CN114994399A - Composite voltage sag detection method and system for energy storage type UPS system - Google Patents
Composite voltage sag detection method and system for energy storage type UPS system Download PDFInfo
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Abstract
The invention discloses a composite voltage Sag detection method and a composite voltage Sag detection system for an energy storage UPS system, wherein the composite voltage Sag detection method comprises the steps of obtaining a power grid voltage Sag detection result Sag1 and a power grid voltage Sag detection result Sag2 through a first voltage Sag detection module and a second voltage Sag detection module respectively, carrying out logic or operation on the power grid voltage Sag detection result Sag1 and the power grid voltage Sag detection result Sag2 to obtain a power grid voltage Sag detection result, and judging whether the power grid voltage Sag detection result is in a voltage Sag state or not according to the power grid voltage Sag detection result. The method adopts a composite detection technology combining a first voltage sag detection module and a second voltage sag detection module, and can still effectively detect the power grid voltage sag under the working conditions that the voltage of a single-phase power grid falls to 0.895 times of rated power grid voltage, the voltage of a two-phase power grid falls to 0.895 times of rated power grid voltage, the voltage of a three-phase power grid falls to 0.895 times of rated power grid voltage and the like.
Description
Technical Field
The invention relates to the technical field of power grid voltage fluctuation detection, in particular to a composite voltage sag detection method and system for an energy storage type UPS system.
Background
As a core of the information technology industry, the chip semiconductor industry is a strategic, fundamental and precedent industry that supports the development of the national economic society and ensures the national security. The semiconductor industry belongs to high-end manufacturing industry, and uses a large amount of high-precision instruments, so that the high-precision instruments are easily influenced by power supply quality. Once power supply quality problems occur, resulting in equipment downtime, direct and indirect economic losses can be as high as a billion dollar. In addition, with the development of 5G and industrial Internet, the Internet is further fused with the traditional industry, and the data center also becomes a basic leading industry on which various industries are developed. The data center has extremely high requirements on power supply quality, and once the power supply quality problem occurs, equipment is shut down, so that service interruption of the data center is caused, and huge loss is caused to enterprises. The intelligent manufacturing industry belongs to continuous production processes, and once production is suspended due to power supply quality problems, great shutdown cost is consumed. Therefore, voltage sag and voltage interruption are the most major power supply quality problems facing industries such as semiconductors, data centers, smart manufacturing, and the like. On the premise of ensuring stable power supply of power utilization facilities, the energy storage type UPS system can also be connected to the grid for power supply to participate in peak clipping and valley filling of a power grid, so that the cost of the energy storage type UPS system is reduced, and the configuration of the energy storage type UPS system is optimized, so that the energy storage type UPS system has great market potential. The main technical problem faced by the energy storage type UPS system is to quickly and accurately detect the voltage sag under multiple working conditions, and further to reduce the economic loss caused by the voltage sag as much as possible.
Therefore, scholars at home and abroad make many studies on the detection of voltage sag. As a voltage sag detection method disclosed in chinese patent application publication (CN 101793918A) at 8/4/2010, a three-phase voltage sag detection method is disclosed, which employs an equivalent filter network to filter the output of a conventional dq algorithm, thereby avoiding harmonic amplification and realizing rapid tracking detection of the grid voltage. For example, in the IEEE document "y.kumsuwan and y.sillapacharn.a fast synchronous rotating reference frame-based voltage detection under active grid voltages for voltage detection systems,6th IET International reference Power Electronics, Machines and Drives (PEMD2012),2012, pp.1-5." ("y.kumsuwan and y.sillapacharn. a grid voltage drop fast detection method based on a synchronous rotating coordinate system, sixth IET Power Electronics, machinery and drive International Conference, p 2012, p 1-5") a voltage drop detection method based on a synchronous rotating coordinate system is proposed, and any drop component generated by the synchronous rotating coordinate transformation under three-phase unbalanced voltage drop conditions is cancelled by a conduction method, thereby realizing detection of any double-fold frequency drop component generated by the synchronous rotating coordinate transformation under three-phase conditions. For example, the invention discloses a phase shift-based rapid detection method for grid voltage sag, which is disclosed in a phase shift-based rapid detection algorithm for grid voltage sag, disclosed in 2018, 4, 3.A published in the patent application publication (CN 107870285A) of China, and the method constructs three new groups of symmetrical three-phase voltages through the phase delay of an all-pass filter and rapidly judges the three-phase asymmetrical sag of the grid voltage by using a conventional dq algorithm.
