Passive damping optimization method and system for power electronic equipment, equipment and medium

Abstract

The invention belongs to the technical field of passive damping, and discloses a passive damping optimization method, system, equipment and medium for power electronic equipment, and the method comprises the steps: obtaining a passive damping circuit parameter, calculating a grid-connected impedance parameter, generating a modulation network equation, and carrying out the impact analysis of a grid-connected resonance peak; performing denominator materialization on the modulation network equation, solving based on an amplitude-frequency expression to obtain a resonance peak value, and performing power loss comprehensive evaluation; and according to a resonance suppression rule and a comprehensive evaluation result, constructing an optimization function considering resonance peak suppression and power frequency loss, and solving to obtain optimized passive damping branch parameters. According to the method, the influence mechanism of the additional damping on the grid-connected voltage can be clarified, the internal relation of the additional damping branch on the grid-connected current peak suppression and the grid-connected voltage peak suppression is disclosed, the resonance peak suppression effect under the large short-circuit ratio range can be comprehensively considered, and the application range of passive damping parameter design is widened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of passive damping, and in particular to a passive damping optimization method, system, device and medium for power electronic equipment. BACKGROUND

[0002] With the acceleration of the construction process of new power systems, new energy such as wind power and photovoltaic power has shown explosive growth, and new energy is gradually changing from a main installation body to a main power body. As the core hub of energy conversion and transmission between new energy and power grids, new energy conversion equipment has become increasingly important in supporting flexible operation of new power systems and energy structure transformation. New energy conversion equipment realizes efficient conversion and control of electric energy through high-frequency on-off of power electronic switching devices. However, the high-frequency on-off of power electronic devices increases the high-order harmonic content in the output voltage and current. Therefore, a low-pass filter is usually used in engineering to filter out high-order harmonics. However, the capacitor elements and inductor elements in the low-pass filter resonate at the natural resonance frequency, causing the harmonics in this frequency band and its field to be amplified, resulting in system oscillation and causing power quality to decline. Therefore, it is necessary to suppress the resonance peak by increasing the system damping. Compared with active damping, passive damping does not need to modify the structure and parameters of the original controller, avoiding interference with the control link.

[0003] However, the existing passive damping design method has the following disadvantages:

[0004] 1. The influence of adding passive damping on grid-connected voltage is ignored, and the internal relationship between the additional damping branch and the suppression of grid-connected current peak and grid-connected voltage peak is not disclosed.

[0005] 2. The influence of the grid strength, i.e. the equivalent line inductance Lg, on the filter resonance peak is not considered, and the damping branch parameter design is mainly focused on specific operating conditions, without considering the resonance peak suppression effect under wide short-circuit ratio conditions.

[0006] 3. The current parameter design mainly uses the trial-and-error method and qualitative analysis, and there is no optimal design method for damping branch parameters considering grid-connected voltage harmonics, grid-connected current harmonics, and additional damping resistance loss. SUMMARY

[0007] The embodiments of the present application provide a passive damping optimization method, system, device and medium for power electronic equipment to solve the above technical problems in the prior art.

[0008] According to a first aspect of the embodiments of the present application, a passive damping optimization method for power electronic equipment is provided.

[0009] In one embodiment, the passive damping optimization method for power electronic equipment comprises:

[0010] obtaining passive damping circuit parameters, calculating grid-connected impedance parameters according to the passive damping circuit parameters, and generating a modulation network equation, implementing influence analysis of grid-connected resonance peaks based on the modulation network equation, and obtaining resonance suppression rules;

[0011] performing denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression, and solving the resonance peak value based on the amplitude-frequency expression, implementing comprehensive power loss evaluation on the resonance peak value, and obtaining comprehensive evaluation results of the power loss;

[0012] constructing an optimization function considering resonance peak suppression and power frequency loss based on the resonance suppression rules and the comprehensive evaluation results, and solving the optimization function based on nonlinear programming to obtain optimized passive damping branch parameters.

[0013] In one embodiment, obtaining passive damping circuit parameters, calculating grid-connected impedance parameters according to the passive damping circuit parameters, and generating a modulation network equation, implementing influence analysis of grid-connected resonance peaks based on the modulation network equation, and obtaining resonance suppression rules include:

[0014] Obtaining passive damping circuit parameters of the power electronic device, and inputting the passive damping circuit parameters into an impedance model to calculate grid-connected impedance parameters;

[0015] Based on Kirchhoff's voltage law and Kirchhoff's current law, and combining with the grid-connected impedance parameters, a network equation is constructed, and when the inverter output is connected to an infinite grid, the influence of grid voltage on the network equation is removed to obtain a modulation network equation;

[0016] Based on the modulation network equation, the influence of different damping branch parameters and different short-circuit ratios on the resonance peaks of the modulation-type grid-connected voltage and the modulation-type grid-connected current is analyzed to obtain resonance suppression rules.

[0017] In one embodiment, the expression of the modulation network equation is:

[0018]

[0019] In the formula, Z1 represents a first impedance; Z2 represents a second impedance; Z g represents a third impedance; u inv represents the voltage from the midpoint of the three-phase inverter bridge arm to the neutral point; u C.1 represents the modulation-type grid-connected voltage; i g.1 represents the modulation-type grid-connected current.

