Method for analyzing instantaneous voltage of direct current side of dual three-phase rectification generator

Abstract

The invention discloses an instantaneous voltage analysis method for a direct current side of a dual three-phase rectification generator, and provides an instantaneous voltage analysis method considering filter capacitor ESR when a load is suddenly changed by establishing an equivalent dual three-phase rectification generator with a pulse power load transient mathematical model. Through finite element simulation and physical experiment comparison under the condition of different rotating speeds and power loads, the accuracy of the dual three-phase rectification generator equivalent model considering the filter capacitor ESR is verified, and then the influence of the filter capacitor C and the parasitic parameter ESR of the filter capacitor C on a direct current side steady-state voltage ripple factor and instantaneous voltage is further analyzed; the method not only considers the influence of a filter capacitor C value on a DC side voltage steady-state ripple factor and a transient voltage, but also further considers the influence of a filter capacitor parasitic parameter ESR on the DC side voltage steady-state ripple factor and the transient voltage, and also considers a special dual three-phase phase shift angle for calculation and analysis. And the power supply quality of the direct-current power supply system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of direct current power supply systems, and in particular to a method for analyzing the instantaneous voltage on the direct current side of a dual three-phase rectifier generator. Background Art

[0002] With the rapid development of power electronics technology, multiphase rectifier generators are widely used in DC power supply systems such as aviation power supply systems, ship power systems, and wind power generation systems due to their advantages of high power generation efficiency, strong fault tolerance, and high transmission stability. The output voltage fluctuation of the DC side of the rectifier generator is an important indicator of the power quality of the power generation system, and a stable voltage is an important guarantee for the normal operation of the power load. However, when the rectifier generator carries a pulse power load, as the pulse load continues to change dynamically and periodically, the terminal voltage of the generator will change sharply, which will have a negative impact on the stability of the entire power generation system. Voltage ripple not only affects the quality of voltage output, but also the temperature rise caused by it will accelerate the evaporation of the electrolyte, thereby reducing the life of the capacitor and the reliability of the system. In order to reduce the dynamic impact of the sudden load on the generator and suppress the DC voltage ripple, the filter capacitor plays a key role at this time. The filter capacitor in the generator rectifier circuit can not only filter out the unnecessary AC components in the DC power, but also play the role of energy storage, maintain the stability of the output voltage, and improve the power supply quality.

[0003] At present, the existing analysis of the DC side voltage of the rectifier generator is based on ideal conditions. In fact, when the rectifier generator is running, it is affected by the parasitic parameters ESR of the filter capacitor, and there are errors between the voltage ripple and the transient voltage and the ideal value. In addition, the special multi-phase rectifier generator phase shift angle also has an impact on the transient voltage, resulting in inaccurate voltage analysis results of the rectifier generator, which in turn causes the load of the rectifier generator to fluctuate and affect the power system. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for analyzing the transient voltage on the DC side of a dual three-phase rectifier generator, aiming to solve the problem that the analysis of the DC side voltage of the rectifier generator in the prior art is affected by the parasitic parameters ESR of the filter capacitor, the voltage ripple and the transient voltage have errors with the ideal value, and the special multi-phase rectifier generator phase shift angle also affects the transient voltage, resulting in inaccurate voltage analysis results of the rectifier generator.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for analyzing instantaneous voltage on the DC side of a dual three-phase rectifier generator, comprising:

[0007] Step 1, based on a dual three-phase rectifier generator with pulse power load and special phase shift angle and parasitic parameter ESR of filter capacitor, establish an equivalent transient teaching model of rectifier generator;

[0008] Step 2: Based on the rectifier generator equivalent transient teaching model, obtain the waveform diagram of the DC side voltage influence of the rectifier generator, perform finite element analysis on the rectifier generator voltage according to the waveform diagram, and obtain the influence of the filter capacitor ESR on the steady-state and transient voltage characteristics of the rectifier generator.