However, in the "voltage sag detection method" disclosed in chinese patent application publication (CN 101793918A) at 2010, 8 and 4, month, the sag detection result is prone to deviation and inaccurate when the phase shift or phase inversion condition occurs in the grid voltage; in addition, the method cannot effectively detect the voltage sag at all under the limit condition that the voltage of any phase power grid falls to 0.895 times of rated power grid voltage. IEEE document "y.kumsuwan and y.sillapachalcarn.a fast synchronous voltage reduction system for voltage reduction compensation system, 6th IET International Conference Power Electronics, Machines and Drives (PEMD2012),2012, pp.1-5." ("y.msuwan and y.sillapachalcarn. a method for fast detecting grid voltage drop based on synchronous rotating coordinate system, sixth IET Power Electronics, machinery and drive International Conference, p 2012, p 1-5") proposes a method for detecting voltage drop based on synchronous rotating coordinate system, but this method uses differential derivation operation, is sensitive to voltage differential harmonics, is prone to transient voltage drop or is prone to phase shift in the grid, and is not prone to accurate detection of grid voltage drop or to phase shift. In a phase shift-based rapid detection algorithm for grid voltage drop, which is disclosed in the patent application publication (CN 107870285 a) of china patent in 2018, 4, 3, the method cannot effectively detect when the grid voltage has a phase shift or phase inversion condition.
Therefore, how to realize the rapid and accurate voltage detection is a technical problem to be solved urgently by the energy storage type UPS system.
Disclosure of Invention
In view of the above, the present invention has been made to provide a composite voltage sag detection method and system for energy storage UPS systems that overcomes or at least partially solves the above mentioned problems.
According to an aspect of the present invention, there is provided a composite voltage sag detection method for an energy storage UPS system, including: the method comprises the steps of obtaining a power grid voltage Sag detection result Sag1 and a power grid voltage Sag detection result Sag2 through a first voltage Sag detection module and a second voltage Sag detection module respectively, conducting logical OR operation on the power grid voltage Sag detection result Sag1 and the power grid voltage Sag detection result Sag2 to obtain a power grid voltage Sag detection result Sag, and judging whether the power grid voltage Sag detection result Sag is in a voltage Sag state or not according to the power grid voltage Sag detection result Sag.
Optionally, the method for acquiring the grid voltage Sag detection result Sag1 by the first voltage Sag detection module includes:
sampling the actual value of the three-phase power grid voltage, and obtaining the phase of the three-phase power grid voltage after phase locking;
according to the obtained three-phase power grid voltage phase, the three-phase power grid voltage is actually measuredThe value is transformed to dq two-phase rotating coordinate system to obtain d-axis component U gd And q-axis component U gq ；
Passing the q-axis component U through an all-pass filter gq Phase-shifting 90 degrees to obtain q-axis component U of three-phase power grid voltage gq1 Will U is gq1 And d-axis component U gd The three-phase power grid voltage amplitude U is obtained by superposition gm ；
Filtering three-phase power grid voltage amplitude U gm Comparing the three-phase grid voltage amplitude after the harmonics are filtered with a grid voltage Sag threshold, when the three-phase grid voltage amplitude after the harmonics are filtered is smaller than the grid voltage Sag threshold, the grid voltage Sag occurs if Sag1 is 1, and when the three-phase grid voltage amplitude after the harmonics are filtered is larger than or equal to the grid voltage Sag threshold, the Sag1 is 0, and the grid voltage Sag does not occur.
Optionally, the filtering removes a three-phase grid voltage amplitude U gm The method for filtering the medium harmonic waves comprises the step of filtering a three-phase power grid voltage amplitude U by adopting a band elimination filter and a low-pass filter in sequence gm Harmonic in (c).
Optionally, the band-elimination filter filters out a three-phase grid voltage amplitude U gm The 6th harmonic in (c).
Optionally, the method for acquiring the grid voltage Sag detection result Sag2 by the second voltage Sag detection module includes:
s1, sampling the actual values of the three-phase grid voltage, and respectively recording A, B, C three-phase voltage as U ga 、U gb 、U gc ；
S2, phase-shifting the A-phase power grid voltage actual value by 90 degrees through an all-pass filter to obtain a power grid voltage actual value U ga1 ；
S3, compacting the electric power of the phase A power grid into an interval value U ga Actual value U of A-phase power grid voltage after 90-degree phase shift ga1 Calculating to obtain the amplitude U of the A-phase power grid voltage gam ；
S4, filtering the A-phase grid voltage amplitude U gam The higher harmonics in the A-phase grid voltage Sag detection result Sag _ a is obtained by comparing the higher harmonics with a grid voltage Sag threshold value, and the A-phase grid voltage amplitude U after the higher harmonics are filtered out gam Less than mains voltage temporaryWhen the amplitude Ugam of the A-phase power grid voltage after filtering out the high-order harmonics is greater than or equal to the threshold value of the power grid voltage Sag, the Sag _ a is 0, and the power grid voltage Sag does not occur;
and S5, repeating the steps S2 to S4 on the B-phase grid voltage and the C-phase grid voltage, respectively obtaining a B-phase grid voltage Sag detection result Sag _ B and a C-phase grid voltage Sag detection result Sag _ C, and carrying out logical OR operation on the Sag _ a, the Sag _ B and the Sag _ C to obtain a grid voltage Sag detection result Sag 2.
