Phase-adaptive distributed power distribution network testing device cooperative control method and system

Abstract

The invention discloses a phase-adaptive distributed power distribution network test device cooperative control method and system, and the method comprises the steps: respectively capturing a periodic zero-crossing event of a local power frequency power supply through a first device and a second device, and building a local physical time sequence reference independent of an operation system clock; after the wireless connection is established, measuring a time parameter of a zero-crossing signal between the devices, and mapping the parameter to a preset discrete phase topological interval, so as to identify a power supply phase topological relation between the devices; the first device generates a phase compensation strategy according to an identification result, and after the second device receives the phase compensation strategy, the second device directly drives the power module to output a collaborative waveform after delay of a hardware timer by taking a future local physical time sequence reference event as a trigger starting point. According to the invention, by constructing a hardware trigger closed loop and phase topology adaptive mechanism of a physical level, random jitter caused by a software system clock is thoroughly eliminated, and the microsecond-level rigid synchronization problem in a satellite-signal-free and out-of-phase power supply environment is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system automation testing, and in particular to a cooperative control method applied between distributed test devices. BACKGROUND

[0002] In the relay protection testing, fault line selection device checking and primary and secondary circuit joint debugging of distribution networks, it is often necessary to simulate real fault conditions. The traditional testing method usually uses a single relay protection tester, which is limited by the length of the test cable and is difficult to meet the synchronous joint debugging requirements of injecting current at the primary side and injecting voltage at the secondary side of the devices distributed in different compartments of the switch cabinet or even different substation areas.

[0003] In order to solve the problem of long-distance wiring, the industry has proposed a distributed testing system architecture, including two or more independent signal generating devices arranged at different positions and cooperatively outputting current signals or voltage signals through wireless communication. However, the core difficulty of the distributed testing system lies in the phase synchronization accuracy of the distributed cooperative output. For high-sensitivity protection devices such as small-current grounding line selection, the phase difference of zero-sequence current and zero-sequence voltage is extremely sensitive to the action logic, and the synchronization error of the signal source is usually required to be less than 1°, i.e. the time error needs to be controlled within 55 microseconds at a power frequency of 50 Hz. In order to achieve this synchronization accuracy, the early distributed testing devices usually have built-in GPS or Beidou satellite timing modules, which use PPS second pulse signals for synchronization, or use optical fiber connection for hard synchronization. However, in the closed environment of the metal switch cabinet in the actual distribution room, satellite signals often cannot be covered, resulting in synchronization failure, and laying long-distance optical fibers violates the initial intention of wireless portability and complicates the on-site operation.

[0004] In order to get rid of the dependence on satellite signals, the industry has proposed to use the power frequency voltage zero-crossing point as a reference benchmark, combined with wireless communication messages to measure the time difference between nodes, and then calibrate the local system clock of each node, trying to achieve time unification of the whole network. However, this scheme only pursues the alignment of timestamps at the software level, ignoring a fundamental physical problem: even if the system time of each device is calibrated, the action of the output waveform of the final driving power module still depends on the scheduling of the microcontroller operating system. The interrupt response delay and task switching jitter of the operating system are usually in the range of tens of microseconds to milliseconds, and this random jitter at the software level will be directly transmitted to the output waveform, resulting in a phase control accuracy that cannot meet the rigid requirements of relay protection testing.

[0005] In addition, in the test environment set up on the spot, two portable devices are often connected to different power sockets nearby. Since the power distribution network is three-phase power supply, the two devices may be connected to different phase sequences, with a phase difference of 120° or 240°. The existing zero-crossing time correction technology usually needs to know the phase relationship between the master and slave nodes in advance, or relies on the master node to broadcast information of all phases for complex numerical calculation and deduction. In the case of unknown phase topology on the spot and the need for rapid deployment, manual intervention or complex configuration is required, which greatly reduces the work efficiency of the on-site test personnel who must carry an oscilloscope for manual phase checking.

[0006] Therefore, under the on-site restricted conditions of satellite signal absence and unknown power supply phase topology, it is urgent to develop a distributed control technology that can break away from the dependence on software system clock. The technology needs to build a physical layer trigger mechanism independent of the operating system, and has the ability of adaptive identification and compensation for different phase power supply, to solve the problem of insufficient phase synchronization accuracy in the existing distribution network distributed test. SUMMARY

[0007] The present application provides a phase-adaptive distributed power distribution network test device cooperative control method, which aims to overcome the problems of insufficient cooperative control accuracy, poor robustness and complicated operation caused by dependence on software clock and lack of phase adaptive ability in the existing technology under complex on-site environment without satellite signal and unknown power supply phase.

