Voltage phase difference field detection method based on ring main unit nuclear phase hole

Abstract

The invention discloses a ring main unit nuclear phase hole-based voltage phase difference field detection method, which is characterized in that a secondary voltage phase difference output by a nuclear phase hole in a ring main unit is measured through a measuring device, the secondary voltage is a secondary voltage phase difference value of two sides of a loop closing point in the ring main unit, and whether the secondary voltage value exceeds a safety threshold value or not is judged to determine whether the secondary voltage value exceeds the safety threshold value or not. And whether safe loop closing can be carried out or not is judged. According to the method, a field loop closing measurement means is provided for solving the technical problem of loop closing switching, and the magnitude of the loop closing current can be accurately calculated, so that safe and stable operation of a power grid is ensured. The method is high in implementability, the secondary voltage replaces the primary voltage to serve as a detection object, the personal safety in the detection process can be effectively guaranteed, meanwhile, the detection means of the nuclear phase hole has no direct influence on operation of the ring main unit, and safe and reliable operation of a power grid is practically guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of closed-loop current detection, and relates to an on-site detection method for voltage phase difference based on a core phase hole of a ring network cabinet. Background Art

[0002] The closing current refers to the current value generated when the primary and secondary sides of the transformer or line in the power system are closed. In the current power system, online monitoring of the closing current has become an important technical means to ensure the stable operation of the power grid. When adjusting the mode of the 10kV distribution network, it is often necessary to perform a closing switch operation. However, if there is a large phase angle difference on both sides of the closing point, the closing current will be too large instantaneously, which may pose a threat to the stable operation of the power grid. Therefore, during the closing process, it is necessary to be able to measure the phase difference on both sides of the on-site closing point to ensure the safety of the closing.

[0003] At present, there are mainly two methods for online monitoring of closed-loop current. The first method is to deploy a closed-loop monitoring device in the switch station. However, the limitation of this method is that there are few installation points for the monitoring device, and once installed, its position is fixed and difficult to flexibly adjust according to actual needs. In addition, data between different closed-loop points cannot be effectively shared for the time being, which undoubtedly limits the comprehensiveness and accuracy of monitoring.

[0004] The second method is to equip the line-side electronic voltage transformer around the magnetic control cabinet to monitor the voltage phase difference. Although this method improves the flexibility of monitoring to a certain extent, both the online monitoring method of the magnetic control cabinet and the switch station requires a lot of manpower and material resources, and the existing power equipment needs to be transformed and upgraded. This means that only modified equipment can support this monitoring method, which undoubtedly increases the difficulty and cost of implementation. At the same time, the flexibility, universality and convenience of this method still need to be improved.

[0005] Therefore, the existing method for measuring the voltage on both sides of the loop closing point has the problems of poor measurement flexibility, low accuracy and complicated measurement process. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a field detection method for voltage phase difference based on the core phase hole of the ring network cabinet to solve the problems of low accuracy, complex measurement method and poor flexibility of the phase difference measurement method on both sides of the ring point in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: The voltage phase difference on-site detection method based on the core phase hole of the ring main unit includes the following steps: S1, collecting the secondary voltage phase difference output by the core phase hole in the ring network cabinet through a measuring device, wherein the secondary voltage phase difference is the secondary voltage phase difference value on both sides of the closing point in the ring network cabinet; S2, judging whether the secondary voltage phase difference exceeds a set threshold value, wherein the threshold value is a safe phase difference value on both sides when the closing point is safely closed.

[0008] A further improvement of the present invention is: Preferably, in S1, the core phase hole is a core phase hole corresponding to the measurement circuit in the ring network cabinet.

[0009] Preferably, in S1, the measurement circuit collects the voltage phase difference through a terminal block.

[0010] Preferably, in S1, the core phase hole is the core phase hole corresponding to the power display in the ring network cabinet.

[0011] Preferably, in S1, the charged display comprises a sensing unit and a display unit, the core phase hole is arranged in the display unit, the sensing unit is electrically connected to the main circuit, and the sensing unit is electrically connected to the display unit.

[0012] Preferably, in S1, the measuring device is a volt-ampere phase meter.

[0013] Preferably, the phase voltage transformation ratio accuracy level of the volt-ampere phase meter is 0.5.

[0014] Preferably, in S1, the secondary voltage phase difference measured by the core phase hole replaces the primary voltage phase difference of the closing point.