Optionally, the electric compaction margin value U of the A-phase power grid is adjusted ga Actual value U of A-phase power grid voltage after 90-degree phase shift ga1 Calculating to obtain the voltage amplitude U of the A-phase power grid gam Is of the formula
In accordance with yet another aspect of the present invention, there is provided a composite voltage sag detection system comprising:
the first voltage Sag detection module is used for acquiring a power grid voltage Sag detection result Sag 1;
the second voltage Sag detection module is used for acquiring a power grid voltage Sag detection result Sag 2;
and the logic unit performs logical OR operation on the power grid voltage Sag detection result Sag1 and the power grid voltage Sag detection result Sag2 to obtain a power grid voltage Sag detection result Sag, and judges whether the power grid voltage Sag detection result Sag is in a voltage Sag state or not according to the power grid voltage Sag detection result Sag.
In accordance with still another aspect of the present invention, there is provided a composite voltage sag detection apparatus for an energy storage UPS system, comprising: a memory and a processor;
the memory is to store program instructions;
the processor is configured to invoke the program instructions in the memory to perform any of the above-described composite voltage sag detection methods for energy-storage UPS systems.
According to yet another aspect of the present invention, there is provided a computer readable storage medium having stored therein computer program instructions which, when executed, implement any of the above-described composite voltage sag detection methods for energy storage UPS systems.
According to a further aspect of the invention, a computer program product is provided, comprising a computer program which, when executed by a processor, implements any of the above-described composite voltage sag detection methods for energy storage UPS systems.
In view of the above, the technical solution of the present invention provides a composite voltage sag detection method for an energy storage UPS system, where the composite voltage sag detection technology that combines a first voltage sag detection module and a second voltage sag detection module is adopted in the method, and the method includes: the first voltage sag detection module is used for shifting the phase through an all-pass filter, is insensitive to voltage harmonics, and adopts a filtering mode of combining a band elimination filter and a low-pass filter, so that when the three-phase power grid voltage simultaneously drops or the power grid voltage has a phase shift or phase inversion working condition, the voltage sag detection result is more accurate; virtual voltages orthogonal to A, B, C-phase power grid voltages are respectively virtualized in the second voltage sag detection module through an all-pass filter, A, B, C-phase power grid voltage amplitudes are respectively obtained through corresponding mathematical operation and low-pass filtering, and power grid voltage sags can still be accurately and effectively detected under the limit working conditions that the single-phase power grid voltage drops to 0.895 times of rated power grid voltage, the two-phase power grid voltage drops to 0.895 times of rated power grid voltage, the three-phase power grid voltage drops to 0.895 times of rated power grid voltage, and the like.
Drawings
Various additional advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 illustrates a functional block diagram of an energy storage UPS system;
FIG. 2 shows a voltage sag detection schematic block diagram;
FIG. 3a shows the voltage waveform of the three-phase power grid when the voltage of the A-phase power grid drops to 0.895 times of the rated power grid voltage under the working condition of the detection method of the invention;
fig. 3b shows the waveform of the grid voltage Sag detection result Sag when the a-phase grid voltage drops to 0.895 times of the rated grid voltage under the working condition of adopting the detection method of the invention;
FIG. 4a is a three-phase grid voltage waveform when the A, B-phase grid voltage drops to 0.895 times of the rated grid voltage under the working condition of the detection method of the invention;
fig. 4b is a waveform of a power grid voltage Sag detection result Sag when the power grid voltage of A, B phases drops to 0.895 times of the rated power grid voltage under the working condition of adopting the detection method of the invention;
FIG. 5a is a three-phase grid voltage waveform when the A, B, C-phase grid voltage drops to 0.895 times of the rated grid voltage under the working condition of the detection method of the invention;
fig. 5b is a waveform of a detection result Sag of the grid voltage Sag when the detection method of the present invention is adopted under the condition that the voltage of the A, B, C-phase grid drops to 0.895 times of the rated grid voltage,
FIG. 6a is a three-phase grid voltage waveform when the detection method of the present invention is employed under the condition that the A-phase grid voltage drops to 0;