[0008] The phase-adaptive distributed power distribution network test device cooperative control method is applied to a test system containing at least one first device and one second device, and includes the following steps:

[0009] S1: The first device and the second device capture the periodic zero-crossing event of the power frequency power supply connected thereto respectively, and establish a local physical time sequence reference independent of the operating system clock;

[0010] S2: The first device initiates a phase negotiation with the second device at a time associated with its local physical time sequence reference through wireless communication;

[0011] S3: In the phase negotiation process, a time parameter representing the phase relationship between the local physical time sequence references of the two devices is measured and obtained;

[0012] S4: The power supply phase topology relationship of the second device relative to the first device is identified according to the time parameter, and a phase compensation strategy for subsequent cooperative action is generated;

[0013] S5: The second device performs a preset control action in phase coordination with the first device based on the phase compensation strategy, with a future local physical time sequence reference event as the trigger starting point.

[0014] On the basis of the above scheme, further has, the time parameter measurement in step S3 specifically includes the following sub-steps:

[0015] S31: using the hardware timestamp function of the wireless communication module bottom, record the physical layer sending time and receiving time of wireless signal;

[0016] S32: the round trip time of wireless transmission is calculated through the bidirectional message interaction, and the original time difference between the local physical time sequence reference of the two devices is compensated by using the round trip time, and the time parameter is obtained.

[0017] On the basis of the above scheme, further has, the power supply phase topology relationship identification in step S4 specifically includes the following sub-steps:

[0018] S41: the time parameter is mapped to the preset discrete phase topology interval;

[0019] S42: when the time parameter falls into different intervals, respectively determine that the second device is in phase, lagging behind a certain angle or leading a certain angle relative to the first device;

[0020] S43: the center value of the discrete phase topology interval corresponds to the theoretical inherent phase difference of the multi-phase alternating current power grid, and each interval is provided with a judgment threshold window allowing wireless communication jitter.

[0021] On the basis of the above scheme, further has, the preset control action execution in step S5 specifically includes the following sub-steps:

[0022] S51: the phase compensation strategy is converted into a hardware delay count value, and loaded into the hardware timer of the microcontroller;

[0023] S52: the corresponding electric signal of the local physical time sequence reference is configured as the external trigger input source of the hardware timer;

[0024] S53: when the future local physical time sequence reference event occurs, the hardware timer is directly triggered to start counting, and when the count reaches the hardware delay count value, the output level is reversed through the hardware channel to drive the power module, and the process is independently executed outside the operating system software intervention of the microcontroller.

[0025] On the basis of the above scheme, further has, the first device and the second device monitor the frequency of the power frequency power supply connected by them in real time, and when the phase compensation strategy is generated in step S4, the delay parameter is calculated in combination with the real-time monitored frequency, to ensure that the phase angle of the cooperative control action remains constant relative to the real-time power frequency period.

[0026] On the basis of the above scheme, further has, the preset control action includes:

[0027] Output high amplitude pulse current in the specific phase window of the power frequency voltage waveform, to simulate intermittent arc ground fault, or output non-power frequency signal superimposed with specific coding characteristics, for anti-interference selection line test.

[0028] On the basis of the above scheme, further has, the first device and the second device adopt the centerless ad hoc network mode for communication between them;

[0029] Any test device accessing the power grid can initiate the phase negotiation, and automatically elect one device as the phase reference device of the whole network by broadcasting the time parameter.

[0030] In order to better realize the above method, the application also provides a phase adaptive distributed power distribution network test device cooperative control system, comprising a first device and a second device, the first device and the second device both comprise:

[0031] Zero-crossing detection circuit, for coupling field power frequency power supply and outputting nanosecond level edge digital zero-crossing signal;

[0032] Wireless communication module, for data interaction and hardware timestamp marking between devices;

[0033] Power generation module, for outputting simulation test signal;

[0034] Controller, configured to execute the above-mentioned phase adaptive distributed power distribution network test device cooperative control method, utilize the digital zero-crossing signal as hardware interrupt or timer gating signal, control the output timing of the power generation module.