[0020] In one embodiment, the resonance suppression rules include: the resonance peak value change rule of the modulation-type grid-connected voltage and the modulation-type grid-connected current with the increase of the damping branch parameters; the resonance peak value change rule and the corresponding frequency shift rule of the modulation-type grid-connected voltage and the modulation-type grid-connected current with the increase of the equivalent line inductance.

[0021] In one embodiment, the denominator of the modulation network equation is rationalized to obtain an amplitude-frequency expression, and the resonance peak value is solved based on the amplitude-frequency expression, and the power loss comprehensive evaluation is performed on the resonance peak value to obtain the comprehensive evaluation result of the power loss, including:

[0022] The denominator of the modulation network equation is rationalized to obtain the amplitude-frequency expression of the modulation type grid-connected voltage, and the first-order derivative of the amplitude-frequency expression is obtained to obtain the amplitude-frequency derivative function;

[0023] The amplitude-frequency derivative function is set to zero, and the resonance frequency of the passive damping branch filter network is solved, and the resonance frequency is substituted into the amplitude-frequency expression to calculate the resonance peak value of the modulation type grid-connected voltage;

[0024] The influence of different damping branch parameters on the resonance peak value is evaluated, and the power loss on the damping resistance is evaluated according to the voltage-current relationship of the passive damping branch to obtain the comprehensive evaluation result of the power loss.

[0025] In one embodiment, the amplitude-frequency expression is:

[0026]

[0027] a1=L g +L1-(C f +C C )L1L g ω 2 ;

[0028] a2=(L g +L1-C f L1L g ω 2 )R C C C ω;

[0029] In the formula, L1 represents the filter inductance; C f represents the filter capacitance; R C represents the first damping branch parameter; C C represents the second damping branch parameter; ω represents the output frequency; R g represents the line resistance; L g represents the line inductance; a1 represents the first impedance after simplification in impedance calculation; a2 represents the second impedance after simplification in impedance calculation.

[0030] In one embodiment, the comprehensive evaluation result of the power loss includes: the resonance peak value of the modulation type grid-connected voltage and the value result of the power loss under different damping branch parameter values.

[0031] According to a second aspect of the embodiments of the present application, there is provided a power electronic device passive damping optimization system.

[0032] In one embodiment, the power electronic device passive damping optimization system comprises:

[0033] a resonance peak influence analysis module configured to obtain passive damping circuit parameters, calculate grid-connected impedance parameters based on the passive damping circuit parameters, and generate a modulation network equation, and perform an influence analysis of grid-connected resonance peaks based on the modulation network equation to obtain a resonance suppression rule;

[0034] a power loss comprehensive evaluation module configured to perform a denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression, and solve the amplitude-frequency expression to obtain a resonance peak value, perform a power loss comprehensive evaluation on the resonance peak value, and obtain a comprehensive evaluation result of the power loss;

[0035] an optimization function solving module configured to construct an optimization function considering resonance peak suppression and power frequency loss based on the resonance suppression rule and the comprehensive evaluation result, and solve the optimization function based on nonlinear programming to obtain optimized passive damping branch parameters.

[0036] In one embodiment, the resonance peak influence analysis module comprises:

[0037] a grid-connected impedance parameter calculation module configured to obtain passive damping circuit parameters of the power electronic device, and input the passive damping circuit parameters into an impedance model to calculate grid-connected impedance parameters;

[0038] a modulation network equation generation module configured to construct a network equation based on Kirchhoff's voltage law and Kirchhoff's current law and fuse the grid-connected impedance parameters, and perform an influence elimination of grid voltage on the network equation to obtain a modulation network equation when the inverter output is connected to an infinite grid;

[0039] a resonance suppression rule obtaining module configured to analyze the influence rule of different damping branch parameters and different short-circuit ratios on modulation-type grid-connected voltage and modulation-type grid-connected current resonance peaks based on the modulation network equation to obtain a resonance suppression rule.

[0040] In one embodiment, the expression of the modulation network equation is:

[0041]

[0042] In the formula, Z1 represents a first impedance; Z2 represents a second impedance; Z g represents a third impedance; u inv represents a voltage from a three-phase inverter bridge arm midpoint to a neutral point; u C.1 represents a modulation-type grid-connected voltage; i g.1 represents a modulation-type grid-connected current.

[0043] In one embodiment, the resonance suppression law comprises: a resonance peak value change law of the modulated grid-connected voltage and the modulated grid-connected current with an increase of the damping branch parameter; a resonance peak value change law and a corresponding frequency shift law of the modulated grid-connected voltage and the modulated grid-connected current with an increase of the equivalent line inductance.

[0044] In one embodiment, the power loss comprehensive evaluation module comprises:

[0045] The amplitude-frequency derivative function determination module is configured to perform denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression of the modulated grid-connected voltage, and perform first-order derivation on the amplitude-frequency expression to obtain an amplitude-frequency derivative function.