[0009] Furthermore, in the equivalent transient teaching model of the rectifier generator, at the moment of pulse load jump, the instantaneous output voltage of the DC side of the dual three-phase rectifier generator shifted by 20° is:

[0010]

[0011] Where: u dc1 ′——instantaneous output voltage on DC side;

[0012] ——ultra-transient potential;

[0013] ω r ——rotor angular velocity;

[0014] ω b —— fundamental frequency angular velocity;

[0015] x t =x t11 (β 1 )+x t12 (β 1 ,β 2 )——commutation reactance;

[0016] x t11 (β 1 )′——transient commutation reactance;

[0017] β 1 , β 2 ——rectifier ignition angle;

[0018] p = d / dt - differential operator;

[0019] i dc1 、i dc2 ——output current of two-phase rectifier;

[0020] x t11 (β 1 )——commutation reactance of one-phase rectifier;

[0021] x t12 (β 1 ,β 2)——cross-commutation reactance of two-phase rectifier;

[0022] R e ——AC side equivalent resistance;

[0023] u s ′——instantaneous phase voltage on the AC side;

[0024] u l ′——Instantaneous line voltage on the AC side.

[0025] Furthermore, in step 1, firstly, the voltage drop in the AC line inductor is ignored by using an analytical method to obtain U from the AC phase voltage. DC Calculate the expression:

[0026]

[0027] Among them, U DC ——is the rectifier DC output voltage;

[0028] U m ——peak value of AC phase balanced sinusoidal voltage;

[0029] N——Number of rectifier phases (N>2);

[0030] Ignore the voltage difference between the DC voltages at any time, and output the DC voltage U DC The output voltage of each phase rectifier can be expressed as:

[0031]

[0032] Among them, u DC1 ,u DC2 ——DC output voltage of two sets of three-phase windings;

[0033] By connecting two phase uncontrolled rectifiers in parallel, we can get u DC =u DC1 =u DC2 , load output voltage U L =U DC The expression can be obtained by applying the case of N = 3

[0034]

[0035] Among them, U S ——RMS value of AC phase voltage;

[0036] U l ——RMS value of AC line voltage.

[0037] Furthermore, in step 1, in order to further analyze the change of the DC side voltage when the rectifier synchronous generator with pulse power load is running, when the pulse power load jumps, according to the rectification characteristics, the DC side resistor R dc Converted to AC, the AC side resistance is R ac , obtain the load resistance equivalent model:

[0038] R dc R is the DC side L After mutation, same as R ESR The change in the total parallel resistance, after conversion to the AC side, is R ac Assuming there is no loss in the generator rectifier system, according to the principle of energy conservation, the output power of the rectifier generator on the AC and DC sides is equal:

[0039]

[0040] Among them, P ac ——AC side output power;

[0041] P dc ——DC side output power;

[0042] AC side equivalent load R ac With the DC side load R dc The relationship between

[0043]

[0044] R ac ≈0.9685R dc

[0045] At this time, the equivalent resistance on the AC side of the dual three-phase synchronous generator rectification system is

[0046] R e =r+0.9685R dc

[0047] Among them, R e ——AC side equivalent resistance;

[0048] R dc =Δ(R L / / R ESR )

[0049] Among them, R L ——Pulse load equivalent resistance; R ESR ——Parasitic parameter resistance of filter capacitor.

[0050] Furthermore, in the rectifier generator equivalent transient teaching model, the damping winding effect is considered; the d-axis ultra-transient reactance and the q-axis ultra-transient reactance are respectively:

[0051]

[0052]

[0053] Among them, x aσ ——armature reaction leakage reactance;

[0054] x sσ ——stator leakage reactance;

[0055] x ad ——direct-axis armature reaction reactance;

[0056] x aq ——quadrature-axis armature reaction reactance;

[0057] x kdσ —— leakage reactance of direct-axis damping winding;

[0058] x kqσ —— leakage reactance of quadrature-axis damping winding;

[0059] x fdσ ——Leakage reactance of the excitation winding;

[0060] The d-axis ultra-transient flux and the q-axis ultra-transient flux are:

[0061]

[0062] Among them, kq is the flux linkage of the quadrature-axis damping winding; fd is the magnetic flux of the excitation winding; the d-axis super-transient potential and the q-axis super-transient potential are respectively:

[0063]

[0064] In the formula, ω r ——rotor angular velocity;

[0065] ω b ——Fundamental frequency angular velocity.