FIG. 6b is a waveform of a grid voltage Sag detection result Sag when the detection method of the present invention is employed under a condition that the A-phase grid voltage drops to 0;
FIG. 7a is a waveform of voltage of a three-phase power grid when the voltage of the A, B-phase power grid falls to 0, and the detection method of the invention is adopted;
fig. 7b is a waveform of a power grid voltage Sag detection result Sag when the detection method of the present invention is adopted under the condition that the voltage of the A, B-phase power grid drops to 0;
FIG. 8a is a waveform of voltage of a three-phase power grid when the voltage of the A, B, C-phase power grid falls to 0, and the detection method of the invention is adopted;
fig. 8b is a waveform of a power grid voltage Sag detection result Sag when the detection method of the present invention is adopted under the condition that the voltage of the A, B, C-phase power grid drops to 0;
FIG. 9a is a waveform of a three-phase grid voltage when the detection method of the present invention is employed under a condition where the A-phase grid voltage is shifted by 90 degrees;
FIG. 9b is a waveform of a grid voltage Sag detection result Sag when the detection method of the present invention is employed under a condition that the A-phase grid voltage deviates by 90 degrees;
FIG. 10a is a waveform of a three-phase grid voltage when the detection method of the present invention is employed under a condition where the A-phase grid voltage is turned over by 180 degrees;
fig. 10b is a waveform of a power grid voltage Sag detection result Sag when the detection method of the present invention is adopted under a working condition that the power grid voltage of the a phase is turned over by 180 °.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
Fig. 1 shows a schematic block diagram of an energy storage UPS system, which, when the voltage of the power grid is temporarily dropped or interrupted, quickly identifies and controls a quick switch to disconnect the power grid through a voltage temporary drop detection algorithm, and controls the energy storage UPS system to supply power to a load, so as to realize high-quality continuous and stable power supply in the voltage temporary drop mode of the power grid.
Fig. 2 illustrates a functional block diagram of a composite voltage sag detection method for an energy storage UPS system according to an embodiment of the present invention. As shown in fig. 2, the method includes: the method comprises the steps of obtaining a power grid voltage Sag detection result Sag1 and a power grid voltage Sag detection result Sag2 through a first voltage Sag detection module and a second voltage Sag detection module respectively, conducting logical OR operation on the power grid voltage Sag detection result Sag1 and the power grid voltage Sag detection result Sag2 to obtain a power grid voltage Sag detection result Sag, and judging whether the power grid voltage Sag detection result Sag is in a voltage Sag state or not according to the power grid voltage Sag detection result Sag.
In an embodiment of the present invention, in the above method, the method for acquiring the grid voltage Sag detection result Sag1 by the first voltage Sag detection module includes:
sampling the actual value of the three-phase power grid voltage, and obtaining the phase of the three-phase power grid voltage after phase locking;
according to the obtained three-phase power grid voltage phase, the actual value of the three-phase power grid voltage is converted into a dq two-phase rotating coordinate system, and a d-axis component U is obtained gd And q-axis component U gq ；
Passing the q-axis component U through an all-pass filter gq Phase-shifting 90 degrees to obtain q-axis component U of three-phase power grid voltage gq1 Will U is gq1 And d-axis component U gd The three-phase power grid voltage amplitude U is obtained by superposition gm ；
Filtering three-phase power grid voltage amplitude U gm The harmonic in the three-phase grid voltage range is compared with a threshold value of grid voltage Sag, when the amplitude of the three-phase grid voltage after the harmonic is filtered is smaller than the threshold value of the grid voltage Sag, the grid voltage Sag occurs if Sag1 is 1, and when the amplitude of the three-phase grid voltage after the harmonic is filtered is larger than or equal to the threshold value of the grid voltage Sag, Sag1 is 0, the grid voltage Sag does not occur.
In an embodiment of the present invention, in the above method, the filtering filters the three-phase grid voltage amplitude U gm The method for filtering the medium harmonic waves comprises the steps of sequentially adopting a band elimination filter and a low-pass filter to filter a three-phase power grid voltage amplitude U gm Harmonic in (c). In specific implementation, the band elimination filter filters out a three-phase power grid voltage amplitude U gm The 6th harmonic in (c).
