An accurate dynamic dq0 equivalent circuit model of a doubly-fed asynchronous generator

Abstract

The present invention discloses a precise dynamic DQ0 equivalent circuit model of a doubly-fed asynchronous generator, comprising a stator circuit, a rotor circuit, and an excitation branch in which the stator circuit and the rotor circuit are mutually coupled, or an excitation branch in which the stator circuit and the rotor circuit are not mutually coupled; an excitation inductance is provided on the excitation branch in which the stator circuit and the rotor circuit are mutually coupled; the stator circuit comprises a stator branch, a stator port voltage, and a stator circuit rotating electromotive force, and the stator branch comprises a stator branch resistance and a stator branch leakage inductance; the rotor circuit comprises a rotor branch, a rotor port voltage, and a rotor circuit rotating electromotive force, and the rotor branch comprises a rotor branch resistance and a rotor branch leakage inductance. This solves the problem that existing conventional models cannot well interpret the internal potential of the stator circuit excited generator and the internal potential of the rotor circuit excited generator / motor potential, as well as the power flow analysis and calculation.

Description

Technical Field

[0001] The present invention relates to the technical field of doubly-fed asynchronous generator circuits, and in particular to an accurate dynamic dq0 equivalent circuit model of a doubly-fed asynchronous generator. Background Art

[0002] With the rapid development of the wind power market and the gradual increase in installed capacity, more than 60% of wind turbines currently use doubly fed wind turbines. At present, the mutual influence between doubly fed wind turbines and the power grid can no longer be ignored.

[0003] The conventional doubly-fed asynchronous generator dq0 equivalent circuit model fails to clearly represent the internal potential of the stator-side generator and the internal potential of the rotor-side generator or the motor potential, the corresponding electromagnetic active power and electromagnetic reactive power, and their corresponding quantitative calculation relationship; and the excitation resistance of the dynamic dq0 equivalent circuit model is not clearly represented.

[0004] Based on this, the conventional doubly fed asynchronous generator dq0 equivalent circuit model cannot well interpret the internal potential of the stator circuit excitation generator and the internal potential of the rotor circuit excitation generator / motor potential in the equivalent circuit of the doubly fed wind asynchronous generator and its power flow analysis and calculation. Summary of the Invention

[0005] To solve the above problems, the present invention provides an accurate dynamic dq0 equivalent circuit model of a doubly-fed asynchronous generator. The specific technical solution is as follows:

[0006] It includes a stator circuit, a rotor circuit, and an excitation branch in which the stator circuit and the rotor circuit are coupled to each other, or an excitation branch in which the stator circuit and the rotor circuit are not coupled to each other;

[0007] An excitation inductor is provided on the excitation branch where the stator circuit and the rotor circuit are coupled to each other;

[0008] The stator circuit includes a stator branch, a stator port voltage and a stator circuit rotational electromotive force, and the stator branch includes a stator branch resistance and a stator branch leakage inductance;

[0009] The stator circuit rotating electromotive force includes the stator branch leakage inductance voltage, the stator side excitation branch excitation inductance voltage and the stator side excitation branch excitation generator internal potential;

[0010] The rotor circuit includes a rotor branch, a rotor port voltage, and a rotor circuit rotational electromotive force, and the rotor branch includes a rotor branch resistance and a rotor branch leakage inductance;

[0011] The rotor circuit rotating electromotive force includes the rotor branch leakage inductance voltage, the rotor side excitation branch excitation inductance voltage and the rotor side excitation branch excitation generator internal potential / motor potential.

[0012] Furthermore, the non-mutually coupled excitation branches of the stator circuit and the rotor circuit include a stator-side excitation branch and a rotor-side excitation branch;

[0013] The stator side excitation branch also includes an excitation resistor and an excitation resistor additional impedance;

[0014] The rotor side excitation branch further includes an excitation resistor and an excitation resistor additional impedance.

[0015] Furthermore, the magnetizing reactance of the stator side excitation branch in the stator circuit rotating electromotive force and the magnetizing reactance of the rotor side excitation branch in the rotor circuit rotating electromotive force are not coupled together;

[0016] The internal potential of the stator side excitation branch excitation generator in the stator circuit rotation electromotive force and the internal potential of the rotor side excitation branch excitation generator / motor potential in the rotor circuit rotation electromotive force are not coupled together.

[0017] Furthermore, the mutually coupled excitation branch of the stator circuit and the rotor circuit includes an excitation resistor, and this model is recorded as a basic type.

[0018] Furthermore, the basic analysis calculation is as follows:

[0019] Calculate the stator port voltage, rotor port voltage, stator circuit current, rotor circuit current, the synthetic current of the stator circuit current and the rotor circuit current on the excitation branch, the stator circuit rotational electromotive force and the rotor circuit rotational electromotive force, the stator circuit transformer electromotive force and the rotor circuit transformer electromotive force, the internal potential of the stator circuit excitation branch excitation generator and / or the internal potential of the rotor circuit excitation branch excitation generator / motor potential. The calculation formula is:

[0020]

[0021] in,

[0022] ;

[0023] Where: is the stator port voltage, is the stator circuit rotational electromotive force, is the stator circuit current, is the stator branch resistance, is the stator branch leakage inductance; is the rotor terminal voltage, is the rotor circuit rotational electromotive force, Rotor circuit current, is the rotor branch resistance, is the rotor branch leakage inductance; It is the composite current of the stator circuit current and the rotor circuit current on the excitation branch; Stator circuit transformer electromotive force, is the voltage drop of the exciting resistance of the stator side exciting branch; is the electromotive force of the rotor circuit transformer, is the voltage drop of the exciting resistance of the rotor side exciting branch; is the exciting resistance of the exciting branch, is the magnetizing inductance of the magnetizing branch; is the slip of the doubly-fed asynchronous generator.

