Power grid phase sequence adaptive inverter control system and method

Abstract

The invention discloses a power grid phase sequence adaptive inverter control system and method. According to the scheme provided by the invention, detection and adaptive correction of the phase sequence of the power grid in the power system are realized, the automation degree and reliability of the whole system are improved, the workload of manual inspection and correction is reduced, and the corresponding labor cost is greatly saved. The phase sequence of the three-phase power is directly corrected through the phase sequence self-adaptive correction module, tedious operation of manual correction is avoided, the overall checking and correction efficiency is effectively improved, meanwhile, the checking and correction accuracy can be guaranteed, the situation of misjudgment or omission existing in the manual checking and correction process is avoided, and the checking and correction efficiency is improved. The operation stability and safety of the inverter system are effectively ensured, and the circuit system is prevented from being abnormal or even damaged due to phase sequence errors.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to a power grid phase sequence adaptive inverter control system and method. Background Art

[0002] In the power system, the phase sequence of three-phase electricity refers to the voltage phase sequence of the three power lines (usually R, S, T). The correct phase sequence is essential for the normal operation of power equipment. If the phase sequence is connected incorrectly, it may cause motor reversal, equipment damage, or abnormal inverter operation. At present, most equipment relies on manual detection or external phase sequence detection devices to ensure the correct phase sequence.

[0003] The method that relies on manual detection is inefficient and prone to misjudgment or missed judgment, which poses certain risks.

[0004] The method of relying on an external phase sequence detection device makes the overall system more complex and leads to an increase in cost.

[0005] At the same time, in a complex environment, it may be difficult to detect the wrong phase sequence in time, affecting the stable operation of power equipment. When the phase sequence is wrong, it cannot be automatically corrected in real time, which may affect the stability of the grid-connected system. In addition, the traditional detection and protection mechanism can only serve as a warning, and cannot achieve automatic processing and rapid correction. Therefore, the existing technology has great hidden dangers and limitations. Summary of the invention

[0006] The object of the present invention is to overcome the deficiencies of the prior art and to provide a grid phase sequence adaptive inverter control system and method.

[0007] The technical solution of the present invention is as follows: a grid phase sequence adaptive inverter control system is provided, comprising: a voltage acquisition module, an analog-to-digital converter, and a processing module, the processing module comprising a phase sequence analysis module and a phase sequence adaptive correction module, the analog-to-digital converter is electrically connected to the voltage acquisition module and the processing module, the phase sequence analysis module is electrically connected to the phase sequence adaptive correction module, wherein:

[0008] Voltage acquisition module: used to collect the three-phase analog voltage signal of the power grid and send the collected analog voltage signal to the analog-to-digital converter for signal conversion;

[0009] Analog-to-digital converter: converts the collected analog voltage signal into a digital signal for subsequent processing modules to perform digital processing;

[0010] Processing module: analyzes the converted digital signal, detects and determines the phase sequence of the three-phase voltage;

[0011] Phase sequence analysis module: uses algorithms to analyze the phase relationship of three-phase voltages;

[0012] Phase sequence adaptive correction module: When a phase sequence error is detected, the phase sequence is corrected and the normal phase relationship is restored.

[0013] Furthermore, the voltage acquisition module uses a voltage transformer to acquire the grid voltage.

[0014] Furthermore, the processing module adopts one of a microcontroller and a digital signal processor.

[0015] Furthermore, a memory is integrated inside the processing module, and the memory is used to store historical data and algorithm parameters.

[0016] Furthermore, the phase sequence adaptive correction module is connected to a protection device.

[0017] Furthermore, the phase sequence analysis module and the phase sequence adaptive correction module are connected to a monitoring system.

[0018] The present invention also provides a grid phase sequence adaptive inverter control method, which adopts the grid phase sequence adaptive inverter control system as described above, and comprises the following steps:

[0019] Step 1: The voltage in the power grid is collected by a voltage collection module to form an analog voltage signal, and the collected analog voltage signal is sent to an analog-to-digital converter;

[0020] Step 2: The analog-to-digital converter processes the analog voltage signal, converts the analog voltage signal into a digital signal, and sends the converted digital signal to the processing module;

[0021] Step 3: In the processing module, the received digital signal is subjected to phase sequence analysis, the phase sequence of the three-phase voltage is detected, and it is determined whether it is a normal phase sequence;

[0022] Step 4: Determine whether there is a phase sequence error according to the phase sequence analysis result. If the phase sequence is normal, end the detection; if the phase sequence is wrong, start the phase sequence adaptive correction module;

[0023] Step 5: The phase sequence adaptive correction module corrects the grid phase sequence accordingly according to the phase sequence error.