In an embodiment of the present invention, in the above method, the method for acquiring the grid voltage Sag detection result Sag2 by the second voltage Sag detection module includes:
s1, sampling the actual values of the three-phase grid voltage, and respectively recording A, B, C three-phase voltage as U ga 、U gb 、U gc ；
S2, phase-shifting the A-phase power grid voltage actual value by 90 degrees through an all-pass filter to obtain a power grid voltage actual value U ga1 ；
S3, compacting the electric power of the phase A power grid into an interval value U ga Actual value U of A-phase power grid voltage after 90-degree phase shift ga1 Calculating to obtain the amplitude of the A-phase grid voltageU gam ；
S4, filtering the A-phase grid voltage amplitude U gam The higher harmonics in the A-phase grid voltage Sag detection result Sag _ a is obtained by comparing the higher harmonics with a grid voltage Sag threshold value, and the A-phase grid voltage amplitude U after the higher harmonics are filtered out gam When the amplitude Ugam of the A-phase power grid voltage after filtering the high-order harmonics is greater than or equal to the threshold value of the power grid voltage Sag, the Sag _ a is 0, and the power grid voltage Sag does not occur;
and S5, repeating the steps S2 to S4 on the B-phase grid voltage and the C-phase grid voltage, respectively obtaining a B-phase grid voltage Sag detection result Sag _ B and a C-phase grid voltage Sag detection result Sag _ C, and carrying out logical OR operation on the Sag _ a, the Sag _ B and the Sag _ C to obtain a grid voltage Sag detection result Sag 2.
Further, the A-phase power grid is electrically compacted to an interval value U ga Actual value U of A-phase power grid voltage after 90-degree phase shift ga1 Calculating to obtain A-phase power grid voltage amplitude U gam Is of the formula
In accordance with yet another aspect of the present invention, there is provided a composite voltage sag detection system comprising:
the first voltage Sag detection module is used for acquiring a power grid voltage Sag detection result Sag 1;
the second voltage Sag detection module is used for acquiring a power grid voltage Sag detection result Sag 2;
and the logic unit is used for carrying out logical OR operation on the power grid voltage Sag detection result Sag1 and the power grid voltage Sag detection result Sag2 to obtain a power grid voltage Sag detection result Sag, and judging whether the power grid voltage Sag detection result Sag is in a voltage Sag state or not according to the power grid voltage Sag detection result Sag.
In accordance with still another aspect of the present invention, there is provided a composite voltage sag detection apparatus for an energy storage UPS system, comprising: a memory and a processor;
the memory is to store program instructions;
the processor is configured to invoke the program instructions in the memory to perform any of the above composite voltage sag detection methods for energy storage UPS systems.
According to yet another aspect of the present invention, there is provided a computer readable storage medium having stored therein computer program instructions which, when executed, implement any of the above-described composite voltage sag detection methods for energy storage UPS systems.
According to a further aspect of the invention, a computer program product is provided, comprising a computer program which, when executed by a processor, implements any of the above-described composite voltage sag detection methods for energy storage UPS systems.
The present invention is described in detail below with reference to specific examples:
the method for acquiring the power grid voltage Sag detection result Sag1 by the first voltage Sag detection module includes:
Step 2, the actual value U of the three-phase power grid voltage sampled in the step 1 is processed ga 、U gb 、U gc Performing phase locking to obtain a three-phase power grid voltage phase theta, and adopting a single synchronous coordinate system software phase-locked loop by the PLL phase-locked loop in order to reduce time delay caused by a filtering link as much as possible;
step 3, converting the actual value U of the three-phase grid voltage sampled in the step 1 through synchronous rotation coordinates ga 、U gb 、U gc Converting the voltage into a d-axis component U of a three-phase power grid under a rotating coordinate system gd And q-axis component U of three-phase network voltage gq The calculation formula is as follows:
step 4, obtaining the q-axis component U of the three-phase power grid voltage obtained in the step 3 through an all-pass filter gq Phase shift of 90 DEG toQ-axis component U of three-phase network voltage after 90-degree phase shift gq1 The purpose of adopting the all-pass filter to shift the phase is to avoid the influence of voltage harmonic on the sag detection result and ensure the accuracy of the sag detection result, and the used all-pass filter transfer function H apf1 (s) the expression is:
wherein ω is apf1 ＝200π；
Step 5, the phase-shifted 90-degree three-phase power grid voltage q-axis component U obtained in the step 4 is subjected to phase shifting gq1 And the d-axis component U of the three-phase power grid voltage obtained in the step 3 gd The three-phase power grid voltage amplitude U is obtained by superposition gm ；
Step 6, obtaining the three-phase power grid voltage amplitude U in the step 5 gm The band elimination filter is used for filtering 6th harmonic waves in the three-phase grid voltage amplitude U to obtain the band elimination filtered three-phase grid voltage amplitude U gm1 The reason is that the actual power grid mainly contains 5 th harmonic and 7 th harmonic which are converted into 6th harmonic through synchronous rotation coordinate transformation, the purpose of adopting the band elimination filter is to filter the harmonic as much as possible, and the transfer function H of the used band elimination filter bsf1 (s) the expression is:
wherein ω is bsf1 ＝600π，B p1 ＝83π；
Step 7, the band-elimination filtered three-phase power grid voltage amplitude U obtained in the step 6 is subjected to gm1 Further filtering out higher harmonics in the three-phase grid voltage amplitude U through a low-pass filter to obtain a band-stop-low-pass filtered three-phase grid voltage amplitude U gm2 The low-pass filter used is a Butterworth low-pass filter, in order to reduce the delay of the filter as much as possible, a first-order Butterworth low-pass filter is adopted, and the transfer function Hlpf1(s) of the first-order Butterworth low-pass filter is expressed as:
wherein ω is lpf1 ＝200π；
Step 8, the band-stop low-pass filtered three-phase power grid voltage amplitude U obtained in the step 7 is subjected to gm2 Comparing with the grid voltage Sag threshold to obtain the grid voltage Sag detection result Sag1 under the voltage Sag detection module 1, wherein the grid voltage Sag threshold is usually selected to be 90% of the rated grid voltage amplitude, and when U is greater than U, the grid voltage Sag detection result Sag1 is obtained gm2 When the grid voltage Sag is smaller than the grid voltage Sag threshold value, if Sag1 is 1, the grid voltage Sag occurs; when U is turned gm2 If the grid voltage Sag is greater than or equal to the grid voltage Sag threshold, Sag1 is 0, and no grid voltage Sag occurs.