[0046] The resonance peak value acquisition module is configured to set the amplitude-frequency derivative function to zero, and solve to obtain a resonance frequency of the passive damping branch filter network, and substitute the resonance frequency into the amplitude-frequency expression to calculate a resonance peak value of the modulated grid-connected voltage.

[0047] The influence evaluation module is configured to perform influence evaluation on the resonance peak value under different damping branch parameters, and evaluate power loss on the damping resistor according to a voltage-current relationship of the passive damping branch to obtain a comprehensive evaluation result of the power loss.

[0048] In one embodiment, the amplitude-frequency expression is:

[0049]

[0050] a1=L g +L1-(C f +C C )L1L g ω 2 ;

[0051] a2=(L g +L1-C f L1L g ω 2 )R C C C ω;

[0052] In the formula, L1 represents a filter inductance; C f represents a filter capacitance; R C represents a first damping branch parameter; C C represents a second damping branch parameter; ω represents an output frequency; R g represents a line resistance; L g represents a line inductance; a1 represents a first impedance after simplification in impedance calculation; and a2 represents a second impedance after simplification in impedance calculation.

[0053] In one embodiment, the comprehensive evaluation result of the power loss comprises: the resonance peak value of the modulated grid-connected voltage and the value result of the power loss under different damping branch parameter values.

[0054] According to a third aspect of the embodiments of the present application, a computer device is provided.

[0055] In some embodiments, the computer device comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0056] According to a fourth aspect of the embodiments of the present application, a computer readable storage medium is provided.

[0057] In one embodiment, the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the above method.

[0058] The technical solutions provided by the embodiments of the present application can include the following beneficial effects:

[0059] The present application clarifies the influence mechanism of the additional damping on the grid-connected voltage through the comprehensive evaluation result of the resonance suppression law and the power loss, reveals the internal relationship between the additional damping branch and the grid-connected current peak suppression and the grid-connected voltage peak suppression, considers the influence of the grid strength on the filter resonance peak, comprehensively considers the resonance peak suppression effect in a large short-circuit ratio range, and increases the application range of the passive damping parameter design; meanwhile, by proposing an optimization function of the damping branch parameter considering the grid-connected voltage harmonic, the grid-connected current harmonic and the additional damping resistance loss, the design of the related passive damping parameter is facilitated.

[0060] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0061] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0062] Figure 1 is a flowchart of a passive damping optimization method of a power electronic device according to an exemplary embodiment;

[0063] Figure 2 is a structural schematic diagram of a passive damping optimization system of a power electronic device according to an exemplary embodiment;

[0064] Figure 3 is a structural schematic diagram of a computer device according to an exemplary embodiment;

[0065] Figure 4 is a schematic diagram of an overall circuit structure of a power electronic device passive damping optimization method according to an exemplary embodiment;

[0066] Figure 5 is a simplified circuit structure schematic diagram of a power electronic device passive damping optimization method according to an exemplary embodiment;

[0067] Figure 6 is one of frequency and amplitude schematic diagrams of a power electronic device passive damping optimization method according to an exemplary embodiment;

[0068] Figure 7 is another of frequency and amplitude schematic diagrams of a power electronic device passive damping optimization method according to an exemplary embodiment;

[0069] Figure 8 is a u distribution schematic diagram of a power electronic device passive damping optimization method according to an exemplary embodiment under different α, R C C.1peak

[0070] Figure 9 is a R C power frequency loss distribution schematic diagram of a power electronic device passive damping optimization method according to an exemplary embodiment under different α, R C

[0071] Figure 10 is a nonlinear optimization framework schematic diagram of a power electronic device passive damping optimization method according to an exemplary embodiment.

[0072] Reference signs:

[0073] 201, resonance peak influence analysis module; 202, power loss comprehensive evaluation module; 203, optimization function solving module. DETAILED DESCRIPTION

[0074] The following description and drawings are illustrative of specific embodiments thereof and are not intended to be limiting thereof. Parts and features of some embodiments can be included or replaced by parts and features of other embodiments. The scope of the embodiments described herein includes the whole scope of the claims and all available equivalents of the claims. Various embodiments are described in a progressive manner, each focusing on the differences from other embodiments, and the same or similar parts between various embodiments can be understood by referring to each other.

[0075] ​​​The various modules in the device or system of the present application can be implemented wholly or partially by software, hardware and combinations thereof. The above modules can be embedded in or independent of the processor in the computer device in hardware form, or stored in the memory in the computer device in software form, so as to call and execute the operations corresponding to the above modules by the processor.

[0076] In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0077] Figure 1 An embodiment of a power electronic device passive damping optimization method of the present application is shown.

[0078] In this optional embodiment, the power electronic device passive damping optimization method comprises:

[0079] Step S101, obtaining passive damping circuit parameters, calculating grid-connected impedance parameters according to the passive damping circuit parameters, and generating a modulation network equation, based on the modulation network equation, implementing the influence analysis of grid-connected resonance peaks, and obtaining resonance suppression rules;

[0080] Step S102, performing denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression, and based on the amplitude-frequency expression, solving to obtain resonance peak values, implementing power loss comprehensive evaluation on the resonance peak values, and obtaining comprehensive evaluation results of power loss;

[0081] Step S103, constructing an optimization function considering resonance peak suppression and power frequency loss according to the resonance suppression rules and the comprehensive evaluation results, and based on nonlinear programming, solving the optimization function to obtain optimized passive damping branch parameters.