[0015] Preferably, in S1, the waveform and period of the secondary voltage at the closing point measured by the core phase hole are equal to the primary voltage at the closing point.

[0016] Preferably, in S1, the voltage phase deviation between the secondary voltage at the closing point and the primary voltage at the closing point measured by the core phase hole is a constant value.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a voltage phase difference field detection method based on the core phase hole of a ring network cabinet. The method measures the secondary voltage output by the core phase hole on the ring network cabinet through a measuring device. The secondary voltage is the secondary voltage phase difference value on both sides of the closing point in the ring network cabinet. By judging whether the secondary voltage value exceeds the safe voltage value, it is judged whether the safe closing can be performed. The present invention provides a method for measuring the voltage phase difference on both sides of the closing point on site. In order to solve the technical problem of closing and switching, a measuring method for closing on site is provided, and the size of the closing current can be accurately calculated, thereby ensuring the safe and stable operation of the power grid. The method of the present invention has strong feasibility. The secondary voltage replaces the primary voltage as the detection object, which can effectively ensure the personal safety of the detection process. At the same time, the detection method of the core phase hole has no direct impact on the operation of the ring network cabinet, which effectively ensures the safe and reliable operation of the power grid. The method of the present invention has strong flexibility. The ring network cabinet is the basic equipment for the hybrid line. The detection principle of the method has wide applicability. Ring network cabinets of different manufacturers, different models and different batches all have measurement conditions.

[0018] Furthermore, the core phase hole used for measurement in the present invention is a corresponding core phase hole in the measurement loop in the ring network cabinet, so that the measuring device can be directly inserted into the core phase hole for rapid measurement.

[0019] Furthermore, the measuring device is a volt-ampere phase meter. The operation and use of the volt-ampere phase meter is similar to that of a nuclear phase meter. The technical threshold is relatively low. Operators can get started quickly and easily and can easily obtain voltage phase difference results with the help of the instrument. More importantly, the volt-ampere phase meter can accurately measure the secondary voltage.

[0020] Furthermore, the secondary voltage phase difference measured by the core phase hole of the present invention is replaced by the primary voltage difference of the closing point, and the accuracy of the detection scheme is verified through field detection tests at different points of different categories. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A voltage phase difference measurement method according to the present invention; Figure 2 The ring network and measurement location diagram of the present invention; Figure 3 It is a working principle diagram of the charged display of the present invention.

[0022] Among them, 1. Ring network cabinet; 2. Connecting switch; 3. Ring network; 4. Branch; 5. Main circuit; 6. Sensor unit; 7. Display unit; 8. Interlocking signal output unit; 9. Connection point; 10. Interlocking device; 11. Nuclear phase hole; a. Signal from the sensor unit; b. Signal from the connection point. DETAILED DESCRIPTION

[0023] In the following, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of the features.

[0024] It should be noted that the terms "first", "second", etc. in the specification and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] As the problem raised in the background technology, at present, the closing current can be monitored online in two ways. One is to deploy it in the switch station and install a closing monitoring device, but the device has few installation points, and the installation position is fixed and cannot be flexibly changed, and the data between different closing points cannot be effectively obtained for the time being. Second, equip the line side electronic voltage transformer around the magnetic control cabinet to monitor the voltage phase difference. The online monitoring methods of the magnetic control cabinet and the switch station require a lot of manpower and material resources, and the existing equipment needs to be transformed and upgraded. It can only be implemented on the modified equipment, and its flexibility, universality and convenience are insufficient. In particular, for the 10kV distribution network, the closing switch needs to be closed when the mode is adjusted, but if there is a large phase angle difference on both sides of the closing point, the closing current will be too large instantaneously. The voltage phase difference on both sides of the closing point is the direct cause of the closing current. In view of the current situation that the voltage phasor monitoring means of the distribution network is limited, the present invention proposes a measurement method for the voltage phase difference of the closing point of the 10kV rack hybrid network.

[0026] See also Figure 1 , the ring network 3 refers to a ring distribution network, that is, the power supply trunk forms a closed ring, the power supply supplies power to this ring trunk, and then distributes power to the outside through high-voltage switches one by one from the trunk. The ring network cabinet 1 is equipped with a switch cabinet (outgoing switch cabinet) for each distribution branch 4, and the busbar of the switch cabinet is also part of the ring trunk. Therefore, the ring trunk is composed of the busbars of each outgoing cabinet connected together, and each outgoing cabinet is a ring network cabinet.