[0066] Furthermore, considering the average voltage drop caused by commutation overlap, the commutation reactance x is introduced t and transient commutation reactance x t ′; The voltage equation of the generator AC side in the equivalent model becomes:

[0067]

[0068] in, ——ultra-transient potential;

[0069] δ = arctan(E d ″ / Eq ″)——power angle;

[0070] p = d / dt - differential operator;

[0071] x t =x t11 (β 1 )+x t12 (β 1 ,β 2 )——commutation reactance;

[0072]

[0073] β 1 =δ+α 1 β 2 =δ+α 2

[0074] Among them, β 1 , β 2 ——rectifier ignition angle;

[0075] α 1 , α 2 ——Rectifier trigger delay angle;

[0076] x t11 (β 1 )——commutation reactance of one-phase rectifier;

[0077] x t12 (β 1 ,β 2 )——Cross-commutation reactance of the two-phase rectifier.

[0078] The technical solution adopted by the present invention has the following beneficial effects:

[0079] 1) Establish an equivalent transient mathematical model of a 20° shifted dual three-phase rectifier generator with pulse power load, and provide an instantaneous voltage analysis method considering the ESR of the filter capacitor when the load changes suddenly. Through finite element simulation and physical experiment comparison under different speeds and power loads, the accuracy of the equivalent model of the dual three-phase rectifier generator considering the ESR of the filter capacitor proposed in the present invention is verified;

[0080] 2) Further analysis of the influence of the filter capacitor C and its parasitic parameter ESR on the steady-state voltage ripple factor and transient voltage on the DC side proves that reasonable selection of the filter capacitor C and its parasitic parameter ESR can optimize the steady-state and transient performance of the generator and improve the power supply quality of the entire generator set. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is the structural principle diagram of the dual three-phase rectifier generator with pulse load system;

[0082] Figure 2 It is a simplified diagram of the system structure;

[0083] Figure 3 It is a schematic diagram of the DC side load resistance conversion;

[0084] Figure 4 This is a comparison chart between simulation results and physical experiments;

[0085] Figure 5 This is a graph showing the influence of the 10% Pn-85% Pn-10% Pn filter capacitor C and its parasitic parameter ESR on the DC side voltage at a speed of 14500. DETAILED DESCRIPTION

[0086] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0087] In order to fully improve the power quality of a DC power supply system and enhance the adaptability of a dual three-phase rectifier generator to pulse power loads, the present invention proposes a method for analyzing the instantaneous voltage on the DC side of a dual three-phase rectifier generator.

[0088] The schematic diagram of the dual three-phase rectifier generator with pulse load system is as follows: Figure 1 First, using the analytical method, ignoring the voltage drop in the AC line inductor, we can obtain U from the AC phase voltage. DC Evaluates an expression.

[0089]

[0090] Among them, U DC ——is the rectifier DC output voltage;

[0091] U m ——peak value of AC phase balanced sinusoidal voltage;

[0092] N——Number of rectifier phases (N>2).

[0093] Ignore the voltage difference between the DC voltages at any time, and output the DC voltage U DC The output voltage of each phase rectifier can be expressed as

[0094]

[0095] Among them, u DC1 ,u DC2 ——DC output voltage of two sets of three-phase windings.

[0096] By connecting two phase uncontrolled rectifiers in parallel, we can get u DC =u DC1 =u DC2 , load output voltage U L =U DC The expression can be obtained by applying the case of N = 3

[0097]

[0098] Among them, U S ——RMS value of AC phase voltage;

[0099] U l ——RMS value of AC line voltage.