The method for acquiring the grid voltage Sag detection result Sag2 by the second voltage Sag detection module includes:
Step 2, the actual value U of the A-phase grid voltage sampled in the step 1 is processed through an all-pass filter ga The phase shift of 90 degrees is carried out to obtain the actual value U of the A-phase power grid voltage after the phase shift of 90 degrees ga1 (ii) a All-pass filter transfer function H used apf2 (s) the expression is:
wherein ω is apf2 ＝100π；
Step 3, according to the A-phase grid voltage actual value U sampled in the step 1 ga And the actual value U of the A-phase power grid voltage after 90-degree phase shift obtained in the step 2 ga1 Calculating to obtain the amplitude U of the A-phase power grid voltage gam The calculation formula is as follows:
step 4, obtaining the amplitude U of the A-phase power grid voltage obtained in the step 3 gam By low passThe filter filters out higher harmonics in the A-phase power grid voltage amplitude U after low-pass filtering gam1 The low-pass filter used is a Butterworth low-pass filter, in order to reduce the filter delay as much as possible, a first-order Butterworth low-pass filter is used, the transfer function H of which lpf2 (s) the expression is:
wherein ω is lpf2 ＝260π；
Step 5, the low-pass filtered A-phase power grid voltage amplitude U obtained in the step 4 is subjected to low-pass filtering gam1 Comparing the voltage Sag with a threshold value of the power grid voltage Sag to obtain an A-phase power grid voltage Sag detection result Sag _ a, wherein the threshold value of the power grid voltage Sag is usually selected to be 90% of the rated power grid voltage amplitude, and when U is used, the U is a zero-crossing point gam1 When the grid voltage Sag is smaller than a grid voltage Sag threshold value, if Sag _ a is 1, the grid voltage Sag occurs; when U is turned gam1 When the grid voltage Sag is greater than or equal to the grid voltage Sag threshold value, if Sag _ a is 0, no grid voltage Sag occurs;
step 6, according to the same steps as the phase a (steps 2 to 5), a B-phase grid voltage Sag detection result Sag _ B and a C-phase grid voltage Sag detection result Sag _ C can be obtained, and logical or operation is performed on the B-phase grid voltage Sag detection result Sag _ B and the C-phase grid voltage Sag detection result Sag _ C with the a-phase grid voltage Sag detection result Sag _ a obtained in the step 5 to obtain a grid voltage Sag detection result Sag2 under the voltage Sag detection module 2;
the voltage sag detection result output comprises:
and carrying out logical OR operation on the grid voltage Sag detection result Sag1 under the voltage Sag detection module 1 and the grid voltage Sag detection result Sag2 under the voltage Sag detection module 2 to obtain the grid voltage Sag detection result Sag under the method.
Example 1
FIG. 3a shows three-phase grid voltage U when the A-phase voltage drops to 0.895 times of the rated grid voltage under the working condition of the detection method of the invention ga 、U gb 、U gc The waveform of the wave is shown as,
FIG. 3b is a waveform of a detection result Sag of the grid voltage Sag when the A-phase voltage drops to 0.895 times of the rated grid voltage under the working condition of the detection method of the present invention,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the method can effectively detect the voltage sag of the power grid, and the detection time is 7.25 ms.