[0027] The following is further described in conjunction with specific embodiments.

[0028] The present invention discloses a voltage phase difference field detection method based on a core phase hole of a ring main unit, comprising the following steps: S1, collecting the secondary voltage phase difference output by the core phase hole on the ring main unit through a measuring device, wherein the secondary voltage phase difference is the secondary voltage phase difference value on both sides of the closing point in the ring main unit; S2, judging whether the secondary voltage phase difference exceeds a set threshold value, wherein the threshold value is a safe voltage value on both sides when the closing point is safely closed.

[0029] In the method of the present invention, the present invention accurately captures the secondary voltage signal output by the core phase hole of the ring network cabinet through a measuring device. This signal reflects the difference in the secondary voltage on both sides of the closing point. By comparing this difference with the safety voltage threshold, it is possible to quickly determine whether it is suitable for safe closing operation under the current conditions. The present invention provides a practical on-site measurement solution to the technical problems in the closing and switching operation, can accurately estimate the scale of the closing current, and provides a strong guarantee for the safe and stable operation of the power grid. This method selects the secondary voltage as the detection object instead of directly measuring the primary voltage, thereby greatly reducing the safety risks that may be caused to personnel during the detection process. At the same time, the detection method of the core phase hole will not cause any interference to the normal operation of the ring network cabinet, ensuring the continuous stability and reliability of the power grid.

[0030] It should be understood that the threshold value set in S3 is usually set according to the actual situation on the actual ring network, and the threshold values ​​are set differently in different ring networks and ring network cabinets.

[0031] See also Figure 1 , two adjacent ring network cabinets 1 in the ring network 3 are connected through the ring network 3 busbar, and an outgoing line connection is also provided. Both sides of each connecting line are connected to the ring network cabinet 1 through a connecting switch 2, respectively. The connecting switch 2 is the closing point measured by each ring network cabinet 1. The measured secondary voltage is the secondary voltage on both sides of the connecting switch 2. Considering that each ring network cabinet 1 will be incorporated into the ring network 3 through a connecting switch 2, the method has universal applicability.

[0032] Example 2 S1, collecting the secondary voltage phase difference output by the core phase hole on the ring main unit through a measuring device, wherein the secondary voltage phase difference is the secondary voltage phase difference value on both sides of the closing point in the ring main unit; S2, judging whether the secondary voltage phase difference exceeds a set threshold value, wherein the threshold value is a safe voltage value on both sides when the closing point is safely closed.

[0033] In this embodiment, in S1, the measuring device is directly inserted into the core phase hole of the ring network cabinet, and the secondary voltage is measured through the measuring circuit in the ring network cabinet. The measuring circuit mainly collects voltage through the terminal block. The specific process is that in the ring network cabinet, the voltage on the high-voltage bus in the ring network cabinet is first converted by the voltage transformer (PT), and the voltage transformer converts the high voltage into a low voltage (usually 100V or lower) for subsequent processing and measurement. The converted low voltage signal is transmitted to the terminal block through a cable or wire. On the terminal block, these signals are distributed to the corresponding wiring terminals.

[0034] During the measurement circuit test, the terminal block and its connection lines must have good insulation performance to prevent electrical contact between the high voltage and low voltage measurement circuits, resulting in short circuits or electric shock accidents. At the same time, ensure that there is sufficient electrical isolation distance between the terminal block and other high voltage components in the ring network cabinet. The terminal block and its related equipment should be properly grounded to provide additional electrical safety protection. In the event of an electrical fault, the grounding system can quickly conduct the fault current to the earth, reducing the risk of electric shock and equipment damage. However, relatively complex secondary safety measures need to be arranged.

[0035] Example 3 S1, collecting the secondary voltage phase difference output by the core phase hole on the ring main unit through a measuring device, wherein the secondary voltage phase difference is the secondary voltage phase difference value on both sides of the closing point in the ring main unit; S2, judging whether the secondary voltage phase difference exceeds a set threshold value, wherein the threshold value is a safe voltage value on both sides when the closing point is safely closed.

[0036] In this embodiment, compared with Embodiment 2, the measuring device is directly inserted into the core phase hole of the live display of the ring main unit.