[0024] Furthermore, the mutually coupled excitation branch of the stator circuit and the rotor circuit does not include an excitation resistor, and the model is recorded as an operating type.

[0025] Furthermore, the operational analysis is calculated as follows:

[0026] Calculate the stator port voltage, rotor port voltage, stator circuit current, rotor circuit current, the composite current of the stator circuit current and the rotor circuit current on the excitation branch, the stator circuit rotational electromotive force and the rotor circuit rotational electromotive force, the stator circuit transformer electromotive force and the rotor circuit transformer electromotive force, the internal potential of the excitation generator on the stator side excitation branch and / or the internal potential of the excitation generator on the rotor side excitation branch / motor potential. The calculation formula is:

[0027]

[0028] in, , , , , , , , , ;

[0029] Where: is the stator port voltage, is the stator circuit rotational electromotive force, is the stator circuit current and , is the stator branch resistance, is the stator branch leakage inductance, is the magnetizing resistance of the stator side magnetizing branch, is the additional resistance of the stator side excitation branch excitation resistance, It is the additional reactance of the exciting resistance of the stator side exciting branch; is the rotor terminal voltage, is the rotor circuit rotational electromotive force, The rotor circuit current and , is the rotor branch resistance, is the rotor branch leakage inductance, is the excitation resistance of the rotor side excitation branch, is the additional resistance of the rotor side excitation branch excitation resistance, It is the additional reactance of the excitation resistance of the rotor side excitation branch; It is the composite current of the stator circuit current and the rotor circuit current on the excitation branch; Stator circuit transformer electromotive force, is the voltage drop of the exciting resistance of the stator side exciting branch; is the electromotive force of the rotor circuit transformer, is the voltage drop of the exciting resistance of the rotor side exciting branch; is the exciting resistance of the exciting branch, is the magnetizing inductance of the magnetizing branch; is the slip of the doubly-fed asynchronous generator.

[0030] Furthermore, it also includes:

[0031] Calculate the stator electromagnetic active power, stator electromagnetic reactive power, stator port active power, stator port reactive power, electromagnetic active power and reactive power due to changes in stator air gap magnetic field energy storage, rotor electromagnetic active power, slip rotor electromagnetic active power, rotor electromagnetic reactive power, slip rotor electromagnetic reactive power, rotor port active power, rotor port reactive power, electromagnetic active power and reactive power due to changes in rotor air gap magnetic field energy storage, and / or the doubly fed asynchronous generator mechanical input active power using the following formula:

[0032]

[0033] in, , ; , ;

[0034] Where: is the stator electromagnetic active power, is the active power of the exciting resistance of the stator side exciting branch, The electromagnetic active power of the air gap magnetic field energy storage changes, is the active power of the stator branch resistance, is the stator port active power; is the stator electromagnetic reactive power, is the reactive power of the magnetizing reactance of the stator side magnetizing branch, is the reactive power of the additional reactance of the excitation resistance of the stator side excitation branch, The electromagnetic reactive power of the air gap magnetic field energy storage changes, is the stator port reactive power, is the stator branch leakage reactance reactive power;

[0035] is the rotor port active power, is the active power of the rotor branch resistance, The electromagnetic active power of the air gap magnetic field energy storage changes, is the active power of the exciting resistance of the rotor side exciting branch, is the rotor electromagnetic active power, is the electromagnetic active power of the slip rotor; is the rotor port reactive power, The electromagnetic reactive power of the air gap magnetic field energy storage changes, The reactive power of the additional reactance of the excitation resistance of the rotor side excitation branch is Reactive power of the magnetizing reactance of the rotor side magnetizing branch, is the rotor electromagnetic reactive power, is the rotor branch leakage reactance reactive power, is the electromagnetic reactive power of the slip rotor;

[0036] is the mechanical input active power of the doubly-fed asynchronous generator set, is the mechanical input active power of the doubly-fed asynchronous generator.

[0037] The beneficial effects of the present invention are as follows:

