysis of the high-voltage cable in which partial discharge occurs, it is found that the lower frequency at about 140 MHz is less likely to correctly analyze the partial discharge phenomenon due to the influence of interference noise. The partial discharge phenomenon can be detected more densely in the frequency range of 140 MHz to 200 MHz. The partial discharge pulse labeled P201~P203 is a pulse with a higher pulse repetition rate in the frequency range of 140 MHz to 200 MHz. It should be noted that the partial discharge pulses P204~P206 obtained in the higher frequency band have higher pulse repetition rates, but the intensity and distribution density of P201~P203 are greater than those of P204~P206. That is to say, partial discharge is easier to detect in the frequency range of 140 MHz to 200 MHz.

Figure 3 is a partial discharge frequency waveform diagram sensed for a failed cast model transformer. After analyzing the full-frequency of the cast model transformer with partial discharge, it is found that the partial discharge phenomenon can be detected more densely in the frequency range of 200MHz to 300MHz compared with the frequency range of 140MHz to 200MHz, which is marked as P301~ The partial discharge pulse of P304 is a pulse with a higher pulse repetition rate in the frequency range of 200 MHz to 300 MHz. And the intensity and density of P301~P304, P301~P304, which are higher than the higher frequency band and higher pulse repetition rate, are generally greater than the intensity of P305~P311. That is to say, it is easier to detect the partial discharge of the cast model transformer in the frequency range of 200 MHz to 300 MHz.

4 is a schematic diagram of an exemplary embodiment of a partial discharge detection system of the present invention. The partial discharge detection system 400 includes a first UHF antenna 402, a second UHF antenna 404, a third UHF antenna 406, and an analysis unit 408. The partial discharge detection system 400 is configured to detect and analyze a partial discharge of an electrical device 410. Electrical device 410 can be a high voltage power device such as a high voltage cable or a cast model transformer. It should be noted that the sensing mode/configuration of the electrical device 410 by the UHF antennas 402-406 is not limited. For example, for different types of UHF antennas 402-406, contact/non-contact methods/configurations may be used. Sensing is performed; in addition, the present invention does not limit the number of UHF antennas. For example, in other embodiments, only a single UHF antenna may be used. In this embodiment, the partial discharge detection system 400 utilizes the respective sensors of the UHF antennas 402-406, that is, a first sensor 4022, a second sensor 4042, and a third sensor. 4062, respectively, sensing and generating three-phase spectrum results (ie, R-phase, S-phase, and T-phase spectrum results) of the electrical device 410 in the frequency band of 30 MHz to 300 MHz, and respectively passing through a first output unit 4024 and a second output unit. The 4044 and a third output unit 4064 output a first spectrum result S _vhf1 , a second spectrum result S _{vhf1 ,} and a third spectrum result S _vhf1 . The analyzing unit 408 is coupled to the UHF antennas _{402-406, and} can determine whether the electrical device 410 has a partial discharge according to the spectrum results S _vhf1 ~ S _vhf3 .

Specifically, a determining unit 4082 in the analyzing unit 408 further determines the specific frequency band in the spectrum results S _vhf1 to S _vhf3 according to the type of the electrical device 410. In this embodiment, when the electrical device 410 is a high voltage cable, the determining unit 4082 determines whether the partial discharge pulse in the frequency band of ₁₄₀ MHz to 200 MHz in the spectrum result S _vhf1 to S _vhf3 meets a first specific condition. When the specific condition is met, the determining unit 4082 determines that the high voltage cable is partially discharged; and when the electrical device 410 is a cast model transformer, the determining unit 4042 determines the frequency _range of 200 MHz to 300 MHz in the spectrum result S _vhf1 to S _vhf3 . Whether the partial discharge pulse conforms to a second specific condition, when the specific condition is met, the determining unit 4082 determines that the cast model transformer has a partial discharge.

It should be noted that the first/second specific condition may include information of the pulse repetition rate and/or the pulse intensity, and is set according to the background spectrum and/or the actual specification of the electrical device 410, but the invention is not limited thereto. . Further, the present invention is not limited to the above numerical ranges. For example, in other embodiments, the above-mentioned frequency range may be adjusted according to actual application requirements as long as the spirit conforms to the characteristics and approximate range of the UHF band.

