Phase-locked loop device, phase-locked method for energy storage power supply, and storage medium

Abstract

The present application relates to the field of phase-locked technology for energy storage power supplies, and in particular to a phase-locked loop device, a phase-locked method for energy storage power supplies, and a storage medium. The phase-locked loop device includes a phase detector, a loop filter, a voltage-controlled oscillator, and a compensation network module, wherein the phase detector, the loop filter, and the voltage-controlled oscillator output an original phase reference angle based on the input grid voltage and the corrected phase reference angle, and the compensation network module obtains a grid power-off flag. When the grid power-off flag is true, the original phase reference angle is corrected based on the difference between the original phase reference angle and the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle to obtain a corrected phase reference angle. The phase-locked loop device of the present application, by adding a compensation network, performs compensation correction when the grid loses power, which can effectively solve the problems of output frequency jump and phase angle offset.

Description

Technical Field

[0001] The present application relates to the technical field of phase-locked energy storage power supplies, and in particular to a phase-locked loop device, a phase-locked method for energy storage power supplies, and a storage medium. Background Art

[0002] As society develops, electricity has become indispensable in our daily lives and work. However, we often encounter a series of problems, such as outdoor power use, equipment power outages, and excessive loads. Portable energy storage power supplies are one option to solve these problems. The waveform quality of portable energy storage power supplies is crucial, especially when powering important loads such as precision instruments. Strict requirements are placed on the output power waveform quality.

[0003] Traditional grid software phase-locked algorithms are widely used due to their fast response. In off-grid conditions, the inverter acts as a constant voltage source to output a stable voltage. In grid-connected conditions, the inverter operates as a current source. When the grid loses power, the software typically sets a 3-millisecond power-loss detection timer to ensure stability. This 3-millisecond power-loss detection period can cause the phase angle of the phase-locked loop to rapidly change, leading to output frequency jumps and phase shifts. Summary of the Invention

[0004] The embodiments of the present application aim to provide a phase-locked loop device, a phase-locked method for an energy storage power supply, and a storage medium to solve the problem of output frequency jump and phase offset that easily occurs when the energy storage power supply uses a conventional software phase-locked solution in the prior art and encounters a power outage in the grid.

[0005] To solve the above technical problems, the embodiments of the present application provide the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a phase-locked loop device, including a phase detector (PD), a loop filter (LF), a voltage-controlled oscillator (VCO), and a compensation network module.

[0007] The phase detector (PD) is used to obtain the phase error between the energy storage power supply and the grid based on the input grid voltage and the corrected phase reference angle;

[0008] The loop filter (LF) is used to process the phase error using a PI controller to obtain a first phase angle correction value;

[0009] The voltage controlled oscillator (VCO) is used to update the original phase reference angle in the PI controller according to the first phase angle correction value;

[0010] The compensation network module is configured to obtain a grid power-off flag and an updated original phase reference angle. When the grid power-off flag is true, the original phase reference angle is corrected based on a difference between the original phase reference angle and an original phase reference angle corresponding to an Nth phase-locked loop cycle before a current phase-locked loop cycle to obtain the corrected phase reference angle, where N is the phase-locked loop operating frequency divided by the grid rated frequency.

[0011] Optionally, the compensation network module is further configured to set the corrected phase reference angle to the original phase reference angle when the grid power-off flag is false.

[0012] Optionally, a phase angle cache module is further included, and the phase angle cache module is used to cyclically cache the updated original phase reference angle in sequence to a preset phase angle cache area.

[0013] Optionally, the calculation formula for the corrected phase reference angle is:

[0014]

[0015] in, is the modified phase reference angle, is the second phase angle correction, is the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle, is the original phase reference angle of the current phase-locked loop cycle, is the second integration constant, is the second proportional constant.

[0016] In a second aspect, an embodiment of the present application provides a phase-locking method for an energy storage power supply, the method comprising:

[0017] The phase error between the energy storage power supply and the grid is obtained based on the input grid voltage and the corrected phase reference angle;

[0018] Processing the phase error using a PI controller to obtain a first phase angle correction value;

[0019] Updating the original phase reference angle in the PI controller according to the first phase angle correction value;

[0020] Obtain a grid power failure flag and an updated original phase reference angle. When the grid power failure flag is true, correct the original phase reference angle based on a difference between the original phase reference angle and an original phase reference angle corresponding to an Nth phase-locked loop cycle before a current phase-locked loop cycle to obtain the corrected phase reference angle, where N is the phase-locked loop operating frequency divided by the grid rated frequency.

