Filter impedance optimization method and apparatus based on harmonic current source control, and device

Abstract

A filter impedance optimization method and apparatus based on harmonic current source control, and a device, relating to the technical field of power system harmonic control. The method comprises: acquiring first harmonic impedance imaginary part component data and electrical quantity parameters; on the basis of the electrical quantity parameters, calculating the maximum parallel impedance when a power alternating-current system and an alternating-current filter are connected in parallel; calculating second harmonic impedance imaginary part component data on the basis of the first harmonic impedance imaginary part component data and the maximum parallel impedance; and calculating filter impedance on the basis of imaginary part component data of system harmonic impedance and the second harmonic impedance imaginary part component data at a tuning point of the alternating-current filter. According to the method, the second harmonic impedance imaginary part component data is obtained by combining the maximum parallel impedance and the first harmonic impedance imaginary part component data, so as to determine a filter impedance range, thereby avoiding repeated trial calculation of the alternating-current filter and reducing the workload. The optimized impedance of the alternating-current filter is determined by calculating the filter impedance, and the optimal design of the alternating-current filter is realized on the basis of the filter impedance.

Description

Filter impedance optimization method, device and equipment based on harmonic current source control

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 8, 2023, with application number 202311485139.5 and invention name “Filter impedance optimization method, device and equipment based on harmonic current source control”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of power system harmonic control, and in particular to a filter impedance optimization method, device and equipment based on harmonic current source control. Background Art

[0003] With the construction of new power systems, a large number of power electronic devices are gradually connected to existing AC and DC power grids. Harmonics generated by these devices also flow into these AC and DC grids, where they are amplified and aggregated, exerting an increasing impact on the grid. Harmonics also increase losses in key power equipment, causing them to heat up, vibrate, generate harmonics, and even burn out.

[0004] In traditional power systems, harmonics are primarily addressed through harmonic source control. This involves configuring active and passive filters to absorb harmonics from the source and prevent them from entering the AC system, thereby achieving harmonic control. The resonance between the AC filter and the power system's harmonic impedance must be considered in both AC filter performance and steady-state rating calculations. These calculations are based on the equivalent circuit of the AC filter's performance and the resonant relationship between the AC system's harmonic impedance and the AC filter's impedance.

[0005] The current process for calculating AC filter performance typically involves first determining the basic capacitance and reactance parameters of the AC filter, calculating the harmonic impedance of the AC filter, and then calculating the harmonic voltage level at the filter point based on the relationship between the harmonic impedance and the impedance of the AC system. If the harmonic voltage still exceeds the standard, the AC filter's impedance range is readjusted and the calculation is repeated, repeating this process until the desired result is achieved. This cumbersome calculation method, through repeated trial and error, can solve the problem, but it cannot achieve the optimal AC filter configuration, often resulting in a waste of equipment investment and a significant design workload.

[0006] Summary of the Invention

[0007] The embodiments of the present application provide a filter impedance optimization method, device and equipment based on harmonic current source management, which is used to solve the technical problems that the impedance calculation method of the AC filter in the existing power system is cumbersome, the optimal AC filter impedance cannot be obtained, the workload is large, and the investment in power equipment is wasted.

[0008] In order to achieve the above objectives, the embodiments of the present application provide the following technical solutions:

[0009] On the one hand, a filter impedance optimization method based on harmonic current source management is provided, comprising the following steps:

[0010] Obtaining data on the imaginary component of the first harmonic impedance of the AC power system and obtaining electrical quantity parameters of the AC power system connected in parallel with the AC filter;

[0011] Calculating the maximum impedance of the AC power system connected in parallel with the AC filter based on the electrical quantity parameters to obtain the maximum parallel impedance; calculating the imaginary component data of the second harmonic impedance of the AC filter based on the imaginary component data of the first harmonic impedance and the maximum parallel impedance;

[0012] Calculating, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, a filter impedance at which the current flowing into the AC filter is minimized;

[0013] The electrical quantity parameters include filter impedance, system harmonic impedance, AC bus fundamental voltage and nth harmonic current, system nth harmonic impedance and nth harmonic filter impedance.

[0014] Preferably, calculating the maximum impedance of the AC power system and the AC filter connected in parallel according to the electrical quantity parameter to obtain the maximum parallel impedance includes:

[0015] Obtaining an nth harmonic voltage distortion rate of the AC bus according to the phasor calculation of the filter impedance, the system harmonic impedance, and the nth harmonic current;

[0016] The maximum parallel impedance is obtained by calculation based on the nth harmonic current, the AC bus fundamental voltage, and the nth harmonic voltage distortion rate.