[0038] This invention combines the operating principles and actual operating characteristics of doubly-fed asynchronous generators, as well as the characteristics of the power system generator power supply equivalent circuit and power system power flow. Based on the conventional doubly-fed asynchronous generator dq0 equivalent circuit model, the present invention adds an excitation resistor to a single excitation branch. Due to this excitation resistor, the excitation current flows through the excitation circuit, presenting a pure resistance, generating active power, and thus having no effect on the distribution range or size of the magnetic flux. The basic model has the excitation branch excitation resistors not separated; the operating model has the excitation branch excitation resistors completely separated. In the operating model, the precise dynamic dq0 equivalent circuit model of the doubly-fed asynchronous generator is constructed, and the excitation branch excitation resistors are completely separated into the stator-side excitation branch excitation resistor, additional resistance, and additional reactance, and the rotor-side excitation branch excitation resistor, additional resistance, and additional reactance. The active power and reactive power flow distributions of the basic and operational precise dynamic dq0 equivalent circuit models of the doubly fed asynchronous generator are given respectively, and a new precise dynamic dq0 equivalent circuit model of the doubly fed asynchronous generator and its power flow analysis and calculation method are innovatively established; through the new precise dynamic dq0 equivalent circuit model of the doubly fed asynchronous generator and its power flow analysis and calculation, the internal potential of the stator side excitation branch excitation generator in the stator circuit rotating electromotive force, the internal potential of the rotor side excitation branch excitation generator in the rotor circuit rotating electromotive force or the motor potential and their corresponding electromagnetic active power and electromagnetic reactive power, as well as their corresponding mutual quantitative relationship can be accurately determined on its equivalent circuit; it can perfectly interpret the doubly fed generator equivalent circuit and its power flow analysis and calculation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the analysis and calculation of the dynamic dq0 equivalent circuit model of the basic precise doubly fed asynchronous generator;

[0040] Figure 2 Basic precise double-fed asynchronous generator dynamic dq0 equivalent circuit model and its power flow analysis and calculation diagram;

[0041] Figure 3 This is a schematic diagram of the analysis and calculation of the dynamic dq0 equivalent circuit model of the operating precise doubly fed asynchronous generator;

[0042] Figure 4 It is the dynamic dq0 equivalent circuit model of the operating precise doubly fed asynchronous generator and the schematic diagram of its power flow analysis calculation;

[0043] Figure 5 Schematic diagram for analysis and calculation of the dq0 equivalent circuit model of a conventional doubly-fed asynchronous generator. DETAILED DESCRIPTION

[0044] The following description clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0045] In the description of the embodiments of the present invention, it should be noted that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is typically placed when in use, or the orientations or positional relationships commonly understood by those skilled in the art, or the orientations or positional relationships in which the inventive product is typically placed when in use. These are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used only to distinguish descriptions and should not be understood as indicating or implying relative importance.

[0046] In describing the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "disposed" and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0047] like Figure 5 The figure shows the dq0 equivalent circuit model of a conventional doubly-fed asynchronous generator. This model is generally equivalent based on the phase circuit, where the number of stator phases and rotor phases are equal. The equivalent circuit formula is as follows. The rotor circuit parameters of the equivalent circuit are equivalent through "winding conversion" but not through "frequency conversion."

[0048]

[0049] in, .

[0050] In the dq0 equivalent circuit model of a conventional doubly fed asynchronous generator, there is no excitation resistance in the excitation branch, there is a stator side transformer electromotive force in the stator circuit, and there is a rotor side transformer electromotive force in the rotor circuit; in addition, there is a stator side rotating electromotive force in the stator circuit, and there is a rotor side rotating electromotive force in the rotor circuit; however, the internal potential of the stator side excitation branch excitation generator in the stator circuit rotating electromotive force and the active power and reactive power it generates cannot be seen, nor can the internal potential of the rotor side excitation branch excitation generator in the rotor circuit rotating electromotive force and the active power and reactive power it generates or the motor potential load input active power and reactive power be seen.

[0051] The present invention is applicable to doubly-fed asynchronous generators of wind and hydroelectric generator sets. In the following embodiments, only the doubly-fed asynchronous generator of a wind generator set is used as an example for illustration, which does not limit the protection scope of the present invention. The equivalent circuit is also called an equivalent circuit.

[0052] Example 1

[0053] Embodiment 1 of the present invention discloses an accurate dynamic dq0 equivalent circuit model of a doubly fed asynchronous generator, such as Figure 1 As shown in Figure 2, the basic equivalent circuit model is as follows:

[0054] It includes a stator circuit, a rotor circuit, and an excitation branch in which the stator circuit and the rotor circuit are coupled to each other;

[0055] An excitation inductor is provided on an excitation branch where the stator circuit and the rotor circuit are coupled to each other.

[0056] The stator circuit includes a stator branch, a stator port voltage and a stator circuit rotational electromotive force, and the stator branch includes a stator branch resistance and a stator branch leakage inductance;

[0057] The stator circuit rotating electromotive force includes the stator branch leakage inductance voltage, the stator side excitation branch excitation inductance voltage and the stator side excitation branch excitation generator internal potential.

[0058] The rotor circuit includes a rotor branch, a rotor port voltage, and a rotor circuit rotational electromotive force, and the rotor branch includes a rotor branch resistance and a rotor branch leakage inductance;

[0059] The rotor circuit rotating electromotive force includes the rotor branch leakage inductance voltage, the rotor side excitation branch excitation inductance voltage and the rotor side excitation branch excitation generator internal potential / motor potential.

[0060] The internal potential of the stator side excitation branch excitation generator in the stator circuit rotating electromotive force and the internal potential of the rotor side excitation branch excitation generator / motor potential in the rotor circuit rotating electromotive force are an ideal power source, both of which participate in the mechanical input power of the doubly fed generator set, distribute the air gap magnetic field power of the doubly fed asynchronous generator into the stator air gap magnetic field power and the rotor air gap magnetic field power, and finally output active power through the stator circuit, and input or output active power through the rotor circuit, thereby dynamically realizing the doubly fed power generation function of the doubly fed asynchronous generator.