[0082] In this optional embodiment, obtaining passive damping circuit parameters, calculating grid-connected impedance parameters according to the passive damping circuit parameters, and generating a modulation network equation, based on the modulation network equation, implementing the influence analysis of grid-connected resonance peaks, and obtaining resonance suppression rules comprises:

[0083] Obtaining passive damping circuit parameters of the power electronic device, and inputting the passive damping circuit parameters into an impedance model to calculate grid-connected impedance parameters;

[0084] Based on Kirchhoff's voltage law and Kirchhoff's current law, and combining the grid-connected impedance parameters, constructing a network equation, when the inverter output is connected to an infinite grid, implementing the influence elimination of grid voltage on the network equation to obtain a modulation network equation;

[0085] Based on the modulation network equation, analyzing the influence rules of different damping branch parameters and different short-circuit ratios on the resonance peaks of the modulation type grid-connected voltage and the modulation type grid-connected current, and obtaining resonance suppression rules.

[0086] In the optional embodiment, the expression of the modulation network equation is:

[0087]

[0088] In the expression, Z1 represents the first impedance; Z2 represents the second impedance; Z g represents the third impedance; u inv represents the voltage from the midpoint of the three-phase inverter bridge arm to the neutral point; u C.1 represents the modulation type grid-connected voltage; i g.1 represents the modulation type grid-connected current.

[0089] In the optional embodiment, the resonance suppression rule includes: the resonance peak value change rule of the modulation type grid-connected voltage and the modulation type grid-connected current with the increase of the damping branch parameter; the resonance peak value change rule and the corresponding frequency shift rule of the modulation type grid-connected voltage and the modulation type grid-connected current with the increase of the equivalent line inductance.

[0090] In the optional embodiment, the denominator rationalization is performed on the modulation network equation to obtain an amplitude-frequency expression, and the resonance peak value is obtained based on the amplitude-frequency expression. The comprehensive evaluation result of the power loss is obtained by performing the power loss comprehensive evaluation on the resonance peak value, including:

[0091] The denominator rationalization is performed on the modulation network equation to obtain an amplitude-frequency expression of the modulation type grid-connected voltage. The first-order derivative of the amplitude-frequency expression is obtained to obtain an amplitude-frequency derivative function;

[0092] The amplitude-frequency derivative function is set to zero, and the resonance frequency of the passive damping branch filter network is obtained by solving. The resonance frequency is substituted into the amplitude-frequency expression to calculate the resonance peak value of the modulation type grid-connected voltage;

[0093] The influence evaluation of the resonance peak value on different damping branch parameters is performed, and the power loss on the damping resistor is evaluated according to the voltage-current relationship of the passive damping branch to obtain the comprehensive evaluation result of the power loss.

[0094] In the optional embodiment, the amplitude-frequency expression is:

[0095]

[0096] a1=L g +L1-(C f +C C )L1L g ω 2 ;

[0097] a2=(L g +L1-C f L1L g ω 2 )R C CC ω;

[0098] wherein, L1 represents a filter inductance; C f represents a filter capacitance; R C represents a first damping branch parameter; C C represents a second damping branch parameter; ω represents an output frequency; R g represents a line resistance; L g represents a line inductance; a1 represents a first impedance simplified in impedance calculation; and a2 represents a second impedance simplified in impedance calculation.

[0099] In the optional embodiment, the comprehensive evaluation result of the power loss includes: the resonance peak value of the modulated grid-connected voltage and the value result of the power loss under different damping branch parameter values.

[0100] Figure 2 An embodiment of a power electronic device passive damping optimization system of the application is shown.

[0101] In the optional embodiment, the power electronic device passive damping optimization system comprises:

[0102] The resonance peak influence analysis module 201 is configured to obtain passive damping circuit parameters, calculate grid-connected impedance parameters according to the passive damping circuit parameters, generate a modulated network equation, perform influence analysis of grid-connected resonance peaks based on the modulated network equation, and obtain a resonance suppression rule.

[0103] The power loss comprehensive evaluation module 202 is configured to perform denominator rationalization on the modulated network equation, obtain an amplitude-frequency expression, solve the resonance peak value based on the amplitude-frequency expression, perform comprehensive evaluation of the power loss on the resonance peak value, and obtain a comprehensive evaluation result of the power loss.

[0104] The optimization function solving module 203 is configured to construct an optimization function considering resonance peak suppression and power loss according to the resonance suppression rule and the comprehensive evaluation result, and solve the optimization function based on nonlinear programming to obtain optimized passive damping branch parameters.

[0105] In the optional embodiment, the resonance peak influence analysis module comprises:

[0106] The grid-connected impedance parameter calculation module is configured to obtain passive damping circuit parameters of the power electronic device, input the passive damping circuit parameters into an impedance model, and calculate grid-connected impedance parameters.