[0024] Furthermore, in step 3, the digital signal is analyzed by adopting fast Fourier transform or phase-locked loop technology to calculate the phase difference of the grid voltage.

[0025] Furthermore, the specific steps of step 5 are:

[0026] The phase sequence error is judged as phase reversal or phase shift, and corresponding correction processing is performed according to the judgment result, wherein:

[0027] For phase reversal, the phase sequence adaptive correction module reverses the polarity of the corresponding reversed phase to achieve correction;

[0028] In response to phase shift, the phase sequence adaptive correction module adjusts the phase angle of the voltage signal to match the correct phase sequence of the power grid.

[0029] Furthermore, when the automatic correction of the phase sequence of the grid voltage in step 5 fails, the protection mechanism is triggered, the equipment is shut down through the protection device and an alarm is triggered.

[0030] By adopting the above scheme, in the scheme provided by the present invention, the detection and adaptive correction of the phase sequence of the power grid in the power system are realized, the automation and reliability of the overall system are improved, the workload of manual inspection and correction is reduced, and the corresponding labor costs are greatly saved. In addition, the present invention directly corrects the phase sequence of the three-phase electricity through the phase sequence adaptive correction module, avoiding the tedious operation of manual correction, effectively improving the overall inspection and correction efficiency, and at the same time, it can ensure the accuracy of inspection and correction, avoid misjudgment or omissions in the manual inspection and correction process, effectively ensure the operating stability and safety of the inverter system, and avoid abnormal circuit system or even damage due to phase sequence errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a block diagram of the grid phase sequence adaptive system of the present invention.

[0032] Figure 2 Schematic diagram of voltage signal acquisition and phase analysis.

[0033] Figure 3 This is the phase sequence adaptive correction flow chart.

[0034] Figure 4 The figure is a flow chart of the protection mechanism. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] See also Figure 1 The present invention provides a grid phase sequence adaptive inverter control system, comprising: a voltage acquisition module, an analog-to-digital converter, and a processing module, wherein the processing module comprises a phase sequence analysis module and a phase sequence adaptive correction module, wherein the analog-to-digital converter is electrically connected to the voltage acquisition module and the processing module, and the phase sequence analysis module is electrically connected to the phase sequence adaptive correction module, wherein:

[0037] Voltage acquisition module: The three-phase analog voltage signal (R, S, T) of the power grid is collected through a voltage transformer (PT), and the collected analog voltage signal is sent to the analog-to-digital converter for signal conversion. A voltage sensor is a device that detects voltage and converts it into a usable electrical signal output. Its main function is to convert high voltage, low voltage or dangerous voltage into a low voltage signal for easy measurement, monitoring and control. Voltage sensors can provide accurate voltage measurement, and the error range is usually small.

[0038] Analog-to-digital converter: It is used to periodically collect analog voltage signals through the voltage acquisition module, convert the analog voltage signals into digital signals, and store the generated digital signals in the buffer for subsequent processing modules to process.

[0039] Processing module: Analyze the converted digital signal, detect and determine the phase sequence of the three-phase voltage. It is used to process the collected voltage digital signal, execute signal processing and signal analysis algorithms, and continuously and periodically output the algorithm processing results to the display device and protection device. When the analog-to-digital converter sends the voltage signal to the processing module, the phase relationship of the voltage signal is analyzed through the fast Fourier transform (FFT) or phase-locked loop (PLL) technology. Using the phase-locked loop (PLL) technology instead of the fast Fourier transform (FFT) for phase analysis can improve real-time performance and computing efficiency. The FFT or PLL algorithm is used in the control program to process the collected data in real time and calculate the phase difference of the grid voltage. According to the phase analysis results, it is judged whether there is an error in the phase sequence of the three-phase electricity, and adaptive correction is performed.

[0040] Phase sequence analysis module: configured in the processing module, analyzes the phase relationship of the voltage signal through fast Fourier transform (FFT) or phase-locked loop (PLL) technology.

[0041] Phase sequence adaptive correction module: configured in the processing module, when a phase sequence error is detected, the phase sequence is corrected and the normal phase relationship is restored according to the phase sequence error type determined by the phase sequence analysis module.

[0042] Protection device: When an abnormality is detected and the phase sequence adaptive correction module fails to correct the phase sequence of the three-phase electricity, the protection device is activated to disconnect the circuit path to protect the safety of the entire circuit. In some embodiments, the circuit breaker or protection relay used as the protection device is generally controlled through the GPIO interface to avoid damage to circuit components due to excessive current.

[0043] In some embodiments, the processing module is internally integrated with a memory, which is used to store historical data and algorithm parameters. By setting the memory, the digital signal corresponding to the voltage signal generated after the analog-to-digital converter conversion can be cached, and the algorithm-related data required for the processing module to perform phase analysis on the digital signal corresponding to the voltage signal can be stored, so that the processing module can quickly call it.