[0021] Optionally, after updating the original phase reference angle in the PI controller according to the first phase angle correction value, the method further includes:

[0022] The updated original phase reference angle is cached in a circular manner in a preset phase angle cache area.

[0023] Optionally, the method further includes:

[0024] When the grid power-off flag is false, the modified phase reference angle is set as the original phase reference angle.

[0025] Optionally, the calculation formula of the original phase reference angle is:

[0026]

[0027] in, is the original phase reference angle of the current phase-locked loop cycle, is the original phase reference angle of the previous phase-locked loop cycle, is the first phase angle correction, is the grid phase angle step, is the rated frequency of the grid, is the phase-locked loop operating frequency.

[0028] Optionally, the calculation formula for the corrected phase reference angle is:

[0029]

[0030] in, is the modified phase reference angle, is the second phase angle correction, is the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle, is the original phase reference angle of the current phase-locked loop cycle, is the second integration constant, is the second proportional constant.

[0031] In a third aspect, an embodiment of the present application provides a computer storage medium, which stores instructions or programs. When the instructions or programs are executed by at least one processor, the at least one processor executes any one of the methods described above.

[0032] The beneficial effects of the embodiments of the present application are as follows: Different from the prior art, the embodiments of the present application provide a phase-locked loop device, including a phase detector, a loop filter, a voltage-controlled oscillator, and a compensation network module. The phase detector, loop filter, and voltage-controlled oscillator output an original phase reference angle based on the input grid voltage and the corrected phase reference angle. The compensation network module is used to obtain a grid power-off flag. When the grid power-off flag is true, the original phase reference angle is corrected based on the difference between the original phase reference angle and the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle to obtain a corrected phase reference angle. The phase-locked loop device of the present application, by adding a compensation network, performs compensation correction when the grid loses power, which can effectively solve the problems of output frequency jump and phase angle offset. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0034] Figure 1a It is a schematic diagram of the structure of a conventional phase-locked loop device;

[0035] Figure 1b yes Figure 1a Model of the phase-locked loop device after expansion;

[0036] Figure 2 Schematic diagram of the structure of the phase-locked loop device provided in an embodiment of the present application;

[0037] Figure 3 This is a flow chart of a phase-locking method provided in an embodiment of the present application;

[0038] Figure 4 It is a schematic diagram of the inverter output phase angle and waveform when the grid is normal and when the grid is powered off. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0041] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0042] Please refer to Figure 1a and Figure 1b , Figure 1a This is a schematic diagram of the structure of a conventional phase-locked loop device. Figure 1b yes Figure 1a The model of the phase-locked loop device after expansion. Figure 1a and Figure 1b As shown, the phase-locked loop device 100 includes a phase detector (PD) 101, a loop filter (LF) 102, and a voltage-controlled oscillator (VCO) 103. The PD detects the phase difference between the grid voltage and the VCO output signal and generates an error voltage; the LF filters out high-frequency noise and optimizes the loop dynamic response; the VCO adjusts the output frequency according to the filtered error signal, ultimately making the inverter angular frequency ω and phase angle θ The input of the phase-locked loop device 100 is the grid voltage, and the output is the synchronized angular frequency and phase angle.

[0043] When the grid loses power, the control program switches from on-grid to off-grid. Due to the inherent time required for power-loss detection, the grid voltage is unstable during this time, causing a phase angle deviation in the phase-locked loop (PLL), resulting in frequency jumps and phase shifts when switching to off-grid. To address these output frequency jumps and phase shifts, the present application adds a compensation network module to a conventional PLL device. This compensation network module corrects the phase shift after a grid power outage, returning it to its normal phase.

[0044] Please refer to Figure 2 , Figure 2 Schematic diagram of the structure of the phase-locked loop device provided in the embodiment of the present application. Figure 2 As shown, the phase-locked loop device 100 includes a phase detector (PD) 101, a loop filter (LF) 102, a voltage-controlled oscillator (VCO) 103 and a compensation network module 104.

[0045] PD101 is used to obtain the phase error between the energy storage power supply and the grid based on the input grid voltage and the corrected phase reference angle.