[0061] In this embodiment, the magnetizing reactance of the stator side excitation branch in the stator circuit rotating electromotive force and the magnetizing reactance of the rotor side excitation branch in the rotor circuit rotating electromotive force are not coupled together;

[0062] The internal potential of the stator side excitation branch excitation generator in the stator circuit rotation electromotive force and the internal potential of the rotor side excitation branch excitation generator / motor potential in the rotor circuit rotation electromotive force are not coupled together.

[0063] The excitation branch of the mutually coupled stator circuit and rotor circuit includes an excitation resistor;

[0064] Due to the excitation resistance, the excitation current flows in the excitation circuit, showing a pure resistance, and active power is generated, so it has no effect on the distribution range or size of the magnetic flux. Figure 1 On this basis, the stator circuit rotating electromotive force can be further decomposed into the stator branch leakage inductance voltage, the stator side excitation branch excitation inductance voltage and the stator side excitation branch excitation generator internal potential; the rotor circuit rotating electromotive force can be decomposed into the rotor branch leakage inductance voltage, the rotor side excitation branch excitation inductance voltage and the rotor side excitation branch excitation generator internal potential / motor potential, that is, Figure 2 shown.

[0065] Based on the above basic equivalent circuit model, combined with Figure 2 As shown, we can get:

[0066]

[0067] This formula is recorded as Formula 1, where

[0068] .

[0069] Where: is the stator port voltage, is the stator circuit rotating electromotive force [including stator branch leakage inductance voltage , stator side excitation branch excitation inductance voltage and the internal potential of the stator side excitation branch excitation generator ], is the stator circuit current, is the stator branch resistance, is the stator branch leakage inductance; is the rotor terminal voltage, is the rotor circuit rotational electromotive force [including the rotor branch leakage inductance voltage , rotor side excitation branch excitation inductance voltage and the internal potential of the rotor side excitation branch excitation generator ], Rotor circuit current, is the rotor branch resistance, is the rotor branch leakage inductance; It is the composite current of the stator circuit current and the rotor circuit current on the excitation branch; Stator circuit transformer electromotive force, is the voltage drop of the exciting resistance of the stator side exciting branch; is the electromotive force of the rotor circuit transformer, is the voltage drop of the exciting resistance of the rotor side exciting branch; is the exciting resistance of the exciting branch, is the magnetizing inductance of the magnetizing branch; is the slip of the doubly-fed asynchronous generator.

[0070] Combine Figure 1 And the above formula 1, the voltage drop or potential on the excitation branch of the stator circuit and the stator circuit components coupled together by the stator circuit current , we can get the apparent capacity or corresponding active power and reactive power of each component. Pure resistance components only have active power, and pure reactance components only have reactive power. However, the excitation resistance of the excitation branch of the stator circuit and the rotor circuit is coupled together. The equivalent capacity on the upper stator side is , so the active power of the exciting resistance of the stator side exciting branch is , the active power of the additional resistance of the exciting resistor is , and the reactive power of the additional reactance of the exciting resistance is ; Rotating electromotive force of stator circuit The upper apparent capacity is , that is, the apparent capacity generated by the potential inside the stator side excitation branch excitation generator , stator side excitation branch reactance The reactive power generated by the voltage drop is , stator branch leakage reactance The reactive power generated by the voltage drop is , stator branch resistance The active power generated by the voltage drop , stator port voltage Apparent capacity ; In addition, the electromagnetic active power of the stator air gap magnetic field energy storage change , electromagnetic reactive power due to the change of stator air gap magnetic field energy storage Therefore, the stator port, stator branch, stator circuit and rotor circuit coupled together, the excitation resistance of the excitation branch, and the active power of the stator side excitation branch are equal to , reactive power identity ,in , .

[0071] The voltage drop or potential on the excitation branch of the rotor circuit and the stator circuit coupled together, multiplied by the rotor circuit current , we can get the apparent capacity or corresponding active power and reactive power of each component. Pure resistance components only have active power, and pure reactance components only have reactive power. However, the stator circuit and the rotor circuit are coupled together, and the exciting branch exciting resistance Upper rotor side equivalent capacity , so the active power of the rotor side excitation branch excitation resistance , Excitation resistance additional resistance active power , reactive power of additional reactance of exciting resistance ; Rotor circuit rotational electromotive force The upper apparent capacity is , that is, the apparent capacity generated by the potential of the motor in the rotor side excitation branch or the potential inside the generator , rotor side excitation branch reactance The reactive power generated by the voltage drop is , leakage reactance on the rotor branch The reactive power generated by the voltage drop is ;Resistance on the rotor branch The active power generated by the voltage drop , rotor port The apparent capacity generated on ; In addition, the electromagnetic active power of the rotor air gap magnetic field energy storage change is , the electromagnetic reactive power of the rotor air gap magnetic field energy storage change is Therefore, the rotor port, rotor branch, rotor circuit and stator circuit coupled together, the excitation resistance of the excitation branch, and the active power of the rotor side excitation branch are equal to , reactive power identity ,in .

[0072] in addition, , , , , , , .