The partial discharge detection system 400 uses the ultra-high frequency detection method instead of the conventional ultra-high frequency detection method, which not only can improve the accuracy of partial discharge detection, but also achieves the purpose of early detection, and the cost thereof is also greatly reduced.

Another spirit of the present invention is to perform frequency down processing and three-phase signal processing on the spectrum sensed by the UHF antenna, so that the convenience of the subsequent analysis program is greatly improved, and the hardware cost is remarkably reduced. The following is a detailed description.

5 is a schematic diagram of another exemplary embodiment of a partial discharge detection system of the present invention. The partial discharge detection system 500 includes a first UHF antenna 502, a second UHF antenna 504, a third UHF antenna 506, and an analysis unit 508. An electrical device 510 can be a high voltage power device, such as a high voltage cable or a cast model transformer. It should be noted that the present invention is not limited to the use of UHF antennas 502-506. In other embodiments, UHF antennas or antennas of other frequency bands may be used instead of UHF antennas, and analysis unit 508 may be employed. Make the corresponding modifications. In addition, the sensing mode/configuration of the UHF antennas 502-506 is not limited to the electrical device 510. For example, for different types of UHF antennas 502-506, the contact/non-contact mode/configuration may be used for sensing; Moreover, the present invention does not limit the number of UHF antennas. For example, in other embodiments, only a single UHF antenna may be used.

The partial discharge detection system 500 utilizes the UHF antennas 502-506 to respectively sense and generate three-phase spectrum results (ie, R-phase, S-phase, and T-phase spectrum results) of the electrical device 510 in the frequency band of 300 MHz to 3 GHz, that is, one. The first spectrum result S _uhf1 , a second spectrum result S _{uhf2 ,} and a third spectrum result S _uhf3 are respectively transmitted to a signal processing unit 5082 in the analyzing unit 508. The signal processing unit 5082 is coupled to the UHF antennas _502-506 for converting the higher frequency spectrum results S _uhf1 ~ S _uhf3 into a lower frequency first output signal S _ch1 and a second output signal respectively. S _ch2 and a third output signal S _ch3 , the subsequent one determining unit 5084 can determine whether the electrical device 510 is partially discharged according to the three-phase output signals S _ch1 ~ S _ch3 .

6 is a schematic diagram of an embodiment of a signal processing unit in a partial discharge detecting system of the present invention. Specifically, the signal processing unit 5082 includes a frequency down unit 50822, a sampling unit 50824, and a phase taking unit 50826. The down-converting unit 50822 down-converts the first spectral result S _uhf1 , the second spectral result S _{uhf2 ,} and the third spectral result S _{uhf3 ,} respectively. For example, the down-conversion integration circuit can be used to implement the down-conversion unit 50822, and the 1.5 GHz signal is reduced to 1.5 MHz. However, the present invention is not limited thereto, and as long as its function or spirit conforms to the above operation, it belongs to the present invention. range. The down-converting unit 50822 outputs a first down-converted signal S _d1 , a second down-converted signal S _{d2 ,} and a third down-converted signal S _d3 . The sampling unit 50824 can sample the first down-converted signal S _d1 , the second down-converted signal S _{d2 ,} and the third down-converted signal S _d3 at a frequency higher than the down-converted signal, for example, a digital frequency of 3 MHz can be used. The analog converter or other sampling circuit implements the sampling unit 50824, and outputs a first sampling signal S _S1 , a second sampling signal S _{S2 ,} and a third sampling signal S _S3 .

The phase taking unit 50826 is configured to separately filter the first sampling signal S _S1 , the second sampling signal S _{S2 ,} and the third sampling signal S _S3 , and cross-talk or cross-signal severe R phase, The S phase and the T phase signal are discarded. Specifically, the phase taking unit 50826 first triggers the first sampling signal S _S1 , the second sampling signal S _{S2 ,} and the third sampling signal S _S3 , respectively, starting from a zero point, and the zero point corresponds to the first sampling signal. S _S1 power phase sequence (R phase). If the result of triggering the first sampling signal S _S1 is greater than the result of triggering the second sampling signal S _S2 and the third sampling signal S _S3 , the result obtained by triggering the first sampling signal S _S1 is output as the first output. The signal S _ch1 ; otherwise, the result obtained by triggering the first sampling signal S _S1 is not output.