Example 2
FIG. 4a shows a three-phase grid voltage U when A, B phase voltage drops to 0.895 times of rated grid voltage under the working condition of the detection method of the invention ga 、U gb 、U gc FIG. 4b is a waveform of a detection result Sag of the grid voltage Sag when the A, B phase voltage drops to 0.895 times of the rated grid voltage under the working condition of the detection method of the present invention,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the voltage sag of the power grid can be effectively detected, and the detection time is 7.25 ms.
Example 3
FIG. 5a shows a three-phase grid voltage U when A, B, C phase voltage drops to 0.895 times of rated grid voltage under the condition of the detection method of the invention ga 、U gb 、U gc FIG. 5b is a waveform of a detection result Sag of the grid voltage Sag when the A, B, C phase voltage drops to 0.895 times of the rated grid voltage under the working condition of the detection method of the present invention,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the method can effectively detect the voltage sag of the power grid, and the detection time is 4.125 ms.
Example 4
FIG. 6a shows three-phase grid voltage U when the A-phase voltage drops to 0 ga 、U gb 、U gc FIG. 6b is a waveform of the detection result Sag of the grid voltage Sag when the A-phase voltage drops to 0 condition by using the detection method of the present invention,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid line is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the method can quickly and effectively detect the voltage sag of the power grid, and the detection time is 0.375 ms.
Example 5
FIG. 7a shows three-phase grid voltage U when A, B phase voltage drops to 0 working condition by using the detection method of the invention ga 、U gb 、U gc FIG. 7b is a waveform of the detection result Sag of the grid voltage Sag when the detection method of the present invention is applied under the condition that the A, B phase voltage falls to 0,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the voltage sag of the power grid can be rapidly and effectively detected, and the detection time is 0.375 ms.
Example 6
FIG. 8a shows a three-phase grid voltage U when the A, B, C phase voltage drops to 0 condition and the detection method of the present invention is applied ga 、U gb 、U gc FIG. 8b is a waveform of the detection result Sag of the grid voltage Sag when the detection method of the present invention is applied under the condition that the A, B, C phase voltage falls to 0,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the method can quickly and effectively detect the voltage sag of the power grid, and the detection time is 0.25 ms.
Example 7
FIG. 9a shows three-phase grid voltage U when the detection method of the present invention is applied under the condition that the A-phase voltage is shifted by 90 degrees ga 、U gb 、U gc FIG. 9b is a waveform of the detection result Sag of the grid voltage Sag when the detection method of the present invention is applied under the condition that the A-phase voltage is shifted by 90 degrees,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid line is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the method can quickly and effectively detect the voltage sag of the power grid, and the detection time is 0.375 ms.
Example 8
FIG. 10a shows the three-phase grid voltage U when the detection method of the present invention is applied under the condition that the A-phase voltage is turned by 180 degrees ga 、U gb 、U gc FIG. 10b is a waveform of the detection result Sag of the grid voltage Sag when the detection method of the present invention is applied under the condition that the phase voltage of A is reversed by 180 degrees,
in simulation, the fundamental wave effective value of the voltage of the three-phase power grid is 400V, 2% of 5-order harmonic waves and 2% of 7-order harmonic waves are contained, the sampling frequency of the voltage of the three-phase power grid is 8kHz, the voltage sag of the power grid can be rapidly and effectively detected, and the detection time is 0.25 ms.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
The various component embodiments of the invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It will be appreciated by those skilled in the art that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functions of some or all of the components of the composite voltage sag detection system for energy storage UPS systems according to embodiments of the present invention. The present invention may also be embodied as apparatus or device programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present invention may be stored on computer-readable media or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
Claims (10)
1. A composite voltage sag detection method for an energy storage UPS system, comprising: the method comprises the steps of obtaining a power grid voltage Sag detection result Sag1 and a power grid voltage Sag detection result Sag2 through a first voltage Sag detection module and a second voltage Sag detection module respectively, conducting logical OR operation on the power grid voltage Sag detection result Sag1 and the power grid voltage Sag detection result Sag2 to obtain a power grid voltage Sag detection result Sag, and judging whether the power grid voltage Sag detection result Sag is in a voltage Sag state or not according to the power grid voltage Sag detection result Sag.