[0017] Preferably, calculating the maximum impedance of the AC power system and the AC filter connected in parallel according to the electrical quantity parameter to obtain the maximum parallel impedance includes:

[0018] The nth harmonic voltage distortion rate of the AC bus is calculated using a distortion rate formula according to the filter impedance, the system harmonic impedance and the phasor of the nth harmonic current;

[0019] Obtain the maximum parallel impedance by using an impedance calculation formula according to the nth harmonic current, the AC bus fundamental voltage, and the nth harmonic voltage distortion rate;

[0020] The distortion rate formula is:

[0021] The impedance calculation formula is: Z n =U1*Dn / I n ;

[0022] Where, is the phasor of the nth harmonic distortion voltage, is the phasor of the nth harmonic current, is the phasor of the filter impedance, is the phasor of the system harmonic impedance, Dn is the nth harmonic voltage distortion rate, U1 is the AC bus fundamental voltage, I n is the nth harmonic current, Z n is the maximum parallel impedance.

[0023] Preferably, obtaining the imaginary component data of the second harmonic impedance of the AC filter by calculating according to the first harmonic impedance imaginary component data and the maximum parallel impedance includes: calculating according to the first harmonic impedance imaginary component data and the maximum parallel impedance using a harmonic impedance formula to obtain the imaginary component data of the second harmonic impedance of the AC filter; the harmonic impedance formula is: X fn ∈[X fnmin , X fnmax ];

[0024] Where Z n is the maximum parallel impedance, X nmax is the maximum value of the imaginary component of the first harmonic impedance, X nmin is the minimum value of the imaginary component of the first harmonic impedance, X fn is the imaginary component data of the second harmonic impedance, X fnmin is the minimum value of the imaginary component of the second harmonic impedance, X fnmax is the maximum value of the imaginary component of the second harmonic impedance.

[0025] Preferably, calculating, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, to obtain the filter impedance with the minimum current flowing into the AC filter comprises: calculating, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, using an impedance shunt relationship formula to obtain the filter impedance with the minimum current flowing into the AC filter; the impedance shunt relationship formula is:

[0026] Where, X fn X is the imaginary component data of the second harmonic impedance of the AC filter at the tuning point, sn is the imaginary component data of the system harmonic impedance, f(X fn ) is the filter impedance with the minimum current flowing into the AC filter.

[0027] In another aspect, a filter impedance optimization device based on harmonic current source management is provided, comprising a data acquisition module, a first calculation module, and a second calculation module;

[0028] The data acquisition module is used to obtain data on the imaginary component of the first harmonic impedance of the AC power system and to obtain electrical quantity parameters of the AC power system connected in parallel with the AC filter;

[0029] The first calculation module is configured to calculate the maximum impedance of the AC power system connected in parallel with the AC filter based on the electrical quantity parameters to obtain the maximum parallel impedance; and to calculate the imaginary component data of the second harmonic impedance of the AC filter based on the first harmonic impedance imaginary component data and the maximum parallel impedance;

[0030] The second calculation module is configured to calculate, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, a filter impedance with a minimum current flowing into the AC filter;

[0031] The electrical quantity parameters include filter impedance, system harmonic impedance, AC bus fundamental voltage and nth harmonic current, system nth harmonic impedance and nth harmonic filter impedance.

[0032] Preferably, the first calculation module is further configured to calculate, using a distortion rate formula based on the filter impedance, the system harmonic impedance, and the phasor of the nth harmonic current, to obtain the nth harmonic voltage distortion rate of the AC bus; and to calculate, using an impedance calculation formula based on the nth harmonic current, the AC bus fundamental voltage, and the nth harmonic voltage distortion rate, to obtain the maximum parallel impedance;

[0033] The distortion rate formula is:

[0034] The impedance calculation formula is: Z n =U1*Dn / I n ;

[0035] Where, is the phasor of the nth harmonic distortion voltage, is the phasor of the nth harmonic current, is the phasor of the filter impedance, is the phasor of the system harmonic impedance, Dn is the nth harmonic voltage distortion rate, U1 is the AC bus fundamental voltage, I n is the nth harmonic current, Z n is the maximum parallel impedance.

[0036] Preferably, the first calculation module is further configured to calculate, based on the first harmonic impedance imaginary component data and the maximum parallel impedance, using a harmonic impedance formula to obtain the second harmonic impedance imaginary component data of the AC filter; the harmonic impedance formula is: X fn ∈[X fnmin , X fnmax ];

[0037] Where Z n is the maximum parallel impedance, X nmax is the maximum value of the imaginary component of the first harmonic impedance, X nmin is the minimum value of the imaginary component of the first harmonic impedance, X fn is the imaginary component data of the second harmonic impedance, X fnmin is the minimum value of the imaginary component of the second harmonic impedance, X fnmax is the maximum value of the imaginary component of the second harmonic impedance.