[0035] On the basis of the above scheme, further has, the zero-crossing detection circuit comprises:

[0036] Optoelectronic isolation unit, for isolating strong electric side interference;

[0037] Hysteresis comparator, for shaping the sine wave into square wave and eliminating noise jitter near zero-crossing point;

[0038] The digital zero-crossing signal is directly connected to the capture / comparison unit pin of the controller.

[0039] On the basis of the above scheme, further has, the system is used for power distribution network primary and secondary circuit linkage test:

[0040] The first device is configured as a voltage source, connected to the secondary side terminal of the power distribution network protection device;

[0041] The second device is configured as a current source connected to a primary side of a primary equipment of a power distribution network.

[0042] The first device and the second device cooperatively output a single-phase ground fault or a short-circuit fault with a set phase angle.

[0043] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0044] 1. The present application establishes a local physical timing reference independent of the operating system clock, and directly introduces a power frequency zero-crossing signal into the external trigger source of a hardware timer, thereby constructing a pure hardware closed-loop control link of "physical zero-crossing - hardware delay - power output". This design completely eliminates software intervention in the execution of cooperative action, ensuring the rigidity and high precision of the output phase between distributed devices, and meeting the stringent requirements of relay protection testing.

[0045] 2. The present application proposes a classification recognition method based on discrete phase topology intervals, and the system can automatically tolerate a certain amount of wireless transmission jitter, accurately recognize the phase relationship between the master and slave devices, and automatically generate a compensation strategy. Test personnel do not need to care about which phase power supply the device is connected to, realizing true plug-and-play, and greatly improving the efficiency and convenience of field testing.

[0046] 3. The present application introduces a real-time frequency monitoring and dynamic parameter adjustment mechanism, which can effectively cope with the frequency drift of the field power frequency power supply, and ensure that the phase angle of the output waveform is always constant relative to the real-time period. And through the hardware filtering and hysteresis processing of the zero-crossing detection circuit, as well as supporting code signal injection in the preset control action, the anti-interference performance of the system in complex electromagnetic environment is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more intuitively show the exemplary embodiments of the present application, the following will briefly introduce the drawings required by the embodiments. It needs to be clear that the following drawings only show part of the embodiments of the present application, and do not constitute a limitation on the whole scope. For ordinary skilled in the art, other related drawings can still be derived from these drawings without involving creative labor.

[0048] Figure 1 Flowchart of Example 1.

[0049] The implementation purpose, functional characteristics and advantages of the present application will be described in more detail in combination with specific embodiments and with reference to the drawings. DETAILED DESCRIPTION

[0050] For the purpose of comprehensive, clear, accurate interpretation of the invention, the core technical solutions and their outstanding advantages, this paper will rely on the drawings to describe the specific embodiments of the invention. It is particularly emphasized that the following mentioned embodiments do not cover all the possibilities of the invention, but only as a part of specific display.

[0051] The embodiments disclosed in the present application can further illustrate the working principle, structural key points and unique technical features. However, in view of the wide range of power system automation test technology, professionals in this field may propose other innovative embodiments, which are within the scope of protection covered by the present application.

[0052] Therefore, the content described herein is not intended to exhaust all specific implementations of the present application, but as a clear guide and inspiration for the technical field. Through the core concept and implementation method shown in the present application, professionals in the relevant field can conceive various other embodiments without having to make regular creative thinking, which are also protected by the present application.

[0053] Embodiment 1

[0054] The present embodiment provides a phase adaptive distributed power distribution network test device cooperative control method, which is applied to a test system composed of a first measuring device and a distributed second device. The first device is usually connected to the secondary side of the power distribution network protection device as a voltage source, and the second device is usually connected to the primary side of the primary equipment as a current source. The core process of the method is as follows:

[0055] After the device is powered on, the first device and the second device do not rely on network clock synchronization protocol for system clock calibration. Both of them monitor the voltage waveform of the local access power supply in real time through the internal integrated zero-crossing detection circuit. Specifically, when the voltage waveform is transferred from the negative half cycle to the positive half cycle, the zero-crossing detection circuit generates a nanosecond rising edge pulse, which directly triggers the external interrupt or capture unit of the MCU. The interrupt signal does not pass through the task scheduling of the operating system, but directly as a physical event with the highest priority. The device uses the physical event to establish a local physical timing reference, and maintains a hardware counter that only increments in the zero-crossing interrupt. This process builds a hard real-time ticker completely independent of the software system clock, which avoids software scheduling jitter from the physical bottom layer.