[0107] The modulated network equation generation module is configured to construct a network equation based on Kirchhoff's voltage law and Kirchhoff's current law and fuse the grid-connected impedance parameters, perform influence elimination of grid voltage on the network equation when the inverter output is connected to an infinite grid, and obtain a modulated network equation.

[0108] The resonance suppression rule acquisition module is configured to analyze the influence rule of different damping branch parameters and different short-circuit ratios on the resonance peak of the modulation type grid-connected voltage and the modulation type grid-connected current based on the modulation network equation, and obtain the resonance suppression rule.

[0109] In the optional embodiment, the expression of the modulation network equation is as follows:

[0110]

[0111] In the formula, Z1 represents the first impedance; Z2 represents the second impedance; Z g represents the third impedance; u inv represents the voltage from the midpoint of the three-phase inverter bridge arm to the neutral point; u C.1 represents the modulation type grid-connected voltage; i g.1 represents the modulation type grid-connected current.

[0112] In the optional embodiment, the resonance suppression rule includes: the change rule of the resonance peak of the modulation type grid-connected voltage and the modulation type grid-connected current with the increase of the damping branch parameter; and the change rule of the resonance peak of the modulation type grid-connected voltage and the modulation type grid-connected current and the corresponding frequency moving rule with the increase of the equivalent line inductance.

[0113] In the optional embodiment, the power loss comprehensive evaluation module includes:

[0114] The amplitude-frequency derivative function determination module is configured to perform denominator rationalization on the modulation network equation to obtain the amplitude-frequency expression of the modulation type grid-connected voltage, and perform first-order derivation on the amplitude-frequency expression to obtain the amplitude-frequency derivative function;

[0115] The resonance peak acquisition module is configured to set the amplitude-frequency derivative function to zero, and solve to obtain the resonance frequency of the passive damping branch filter network, substitute the resonance frequency into the amplitude-frequency expression, and calculate to obtain the resonance peak of the modulation type grid-connected voltage;

[0116] The influence evaluation module is configured to evaluate the influence of different damping branch parameters on the resonance peak, and evaluate the power loss on the damping resistor according to the voltage-current relationship of the passive damping branch, to obtain the comprehensive evaluation result of the power loss.

[0117] In the optional embodiment, the amplitude-frequency expression is as follows:

[0118]

[0119] a1=L g +L1-(C f +C C )L1L g ω 2 ;

[0120] a2=(L g +L1-C f L1L g ω 2 )R C C C ω;

[0121] In the formula, L1 represents the filter inductance; C f Represents the filter capacitor; R C Indicates the parameters of the first damping branch; C C Represents the parameters of the second damping branch; ω represents the output frequency; R g Indicates line resistance; L g a1 represents the line inductance; a2 represents the simplified first impedance after impedance calculation; a3 represents the simplified second impedance after impedance calculation.

[0122] In this optional embodiment, the comprehensive evaluation results of power loss include: the resonant peak value of the modulated grid-connected voltage and the power loss values ​​under different damping branch parameter values.

[0123] To facilitate understanding of the above technical solutions of the present invention, the following further explains the above technical solutions of the present invention from the perspective of architecture and principle, as follows:

[0124] The first step is to establish a unified analysis model (i.e., modulation network equation) for the filtering stage of the converter equipment, and analyze the influence of different damping branch parameters and different short-circuit ratios (i.e., line inductance Lg) on ​​the grid-connected voltage and grid-connected current resonant peaks.

[0125] The second step is to analyze the resonant frequency and peak value of the grid-connected voltage under different parameter configurations and system strengths, and to evaluate the power loss on the additional damping resistor.

[0126] The third step is to establish an optimization function that takes into account both resonance peak suppression and power frequency loss, and to optimize the design of passive damping branch parameters based on nonlinear programming.

[0127] It should be added that, following the steps above, firstly, as Figure 4 As shown, u inv The voltage u is the voltage from the midpoint of the three-phase inverter bridge arm to the neutral point. g For example, the grid voltage. Figure 5 As shown, impedances Z1, Z2, Z g (That is, the grid-connected impedance parameters calculated by the impedance model) are as follows:

[0128] Z1 = jωL1;

[0129]

[0130] Zg = R g + jωL g ;

[0131] wherein Z1 represents the first impedance; Z2 represents the second impedance; Z g represents the third impedance; j represents the imaginary unit in the impedance calculation; ω represents the output frequency; L1 represents the filter inductance; represents the filter capacitance branch impedance; Z RC represents the additional resistance branch impedance; C f represents the filter capacitance; R C represents the first damping branch parameter; C C represents the first damping branch parameter; R g represents the line resistance; L g represents the line inductance.

[0132] wherein, as shown in Figure 4 , i a represents the first current on the inductance; i b represents the second current on the inductance; i c represents the third current on the inductance; u a represents the first voltage on the capacitance; u b represents the second voltage on the capacitance; u c represents the third voltage on the capacitance; i ga represents the first grid-side current; i gb represents the second grid-side current; i gc represents the third grid-side current; V DC represents the DC-side voltage. As shown in Figure 5 , wherein u inv represents the voltage from the three-phase inverter bridge arm midpoint to the neutral point, that is, it represents the inverter output voltage; Z1 represents the first impedance, that is, it represents the impedance of the filter inductance part; Z2 represents the second impedance, that is, it represents the impedance of the filter capacitance part, and Z g represents the third impedance, that is, it represents the impedance of the line part. Figure 4 and Figure 5 The working principle is that: V DC The output power provides power for the entire converter, and the output power is filtered by the filter composed of L1 and C C , and then transmitted to the grid side.