[0038] Preferably, the second calculation module is further configured to calculate, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, using an impedance shunt relationship formula to obtain a filter impedance with the minimum current flowing into the AC filter; the impedance shunt relationship formula is:

[0039] Where, X fn X is the imaginary component data of the second harmonic impedance of the AC filter at the tuning point, sn is the imaginary component data of the system harmonic impedance, f(X fn ) is the filter impedance with the minimum current flowing into the AC filter.

[0040] In another aspect, a terminal device is provided, comprising a processor and a memory;

[0041] The memory is used to store program code and transmit the program code to the processor;

[0042] The processor is used to execute the above-mentioned filter impedance optimization method based on harmonic current source management according to the instructions in the program code.

[0043] The filter impedance optimization method, device and equipment based on harmonic current source management include obtaining imaginary component data of the first harmonic impedance of an AC power system and obtaining electrical quantity parameters of the AC power system connected in parallel with an AC filter; calculating the maximum impedance of the AC power system connected in parallel with the AC filter based on the electrical quantity parameters to obtain the maximum parallel impedance; obtaining imaginary component data of the second harmonic impedance of the AC filter based on the imaginary component data of the first harmonic impedance and the maximum parallel impedance; and obtaining the filter impedance with the minimum current flowing into the AC filter based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance of the AC filter at a tuning point. It can be seen from the above technical solution that the embodiments of the present application have the following advantages: the filter impedance optimization method based on harmonic current source control calculates the maximum parallel impedance through the control requirements of the harmonic voltage distortion rate, and combines the harmonic impedance range of the AC system determined according to the imaginary component data of the first harmonic impedance to obtain the imaginary component data of the second harmonic impedance to determine the filter impedance range, thereby avoiding repeated trial calculations of the AC filter and reducing the workload of the AC filter design; the optimized impedance of the AC filter is determined by calculating the filter impedance with the minimum constant value, and the purpose of optimizing the AC filter design is achieved according to the filter impedance, which solves the technical problems that the impedance calculation method of the AC filter in the existing power system is cumbersome, the optimal AC filter impedance cannot be obtained, the workload is large, and the investment in power equipment is wasted. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0045] FIG1 is a flowchart of the steps of a filter impedance optimization method based on harmonic current source management according to an embodiment of the present application;

[0046] FIG2 is a schematic diagram of an equivalent circuit in a filter impedance optimization method based on harmonic current source control according to an embodiment of the present application;

[0047] FIG3 is a schematic diagram of a framework of a filter impedance optimization device based on harmonic current source management according to an embodiment of the present application;

[0048] FIG4 is a schematic diagram of a terminal device according to an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, 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 embodiments described below are only 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 work are within the scope of protection of this application.

[0050] In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0051] In the embodiments of the present application, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections; direct connections, or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0052] The low-order harmonic impedance of an AC power system connected in parallel with an AC filter is generally represented by a fan-shaped diagram. The parameters of the low-order harmonic impedance include: maximum impedance amplitude, minimum impedance amplitude, maximum impedance angle, and minimum impedance angle. The high-order harmonic impedance of an AC power system connected in parallel with an AC filter is generally represented by an impedance circle. The parameters of the high-order harmonic impedance include: minimum and maximum resistance, minimum impedance, maximum impedance, maximum impedance angle, minimum impedance angle, and impedance circle radius R.

[0053] The sector-shaped or circular harmonic impedance proposed above is a common form of harmonic impedance expression in this field, and is also often used in existing DC engineering designs.

[0054] With the advancement of technology, the Cigre Working Group's 14.30 research report, "Guide to the specification and design evaluation of AC filters for HVDC systems," proposed using polygons to represent harmonic impedances. It also suggested using different polygons based on the characteristics of different subharmonic impedances to avoid the risk of widening the impedance range in sector-shaped harmonic impedances. However, the report did not propose principles for constructing polygonal harmonic impedances, nor did it further explore filter design principles using polygonal harmonic impedances.

[0055] The embodiments of the present application provide a filter impedance optimization method, apparatus, and device based on harmonic current source management. This method addresses the technical issues of AC filter impedance calculation in existing power systems, which are cumbersome, unable to obtain the optimal AC filter impedance, resulting in a large workload and wasted power equipment investment. The filter impedance optimization method, apparatus, and device based on harmonic current source management are illustrated using an equivalent circuit of an AC power system connected in parallel with an AC filter as an example.

[0056] Example 1:

[0057] Figure 1 is a step flow chart of the filter impedance optimization method based on harmonic current source management described in an embodiment of the present application, and Figure 2 is a schematic diagram of the equivalent circuit in the filter impedance optimization method based on harmonic current source management described in an embodiment of the present application.