[0044] The phase sequence analysis module and the phase sequence adaptive correction module are connected to a monitoring system so as to display the collected voltage signal in a numerical form in real time, and when there is an abnormality in the three-phase electrical phase sequence, by displaying the corresponding alarm prompt, it is convenient for the operator to quickly identify the fault point in the three-phase electrical phase sequence, and to quickly respond to and handle the abnormal situation.

[0045] The present invention also provides a grid phase sequence adaptive inverter control method, which adopts the grid phase sequence adaptive inverter control system as described above, and comprises the following steps:

[0046] Step 1: The voltage in the power grid is collected through the voltage collection module to form an analog voltage signal, and the collected analog voltage signal is sent to the analog-to-digital converter.

[0047] Step 2: The analog-to-digital converter processes the analog voltage signal, converts the analog voltage signal into a digital signal, and sends the converted digital signal to the processing module.

[0048] By setting the size of the sampling buffer, the sampling frequency of the analog-to-digital converter for the voltage signal can be controlled. Define the three-phase voltage array, and the array size is the size of the sampling buffer. After collecting the voltage signals of the three-phase electricity and integrating them into the three-phase voltage array, the analog-to-digital converter assigns values ​​to the collected three-phase voltage array to complete the collection of the voltage signal.

[0049] Step 3: Please refer to Figure 2 In the processing module, the received digital signal is subjected to phase sequence analysis, the phase sequence of the three-phase voltage is detected, and it is determined whether it is a normal phase sequence. The digital signal is analyzed by adopting fast Fourier transform or phase-locked loop technology to calculate the phase difference of the grid voltage. In the embodiment provided by the present invention, the voltage signal is analyzed by fast Fourier transform (FFT), the phase information is extracted, and the fundamental phase of each phase voltage signal is calculated.

[0050] The voltage signal is subjected to FFT transformation using the fast Fourier transform function in the memory, and the first frequency point is extracted from the result obtained after the FFT transformation as the fundamental phase, and the fundamental phase of the three-phase voltage is calculated using the fundamental phase of this frequency point.

[0051] Step 4: Determine whether there is a phase sequence error based on the phase sequence analysis result. If the phase sequence is normal, end the detection; if the phase sequence is wrong, start the phase sequence adaptive correction module.

[0052] The phase relationship of the three-phase voltage signals is compared according to the fundamental phase of the three-phase voltage calculated in step 3. Under normal circumstances, the sequence between the three-phase RST should have a phase difference of 120°. If the phase difference of the three-phase RST is different from 120°, it is determined that the three-phase phase sequence of the sampling point is wrong, triggering correction or alarm.

[0053] Step 5: Please refer to Figure 3 ,The phase sequence adaptive correction module makes corresponding correction to the grid phase sequence according to the phase sequence error.

[0054] When a phase sequence error is detected, the system can automatically adjust the current phase or swap the connection of the output port to adjust the current output so that the phase sequence and phase difference of the three-phase electricity meet the normal three-phase electricity output requirements.

[0055] According to the phase difference of the three-phase voltage signal, it can be judged whether there is phase reversal or phase shift in the three-phase electricity at the current acquisition point. If there is a phase reversal in the three-phase electricity, the value of its fundamental phase is the opposite of the normal value. If there is a phase shift in the three-phase electricity, the phase difference between this phase and the other two phases is not 120°.

[0056] When phase reversal occurs, the phase sequence adaptive correction module reverses the polarity of the corresponding reversed phase so that the polarity of the phase meets the grid's polarity requirements for three-phase electricity, avoiding abnormal situations such as circuit damage caused by phase reversal, and providing effective protection for the overall circuit system.

[0057] When phase shift occurs, the phase sequence adaptive correction module adjusts the corresponding phase by adjusting the output of the power frequency to meet the phase angle requirements of the three-phase electricity.

[0058] When a phase sequence error occurs, the R and S phase outputs of the inverter are swapped.

[0059] The phase sequence adaptive correction module performs corresponding adaptive correction and adjustment processing on different phase sequence error conditions to ensure the normal operation of power equipment, especially in the inverter grid-connected system, effectively reducing the operating risks caused by phase sequence errors.

[0060] Furthermore, the specific steps of step 5 are:

[0061] The phase sequence error is judged as phase reversal or phase shift, and corresponding correction processing is performed according to the judgment result, wherein:

[0062] For phase reversal, the phase sequence adaptive correction module reverses the polarity of the corresponding reversed phase to achieve correction;

[0063] In response to phase shift, the phase sequence adaptive correction module adjusts the phase angle of the voltage signal to match the correct phase sequence of the power grid.