[0037] See also Figure 3 , is a working principle diagram of the charged display, the charged display sensor unit 6, the display unit 7 and the interlocking signal transmission unit 8, wherein the sensor unit 6 is electrically connected to the main circuit 5, the sensor unit 6 and the display unit 7 are electrically connected, so that the display unit 7 can receive the signal a transmitted back from the sensor unit 6, the display unit 7 is electrically connected to the interlocking signal output unit 8, and the interlocking signal output unit 8 is electrically connected to the interlocking device 10; the display unit 7 is also provided with a connection point 9 for connecting other devices, and the display unit 7 is provided with a core phase hole 11.

[0038] The sensor unit contains a voltage transformer, which uses the principle of electromagnetic induction to achieve voltage conversion. When the primary side (input side) winding is connected to a high voltage, an alternating magnetic field is generated in the iron core, which then induces a voltage in the secondary side (output side) winding.

[0039] The sensing unit 6 converts the primary voltage collected from the main circuit 5 into a secondary voltage, and outputs it to a measuring device connected to the core phase hole through the core phase hole.

[0040] Example 4 S1, collecting the secondary voltage phase difference output by the core phase hole on the ring main unit through a measuring device, wherein the secondary voltage phase difference is the secondary voltage phase difference value on both sides of the closing point in the ring main unit; S2, judging whether the secondary voltage phase difference exceeds a set threshold value, wherein the threshold value is a safe voltage value on both sides when the closing point is safely closed.

[0041] In this embodiment, the measuring device is a high-precision instrument with a display provided thereon, which is plugged into the core phase hole to obtain the voltage phase difference at different intervals.

[0042] In this embodiment, as a preferred solution, the measuring device is a volt-ampere phase meter, which measures the core-phase hole phase difference. Based on the principle of electromagnetic induction, the phase difference is calculated by measuring the mutual inductance between the current coil and the voltage coil. The working principle of the volt-ampere phase meter is based on electromagnetic induction. When the measured current passes through the current coil, a magnetic field is generated. At the same time, the measured voltage acts on the voltage coil and also generates a magnetic field. By measuring the interaction between the two magnetic fields (i.e., mutual inductance), the phase difference between the current and voltage can be calculated. The phase voltage transformation ratio accuracy level of the volt-ampere phase meter is 0.5.

[0043] Usually, the phase hole in the ring network cabinet 1 in the ring network 3 is used for inserting tools such as a phase meter or a phase stick. By measuring the phase relationship of voltage or current, it is confirmed whether the phases of two power supplies or circuits are consistent. It is a key step for the ring network cabinet to achieve safe grid connection or switching operation in the power system. In this case of use, the voltage accuracy transmitted by the phase meter is low and the voltage cannot be accurately measured. In this embodiment, the volt-ampere phase meter used uses high-precision digital integrated circuits and sensors. These components have excellent stability and linearity and can provide accurate voltage readings within a wide measurement range. The introduction of digital integrated circuits also makes the measurement results more stable and reduces the problems of temperature drift and time drift that may be caused by analog circuits. The volt-ampere phase meter integrates advanced signal processing technologies such as filtering, amplification, A / D conversion, etc. These technologies can effectively suppress external interference and noise and improve the signal-to-noise ratio of voltage measurement. At the same time, through precise algorithm processing, the measurement error can be further corrected to ensure the high accuracy of voltage measurement.

[0044] Example 5 In this embodiment, in order to verify that the secondary voltage can accurately reflect the phase difference of the primary voltage, the detection method needs to satisfy that the waveform of the secondary measured value of the voltage is consistent with the primary true value or there is a stable phase offset relationship.

[0045] Build a ring main unit core phase hole detection environment, apply AC voltage to the cable contact of ring main unit 1 through a withstand voltage tester, measure the secondary voltage at the core phase hole of the live display, and draw the voltage time domain and frequency domain waveforms respectively through a power analyzer.

[0046] By applying a higher and lower voltage twice to the primary, it can be found that the secondary output waveform has the same period as the primary waveform, the voltage phase deviation is stable at a fixed value, and the transmission coefficient is similar. Frequency domain analysis shows that the primary voltage and secondary voltage fundamental waves have the same period, and the phase angle deviation meets the requirements. Therefore, the voltage amplitude measured by the phase hole of the live display can linearly reflect the voltage amplitude of the primary voltage waveform, while the phase is stable and lags behind the primary voltage phase quantity, and the phase difference can directly reflect the primary voltage phase difference.