[0058] As shown in FIG1 , an embodiment of the present application provides a filter impedance optimization method based on harmonic current source management, comprising the following steps:

[0059] S1. Obtain the imaginary component data of the first harmonic impedance of the AC power system and the electrical quantity parameters of the AC power system connected in parallel with the AC filter. The electrical quantity parameters include the filter impedance, the system harmonic impedance, the AC bus fundamental voltage and the nth harmonic current, the system nth harmonic impedance and the nth harmonic filter impedance. The imaginary component data of the first harmonic impedance includes the maximum value X of the imaginary component data of the first harmonic impedance. nmax and the minimum value X of the imaginary component of the first harmonic impedance nmin .

[0060] It should be noted that in step S1, first, existing AC system harmonic impedance scanning software is used to scan the AC power system to obtain data on the imaginary component of the first harmonic impedance. Second, based on the equivalent circuit shown in FIG2 , electrical quantity data such as the filter impedance connected in parallel with the AC filter, the system harmonic impedance, the AC bus fundamental voltage and nth harmonic current, the system nth harmonic impedance, and the nth harmonic filter impedance are obtained, thereby subsequently obtaining the optimized filter impedance. In this embodiment, the existing AC system harmonic impedance scanning software includes power AC system software such as PSSE and DSP.

[0061] S2. Calculate the maximum impedance of the parallel connection between the AC power system and the AC filter based on the electrical quantity parameters to obtain the maximum parallel impedance; and calculate the imaginary component data of the second harmonic impedance of the AC filter based on the imaginary component data of the first harmonic impedance and the maximum parallel impedance.

[0062] It should be noted that in step S2, the maximum parallel impedance is first calculated based on the electrical quantity parameters obtained in step S1, and then the second harmonic impedance imaginary component data of the AC filter is calculated and determined based on the first harmonic impedance imaginary component data and the maximum parallel impedance in step S1. In this embodiment, the filter impedance optimization method based on harmonic current source management determines the harmonic impedance range of the AC filter using the second harmonic impedance imaginary component data in step S2. The harmonic impedance range determined by the second harmonic impedance imaginary component data can be used as an input condition for AC filter impedance design, thereby achieving optimized design of the AC filter impedance.

[0063] S3. Calculate the filter impedance with the minimum current flowing into the AC filter based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter.

[0064] It should be noted that, since the cost of the AC filter mainly depends on the harmonic current flowing into the AC filter, the current of the AC filter depends on the tuning point of the AC filter, that is, taking the maximum value at the tuning point can ensure that the current flowing into the AC filter is minimized and the cost is lowest. Among them, the tuning point refers to the point where the harmonic impedance of the AC filter is minimized. In step S3, the harmonic impedance range of the AC filter is first determined based on the imaginary component data of the second harmonic impedance calculated in step S2, and then the imaginary component data of the second harmonic impedance of the AC filter at the tuning point is screened out from the harmonic impedance range of the AC filter and combined with the imaginary component data of the system harmonic impedance obtained according to step S1 as calculation data to obtain the filter impedance with the minimum current flowing into the AC filter, and obtain the impedance of the AC filter after impedance optimization based on the harmonic current source control.

[0065] The present application provides a filter impedance optimization method based on harmonic current source management, which includes obtaining imaginary component data of the first harmonic impedance of an AC power system and obtaining electrical quantity parameters of the AC power system connected in parallel with an AC filter; calculating the maximum impedance of the AC power system connected in parallel with the AC filter based on the electrical quantity parameters to obtain the maximum parallel impedance; obtaining imaginary component data of the second harmonic impedance of the AC filter based on the imaginary component data of the first harmonic impedance and the maximum parallel impedance; and obtaining the filter impedance with the minimum current flowing into the AC filter based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance of the AC filter at a tuning point. The filter impedance optimization method based on harmonic current source control calculates the maximum parallel impedance through the control requirement of the harmonic voltage distortion rate, and combines the harmonic impedance range of the AC system determined according to the imaginary component data of the first harmonic impedance to obtain the imaginary component data of the second harmonic impedance to determine the filter impedance range, thereby avoiding repeated trial calculations of the AC filter and reducing the workload of the AC filter design; and also determines the optimized impedance of the AC filter by calculating the filter impedance with the minimum constant value, and achieves the purpose of optimizing the AC filter design according to the filter impedance, thereby solving the technical problems that the impedance calculation method of the AC filter in the existing power system is cumbersome, the optimal AC filter impedance cannot be obtained, the workload is large, and the investment in power equipment is wasted.