[0073] Combine Figure 2 As shown, Figure 1 As the basis for power flow calculation, the double-fed asynchronous generator mechanical input active power Active power of air gap magnetic field to each phase Then, the stator electromagnetic active power is allocated according to the actual slip s of the doubly fed asynchronous generator and slip rotor electromagnetic active power (After winding conversion only, the current and voltage are inversely proportional, and the apparent capacity, active power and reactive power before and after conversion remain unchanged); the electromagnetic active power of the slip rotor after winding conversion is It is based on the internal potential of the excitation generator or the motor potential of the excitation branch on the slip rotor side after winding conversion. and the rotor circuit current converted by the winding Coupling occurs; due to the need to maintain Figure 4 The potential of the equivalent circuit abc remains unchanged, so the potential of the excitation branch on the rotor side of the equivalent circuit is the internal potential of the excitation generator or the potential of the motor Next, the slip transformation -1 / s is introduced to Figure 4 The equivalent circuit has slip rotor electromagnetic active power Through slip conversion -1 / s, it becomes rotor electromagnetic active power Similarly, through the slip transformation -1 / s, there will be slip rotor electromagnetic reactive power become Figure 2 Equivalent circuit rotor electromagnetic reactive power ;

[0074] and Figure 2 The other active power and reactive power of the rotor circuit in the equivalent circuit need to be separated separately Figure 2 The equivalent circuit in the figure is converted into its actual active power and reactive power through slip transformation s.

[0075] Therefore, according to the basic accurate double-fed asynchronous generator dynamic dq0 equivalent circuit model and its power flow analysis calculation, the following formula can be derived and obtained: Figure 2 .

[0076]

[0077] Example 2

[0078] Embodiment 2 of the present invention discloses an accurate dynamic dq0 equivalent circuit model of a doubly fed asynchronous generator, such as Figure 3 As shown in Figure 2, the operational equivalent circuit model is as follows:

[0079] It includes a stator circuit, a rotor circuit, and an excitation branch in which the stator circuit and the rotor circuit are not coupled with each other;

[0080] The stator circuit and the rotor circuit are provided with excitation inductances at mutually coupled portions of the excitation branches.

[0081] The stator circuit includes a stator branch, a stator port voltage and a stator circuit rotational electromotive force, and the stator branch includes a stator branch resistance and a stator branch leakage inductance;

[0082] The stator circuit rotating electromotive force includes the stator branch leakage inductance voltage, the stator side excitation branch excitation inductance voltage and the stator side excitation branch excitation generator internal potential.

[0083] The rotor circuit includes a rotor branch, a rotor port voltage, and a rotor circuit rotational electromotive force, and the rotor branch includes a rotor branch resistance and a rotor branch leakage inductance;

[0084] The rotor circuit rotating electromotive force includes the rotor branch leakage inductance voltage, the rotor side excitation branch excitation inductance voltage and the rotor side excitation branch excitation generator internal potential / motor potential.

[0085] In this embodiment, the non-mutually coupled excitation branches of the stator circuit and the rotor circuit include a stator-side excitation branch and a rotor-side excitation branch;

[0086] The stator side excitation branch also includes an excitation resistor and an excitation resistor additional impedance;

[0087] The rotor side excitation branch further includes an excitation resistor and an excitation resistor additional impedance.

[0088] The internal potential of the stator side excitation branch excitation generator in the stator circuit rotating electromotive force and the internal potential of the rotor side excitation branch excitation generator / motor potential in the rotor circuit rotating electromotive force are an ideal power source, both of which participate in the mechanical input power of the doubly fed generator set, distribute the air gap magnetic field power of the doubly fed asynchronous generator into the stator air gap magnetic field power and the rotor air gap magnetic field power, and finally output active power through the stator circuit, and input or output active power through the rotor circuit, thereby dynamically realizing the doubly fed power generation function of the doubly fed asynchronous generator.

[0089] In this embodiment, the magnetizing reactance of the stator side excitation branch in the stator circuit rotating electromotive force and the magnetizing reactance of the rotor side excitation branch in the rotor circuit rotating electromotive force are not coupled together;

[0090] The internal potential of the stator side excitation branch excitation generator in the stator circuit rotation electromotive force and the internal potential of the rotor side excitation branch excitation generator / motor potential in the rotor circuit rotation electromotive force are not coupled together.

[0091] The excitation branch of the mutually coupled stator circuit and rotor circuit includes an excitation resistor;

[0092] That is, the excitation resistance and the excitation resistance additional impedance of the stator side excitation branch in the stator circuit are not coupled with the excitation resistance and the excitation resistance additional impedance of the rotor side excitation branch in the rotor circuit.

[0093] Combine Figure 1 and Figure 3 As shown in the figure, the operational equivalent circuit model is based on the basic equivalent circuit model. The potential at each point abc of the excitation branch remains unchanged. The excitation resistance of the excitation branch is completely separated into a single circuit. That is, the original current is only Flow through the magnetizing resistor The single loop is split into two parts. Figure 3 The stator side excitation branch and the rotor side excitation branch are shown in the figure. Since the excitation resistance of the excitation circuit is pure resistance before being decomposed into the stator side excitation branch and the rotor side excitation branch, there is active power loss, which has no effect on the distribution range or size of the magnetic flux. According to the equivalent principle, the excitation resistance of the excitation circuit is decomposed into the excitation resistance additional impedance of the stator side excitation branch and the rotor side excitation branch, which has no effect on the distribution range or size of the magnetic flux. Among them, one is that the stator side excitation branch is the stator circuit current The current flowing through the magnetizing resistor is and the additional resistance of the excitation resistor is And the additional resistive reactance of the excitation resistance is , the total voltage drop is ; The second is the rotor side excitation branch and the rotor circuit current The current flowing through the magnetizing resistor is and the additional resistance of the excitation resistor is And the additional resistive reactance of the excitation resistance is , the total voltage drop is , the potential of point b in the stator circuit is the same as the potential of point b in the rotor circuit, and no current flows between the two points b. Figure 3 In the stator side excitation branch and the rotor side excitation branch, the voltage drop of ab, bc, ac, and the stator circuit current and rotor circuit current and stator port voltage and rotor port voltage ,and Figure 1 The voltage drop of ab, bc, ac, and the stator circuit current and rotor circuit current and stator port voltage and rotor port voltage , the corresponding equality remains unchanged.