[0046] Specifically, PD101 first performs orthogonal decomposition on the input grid voltage to generate a set of orthogonal signals. For a single-phase grid voltage, the grid voltage can be input into an orthogonal generator to generate a set of orthogonal signals. The orthogonal generator is preferably a second-order generalized integrator. For a three-phase grid voltage, the grid voltage can be subjected to a Clarke transform to generate a set of orthogonal signals. The calculation formula for the Clarke transform is:

[0047]

[0048] in, 、 and is the collected three-phase grid voltage, and is the generated quadrature signal.

[0049] Secondly, PD101 performs phase difference detection based on the orthogonal signal and the modified phase reference angle to obtain the phase error between the energy storage power supply and the grid. In the initial state, the modified phase reference angle is pre-set to be the same as the original phase reference angle.

[0050] In one embodiment, a Park transform is performed based on the quadrature signal and the modified phase reference angle to obtain the d-axis component voltage and the q-axis component voltage. When there is a deviation between the modified phase reference angle and the grid phase angle, the q-axis component voltage is non-zero, and the q-axis component voltage is used as the phase error between the energy storage system and the grid. Specifically, the calculation formula of the Park transform is:

[0051]

[0052] in, is the d-axis component voltage, is the q-axis component voltage.

[0053] In other embodiments, the grid phase angle is first calculated based on the orthogonal signal using the inverse tangent formula, and then the difference between the grid phase angle and the corrected phase reference angle is used as the phase error between the energy storage system and the grid. Specifically, the calculation formula for the grid phase angle is:

[0054]

[0055] The calculation formula for phase error is:

[0056]

[0057] in, is the grid phase angle, is the phase error, To correct the phase reference angle.

[0058] LF102 is used to process the phase error using a PI controller to obtain a first phase angle correction value. The calculation formula of the first phase angle correction value is:

[0059] in, is the first phase angle correction, is the phase error, is the first integration constant, is the first proportional constant.

[0060] VCO103 is used to update the original phase reference angle in the PI controller according to the first phase angle correction value.

[0061] Specifically, the original phase reference angle is updated according to the first phase angle correction value obtained by LF102 and the grid phase angle change step. The calculation formula of the original phase reference angle is:

[0062]

[0063] in, is the original phase reference angle of the current phase-locked loop cycle, is the original phase reference angle of the previous phase-locked loop cycle, is the first phase angle correction, is the grid phase angle step, is the rated frequency of the grid, is the operating frequency of the phase-locked loop. For example, if the rated frequency of the power grid is 50 Hz, the operating frequency of the phase-locked loop is 10 kHz.

[0064] The compensation network module 104 is configured to obtain a grid power failure flag and an updated original phase reference angle. When the grid power failure flag is true, the original phase reference angle is corrected based on the difference between the original phase reference angle and the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle to obtain a corrected phase reference angle. When the grid power failure flag is false, the corrected phase reference angle is set as the original phase reference angle. N is the phase-locked loop operating frequency divided by the grid rated frequency.

[0065] Specifically, the difference between the original phase reference angle and the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle is first calculated, and then the difference is processed by the PI controller to obtain a second phase angle correction value. Finally, the original phase reference angle is corrected based on the second phase angle correction value to obtain a corrected phase reference angle. The calculation formula for the corrected phase reference angle is:

[0066]

[0067] in, To correct the phase reference angle, is the second phase angle correction, is the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle, is the original phase reference angle of the current phase-locked loop cycle, is the second integration constant, is the second proportional constant.

[0068] In one embodiment, the phase-locked loop device 100 further includes a phase angle buffer module (not shown in the figure), which is used to sequentially and cyclically buffer the updated original phase reference angle into a preset phase angle buffer area. The size of the phase angle storage area is determined according to the power failure detection duration. As mentioned above, one grid voltage cycle contains N phase-locked loop cycles, that is, one grid voltage cycle corresponds to N original phase reference angles, so the size of the phase angle storage area can be set to N. M, where M= For example, if the rated grid frequency is 50 Hz (period is 20 ms) and the power failure detection duration is 3 ms, the size of the phase angle storage area can be set to 20. Using circular caching technology, the original phase reference angle output from the most recent N phase-locked loop cycles can be stored in the phase angle buffer area.

[0069] Please refer to Figure 3 , Figure 3 This is a flow chart of a phase-locked method for an energy storage power supply provided in an embodiment of the present application, wherein the energy storage power supply includes a phase-locked loop device, which can be Figure 2 The structural implementation shown in the figure has been described in detail in the above embodiments and will not be repeated here.