2. The composite voltage Sag detection method according to claim 1, wherein the method for acquiring the grid voltage Sag detection result Sag1 by the first voltage Sag detection module comprises:
sampling the actual value of the three-phase power grid voltage, and obtaining the phase of the three-phase power grid voltage after phase locking;
according to the obtained three-phase power grid voltage phase, the actual value of the three-phase power grid voltage is converted into a dq two-phase rotating coordinate system, and a d-axis component U is obtained gd And q-axis component U gq ；
Passing the q-axis component U through an all-pass filter gq Phase-shifting 90 degrees to obtain q-axis component U of three-phase power grid voltage gq1 Will U is gq1 And d-axis component U gd The three-phase power grid voltage amplitude U is obtained by superposition gm ；
Filtering three-phase power grid voltage amplitude U gm In (1)And comparing the harmonic waves with a threshold value of the grid voltage Sag, when the amplitude of the three-phase grid voltage after the harmonic waves are filtered is smaller than the threshold value of the grid voltage Sag, if Sag1 is 1, the grid voltage Sag occurs, and when the amplitude of the three-phase grid voltage after the harmonic waves are filtered is larger than or equal to the threshold value of the grid voltage Sag, if Sag1 is 0, the grid voltage Sag does not occur.
3. The composite voltage sag detection method according to claim 2, wherein: filtering three-phase power grid voltage amplitude U gm The method for filtering the medium harmonic waves comprises the steps of sequentially adopting a band elimination filter and a low-pass filter to filter a three-phase power grid voltage amplitude U gm Harmonic in (c).
4. The composite voltage sag detection method according to claim 3, wherein: the band elimination filter filters the three-phase power grid voltage amplitude U gm The 6th harmonic in (c).
5. The composite voltage Sag detection method according to claim 1, wherein the method for acquiring the grid voltage Sag detection result Sag2 by the second voltage Sag detection module comprises:
s1, sampling the actual values of the three-phase grid voltage, and respectively recording A, B, C three-phase voltage as U ga 、U gb 、U gc ；
S2, phase-shifting the A-phase power grid voltage actual value by 90 degrees through an all-pass filter to obtain a power grid voltage actual value U ga1 ；
S3, compacting the electric power of the phase A power grid into an interval value U ga Actual value U of A-phase power grid voltage after 90-degree phase shift ga1 Calculating to obtain the amplitude U of the A-phase power grid voltage gam ；
S4, filtering the A-phase grid voltage amplitude U gam The higher harmonics in the A-phase grid voltage Sag detection result Sag _ a is obtained by comparing the higher harmonics with a grid voltage Sag threshold value, and the A-phase grid voltage amplitude U after the higher harmonics are filtered out gam When the voltage Sag is smaller than the threshold value of the network voltage Sag, if Sag _ a is 1, the network voltage Sag occurs, and higher harmonics are filteredLater A-phase power grid voltage amplitude U gam When the grid voltage Sag is greater than or equal to the grid voltage Sag threshold value, if Sag _ a is 0, no grid voltage Sag occurs;
and S5, repeating the steps S2 to S4 on the B-phase grid voltage and the C-phase grid voltage, respectively obtaining a B-phase grid voltage Sag detection result Sag _ B and a C-phase grid voltage Sag detection result Sag _ C, and carrying out logical OR operation on the Sag _ a, the Sag _ B and the Sag _ C to obtain a grid voltage Sag detection result Sag 2.
6. The composite voltage sag detection method according to claim 5,
the A-phase power grid voltage compaction actual value Uga and the A-phase power grid voltage actual value U after 90-degree phase shift ga1 Calculating to obtain the voltage amplitude U of the A-phase power grid gam Is of the formula
7. A composite voltage sag detection system, comprising:
the first voltage Sag detection module is used for acquiring a power grid voltage Sag detection result Sag 1;
the second voltage Sag detection module is used for acquiring a power grid voltage Sag detection result Sag 2;
and the logic unit is used for carrying out logical OR operation on the power grid voltage Sag detection result Sag1 and the power grid voltage Sag detection result Sag2 to obtain a power grid voltage Sag detection result Sag, and judging whether the power grid voltage Sag detection result Sag is in a voltage Sag state or not according to the power grid voltage Sag detection result Sag.
8. A composite voltage sag detection device for an energy storage UPS system, comprising: a memory and a processor;
the memory is to store program instructions;
the processor is configured to invoke the program instructions in the memory to perform the composite voltage sag detection method for an energy-storage UPS system according to any one of claims 1 to 6.
9. A computer-readable storage medium characterized by: the computer-readable storage medium has stored therein computer program instructions which, when executed, implement the composite voltage sag detection method for energy storage UPS systems according to any one of claims 1 to 6.
10. A computer program product comprising a computer program characterized in that: the computer program, when being executed by a processor, implements a composite voltage sag detection method for an energy storage UPS system according to any one of claims 1-6.
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| CN117434334A (en) * | 2023-12-21 | 2024-01-23 | 广州智光储能科技有限公司 | Voltage sag detection method, device, equipment and storage medium |
| CN117434334B (en) * | 2023-12-21 | 2024-05-28 | 广州智光储能科技有限公司 | Voltage sag detection method, device, equipment and storage medium |
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