[0094] based on Figure 3 The operational equivalent circuit model is based on formula 1, and the excitation resistance is increased in the excitation branch. Then it is decomposed into the stator side excitation branch excitation resistance and the additional resistance of the excitation resistor is And the additional resistive reactance of the excitation resistance is , and the rotor side excitation branch excitation resistance is and the additional resistance of the excitation resistor is And the additional resistive reactance of the excitation resistance is , therefore, we can get the following formula:

[0095]

[0096] This formula is recorded as formula 2, where, , , , , , , , , .

[0097] Where: is the stator port voltage, is the stator circuit rotating electromotive force [including stator branch leakage inductance voltage , stator side excitation branch excitation inductance voltage and the internal potential of the stator side excitation branch excitation generator ], is the stator circuit current and , is the stator branch resistance, is the stator branch leakage inductance, is the magnetizing resistance of the stator side magnetizing branch, is the additional resistance of the stator side excitation branch excitation resistance, It is the additional reactance of the exciting resistance of the stator side exciting branch; is the rotor terminal voltage, is the rotor circuit rotational electromotive force [including the rotor branch leakage inductance voltage , rotor side excitation branch excitation inductance voltage and the internal potential of the rotor side excitation branch excitation generator ], The rotor circuit current and , is the rotor branch resistance, is the rotor branch leakage inductance, is the excitation resistance of the rotor side excitation branch, is the additional resistance of the rotor side excitation branch excitation resistance, It is the additional reactance of the excitation resistance of the rotor side excitation branch; It is the composite current of the stator circuit current and the rotor circuit current on the excitation branch; Stator circuit transformer electromotive force, is the voltage drop of the exciting resistance of the stator side exciting branch; is the electromotive force of the rotor circuit transformer, is the voltage drop of the exciting resistance of the rotor side exciting branch; is the exciting resistance of the exciting branch, is the magnetizing inductance of the magnetizing branch; is the slip of the doubly-fed asynchronous generator.

[0098] according to Figure 3 According to formula 2, the excitation resistance of the stator side excitation branch and the excitation resistance of the rotor side excitation branch are no longer coupled. The voltage drop or potential on the components in the stator side excitation branch is multiplied by the stator circuit current. , we can get the apparent capacity or corresponding active power and reactive power of each component. Pure resistance components only have active power, and pure reactance components only have reactive power. Upper equivalent stator side equivalent capacity

[0099] , so the active power of the exciting resistance of the stator side exciting branch is , the active power of the additional resistance of the exciting resistor is and the reactive power of the additional reactance of the excitation resistance ; Rotating electromotive force of stator circuit The apparent capacity generated by the potential in the stator side excitation branch generator is , stator side excitation branch reactance The reactive power generated by the voltage drop is , stator branch leakage reactance The reactive power generated by the voltage drop is , stator branch resistance The active power generated by the voltage drop is , stator branch port The apparent capacity generated by ; In addition, the electromagnetic active power of the stator air gap magnetic field energy storage change , electromagnetic reactive power due to the change of stator air gap magnetic field energy storage Therefore, the active power identity of the stator port, stator branch and stator side excitation branch is , reactive power identity ,in , .

[0100] The rotor circuit and the stator circuit are no longer coupled, and the voltage drop or potential on the rotor side excitation branch element is multiplied by the rotor circuit current. , we can get the apparent capacity or corresponding active power and reactive power of each component. Pure resistance components only have active power, and pure reactance components only have reactive power. However, the excitation resistance of the excitation branch of the stator circuit and the rotor circuit is coupled together. Equivalent capacity of rotor side after decomposition

[0101] Therefore, the active power of the rotor side excitation resistance is , Excitation resistance additional resistance active power , and the reactive power of the additional reactance of the exciting resistance ; Rotor circuit rotational electromotive force The upper apparent capacity is , that is, the apparent capacity generated by the potential of the motor or the potential inside the generator in the rotor side excitation branch , rotor side excitation branch reactance The reactive power generated by the voltage drop is , leakage reactance on the rotor branch The reactive power generated by the voltage drop is , rotor branch resistance The active power generated by the voltage drop is , rotor port voltage The apparent capacity generated ; In addition, the rotor air gap magnetic field energy storage changes the electromagnetic active power , the electromagnetic reactive power of the rotor air gap magnetic field energy storage change is Therefore, the active power identities of the rotor port, rotor branch and rotor side excitation branch are , reactive power identity ,in , .

[0102] in addition, , , , , , .