[0056] When the test task starts, the first device as the initiator sends a cooperative instruction to the second device through the wireless communication module when the local counter value is N. The instruction contains the target trigger count value of the cooperative action. In an embodiment, the instruction instructs the second device to act at the N+100 zero-crossing point event in the future.

[0057] The second device is in a listening state. When its wireless communication module receives the coordination instruction, it records the precise physical layer receiving time instant by using the hardware timestamp function of the wireless module bottom layer . Subsequently, the second device continues to monitor its local physical timing reference, and when the next local physical zero-crossing event occurs, it records the time instant . The second device calculates the difference between the two time instants . This is the time parameter representing the phase relationship between the local physical timing references of the two devices in this embodiment.

[0058] The second device autonomously judges the power supply phase topology relationship with the first device according to the measured , combined with the power frequency period . Taking 50 Hz as an example, , the second device judges the power supply phase topology relationship with the first device. The core innovation of the present application is to use the recognition logic of discrete interval mapping, rather than the traditional numerical calculation time correction. Since the phase difference of three-phase power is fixed (0°, 120°, 240°), the corresponding theoretical time difference is discrete. The second device predefines three discrete time intervals with a tolerance window.

[0059] If ∈[0ms, 3ms], it is determined to be in phase, and the theoretical value is the wireless transmission delay, usually <1ms, with a 3ms margin;

[0060] If ∈[5ms, 8ms], it is determined that the power supply of the second device lags 120°, and the theoretical value is 6.67ms+transmission delay, which covers the communication jitter;

[0061] If ∈[11ms, 15ms], it is determined that the power supply of the second device lags 240°, and the theoretical value is 13.33ms+transmission delay.

[0062] For example, if falls into the 120° lag interval, the second device determines that its power supply lags 120° behind the first device.

[0063] Based on the recognition result, the second device generates a phase compensation strategy. For example, if it is recognized as 120° lag, in order to achieve waveform alignment, the second device needs to add a hardware delay corresponding to the 120° phase difference to the target trigger point of the first device.

[0064] After generating the strategy, the second device enters a waiting state. Assuming that the target of the first device is to act when its counter is N+100. The second device monitors its local physical timing reference, and when its local counter reaches N+100, it takes this as the hardware trigger starting point.

[0065] At this time, the second device starts a high-precision hardware timer, loads the aforementioned hardware delay amount, and starts counting down. When the countdown is over, the hardware timer directly flips the output pin, driving the power module to output an analog fault waveform. The entire triggering process is executed independently outside the operating system software of the microcontroller, achieving microsecond-level rigid alignment of the output waveforms of the two devices on the physical time axis.

[0066] Embodiment 2

[0067] On the basis of Embodiment 1, this embodiment further introduces a frequency tracking mechanism to cope with the problem of frequency drift caused by on-site generator power supply or power grid fluctuations.

[0068] To obtain more accurate time parameters, this embodiment uses bidirectional message interaction in step S3. The first device sends a Ping message, and the second device returns a Pong message. Using the hardware timestamp function of the wireless module bottom layer, the four physical layer times of sending and receiving are recorded , and the wireless round-trip time RTT is calculated:

[0069] ;

[0070] When calculating the time parameter , the original time difference is compensated for transmission delay:

[0071] ;

[0072] After compensation, the eliminates the influence of wireless transmission delay, and purely reflects the phase distance between physical zero-crossing points, making the subsequent interval mapping judgment more accurate and able to adapt to more severe wireless communication environments.

[0073] Unlike the distributed decision-making of Embodiment 1, this embodiment supports centralized strategy generation. Specifically, the second device measures and compensates for and returns it to the first device through the wireless network. The first device centrally identifies the phase topology.

[0074] The first device calculates all slave compensation parameters according to the global test requirements, in an embodiment, the test requirements are to simulate A-phase metallic grounding, and require the B-phase device to cooperate to output a specific angle. Combined with the topology relationship identified according to , unified calculation of all slave compensation parameters, generation of trigger control instructions containing specific phase compensation amount, and delivery to the second device. This architecture is particularly suitable for test scenarios with multiple devices cooperating and complex logic.