[0047] By applying two different voltages, higher and lower, to the primary side, it can be observed that the secondary output waveform is completely equal to the primary waveform in terms of period, which indicates the time domain consistency of voltage transmission. Further analysis shows that the voltage phase deviation in both tests is stably maintained at a fixed value, which is 72° in this embodiment, which not only proves the similarity of the transmission coefficient, but also reveals the regularity of phase transmission. When performing frequency domain analysis, the fundamental components of the primary voltage and the secondary voltage are strictly in the same period, and the phase angle deviation fully meets the preset technical requirements, which further verifies the accuracy and stability of voltage transmission. Through the above process, it can be concluded that the voltage amplitude measured by the phase hole of the live display can linearly and accurately reflect the voltage amplitude of the primary voltage waveform, so any slight change in the primary side voltage will be reflected accordingly and proportionally on the secondary side. At the same time, the phase of the secondary voltage stably lags behind the primary voltage phase by a fixed angle, that is, the phase difference remains constant. The voltage phase difference on the primary side can be directly and reliably inferred by measuring the voltage phase difference on the secondary side, making it possible to insert a volt-ampere phase meter into the core phase hole and measure the phase difference of the secondary voltage to replace the judgment of the primary voltage.

[0048] Example 6 In this embodiment, in order to verify the accuracy of the voltage phase difference measurement scheme based on the core phase hole, relying on the online monitoring device of the switch station built in the early stage, the voltage phase difference points are finely deployed, and the on-site detection results are compared and analyzed with the real-time monitoring results of the switch station.

[0049] An overhead line was selected for verification, and the voltage phase difference on both sides of the ring network cabinet closing point was measured using the phase hole, and compared with the value monitored by the upper-level switch station. The results are as follows.

[0050] Table 1 Comparison of voltage phase difference between on-site measurement of overhead lines and online monitoring at switch stations

[0051] It can be seen that the actual on-site measurement is consistent with the online real-time monitoring value, which verifies the accuracy of the voltage phase difference measurement based on the core phase hole of the ring network cabinet. In addition, the on-site core phase hole phase measurement is carried out on the basis of the online monitoring of the magnetic control cabinet. The two form a non-homologous monitoring form, which confirms each other and ensures the correctness and accuracy of the on-site data collection of this scheme.

[0052] The present invention constructs a technical solution for measuring phase difference of the core phase hole by comparing and analyzing the universal live indicators of two major equipment suppliers and conducting a transmission characteristic test on the voltage signal output by the core phase hole. By adopting the technical solution of plugging a high-precision volt-ampere phase meter into the core phase hole of the ring main unit, the voltage phase difference of different intervals can be directly measured under the premise of ensuring operation safety.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A voltage phase difference field detection method based on the core phase hole of the ring main unit is characterized in that: The following steps are involved: S1, collecting the secondary voltage phase difference output by the core phase hole in the ring network cabinet through a measuring device, wherein the secondary voltage phase difference is the secondary voltage phase difference value on both sides of the closing point in the ring network cabinet; S2, judging whether the secondary voltage phase difference exceeds a set threshold value, wherein the threshold value is a safe phase difference value on both sides when the closing point is safely closed.

2. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 1 is characterized in that: In S1, the core phase hole is the core phase hole corresponding to the measurement circuit in the ring network cabinet.

3. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 2 is characterized in that: In S1, the measurement circuit collects the voltage phase difference through the terminal block.

4. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 1 is characterized in that: In S1, the core phase hole is the core phase hole corresponding to the live display in the ring network cabinet.

5. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 4 is characterized in that: In S1, the charged display comprises a sensing unit and a display unit, the core phase hole is arranged in the display unit, the sensing unit is connected to the main circuit electrical signal, and the sensing unit is connected to the display unit electrical signal.

6. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 1 is characterized in that: In S1, the measuring device is a volt-ampere phase meter.

7. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 6 is characterized in that: The phase voltage transformation ratio accuracy level of the volt-ampere phase meter is 0.5 level.

8. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 1 is characterized in that: In S1, the secondary voltage phase difference measured by the core phase hole replaces the primary voltage phase difference at the closing point.

9. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 8 is characterized in that: In S1, the waveform and period of the secondary voltage at the closing point measured through the core phase hole are equal to the primary voltage at the closing point.

10. The voltage phase difference on-site detection method based on the core phase hole of the ring main unit according to claim 8 is characterized in that: In S1, the voltage phase deviation between the secondary voltage at the closing point measured by the core phase hole and the primary voltage at the closing point is a constant value.

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