[0070] like Figure 3 As shown, the phase locking method of the energy storage power supply includes:

[0071] Step S301: obtaining a phase error between the energy storage power supply and the grid based on the input grid voltage and the corrected phase reference angle.

[0072] Specifically, the energy storage power supply samples the grid voltage and inputs the sampled grid voltage into a phase-locked loop (PLL) device, which then initializes the device's corrected phase reference angle and original phase reference angle. The PLL device first performs orthogonal decomposition on the input grid voltage to generate a set of orthogonal signals. It then performs phase difference detection based on the orthogonal signals and the corrected phase reference angle to determine the phase error between the energy storage power supply and the grid.

[0073] Step S302: Process the phase error using a PI controller to obtain a first phase angle correction value.

[0074] In one embodiment, the calculation formula of the first phase angle correction value is:

[0075] in, is the first phase angle correction, is the phase error, is the first integration constant, is the first proportional constant.

[0076] Step S303: updating the original phase reference angle in the PI controller according to the first phase angle correction value.

[0077] Specifically, the original phase reference angle is updated according to the first phase angle correction value and the grid phase angle change step. The calculation formula of the original phase reference angle is:

[0078]

[0079] in, is the original phase reference angle of the current phase-locked loop cycle, is the original phase reference angle of the previous phase-locked loop cycle, is the first phase angle correction, is the grid phase angle step, is the rated frequency of the grid, is the phase-locked loop operating frequency.

[0080] Step S304: Obtain a grid power failure flag and an updated original phase reference angle. When the grid power failure flag is true, correct the original phase reference angle based on the difference between the original phase reference angle and the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle to obtain a corrected phase reference angle, where N is the phase-locked loop operating frequency divided by the grid rated frequency.

[0081] In one embodiment, the output waveform of the energy storage power supply is detected in real time to determine whether the power grid has lost power. When the power grid loss flag is true, the difference between the original phase reference angle and the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle is calculated. This difference is then processed using a PI controller to obtain a second phase angle correction value. Finally, the original phase reference angle is corrected based on the second phase angle correction value to obtain a corrected phase reference angle. The calculation formula for the corrected phase reference angle is:

[0082]

[0083] in, To correct the phase reference angle, is the second phase angle correction, is the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle, is the original phase reference angle of the current phase-locked loop cycle, is the second integration constant, is the second proportional constant.

[0084] When the grid power failure flag is false, the second phase angle correction amount is set to 0, that is, the corrected phase reference angle is set to the original phase reference angle.

[0085] In one embodiment, after step S303, the method further includes: cyclically caching the updated original phase reference angle in a preset phase angle cache area. The size of the phase angle storage area is determined according to the power failure detection duration. As mentioned above, one grid voltage cycle contains N phase-locked loop cycles, that is, one grid voltage cycle corresponds to N original phase reference angles, and the size of the phase angle storage area can be set to N. M, where M= For example, if the rated grid frequency is 50 Hz (period is 20 ms) and the power failure detection duration is 3 ms, the size of the phase angle storage area can be set to 20. Using circular caching technology, the original phase reference angle output from the most recent N phase-locked loop cycles can be stored in the phase angle buffer area.

[0086] Please refer to Figure 4 , where (a) is a schematic diagram of the inverter output phase angle and waveform when the power grid is normal, (b) is a schematic diagram of the inverter output phase angle and waveform obtained based on a conventional phase-locked loop device when the power grid is powered off, and (c) is a schematic diagram of the inverter output phase angle and waveform obtained based on the phase-locked loop device of the present application when the power grid is powered off.

[0087] like Figure 4 As shown, the red waveform is the output voltage, the green waveform is the output phase angle, when the grid is normal, the output voltage is the grid voltage, when the grid is abnormal, the output voltage is the inverter voltage, and the time between the two peaks is the output voltage cycle. Figure 4 As shown in (b), when the grid loses power, the voltage drops instantly, and the output phase angle slope changes, with a very small slope. After 3ms of grid power failure recognition, the inverter switches to the off-grid state, and the output phase angle is output according to the off-grid phase angle. The slope returns to normal, but at this time a frequency jump occurs, from 50Hz to 43Hz, and the output phase angle also shifts. Figure 4 As shown in (c), when the grid loses power and switches to the off-grid state, the output phase angle is corrected by the compensation network, and the slope becomes larger. After a short correction, the normal phase angle can be restored. The output phase angle after correction is the same as Figure 4 It is completely consistent with (a), avoiding frequency hopping and phase shift problems.