[0075] This embodiment introduces real-time frequency monitoring and adaptive mechanism. The device measures the time interval between two consecutive zero-crossing interrupts in real time, calculates the real-time grid frequency F. When generating the phase compensation strategy, instead of using the fixed power frequency period constant, the delay parameter is dynamically adjusted in combination with the real-time frequency. The specific calculation formula is:

[0076] ;

[0077] Wherein, is the inherent deviation determined according to the topology identification result, is the phase angle that needs to be compensated. It ensures that even in the case of using a generator for power supply in the field, the phase angle of the output waveform can still remain constant relative to the real-time power frequency period, meeting the high-precision test standard.

[0078] In order to prevent the false triggering of physical reference by on-site harmonics or switching noise, the system sets a filtering logic: if the time interval of two consecutive zero-crossing signals is significantly less than the normal period, it is determined as a false zero-crossing event, and the hardware timer is not reset or counted, thereby ensuring the purity of the local physical timing reference.

[0079] Embodiment 3

[0080] This embodiment focuses on the hardware system architecture supporting the above method and its application in advanced test scenarios. The system includes a first device as a voltage source connected to the secondary side of the power distribution terminal, and a second device as a current source connected to the primary side of the circuit breaker. Both the first device and the second device of the system include the following key modules:

[0081] Zero-crossing detection circuit: linear optocoupler is used to isolate strong electrical side interference, and a hysteresis comparator is connected at the back end to shape the sine wave into a nanosecond-level edge digital square wave signal. This signal is directly connected to the advanced timer capture pin of the MCU as the interrupt source of the physical time base.

[0082] Wireless communication module: Sub-1G LoRa module or Wi-Fi module is used to transmit time parameters and coordination instructions, supporting a self-organizing network mode without a center. It should be noted that in this embodiment, the wireless module is only used for data transmission, and is not used for transmitting high-precision clock synchronization signals such as PTP protocol, thereby reducing the requirements for communication bandwidth and stability.

[0083] Power generation module: directly controlled by the output channel of the hardware timer of the MCU, used to output high-precision analog voltage or current.

[0084] After the device is powered on, it enters the ad hoc network mode. Any test device connected to the power grid can initiate a phase negotiation broadcast. Other devices in the network respond and feed back their respective time parameters. Through the built-in automatic election algorithm, in one embodiment, the node with the best signal quality or the most centered phase is selected, and the system automatically elects a device as the network phase reference device. Other devices automatically become slave devices and calculate the phase relationship relative to the reference device. This design makes the system highly adaptable to the field, without the need for manual designation of the master.

[0085] Based on the microsecond-level physical layer coordination capability established by the present application, the system can perform intermittent arc grounding simulation tasks.

[0086] In this scenario, the first device outputs a normal rated voltage, and the second device, after identifying its phase topology and completing compensation, is programmed to trigger a high-amplitude transient pulse current only in a very narrow time window near the peak of the voltage waveform, and stop outputting near the zero crossing point.

[0087] Due to the use of a hard real-time trigger mechanism based on physical zero crossing, the trigger time of the current source can be strictly locked with the waveform phase of the voltage source, with an error controlled at the microsecond level. This is not achievable by existing solutions that rely on software system clock calibration, because the random jitter of software scheduling can cause the pulse to deviate from the voltage peak, resulting in test failure. The hard real-time trigger mechanism based on physical zero crossing of the present application can perfectly implement this complex fault simulation with extremely high phase synchronization accuracy requirements, effectively verifying the line selection accuracy of the fault line selection device under arc grounding conditions.

[0088] The above specific embodiments have explained the purpose, technical solutions and beneficial effects of the present application in detail and depth. It should be clear that the above content is only some specific implementations of the present application, and should not be used to limit the scope of protection of the present application. Any equivalent structure or equivalent process transformation based on the present application specification and drawings, whether directly or indirectly applied to other related technical fields, should be included in the patent protection scope of the present application.

Claims

1. A phase-adaptive distributed distribution network testing device cooperative control method, applied to a testing system comprising at least one first device and one second device, characterized in that, Includes the following steps: S1: The first device and the second device respectively capture the periodic zero-crossing events of the power frequency power supply connected to them and establish a local physical timing reference independent of the operating system clock. S2: At a time associated with its local physical timing reference, the first device initiates a phase negotiation with the second device via wireless communication; S3: During the phase negotiation process, a time parameter characterizing the phase relationship between the local physical timing references of the two devices is measured and obtained; S4: Identify the power supply phase topology relationship between the second device and the first device based on the time parameters, and generate a phase compensation strategy for subsequent coordinated actions; S5: Based on the phase compensation strategy, the second device takes a future local physical timing reference event as the trigger point and executes a preset control action that coordinates with the phase of the first device.