[0066] It should be noted that the filter impedance optimization method based on harmonic current source management determines the imaginary component data of the second harmonic impedance within the reasonable impedance range of the AC filter through the requirements of harmonic voltage distortion rate control, thereby serving as a guide for the AC filter parameter design.

[0067] In one embodiment of the present application, calculating the maximum impedance of the AC power system connected in parallel with the AC filter based on electrical quantity parameters, to obtain the maximum parallel impedance includes:

[0068] The distortion rate formula is used to calculate the nth harmonic voltage distortion rate of the AC bus based on the filter impedance, system harmonic impedance and the phase quantity of the nth harmonic current;

[0069] The maximum parallel impedance is calculated using the impedance calculation formula based on the nth harmonic current, AC bus fundamental voltage and nth harmonic voltage distortion rate;

[0070] The distortion rate formula is:

[0071] The impedance calculation formula is: Z n =U1*Dn / I n ;

[0072] Where, is the phasor of the nth harmonic distortion voltage, is the phasor of the nth harmonic current, is the phasor of the filter impedance, is the phasor of the system harmonic impedance, Dn is the nth harmonic voltage distortion rate, U1 is the AC bus fundamental voltage, I n is the nth harmonic current, Z n is the maximum parallel impedance.

[0073] It should be noted that the filter impedance optimization method based on harmonic current source management is that the harmonic voltage distortion rate at different orders should meet the power quality requirements of the power system. Therefore, the impedance calculation formula is used to calculate the maximum parallel impedance of the power AC system connected in parallel with the AC filter.

[0074] In one embodiment of the present application, obtaining the imaginary component data of the second harmonic impedance of the AC filter according to the imaginary component data of the first harmonic impedance and the maximum parallel impedance includes: calculating the imaginary component data of the second harmonic impedance of the AC filter using a harmonic impedance formula according to the imaginary component data of the first harmonic impedance and the maximum parallel impedance; the harmonic impedance formula is: X fn ∈[X fnmin , X fnmax ];

[0075] Where Z n is the maximum parallel impedance, X nmax is the maximum value of the imaginary component of the first harmonic impedance, X nmin is the minimum value of the imaginary component of the first harmonic impedance, X fn is the imaginary component data of the second harmonic impedance, X fnmin is the minimum value of the imaginary component of the second harmonic impedance, X fnmax is the maximum value of the imaginary component of the second harmonic impedance.

[0076] In the embodiment of the present application, the filter impedance optimization method based on harmonic current source management obtains the harmonic impedance formula including:

[0077] According to the system nth harmonic impedance Z sn and nth harmonic filter impedance Z fn The parallel impedance formula is used to calculate the parallel harmonic impedance of the power AC system connected in parallel with the AC filter;

[0078] The parallel harmonic impedance calculated based on the imaginary component of the system's nth harmonic impedance phasor and the imaginary component of the nth harmonic filter's impedance phasor is not less than the maximum parallel impedance, and the harmonic impedance calculation formula inequality is obtained;

[0079] Determine the harmonic impedance formula according to the maximum value of the first harmonic impedance imaginary component data, the minimum value of the first harmonic impedance imaginary component data and the harmonic impedance calculation formula inequality;

[0080] The parallel impedance formula is:

[0081] The inequality for calculating harmonic impedance is:

[0082] Where Z sn is the system nth harmonic impedance, Z fn is the nth harmonic filter impedance of the AC filter, Z pn is the nth parallel harmonic impedance, Z n is the maximum parallel impedance; X fn is the imaginary component of the impedance phasor of the nth harmonic filter, that is, the imaginary component data of the second harmonic impedance; X sn is the imaginary component of the system's nth harmonic impedance phasor. n is the nth harmonic order.

[0083] It should be noted that the system nth harmonic impedance phasor is Z sn =R sn +jX sn , the impedance phasor of the nth harmonic filter is Z fn =R fn +jX fn , where R fn is the real component of the impedance phasor of the nth harmonic filter, R sn is the real component of the system's nth harmonic impedance phasor, and j is the imaginary unit. The real component mainly plays a role in suppressing harmonics. At the same time, the real component is relatively small compared to the imaginary component, so the real component can be ignored, and Z is obtained. sn =jX sn , Z fn =jX fn , then the parallel impedance formula can be converted to:

[0084] The parallel harmonic impedance should satisfy |Z pn |≤Z n , then we can get the first formula:

[0085] According to the first formula, the harmonic impedance calculation formula inequality is obtained. Then, according to the harmonic impedance calculation formula inequality, the imaginary component of the system nth harmonic impedance meets the operating range of the imaginary component data of the first harmonic impedance [X nmin , X nmax], then the harmonic impedance formula can be obtained. The filter impedance optimization method based on harmonic current source management determines the reasonable range of the second harmonic impedance imaginary component data according to the harmonic impedance formula [X fnmin , X fnmax ], that is, the reasonable impedance range of the AC filter is determined [X fnmin , X fnmax ], the impedance range [X fnmin , X fnmax ] can be used as the design requirement of AC filter, so as to optimize the design of AC filter.