[0133] According to Kirchhoff's voltage law and Kirchhoff's current law, the grid-connected voltage u C and the grid-connected current i g (i.e. network equation) are respectively:

[0134]

[0135] In the formula, u C Indicates grid-connected voltage; u g Indicates grid voltage; i g Indicates grid-connected current; u inv This represents the voltage from the midpoint of the bridge arm to the neutral point of the three-phase inverter.

[0136] From the grid voltage u C and grid-connected current i g The calculation formula shows that the grid-connected voltage u C and grid-connected current i g Due to the coupling effect of filter impedance and line impedance, it is not only affected by modulation (i.e., u inv It is also affected by the grid voltage u g The impact of this. If we assume the inverter output is connected to an infinite grid, then the grid voltage u... g For u C and i g The influence of [the modulator] can be eliminated, so only the modulation effect needs to be considered, denoted as u. C.1 i g.1 Then the modulation network equations are:

[0137]

[0138] In the formula, u C.1 This refers to the modulated grid-connected voltage, i.e., the grid-connected voltage where only the modulation effect needs to be considered; i g.1 This indicates modulated grid-connected current, which is the grid-connected current for which only the modulation effect needs to be considered.

[0139] C C =α·C f (α<1), where α represents the ratio of the additional capacitor to the filter capacitor. Record α as constant, R C The effect of grid-connected voltage resonance suppression under varying conditions. Record R. C Record the resonance suppression effect of the grid-connected voltage under the condition of constant α and varying α. Keep the damping branch parameters (R) constant. C C C Keeping the short-circuit ratio (line inductance Lg) constant, the resonance suppression effect of the grid-connected voltage under different Lg values ​​is recorded.

[0140] Based on the above recorded results, analyze the parameters (R) of different damping branches. C C C The influence of different short-circuit ratios (line inductance Lg) on ​​the resonant peaks of grid-connected voltage and current is investigated, i.e., the resonance suppression law. The results show that as the damping branch parameter R... C The increase of u C.1 The resonant peak value will increase, i g.1The resonant peak value will decrease; as the damping branch parameter C... C The increase of u C.1 The resonant peak value will decrease, i g.1 The resonant peak value will also decrease; for example Figure 6 and Figure 7 As shown, with the increase of the equivalent line inductance Lg (i.e., the SCR decreases and the grid strength decreases), u C.1 i g.1 The frequency corresponding to the resonant peak shifts downward. Simultaneously, u C.1 The resonant peak value increases with the increase of Lg, i g.1 The resonant peak value decreases as Lg increases.

[0141] Secondly, substituting the calculation formula of the impedance model into the calculation formula of the modulated grid-connected voltage, and rationalizing the denominator, we can obtain u. C.1 The amplitude-frequency expression is:

[0142]

[0143] a1=L g +L1-(C f +C C L1L g ω 2 ;

[0144] a2=(L g +L1-C f L1L g ω 2 )R C C C ω;

[0145] In the formula, a1 represents the first impedance after simplification in impedance calculation; a2 represents the second impedance after simplification in impedance calculation.

[0146] Let ω be the independent variable, and let u C.1 The first derivative of the amplitude-frequency expression with respect to ω is 0, that is:

[0147]

[0148] Solving for:

[0149]

[0150] in,

[0151]

[0152]

[0153] In the formula, ω peak Indicates the presence of RC -C C The resonant frequency of the filter network of the passive damping branch; q represents the third impedance formula after simplifying calculation; p represents the fourth impedance formula after simplifying calculation; b0 represents the fifth impedance formula after simplifying calculation; b1 represents the sixth impedance formula after simplifying calculation; b2 represents the seventh impedance formula after simplifying calculation; b3 represents the eighth impedance formula after simplifying calculation.

[0154] In the above conclusion, ω peak That is, the R C -C C The resonant frequency of the filter network of the passive damping branch is substituted into the amplitude-frequency expression, and the grid-connected voltage u C.1 The resonant peak value u C.1peak .

[0155] Combined with the calculation results, the influence law of different damping branch parameters (R C , C C ) on the resonant peak value u C.1peak , that is, the comprehensive evaluation result of power loss, is analyzed. As shown in FIGS. Figure 8 and Figure 9 , the results show that when R C tends to 0 and α tends to 0, the value of u C.1peak is large, and the minimum value of u C.1peak is obtained when α tends to 1. It can also be concluded that within the feasible region of limited R C , α, u C.1peak cannot be weakened to below 0 dB;

[0156] For a given R C -C C passive damping branch, the loss depends on the voltage u C applied to it, and the higher u C , the greater the loss p C on the three-phase R RC . According to the voltage-current relationship of the R C -C C branch, we have:

[0157]

[0158] In the formula, p RC represents the loss on the three-phase RC; u C.rms represents the effective value of u C .