[0100] The system is simplified as Figure 2 To further analyze the change of DC side voltage when the rectifier synchronous generator with pulse power load is running, when the pulse power load jumps, according to the rectification characteristics, the DC side resistor R dc Converted to AC, the AC side resistance is R ac , the load resistance equivalent model is as follows Figure 3 shown.

[0101] R dc R is the DC side L After mutation, same as R ESR The change in the total parallel resistance, after conversion to the AC side, is R ac Assuming there is no loss in the generator rectifier system, according to the principle of energy conservation, the output power of the rectifier generator on the AC and DC sides is equal

[0102]

[0103] Among them, P ac ——AC side output power;

[0104] P dc ——DC side output power.

[0105] AC side equivalent load R ac With the DC side load R dc The relationship between

[0106]

[0107] Substitute formula (3) into formula (5):

[0108] R ac ≈0.9685R dc (6)

[0109] At this time, the equivalent resistance on the AC side of the dual three-phase synchronous generator rectification system is

[0110] R e =r+0.9685R dc (7)

[0111] Among them, R e ——AC side equivalent resistance;

[0112] R dc =Δ(R L / / R ESR )(8)

[0113] Among them, R L ——Equivalent resistance of pulse load;

[0114] R ESR ——parasitic resistance of filter capacitor;

[0115] This paper considers the damping winding effect. The d-axis ultra-transient reactance and the q-axis ultra-transient reactance are respectively

[0116] Among them, x aσ ——armature reaction leakage reactance;

[0117] x sσ ——stator leakage reactance;

[0118] x ad ——direct-axis armature reaction reactance;

[0119] x aq ——quadrature-axis armature reaction reactance;

[0120] x kdσ —— leakage reactance of direct-axis damping winding;

[0121] x kqσ —— leakage reactance of quadrature-axis damping winding;

[0122] x fdσ ——Leakage reactance of the excitation winding.

[0123] The d-axis ultratransient flux and the q-axis ultratransient flux are

[0124]

[0125] Among them, kq is the flux linkage of the quadrature-axis damping winding;

[0126] Ψ fd is the magnetic flux of the field winding.

[0127] The d-axis supertransient potential and the q-axis supertransient potential are

[0128]

[0129] In the formula, ω r ——rotor angular velocity;

[0130] ω b ——Fundamental frequency angular velocity.

[0131] Considering the average voltage drop caused by commutation overlap, the commutation reactance x is introduced t and transient commutation reactance x t ′. The voltage equation of the generator AC side in the equivalent model becomes

[0132]

[0133] in, ——ultra-transient potential;

[0134] δ = arctan(E d ″ / E q ″)——power angle;

[0135] p = d / dt - differential operator;

[0136] x t =x t11 (β 1 )+x t12 (β 1 ,β 2 )——Commutation reactance.

[0137]

[0138] x t12 (β 1 ,β 2 )=(x dx ″-x qx ″)sin(β 1 +β 2 )-(x dx ″+x qx ″)sin(β 1 -β 2 )(17)

[0139]

[0140] β 1 =δ+α 1 (19)

[0141] β 2 =δ+α 2 (20)

[0142] Among them, β 1 , β 2 ——rectifier ignition angle;

[0143] α 1 , α 2 ——Rectifier trigger delay angle;

[0144] x t11 (β 1 )——commutation reactance of one-phase rectifier;

[0145] x t12 (β 1 ,β 2 )——Cross-commutation reactance of the two-phase rectifier.

[0146] At the moment of pulse power load jump, the DC side output voltage of a three-phase rectifier generator is

[0147]

[0148] Among them, u s ′——instantaneous phase voltage on the AC side;

[0149] u l ′——Instantaneous line voltage on the AC side.