[0088] The phase-locked loop device provided in this application includes a phase detector, a loop filter, a voltage-controlled oscillator, and a compensation network module. The phase detector, loop filter, and voltage-controlled oscillator output an original phase reference angle based on the input grid voltage and the corrected phase reference angle. The compensation network module is used to obtain a grid power-off flag. When the grid power-off flag is true, the original phase reference angle is corrected based on the difference between the original phase reference angle and the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle to obtain a corrected phase reference angle. By adding a compensation network, the phase-locked loop device of this application can effectively solve the problems of output frequency jumps and phase angle offsets by performing compensation correction when the grid loses power.

[0089] An embodiment of the present application further provides a computer storage medium storing instructions or programs, which are executed by one or more processors, enabling the one or more processors to execute the phase-locked method of the energy storage power supply in any of the above method embodiments.

[0090] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the relevant technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each embodiment or certain portions of the embodiments.

[0091] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of variations or substitutions within the technical scope disclosed in the present application. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A phase-locked loop device, characterized in that: Including phase detector, loop filter, voltage controlled oscillator and compensation network modules, The phase detector is used to obtain the phase error between the energy storage power supply and the grid based on the input grid voltage and the corrected phase reference angle; The loop filter is used to process the phase error using a PI controller to obtain a first phase angle correction value; The voltage-controlled oscillator is configured to update an original phase reference angle in the PI controller according to the first phase angle correction value; The compensation network module is configured to obtain a grid power-off flag and an updated original phase reference angle. When the grid power-off flag is true, the original phase reference angle is corrected based on a difference between the original phase reference angle and an original phase reference angle corresponding to an Nth phase-locked loop cycle before a current phase-locked loop cycle to obtain the corrected phase reference angle, where N is the phase-locked loop operating frequency divided by the grid rated frequency.

2. The device according to claim 1, characterized in that The compensation network module is further configured to set the modified phase reference angle to the original phase reference angle when the grid power-off flag is false.

3. The device according to claim 1, characterized in that It also includes a phase angle cache module, which is used to cyclically cache the updated original phase reference angle in sequence to a preset phase angle cache area.

4. The device according to any one of claims 1 to 3, characterized in that The calculation formula of the corrected phase reference angle is: in, is the modified phase reference angle, is the second phase angle correction, is the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle, is the original phase reference angle of the current phase-locked loop cycle, is the second integration constant, is the second proportional constant.

5. A phase-locking method for an energy storage power supply, characterized in that: The method comprises: The phase error between the energy storage power supply and the grid is obtained based on the input grid voltage and the corrected phase reference angle; Processing the phase error using a PI controller to obtain a first phase angle correction value; Updating the original phase reference angle in the PI controller according to the first phase angle correction value; Obtain a grid power failure flag and an updated original phase reference angle. When the grid power failure flag is true, correct the original phase reference angle based on a difference between the original phase reference angle and an original phase reference angle corresponding to an Nth phase-locked loop cycle before a current phase-locked loop cycle to obtain the corrected phase reference angle, where N is the phase-locked loop operating frequency divided by the grid rated frequency.

6. The method according to claim 5, characterized in that After updating the original phase reference angle in the PI controller according to the first phase angle correction value, the method further includes: The updated original phase reference angle is cached in a circular manner in a preset phase angle cache area.

7. The method according to claim 5, characterized in that The method further comprises: When the grid power-off flag is false, the modified phase reference angle is set as the original phase reference angle.

8. The method according to claim 5, characterized in that The calculation formula of the original phase reference angle is: in, is the original phase reference angle of the current phase-locked loop cycle, is the original phase reference angle of the previous phase-locked loop cycle, is the first phase angle correction, is the grid phase angle step, is the rated frequency of the grid, is the phase-locked loop operating frequency.

9. The method according to any one of claims 5 to 8, characterized in that The calculation formula of the corrected phase reference angle is: in, is the modified phase reference angle, is the second phase angle correction, is the original phase reference angle corresponding to the Nth phase-locked loop cycle before the current phase-locked loop cycle, is the original phase reference angle of the current phase-locked loop cycle, is the second integration constant, is the second proportional constant.

10. A computer storage medium, characterized in that The computer storage medium stores instructions or programs, and when the instructions or programs are executed by at least one processor, the at least one processor is caused to perform the method according to any one of claims 5 to 9.

Images