[0159] Combined with the calculation results, p RC and α, R C are not positively correlated, and different α, R C values will result in significant pRC The difference. Overall, R C Take smaller values, p RC Smaller.

[0160] As Figure 10 shown, then based on nonlinear programming, establish passive damping branch to consider the resonance peak suppression, power loss optimization function.

[0161] The optimization function can be described as:

[0162] min u C.1peak

[0163] s.t.p RC <p limited ;

[0164] In the formula, u C.1peak indicates the resonance peak value of the grid-connected voltage u C.1 ; p limited indicates the maximum allowable power loss, which can be determined by the following formula:

[0165]

[0166] In the formula, P rated is the rated power of the converter, η limited is the lower limit of the efficiency of the converter only considering R C loss.

[0167] Where, as Figure 10 shown, including the objective function and constraint conditions, fmincom rolling optimization, compared to the optimal target output. Among them, the objective function and constraint conditions:

[0168]

[0169] In the formula, f cost.(·) (·) indicates the optimization objective function; d1 indicates the first parameter; d2 indicates the second parameter; d3 indicates the third parameter; indicates the phase angle parameter; i L.RMS indicates the effective value of inductance current; indicates the initial power; P target indicates the target power; indicates the first constraint; indicates the second constraint; indicates the third constraint; indicates the fourth constraint; indicates the fifth constraint; indicates the auxiliary constraint.

[0170] From the above analysis, it can be seen that the optimization design process of the passive branch itself is a simple single-objective, single-inequality-constrained optimization problem, but due to the complexity and nonlinearity of the fitness function and the constraint condition, an analytical solution of the optimization function cannot be obtained, and therefore a numerical optimization tool needs to be used to obtain the solution. For example, the present application uses a mature nonlinear programming tool of Matlab to solve the problem, and in order to avoid falling into a local optimum, the optimal value is taken after multiple executions.

[0171] In one embodiment, a computer device, which can be a server, has an internal structure diagram as shown in Figure 3 The computer device includes a processor, a memory and a network interface connected through a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The database of the computer device is configured to store static information and dynamic information data. The network interface of the computer device is configured to communicate with an external terminal through a network connection. The computer program is executed by the processor to implement the steps in the above method embodiments.

[0172] Those skilled in the art can understand that Figure 3 The structure shown in the above

[0173] In addition, the present application also provides a computer device including a memory and a processor, the memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0174] In addition, the present application also provides a computer readable storage medium, which stores a computer program, and the computer program implements the steps in the above method embodiments when executed by a processor.

[0175] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium used in each embodiment of the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0176] The present application is not limited to the structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is only limited by the appended claims.

Claims

1. A method for power electronic device passive damping optimization, characterized in that, The method comprises the following steps: acquiring passive damping circuit parameters, calculating grid-connected impedance parameters according to the passive damping circuit parameters, generating a modulation network equation, and analyzing the influence of grid resonance peaks based on the modulation network equation to obtain a resonance suppression rule; performing denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression, and solving the resonance peak value based on the amplitude-frequency expression to obtain a comprehensive evaluation result of power loss; constructing an optimization function considering resonance peak suppression and power loss based on the resonance suppression rule and the comprehensive evaluation result, and solving the optimization function based on nonlinear programming to obtain optimized passive damping branch parameters.

2. The power electronic device passive damping optimization method of claim 1, wherein, The method comprises the following steps: acquiring passive damping circuit parameters of the power electronic equipment, inputting the passive damping circuit parameters into an impedance model, and calculating grid-connected impedance parameters; constructing a network equation based on Kirchhoff's voltage law and Kirchhoff's current law and combining the grid-connected impedance parameters, and removing the influence of grid voltage on the network equation when the inverter output is connected to an infinite grid to obtain a modulation network equation; analyzing the influence of different damping branch parameters and different short-circuit ratios on the resonance peaks of the modulation-type grid voltage and the modulation-type grid current based on the modulation network equation to obtain a resonance suppression rule.

3. The power electronic device passive damping optimization method of claim 2, wherein, The expression of the modulation network equation is as follows: In the formula, Z1 represents a first impedance; Z2 represents a second impedance; Z g represents a third impedance; u inv represents a voltage from a three-phase inverter bridge arm midpoint to a neutral point; u C.1 represents a modulated grid-connected voltage; i g.1 represents a modulated grid-connected current.

4. The power electronic device passive damping optimization method of claim 2, wherein, The resonance suppression rule comprises the following aspects: with the increase of the damping branch parameter, the resonance peak value change rule of the modulation-type grid voltage and the modulation-type grid current; and with the increase of the equivalent line inductance, the resonance peak value change rule and the corresponding frequency shift rule of the modulation-type grid voltage and the modulation-type grid current.