[0150] The accuracy of the established mathematical model was verified by comparing the finite element analysis method with physical experiments. Figure 4 Then the finite element analysis method is used to analyze the influence of the filter capacitor C and its parasitic parameter ESR on the DC side steady-state voltage ripple factor and transient voltage. Figure 5 As shown, Figure 5 (a) shows the effect of 10% Pn-85% Pn C and ESR on the DC side voltage, and (b) shows the effect of 85% Pn-10% Pn C and ESR on the DC side voltage.

[0151] In summary, the present invention proposes a method for analyzing the transient voltage on the DC side of a 20° shifted dual three-phase rectifier generator considering the parasitic parameter ESR of the filter capacitor. By establishing an equivalent transient mathematical model of a dual three-phase rectifier generator with pulse power load, a transient voltage analysis method considering the filter capacitor ESR when the load changes suddenly is given. The accuracy of the equivalent model of the dual three-phase rectifier generator considering the filter capacitor ESR proposed by the present invention is verified by finite element simulation and physical experiment comparison under different speeds and power loads. Subsequently, the influence of the filter capacitor C and its parasitic parameter ESR on the steady-state voltage ripple factor and transient voltage on the DC side is further analyzed. The results show that the established equivalent mathematical model of the dual three-phase rectifier generator with pulse power load has high precision and has high accuracy for the calculation of the DC side output transient voltage. At the same time, it shows that the study of the steady-state and transient voltage characteristics of the rectifier generator considering the filter capacitor ESR is of great significance to improving the power quality of the entire DC power supply system.

[0152] In summary, the present invention is comprehensive and the analysis method is reasonable and effective. It not only considers the influence of the filter capacitor C value on the DC side voltage steady-state ripple factor and transient voltage, but also further considers the influence of the filter capacitor parasitic parameter ESR on the DC side voltage steady-state ripple factor and transient voltage, and also considers the special dual three-phase phase shift angle for calculation and analysis. It contributes to improving the power supply quality of the DC power supply system.

[0153] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the schemes disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed in this disclosure. The description and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the claims.

Claims

1. A method for analyzing the instantaneous voltage on the DC side of a dual three-phase rectifier generator, characterized in that: include: Step 1, based on a dual three-phase rectifier generator with pulse power load and special phase shift angle and parasitic parameter ESR of filter capacitor, establish an equivalent transient teaching model of rectifier generator; Step 2: Based on the rectifier generator equivalent transient teaching model, obtain the waveform diagram of the DC side voltage of the rectifier generator, perform finite element analysis on the rectifier generator voltage according to the waveform diagram, and obtain the influence of the filter capacitor ESR on the steady-state and transient voltage characteristics of the rectifier generator.

2. The method for analyzing the instantaneous voltage on the DC side of a dual three-phase rectifier generator according to claim 1, characterized in that: In the rectifier generator equivalent transient teaching model, at the moment of pulse load jump, the instantaneous output voltage of the DC side of the dual three-phase rectifier generator shifted by 20° is: Where: u dc1 ′——instantaneous output voltage on DC side; ——ultra-transient potential; ω r ——rotor angular velocity; ω b —— fundamental frequency angular velocity; x t =x t11 (β1)+x t12 (β1,β2)——commutation reactance; x t11 (β1)′——transient commutation reactance; β1, β2 – rectifier ignition angle; p = d / dt - differential operator; i dc1 、i dc2 ——output current of two-phase rectifier; x t11 (β1)——commutation reactance of one-phase rectifier; x t12 (β1,β2)——cross-commutation reactance of two-phase rectifier; R e ——AC side equivalent resistance; u s ′——instantaneous phase voltage on the AC side; u l ′——Instantaneous line voltage on the AC side.