Then, the phase taking unit 50826 triggers the first sampling signal S _S1 , the second sampling signal S _{S2 ,} and the third sampling signal S _S3 respectively by using the zero point plus a specific time interval as a starting reference, and the zero point is added to the specific The time corresponds to the power phase sequence (S phase) of the second sampling signal S _S2 . In this embodiment, the specific time interval is 5.557 ms, but the invention is not limited thereto. If the result obtained by triggering the second sampling signal S _S1 is greater than the result obtained by triggering the first sampling signal S _S1 and the third sampling signal S _S3 , the result obtained by triggering the second sampling signal S _S2 is output as the second output. The signal S _ch2 ; otherwise, the result obtained by triggering the second sampling signal S _S2 is not output.

Finally, the phase taking unit 50826 triggers the first sampling signal S _S1 , the second sampling signal S _S2 and the third sampling signal S _S3 as the starting reference by subtracting the specific time interval from the zero point, and subtracting the specific point from the zero point. The time corresponds to the power phase sequence (T phase) of the third sampled signal S _S3 . If the result obtained by triggering the third sampling signal S _S3 is greater than the result obtained by triggering the first sampling signal S _S1 and the second sampling signal S _S2 , the result obtained by triggering the third sampling signal S _S3 is output as the third output. The signal S _ch3 ; otherwise, the result obtained by triggering the third sampling signal S _S3 is not output.

The judging unit 5084 in the analyzing unit 508 of FIG. 5 judges whether or not the electric device 510 is partially discharged according to the three-phase output signals S _ch1 to S _ch3 . For example, the determining unit 5084 obtains the amount of discharge per phase, the maximum discharge amount per unit time (for example, every minute), and the maximum number of discharges per unit time (for example, per minute) according to the output signals S _ch1 to S _ch3 , and the specific calculation is performed. The method automatically determines whether the electrical device 510 is partially discharged; or the above information is transmitted or outputted to the display through the network for human determination, and the invention is not limited. Compared with the conventional method for directly analyzing and judging the GHz-level UHF signal, the hardware requirement of the determining unit 5084 is for the low-frequency signal of the MHz level, and thus has economic benefits.

The spirit of the present invention relating to the partial discharge detecting system 500 is to use a lower-order system and a lower-resolution signal processing method to instantly and quickly distinguish whether or not electrical equipment is partially discharged, due to low cost. It can be used universally on all electrical equipment and monitored at any time. Once a partial discharge has occurred, a higher order instrument is used for localized discharge positioning and other more precise operations.

In the previous embodiment, the partial discharge detection system 500 is implemented by using a Field-Programmable Gate Array (FPGA) and a low-order Central Processing Unit (CPU), but the above The concepts of the present invention can also be implemented in any integrated circuit, including radio frequency and/or synchronous clock applications, by semiconductors. For example, the invention can be implemented in a single semiconductor design or in a particular application integrated circuit and/or any other subsystem.

In other words, the invention can be implemented in any suitable form, including hardware, software, firmware, or any combination of the above. At least some of the present invention can be selectively implemented as a computer software running on one or more data processors and/or digital signal processors or configurable modular components (eg, FPGAs). Thus, the elements and components of an embodiment of the invention are physically, functionally and logically implemented in any suitable manner. Indeed, the functionality of the present invention can be implemented in a single unit, in a plurality of units or as part of other functional units.

Although the invention has been described in connection with some embodiments, the invention It is not limited to the specific forms of the description in this specification. Rather, the scope of the invention is limited only by the appended claims. In addition, although the inventive features may be described in conjunction with the specific embodiments, those skilled in the art will appreciate that the various features of the described embodiments can be combined in accordance with the present invention. In the claims, the <RTIgt; "comprising" does not exclude the presence of other elements or steps.

In addition, although a plurality of means, elements or methods are separately listed, they should be implemented by, for example, a single unit, a processor, or a controller. In addition, although individual features may be included in different claims, the combination may be advantageously combined, and the inclusion in the different claims does not mean that the combination of features is not feasible and/or advantageous. Further, a feature contained in a category of claims is not meant to be limited to the category, but rather to the same.

In addition, the order of features in the claims is not intended to be in any specific order, and the order of the various steps in the method claims does not mean that the steps must be performed in the order. Rather, these steps can be performed in any suitable order. In addition, singular references do not exclude a plurality. Therefore, terms such as "a", "first" and "second" do not exclude a plurality.