[0103] Figure 4 In Figure 3 As the basis for power flow calculation, the double-fed asynchronous generator mechanical input active power Active power of air gap magnetic field to each phase Then, the stator electromagnetic active power is allocated according to the actual slip s of the doubly fed asynchronous generator and slip rotor electromagnetic active power (After winding conversion only, the current and voltage are inversely proportional, and the apparent capacity, active power and reactive power before and after conversion remain unchanged); the electromagnetic active power of the slip rotor after winding conversion is It is based on the internal potential of the excitation generator or the motor potential of the excitation branch on the slip rotor side after winding conversion. and the rotor circuit current converted by the winding Coupling occurs; due to the need to maintain Figure 5 The potential of the equivalent circuit abc remains unchanged, so the potential of the excitation branch on the rotor side of the equivalent circuit is the internal potential of the excitation generator or the potential of the motor Next, the slip transformation -1 / s is introduced to Figure 4 The equivalent circuit has slip rotor electromagnetic active power Through slip conversion -1 / s, it becomes rotor electromagnetic active power Similarly, through the slip transformation -1 / s, there will be slip rotor electromagnetic reactive power become Figure 4 Equivalent circuit rotor electromagnetic reactive power .

[0104] and Figure 4 The other active power and reactive power of the rotor circuit in the equivalent circuit need to be separated separately Figure 4 The equivalent circuit in the figure is converted into its actual active power and reactive power through slip transformation s.

[0105] Therefore, according to the dynamic dq0 equivalent circuit model of the operating precise doubly fed asynchronous generator and its power flow analysis calculation, the following formula can be derived and obtained: Figure 4 .

[0106] .

[0107] The present invention is not limited to the aforementioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. An accurate dynamic dq0 equivalent circuit model of a doubly-fed asynchronous generator, characterized in that: The invention comprises a stator circuit, a rotor circuit, and an excitation branch in which the stator circuit and the rotor circuit are coupled to each other, wherein the excitation branch in which the stator circuit and the rotor circuit are coupled to each other comprises an excitation resistor; An excitation inductor is provided on the excitation branch where the stator circuit and the rotor circuit are coupled to each other; The stator circuit includes a stator branch, a stator port voltage and a stator circuit rotational electromotive force, and the stator branch includes a stator branch resistance and a stator branch leakage inductance; The stator circuit rotating electromotive force includes the stator branch leakage inductance voltage, the stator side excitation branch excitation inductance voltage and the stator side excitation branch excitation generator internal potential; The rotor circuit includes a rotor branch, a rotor port voltage, and a rotor circuit rotational electromotive force, and the rotor branch includes a rotor branch resistance and a rotor branch leakage inductance; The rotor circuit rotating electromotive force includes the rotor branch leakage inductance voltage, the rotor side excitation branch excitation inductance voltage and the rotor side excitation branch excitation generator internal potential / motor potential; The analysis and calculation are as follows: Calculate the stator port voltage, rotor port voltage, stator circuit current, rotor circuit current, the synthetic current of the stator circuit current and the rotor circuit current on the excitation branch, the stator circuit rotational electromotive force and the rotor circuit rotational electromotive force, the stator circuit transformer electromotive force and the rotor circuit transformer electromotive force, the internal potential of the stator circuit excitation branch excitation generator and / or the internal potential of the rotor circuit excitation branch excitation generator / motor potential. The calculation formula is: in, ； Where: is the stator port voltage, is the stator circuit rotational electromotive force, is the stator circuit current, is the stator branch resistance, is the stator branch leakage inductance; is the rotor terminal voltage, is the rotor circuit rotational electromotive force, Rotor circuit current, is the rotor branch resistance, is the rotor branch leakage inductance; It is the composite current of the stator circuit current and the rotor circuit current on the excitation branch; Stator circuit transformer electromotive force, is the voltage drop of the exciting resistance of the stator side exciting branch; is the electromotive force of the rotor circuit transformer, is the voltage drop of the exciting resistance of the rotor side exciting branch; is the exciting resistance of the exciting branch, is the magnetizing inductance of the magnetizing branch; is the slip of the doubly-fed asynchronous generator.

2. The accurate dynamic dq0 equivalent circuit model of the doubly-fed asynchronous generator according to claim 1 is characterized in that: The magnetizing reactance of the stator side excitation branch in the stator circuit rotating electromotive force and the magnetizing reactance of the rotor side excitation branch in the rotor circuit rotating electromotive force are not coupled together; The internal potential of the stator side excitation branch excitation generator in the stator circuit rotation electromotive force and the internal potential of the rotor side excitation branch excitation generator / motor potential in the rotor circuit rotation electromotive force are not coupled together.