3. The method for analyzing the instantaneous voltage on the DC side of a dual three-phase rectifier generator according to claim 2, characterized in that: In step 1, firstly, the analytical method is used to obtain U from the AC phase voltage by ignoring the voltage drop in the AC line inductor. DC Calculate the expression: Among them, U DC ——is the rectifier DC output voltage; U m ——peak value of AC phase balanced sinusoidal voltage; N——Number of rectifier phases (N>2); Ignore the voltage difference between the DC voltages at any time, and output the DC voltage U DC The output voltage of each phase rectifier can be expressed as: Among them, u DC1 ,u DC2 ——DC output voltage of two sets of three-phase windings; By connecting two phase uncontrolled rectifiers in parallel, we can get u DC =u DC1 =u DC2 , load output voltage U L =U DC ; The expression can be obtained by applying the case of N = 3 Among them, U S ——RMS value of AC phase voltage; U l ——RMS value of AC line voltage.

4. The method for analyzing the instantaneous voltage on the DC side of a dual three-phase rectifier generator according to claim 2, characterized in that: In step 1, in order to further analyze the change of the DC side voltage when the rectifier synchronous generator with pulse power load is running, when the pulse power load jumps, the DC side resistor R is changed according to the rectification characteristics. dc Converted to AC, the AC side resistance is R ac , obtain the load resistance equivalent model: R dc R is the DC side L After mutation, same as R ESR The change in the total parallel resistance, after conversion to the AC side, is R ac ; Assuming there is no loss in the generator rectifier system, according to the principle of energy conservation, the output power of the rectifier generator on the AC and DC sides is equal: Among them, P ac ——AC side output power; P dc ——DC side output power; AC side equivalent load R ac With the DC side load R dc The relationship between <h2 style=";text-align:left;direction:ltr">R<h2 style=";text-align:left;direction:ltr"> ac <h2 style=";text-align:left;direction:ltr"> ≈0.9685R<h2 style=";text-align:left;direction:ltr"> dc At this time, the equivalent resistance on the AC side of the dual three-phase synchronous generator rectification system is R e =r+0.9685R dc Among them, R e ——AC side equivalent resistance; R dc =Δ(R L / / R ESR ) Among them, R L ——Pulse load equivalent resistance; R ESR ——Parasitic parameter resistance of filter capacitor.

5. The method for analyzing the instantaneous voltage on the DC side of a dual three-phase rectifier generator according to claim 2, characterized in that: In the rectifier generator equivalent transient teaching model, the damping winding effect is considered; the d-axis ultra-transient reactance and the q-axis ultra-transient reactance are respectively: Among them, x aσ ——armature reaction leakage reactance; x sσ ——stator leakage reactance; x ad ——direct-axis armature reaction reactance; x aq ——quadrature-axis armature reaction reactance; x kdσ —— leakage reactance of direct-axis damping winding; x kqσ —— leakage reactance of quadrature-axis damping winding; x fdσ ——Leakage reactance of the excitation winding; The d-axis ultra-transient flux and the q-axis ultra-transient flux are: Among them, kq is the flux linkage of the quadrature-axis damping winding; fd is the magnetic flux of the excitation winding; the d-axis super-transient potential and the q-axis super-transient potential are respectively: In the formula, ω r ——rotor angular velocity; ω b ——Fundamental frequency angular velocity.

6. The method for analyzing the instantaneous voltage on the DC side of a dual three-phase rectifier generator according to claim 2, characterized in that: Considering the average voltage drop caused by commutation overlap, the commutation reactance x is introduced t and transient commutation reactance x t ′; The voltage equation of the generator AC side in the equivalent model becomes: in, ——ultra-transient potential; δ = arctan(E d ″ / E q ″)——power angle; p = d / dt - differential operator; x t =x t11 (β1)+x t12 (β1,β2)——commutation reactance; x t12 (β1,β2)=(x dx ″-x qx ″)sin(β1+β2)-(x dx ″+x qx ″)sin(β1-β2) β1=δ+α1;β2=δ+α2 Among them, β1, β2 – rectifier ignition angle; α1, α2——rectifier trigger delay angle; x t11 (β1)——commutation reactance of one-phase rectifier; x t12 (β1,β2)——The cross-commutation reactance of the two-phase rectifier.

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