[0064] See also Figure 4 When the automatic correction of the phase sequence of the grid voltage in step 5 fails, the protection mechanism is triggered, the equipment is shut down and an alarm is triggered through the protection device, and the alarm information is sent to the monitoring system or display for display, so that the operator can check and deal with it in time to avoid damage to the inverter grid-connected system.

[0065] In summary, in the solution provided by the present invention, the detection and adaptive correction of the phase sequence of the power grid in the power system are realized, the automation and reliability of the overall system are improved, the workload of manual inspection and correction is reduced, and the corresponding labor costs are greatly saved. In addition, the present invention directly corrects the phase sequence of the three-phase electricity through the phase sequence adaptive correction module, avoiding the cumbersome operation of manual correction, effectively improving the overall inspection and correction efficiency, and at the same time, it can ensure the accuracy of inspection and correction, avoid misjudgment or omissions in the manual inspection and correction process, effectively ensure the operating stability and safety of the inverter system, and avoid abnormal circuit system or even damage due to phase sequence errors.

[0066] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A grid phase sequence adaptive inverter control system, characterized in that: include: A voltage acquisition module, an analog-to-digital converter, and a processing module, wherein the processing module includes a phase sequence analysis module and a phase sequence adaptive correction module, the analog-to-digital converter is electrically connected to the voltage acquisition module and the processing module, and the phase sequence analysis module is electrically connected to the phase sequence adaptive correction module, wherein: Voltage acquisition module: used to collect the three-phase analog voltage signal of the power grid and send the collected analog voltage signal to the analog-to-digital converter for signal conversion; Analog-to-digital converter: converts the collected analog voltage signal into a digital signal for subsequent processing modules to perform digital processing; Processing module: analyzes the converted digital signal, detects and determines the phase sequence of the three-phase voltage; Phase sequence analysis module: uses algorithms to analyze the phase relationship of three-phase voltages; Phase sequence adaptive correction module: When a phase sequence error is detected, the phase sequence is corrected and the normal phase relationship is restored.

2. The grid phase sequence adaptive inverter control system according to claim 1, characterized in that: The voltage acquisition module uses a voltage transformer to acquire the grid voltage.

3. The grid phase sequence adaptive inverter control system according to claim 1, characterized in that: The processing module is a microcontroller or a digital signal processor.

4. The grid phase sequence adaptive inverter control system according to claim 1, characterized in that: The processing module is internally integrated with a memory, and the memory is used to store historical data and algorithm parameters.

5. The grid phase sequence adaptive inverter control system according to claim 1, characterized in that: The phase sequence adaptive correction module is connected with a protection device.

6. The grid phase sequence adaptive inverter control system according to claim 1, characterized in that: The phase sequence analysis module and the phase sequence adaptive correction module are connected to a monitoring system.

7. A grid phase sequence adaptive inverter control method, using the grid phase sequence adaptive inverter control system according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: The voltage in the power grid is collected by a voltage collection module to form an analog voltage signal, and the collected analog voltage signal is sent to an analog-to-digital converter; Step 2: The analog-to-digital converter processes the analog voltage signal, converts the analog voltage signal into a digital signal, and sends the converted digital signal to the processing module; Step 3: In the processing module, the received digital signal is subjected to phase sequence analysis, the phase sequence of the three-phase voltage is detected, and it is determined whether it is a normal phase sequence; Step 4: Determine whether there is a phase sequence error according to the phase sequence analysis result. If the phase sequence is normal, end the detection; if the phase sequence is wrong, start the phase sequence adaptive correction module; Step 5: The phase sequence adaptive correction module corrects the grid phase sequence accordingly according to the phase sequence error.

8. The grid phase sequence adaptive inverter control method according to claim 7, characterized in that: In step 3, the digital signal is analyzed by adopting fast Fourier transform or phase-locked loop technology to calculate the phase difference of the grid voltage.

9. The grid phase sequence adaptive inverter control method according to claim 7, characterized in that: The specific steps of step 5 are: The phase sequence error is judged as phase reversal or phase shift, and corresponding correction processing is performed according to the judgment result, wherein: For phase reversal, the phase sequence adaptive correction module reverses the polarity of the corresponding reversed phase to achieve correction; In response to phase shift, the phase sequence adaptive correction module adjusts the phase angle of the voltage signal to match the correct phase sequence of the power grid.

10. The grid phase sequence adaptive inverter control method according to claim 7, characterized in that: When the automatic correction of the phase sequence of the grid voltage fails in step 5, the protection mechanism is triggered, the equipment is shut down through the protection device and an alarm is triggered.

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