2. The collaborative control method for a phase-adaptive distributed distribution network testing device according to claim 1, characterized in that, The measurement of the time parameter in step S3 specifically includes the following sub-steps: S31: Utilize the hardware timestamp function at the bottom layer of the wireless communication module to record the physical layer transmission and reception times of the wireless signal; S32: Calculate the round-trip time of wireless transmission through bidirectional message interaction, and use the round-trip time to compensate for the transmission delay between the original time difference between the local physical timing references of the two devices to obtain the time parameter.

3. The cooperative control method for a phase-adaptive distributed distribution network testing device according to claim 1, characterized in that, The power supply phase topology identification in step S4 specifically includes the following sub-steps: S41: Map the time parameters to a preset discrete phase topology interval; S42: When the time parameter falls into different intervals, determine whether the second device is in phase with the first device, lagging behind by a specific angle, or leading by a specific angle. S43: The center value of the discrete phase topology interval corresponds to the theoretical inherent phase difference of the multiphase AC power grid, and each interval is set with a threshold window for allowing wireless communication jitter.

4. The collaborative control method for a phase-adaptive distributed distribution network testing device according to claim 1, characterized in that, The execution of the preset control action in step S5 specifically includes the following sub-steps: S51: Convert the phase compensation strategy into a hardware delay count value and load it into the hardware timer of the microcontroller; S52: Configure the electrical signal corresponding to the local physical timing reference as the external trigger input source of the hardware timer; S53: When the future local physical timing reference event occurs, the hardware timer is directly triggered to start counting, and when the count reaches the hardware delay count value, the output level is flipped through the hardware channel to drive the power module. The process is executed independently outside the intervention of the microcontroller's operating system software.

5. The cooperative control method for a phase-adaptive distributed distribution network testing device according to claim 1, characterized in that, The first and second devices monitor the frequency of the power supply connected to them in real time. When generating the phase compensation strategy in step S4, the delay parameter is calculated in combination with the real-time monitored frequency to ensure that the phase angle of the coordinated control action remains constant relative to the real-time power frequency cycle.

6. The collaborative control method for a phase-adaptive distributed distribution network testing device according to claim 1, characterized in that, The preset control actions include: High-amplitude pulse currents are output within a specific phase window of the power frequency voltage waveform to simulate intermittent arcing ground faults; or non-power frequency signals superimposed with specific coding features are output for anti-interference line selection tests.

7. A collaborative control method for a phase-adaptive distributed distribution network testing device according to any one of claims 1-6, characterized in that, The first device and the second device communicate using a decentralized self-organizing network mode. Any test device connected to the power grid can initiate the phase negotiation and automatically select one of the devices as the phase reference device for the entire network by broadcasting the time parameters.

8. A phase-adaptive distributed distribution network testing device collaborative control system, characterized in that, It includes a first device and a second device, each of which includes: Zero-crossing detection circuit is used to couple the field power frequency power supply and output a digital zero-crossing signal with a nanosecond-level edge. Wireless communication module, used for data exchange between devices and hardware timestamp marking; Power generation module, used to output analog test signals; The controller is configured to execute a phase-adaptive distributed distribution network test device collaborative control method as described in any one of claims 1-7, using the digital zero-crossing signal as a hardware interrupt or timer gating signal to control the output timing of the power generation module.

9. The phase-adaptive distributed distribution network testing device collaborative control system according to claim 8, characterized in that, The zero-crossing detection circuit includes: Opto-isolation units are used to isolate high-voltage side interference; Hysteresis comparators are used to shape sine waves into square waves and eliminate noise jitter near zero crossings; The digital zero-crossing signal is directly connected to the capture / compare unit pin of the controller.

10. The phase-adaptive distributed distribution network testing device collaborative control system according to claim 8, characterized in that, The system is used for the linkage testing of primary and secondary circuits in power distribution networks. The first device is configured as a voltage generator and is connected to the secondary side terminal of the power distribution network protection device; The second device is configured as a current generator and is connected to the primary side of the primary equipment of the power distribution network; The first and second devices work together to output a simulated single-phase ground fault or short-circuit fault with a set phase angle.

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