5. The power electronic device passive damping optimization method of claim 1, wherein, The method comprises the following steps: performing denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression, and solving the resonance peak value based on the amplitude-frequency expression to obtain a comprehensive evaluation result of power loss; performing denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression, and solving the resonance peak value based on the amplitude-frequency expression to obtain a comprehensive evaluation result of power loss. The amplitude-frequency expression is as follows:

6. The power electronic device passive damping optimization method of claim 5, wherein, The comprehensive evaluation result of power loss comprises the following aspects: under different damping branch parameter values, the resonance peak value of the modulation-type grid voltage and the power loss value. a1 = L g + L1-(C f + C C ) L1L g ω 2 ; a2= (L g +L1-C f L1L g ω 2 )R C C C ω; wherein L1 represents a filter inductance; C f represents a filter capacitance; R C represents a first damping branch parameter; C C represents a second damping branch parameter; ω represents an output frequency; R g represents a line resistance; L g represents a line inductance; a1 represents a first simplified impedance for impedance calculation; and a2 represents a second simplified impedance for impedance calculation.

7. The power electronic device passive damping optimization method of claim 5, wherein, The method comprises the following steps:

8. A power electronic device passive damping optimization system, characterized by, a resonance peak influence analysis module for acquiring passive damping circuit parameters, calculating grid-connected impedance parameters according to the passive damping circuit parameters, generating a modulation network equation, and analyzing the influence of grid resonance peaks based on the modulation network equation to obtain a resonance suppression rule; ​ The power loss comprehensive evaluation module is configured to perform denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression, and solve the amplitude-frequency expression to obtain a resonance peak value, and perform power loss comprehensive evaluation on the resonance peak value to obtain a comprehensive evaluation result of the power loss. The optimization function solving module is configured to construct an optimization function considering resonance peak suppression and power loss according to the resonance suppression rule and the comprehensive evaluation result, and solve the optimization function based on nonlinear programming to obtain optimized passive damping branch parameters.

9. The power electronic device passive damping optimization system of claim 8, wherein, The resonance peak influence analysis module includes: The grid-connected impedance parameter calculation module is configured to obtain passive damping circuit parameters of the power electronic device, and input the passive damping circuit parameters into an impedance model to calculate grid-connected impedance parameters. The modulation network equation generation module is configured to construct a network equation based on Kirchhoff's voltage law and Kirchhoff's current law and fuse the grid-connected impedance parameters, and perform influence elimination of grid voltage on the network equation to obtain a modulation network equation when the inverter output is connected to an infinite grid. The resonance suppression rule acquisition module is configured to analyze the influence rule of different damping branch parameters and different short-circuit ratios on the resonance peak of the modulation-type grid-connected voltage and the modulation-type grid-connected current based on the modulation network equation to obtain a resonance suppression rule.

10. The power electronic device passive damping optimization system of claim 9, wherein, The expression of the modulation network equation is: In the formula, Z1 represents a first impedance; Z2 represents a second impedance; Z g represents a third impedance; u inv represents a voltage from a three-phase inverter bridge arm midpoint to a neutral point; u C.1 represents a modulated grid-connected voltage; i g.1 represents a modulated grid-connected current.

11. The power electronic device passive damping optimization system of claim 9, wherein, The resonance suppression rule includes: a resonance peak change rule of the modulation-type grid-connected voltage and the modulation-type grid-connected current with the increase of the damping branch parameter; and a resonance peak change rule and a corresponding frequency shift rule of the modulation-type grid-connected voltage and the modulation-type grid-connected current with the increase of the equivalent line inductance.

12. The power electronic device passive damping optimization system of claim 8, wherein, The power loss comprehensive evaluation module includes: The amplitude-frequency derivative function determination module is configured to perform denominator rationalization on the modulation network equation to obtain an amplitude-frequency expression of the modulation-type grid-connected voltage, and perform first-order derivation on the amplitude-frequency expression to obtain an amplitude-frequency derivative function. The resonance peak value acquisition module is configured to set the amplitude-frequency derivative function to zero, and solve to obtain a resonance frequency of the passive damping branch filter network, and substitute the resonance frequency into the amplitude-frequency expression to calculate a resonance peak value of the modulation-type grid-connected voltage. The influence evaluation module is configured to perform influence evaluation of different damping branch parameters on the resonance peak value, and evaluate power loss on the damping resistor according to the voltage-current relationship of the passive damping branch to obtain a comprehensive evaluation result of the power loss.

13. The power electronic device passive damping optimization system of claim 12, wherein, The amplitude-frequency expression is: a1= L g + L1- (C f + C C ) L1L g ω 2 ; a2= (L g +L1-C f L1L g ω 2 )R C C C ω; wherein L1 represents a filter inductance; C f represents a filter capacitance; R C represents a first damping branch parameter; C C represents a second damping branch parameter; ω represents an output frequency; R g represents a line resistance; L g represents a line inductance; a1 represents a first simplified impedance for impedance calculation; and a2 represents a second simplified impedance for impedance calculation.

14. The power electronic device passive damping optimization system of claim 12, wherein, The comprehensive evaluation result of the power loss includes: a resonance peak value of the modulation-type grid-connected voltage and a power loss value result under different damping branch parameter values.

15. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that, The processor executes the computer program to implement the steps of the method of any one of claims 1 to 7.

16. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the method of any one of claims 1 to 7.

Images