[0086] In one embodiment of the present application, calculating based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter to obtain the filter impedance with the minimum current flowing into the AC filter includes: calculating based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter using an impedance shunt relationship formula to obtain the filter impedance with the minimum current flowing into the AC filter; the impedance shunt relationship formula is:

[0087] Where, X fn X is the imaginary component data of the second harmonic impedance of the AC filter at the tuning point, sn is the imaginary component data of the system harmonic impedance, f(X fn ) is the filter impedance with the minimum current flowing into the AC filter.

[0088] It should be noted that the filter impedance optimization method based on harmonic current source control is based on the impedance shunt relationship formula, which is mainly due to the shunt relationship between the AC filter impedance and the AC system impedance. When the impedance shunt relationship formula takes the minimum value, the AC filter shunt is the smallest, that is, |1+X fn / X sn | Take the maximum value. The impedance range of the AC filter determined in step S2 [X fnmin , X fnmax ]Substitute the impedance at the tuning point into the impedance shunt relationship formula to determine f(X fn ), thereby determining the value at the tuning point, that is, determining the filter impedance with the minimum current flowing into the filter.

[0089] Example 2:

[0090] FIG3 is a schematic diagram of a framework of a filter impedance optimization device based on harmonic current source control according to an embodiment of the present application.

[0091] As shown in FIG3 , the embodiment of the present application provides a filter impedance optimization device based on harmonic current source management, including a data acquisition module 10 , a first calculation module 20 and a second calculation module 30 ;

[0092] The data acquisition module 10 is used to obtain the imaginary component data of the first harmonic impedance of the AC power system and the electrical quantity parameters of the AC power system connected in parallel with the AC filter;

[0093] The first calculation module 20 is used to calculate the maximum impedance of the AC power system connected in parallel with the AC filter based on the electrical quantity parameters to obtain the maximum parallel impedance; and to calculate the imaginary component data of the second harmonic impedance of the AC filter based on the imaginary component data of the first harmonic impedance and the maximum parallel impedance;

[0094] The second calculation module 30 is used to calculate the filter impedance with the minimum current flowing into the AC filter based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter;

[0095] Among them, the electrical quantity parameters include filter impedance, system harmonic impedance, AC bus fundamental voltage and nth harmonic current, system nth harmonic impedance and nth harmonic filter impedance.

[0096] In the embodiment of the present application, the first calculation module 20 is further configured to calculate the nth harmonic voltage distortion rate of the AC bus using the distortion rate formula according to the filter impedance, the system harmonic impedance, and the phasor of the nth harmonic current; and to calculate the maximum parallel impedance using the impedance calculation formula according to the nth harmonic current, the AC bus fundamental voltage, and the nth harmonic voltage distortion rate.

[0097] The distortion rate formula is:

[0098] The impedance calculation formula is: Z n =U1*Dn / I n ;

[0099] Where, is the phasor of the nth harmonic distortion voltage, is the phasor of the nth harmonic current, is the phasor of the filter impedance, is the phasor of the system harmonic impedance, Dn is the nth harmonic voltage distortion rate, U1 is the AC bus fundamental voltage, I n is the nth harmonic current, Z n is the maximum parallel impedance.

[0100] In the embodiment of the present application, the first calculation module 20 is further configured to calculate the imaginary component data of the second harmonic impedance of the AC filter using the harmonic impedance formula according to the imaginary component data of the first harmonic impedance and the maximum parallel impedance; the harmonic impedance formula is: X fn ∈[X fnmin , X fnmax ];

[0101] Where Z n is the maximum parallel impedance, X nmax is the maximum value of the imaginary component of the first harmonic impedance, X nmin is the minimum value of the imaginary component of the first harmonic impedance, X fn is the imaginary component data of the second harmonic impedance, X fnmin is the minimum value of the imaginary component of the second harmonic impedance, X fnmax is the maximum value of the imaginary component of the second harmonic impedance.

[0102] In the embodiment of the present application, the second calculation module 30 is further configured to calculate, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, the filter impedance with the minimum current flowing into the AC filter using the impedance shunt relationship formula; the impedance shunt relationship formula is:

[0103] Where, X fn X is the imaginary component data of the second harmonic impedance of the AC filter at the tuning point, sn is the imaginary component data of the system harmonic impedance, f(X fn ) is the filter impedance with the minimum current flowing into the AC filter.