The technical content and technical features of the present disclosure have been disclosed as above, and those of ordinary skill in the art should understand that the teachings of the present disclosure and the scope of the disclosure and the scope of the disclosure are defined without departing from the scope of the appended claims. It is revealed that various alternatives and modifications can be made. For example, many of the devices or structures disclosed above may be implemented in different ways or substituted with other structures, or a combination of the two.

400‧‧‧Partial Discharge Detection System

402‧‧‧First UHF Antenna

4022‧‧‧first sensor

4024‧‧‧First output unit

404‧‧‧Second UHF antenna

4042‧‧‧Second sensor

4044‧‧‧second output unit

406‧‧‧Third UHF antenna

4062‧‧‧ third sensor

4064‧‧‧ third output unit

408‧‧‧Analysis unit

4082‧‧‧Judgement unit

410‧‧‧Electrical equipment

Claims (9)

A partial discharge detecting method comprising: sensing an electrical device using at least one UHF antenna, and generating at least one spectral result; and in a frequency band of 140 MHz to 200 MHz and/or 200 MHz according to the at least one spectral result A partial discharge pulse in a frequency band of ~300 MHz is used to determine whether or not a partial discharge occurs in the electrical device. The partial discharge detecting method according to claim 1, wherein the electrical device is a high voltage cable, and the step of determining whether the electrical device is partially discharged according to the at least one spectral result comprises: according to the at least one spectral result A partial discharge pulse in a frequency band of 140 MHz to 200 MHz determines that a partial discharge occurs in the high voltage cable. The partial discharge detecting method according to claim 1, wherein the electrical device is a cast model transformer, and the step of determining whether the electrical device is partially discharged according to the at least one spectral result comprises: according to the at least one spectral result A partial discharge pulse in a frequency band of 200 MHz to 300 MHz is used to determine a partial discharge of the cast model transformer. A UHF antenna for detecting partial discharge includes: a sensor for sensing an electrical device and generating a spectral result; and an output unit for outputting the spectral result; Based on the frequency of 140MHz~200MHz in the spectrum result and/or A partial discharge pulse in a frequency band of 200 MHz to 300 MHz is used to determine whether or not partial discharge occurs in the electrical device. A partial discharge detection system comprising: at least one UHF antenna for sensing an electrical device and generating at least one spectral result; and an analysis unit coupled to the at least one UHF antenna And determining whether the electrical device is partially discharged according to a partial discharge pulse in a frequency band of 140 MHz to 200 MHz and/or a frequency band of 200 MHz to 300 MHz in the at least one spectrum result. A partial discharge detection method includes: sensing at least one antenna for an electrical device, and generating at least one spectral result; performing frequency reduction processing on the at least one spectral result, and generating at least one frequency down spectrum result; triggering the And at least one frequency-down spectrum result, generating a trigger result; and determining whether the electrical device has a partial discharge according to the at least one frequency-down spectrum result and the trigger result. The partial discharge detection method of claim 6, wherein the at least one antenna comprises a first UHF antenna and a second UHF antenna, the at least one spectral result comprising a first spectral result and a second The result of the spectrum, the at least one down-converted spectrum result includes a first down-converted spectrum result and a second down-converted spectrum result, the trigger result includes a first trigger result and a second trigger result; and the partial discharge detecting method Also includes: The first frequency-down spectrum result and the second frequency-down spectrum result are respectively triggered by using a power phase corresponding to the first frequency-down spectrum result, and the first trigger result and the second trigger result are generated; The step of determining the partial discharge of the electrical device by the at least one frequency-down spectrum result comprises: determining whether the electrical device has a partial discharge according to the first frequency-down spectrum result when the first trigger result is greater than the second trigger result . A partial discharge detection system includes: at least one antenna for sensing an electrical device and generating at least one spectral result; and a frequency reduction unit for performing frequency reduction processing on the at least one spectral result and generating At least one frequency-down spectrum result; a phase-taking unit coupled to the frequency-down unit; and a determining unit configured to determine whether the electrical device is partially discharged according to the at least one frequency-down spectrum result. The partial discharge detection system of claim 8, wherein the phase phasing unit is configured to determine the at least one frequency reduction according to the at least one frequency down spectrum result and the at least one power phase corresponding to the at least one frequency down spectrum result. Whether the spectral result is interfered by crosstalk and generates at least one determination result; and the determining unit further determines whether the electrical device has a partial discharge according to the at least one determination result and the at least one frequency down spectrum result.