3. The accurate dynamic dq0 equivalent circuit model of the doubly-fed asynchronous generator according to claim 1 is characterized in that: Also includes: Calculate the stator electromagnetic active power, stator electromagnetic reactive power, stator port active power, stator port reactive power, electromagnetic active power and reactive power due to changes in stator air gap magnetic field energy storage, rotor electromagnetic active power, slip rotor electromagnetic active power, rotor electromagnetic reactive power, slip rotor electromagnetic reactive power, rotor port active power, rotor port reactive power, electromagnetic active power and reactive power due to changes in rotor air gap magnetic field energy storage, and / or the doubly fed asynchronous generator mechanical input active power using the following formula: in, , ; , ; Where: is the stator electromagnetic active power, is the active power of the exciting resistance of the stator side exciting branch, The electromagnetic active power of the air gap magnetic field energy storage changes, is the active power of the stator branch resistance, is the stator port active power; is the stator electromagnetic reactive power, is the reactive power of the magnetizing reactance of the stator side magnetizing branch, is the reactive power of the additional reactance of the excitation resistance of the stator side excitation branch, The electromagnetic reactive power of the air gap magnetic field energy storage changes, is the stator port reactive power, is the stator branch leakage reactance reactive power; is the rotor port active power, is the active power of the rotor branch resistance, The electromagnetic active power of the air gap magnetic field energy storage changes, is the active power of the exciting resistance of the rotor side exciting branch, is the rotor electromagnetic active power, is the electromagnetic active power of the slip rotor; is the rotor port reactive power, The electromagnetic reactive power of the air gap magnetic field energy storage changes, The reactive power of the additional reactance of the excitation resistance of the rotor side excitation branch is Reactive power of the magnetizing reactance of the rotor side magnetizing branch, is the rotor electromagnetic reactive power, is the rotor branch leakage reactance reactive power, is the electromagnetic reactive power of the slip rotor; is the mechanical input active power of the doubly-fed asynchronous generator set, is the mechanical input active power of the doubly-fed asynchronous generator.

4. An accurate dynamic dq0 equivalent circuit model of a doubly-fed asynchronous generator, characterized in that: It includes a stator circuit, a rotor circuit, an excitation branch in which the stator circuit and the rotor circuit are mutually coupled, and an excitation branch in which the stator circuit and the rotor circuit are not mutually coupled; The excitation branch of the mutually coupled stator circuit and rotor circuit does not include an excitation resistor; The non-mutually coupled excitation branches of the stator circuit and the rotor circuit include a stator-side excitation branch and a rotor-side excitation branch; The stator side excitation branch also includes an excitation resistor and an excitation resistor additional impedance; The rotor side excitation branch also includes an excitation resistor and an excitation resistor additional impedance; An excitation inductor is provided on the excitation branch where the stator circuit and the rotor circuit are coupled to each other; The stator circuit includes a stator branch, a stator port voltage and a stator circuit rotational electromotive force, and the stator branch includes a stator branch resistance and a stator branch leakage inductance; The stator circuit rotating electromotive force includes the stator branch leakage inductance voltage, the stator side excitation branch excitation inductance voltage and the stator side excitation branch excitation generator internal potential; The rotor circuit includes a rotor branch, a rotor port voltage, and a rotor circuit rotational electromotive force, and the rotor branch includes a rotor branch resistance and a rotor branch leakage inductance; The rotor circuit rotating electromotive force includes the rotor branch leakage inductance voltage, the rotor side excitation branch excitation inductance voltage and the rotor side excitation branch excitation generator internal potential / motor potential; The analysis and calculation are as follows: Calculate the stator port voltage, rotor port voltage, stator circuit current, rotor circuit current, the composite current of the stator circuit current and the rotor circuit current on the excitation branch, the stator circuit rotational electromotive force and the rotor circuit rotational electromotive force, the stator circuit transformer electromotive force and the rotor circuit transformer electromotive force, the internal potential of the excitation generator on the stator side excitation branch and / or the internal potential of the excitation generator on the rotor side excitation branch / motor potential. The calculation formula is: in, , , , , , , , , ; Where: is the stator port voltage, is the stator circuit rotational electromotive force, is the stator circuit current and , is the stator branch resistance, is the stator branch leakage inductance, is the excitation resistance of the stator side excitation branch, is the additional resistance of the stator side excitation branch excitation resistance, It is the additional reactance of the exciting resistance of the stator side exciting branch; is the rotor terminal voltage, is the rotor circuit rotational electromotive force, The rotor circuit current and , is the rotor branch resistance, is the rotor branch leakage inductance, is the excitation resistance of the rotor side excitation branch, is the additional resistance of the rotor side excitation branch excitation resistance, It is the additional reactance of the excitation resistance of the rotor side excitation branch; It is the composite current of the stator circuit current and the rotor circuit current on the excitation branch; Stator circuit transformer electromotive force, is the voltage drop of the exciting resistance of the stator side exciting branch; is the electromotive force of the rotor circuit transformer, is the voltage drop of the exciting resistance of the rotor side exciting branch; is the exciting resistance of the exciting branch, is the magnetizing inductance of the magnetizing branch; is the slip of the doubly-fed asynchronous generator.

5. The accurate dynamic dq0 equivalent circuit model of the doubly-fed asynchronous generator according to claim 4 is characterized in that: The magnetizing reactance of the stator side excitation branch in the stator circuit rotating electromotive force and the magnetizing reactance of the rotor side excitation branch in the rotor circuit rotating electromotive force are not coupled together; The internal potential of the stator side excitation branch excitation generator in the stator circuit rotation electromotive force and the internal potential of the rotor side excitation branch excitation generator / motor potential in the rotor circuit rotation electromotive force are not coupled together.

6. The accurate dynamic dq0 equivalent circuit model of the doubly-fed asynchronous generator according to claim 4, characterized in that: According to the dynamic dq0 equivalent circuit model of the operating precise doubly fed asynchronous generator and its power flow analysis and calculation, the following relationship is obtained: 。

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