[0104] It should be noted that the contents of the modules in the apparatus of Example 2 correspond to the steps of the method of Example 1. The contents of the filter impedance optimization method based on harmonic current source management have been described in Example 1, and the module contents of the filter impedance optimization apparatus based on harmonic current source management will not be described in detail in this embodiment.

[0105] Example 3:

[0106] FIG4 is a schematic diagram of a terminal device according to an embodiment of the present application.

[0107] As shown in FIG4 , an embodiment of the present application provides a terminal device including a processor and a memory;

[0108] A memory, configured to store program codes and transmit the program codes to a processor;

[0109] The processor is configured to execute the filter impedance optimization method based on harmonic current source management according to the instructions in the program code.

[0110] It should be noted that the processor is configured to execute the steps of the aforementioned embodiment of a filter impedance optimization method based on harmonic current source management according to the instructions in the program code. Alternatively, the processor implements the functions of the modules / units in the aforementioned system / device embodiments when executing the computer program.

[0111] For example, a computer program may be divided into one or more modules / units, one or more of which are stored in a memory and executed by a processor to complete the present application. One or more modules / units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in a terminal device.

[0112] Terminal devices can be computing devices such as desktop computers, laptops, PDAs, and cloud servers. Terminal devices may include, but are not limited to, processors and memory. Those skilled in the art will appreciate that this does not constitute a limitation on terminal devices and may include more or fewer components than shown, or a combination of certain components, or different components. For example, terminal devices may also include input / output devices, network access devices, buses, and the like.

[0113] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (dSIC), field-programmable gate arrays (FPGAs), other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0114] The memory can be an internal storage unit of a terminal device, such as a hard drive or memory of the terminal device. The memory can also be an external storage device of the terminal device, such as a plug-in hard drive, a Smart Memory Card (SMC), a Secure Digital (SD) card, a flash memory card, etc. Furthermore, the memory can include both the internal storage unit of the terminal device and an external storage device. The memory is used to store computer programs and other programs and data required by the terminal device. The memory can also be used to temporarily store data that has been output or is about to be output.

[0115] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0116] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0117] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0118] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0119] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RdM), a magnetic disk or an optical disk.

[0120] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A filter impedance optimization method based on harmonic current source management, characterized in that: The following steps are involved: Acquiring data of the imaginary component of the first harmonic impedance of the AC power system and acquiring electrical quantity parameters of the AC power system connected in parallel with the AC filter; Calculate the maximum impedance of the AC power system connected in parallel with the AC filter according to the electrical quantity parameter to obtain the maximum parallel impedance; calculate the imaginary component data of the second harmonic impedance of the AC filter according to the first harmonic impedance imaginary component data and the maximum parallel impedance; Calculate, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, to obtain the filter impedance with the minimum current flowing into the AC filter; The electrical quantity parameters include filter impedance, system harmonic impedance, AC bus fundamental voltage and nth harmonic current, system nth harmonic impedance and nth harmonic filter impedance.

2. The filter impedance optimization method based on harmonic current source management according to claim 1 is characterized in that: Calculating the maximum impedance of the AC power system connected in parallel with the AC filter according to the electrical quantity parameter, and obtaining the maximum parallel impedance includes: Obtaining the nth harmonic voltage distortion rate of the AC bus according to the filter impedance, the system harmonic impedance and the nth harmonic current phasor calculation; The maximum parallel impedance is obtained by calculation based on the nth harmonic current, the AC bus fundamental voltage and the nth harmonic voltage distortion rate.

3. The filter impedance optimization method based on harmonic current source management according to claim 2 is characterized in that: Calculating the maximum impedance of the AC power system connected in parallel with the AC filter according to the electrical quantity parameter, and obtaining the maximum parallel impedance includes: The nth harmonic voltage distortion rate of the AC bus is calculated by using the distortion rate formula according to the filter impedance, the system harmonic impedance and the phase quantity of the nth harmonic current; The maximum parallel impedance is obtained by using an impedance calculation formula according to the nth harmonic current, the AC bus fundamental voltage and the nth harmonic voltage distortion rate; Wherein, the distortion rate formula is: The impedance calculation formula is: Z n =U1*Dn / I n ; In the formula, is the phasor of the nth harmonic distortion voltage, is the phasor of the nth harmonic current, is the phasor of the filter impedance, is the phase quantity of the system harmonic impedance, Dn is the nth harmonic voltage distortion rate, U1 is the AC bus fundamental voltage, I n is the nth harmonic current, Z n is the maximum parallel impedance.

4. The filter impedance optimization method based on harmonic current source management according to claim 1 is characterized in that: Calculating according to the first harmonic impedance imaginary component data and the maximum parallel impedance to obtain the second harmonic impedance imaginary component data of the AC filter includes: calculating according to the first harmonic impedance imaginary component data and the maximum parallel impedance using a harmonic impedance formula to obtain the second harmonic impedance imaginary component data of the AC filter; the harmonic impedance formula is: X fn ∈[X fnmin , X fnmax ]; In the formula, Z n is the maximum parallel impedance, X nmax is the maximum value of the imaginary component of the first harmonic impedance, X nmin is the minimum value of the imaginary component of the first harmonic impedance, X fn is the imaginary component data of the second harmonic impedance, X fnmin is the minimum value of the imaginary component of the second harmonic impedance, X fnmax It is the maximum value of the imaginary component data of the second harmonic impedance.

5. The filter impedance optimization method based on harmonic current source management according to claim 1 is characterized in that: Calculating according to the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter to obtain the filter impedance with the minimum current flowing into the AC filter includes: calculating according to the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter using an impedance shunt relationship formula to obtain the filter impedance with the minimum current flowing into the AC filter; the impedance shunt relationship formula is: Where, X fn is the imaginary component data of the second harmonic impedance of the AC filter at the tuning point, X sn is the imaginary component data of the system harmonic impedance, f(X fn ) is the filter impedance with the minimum current flowing into the AC filter.

6. A filter impedance optimization device based on harmonic current source management, characterized in that: It includes a data acquisition module, a first calculation module and a second calculation module; The data acquisition module is used to acquire the imaginary component data of the first harmonic impedance of the power AC system and to acquire the electrical quantity parameters of the power AC system connected in parallel with the AC filter; The first calculation module is used to calculate the maximum impedance of the parallel connection between the power AC system and the AC filter according to the electrical quantity parameter to obtain the maximum parallel impedance; Obtaining the imaginary component data of the second harmonic impedance of the AC filter according to the first harmonic impedance imaginary component data and the maximum parallel impedance; The second calculation module is used to calculate, based on the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter, to obtain the filter impedance with the minimum current flowing into the AC filter; The electrical quantity parameters include filter impedance, system harmonic impedance, AC bus fundamental voltage and nth harmonic current, system nth harmonic impedance and nth harmonic filter impedance.

7. The filter impedance optimization device based on harmonic current source management according to claim 6 is characterized in that: The first calculation module is further used to calculate the nth harmonic voltage distortion rate of the AC bus according to the filter impedance, the system harmonic impedance and the phase of the nth harmonic current using the distortion rate formula; and to calculate the maximum parallel impedance according to the nth harmonic current, the AC bus fundamental voltage and the nth harmonic voltage distortion rate using the impedance calculation formula; Wherein, the distortion rate formula is: The impedance calculation formula is: Z n =U1*Dn / I n ; In the formula, is the phasor of the nth harmonic distortion voltage, is the phasor of the nth harmonic current, is the phasor of the filter impedance, is the phase quantity of the system harmonic impedance, Dn is the nth harmonic voltage distortion rate, U1 is the AC bus fundamental voltage, I n is the nth harmonic current, Z n is the maximum parallel impedance.

8. The filter impedance optimization device based on harmonic current source management according to claim 6, characterized in that: The first calculation module is further used to calculate the imaginary component data of the second harmonic impedance of the AC filter using the harmonic impedance formula according to the first harmonic impedance imaginary component data and the maximum parallel impedance; the harmonic impedance formula is: X fn ∈[X fnmin , X fnmax ]; In the formula, Z n is the maximum parallel impedance, X nmax is the maximum value of the imaginary component of the first harmonic impedance, X nmin is the minimum value of the imaginary component of the first harmonic impedance, X fn is the imaginary component data of the second harmonic impedance, X fnmin is the minimum value of the imaginary component of the second harmonic impedance, X fnmax It is the maximum value of the imaginary component data of the second harmonic impedance.

9. The filter impedance optimization device based on harmonic current source management according to claim 6, characterized in that: The second calculation module is further used to calculate the filter impedance with the minimum current flowing into the AC filter by using the impedance shunt relationship formula according to the imaginary component data of the system harmonic impedance and the imaginary component data of the second harmonic impedance at the tuning point of the AC filter; The impedance shunt relationship formula is: Where, X fn is the imaginary component data of the second harmonic impedance of the AC filter at the tuning point, X sn is the imaginary component data of the system harmonic impedance, f(X fn ) is the filter impedance with the minimum current flowing into the AC filter.

10. A terminal device, characterized in that: including a processor and a memory; The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the filter impedance optimization method based on harmonic current source management as described in any one of claims 1-5 according to the instructions in the program code.

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