A method of instantaneous complex power and complex frequency control of a grid connected converter

Abstract

The application discloses a kind of instantaneous complex power and complex frequency control method of grid-connected converter, first measure the three-phase voltage and current of grid-connected point, construct voltage complex vector and current complex vector, calculate the actual value of current instantaneous complex frequency and the instantaneous complex power of power grid;Second, the complex power error amount is controlled to the outer ring, obtains the reference value of inner ring current complex frequency, the deviation of the reference value with rated frequency constructs complex damping term, corrects the reference value of outer ring complex power;Subsequently, the current complex frequency error amount is controlled to inner ring, obtains the reference voltage complex frequency of converter;Finally, the complex phase angle is obtained by integrating and feedback to reference voltage complex frequency, thus calculate the reference voltage complex vector of converter, for the control of grid-connected converter output voltage.The application is a kind of control method based on instantaneous complex power and complex frequency, not dependent on phase-locked loop synchronization and control structure is simple, get rid of the imitation to the characteristics of traditional synchronous machine, exert the fast dynamic response and flexible control ability of power electronic equipment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of converter control, and particularly relates to a transient complex power and complex frequency control method of a grid-connected converter. BACKGROUND

[0002] With the rapid development of new energy and the continuous transformation of energy structure, a large number of distributed energy represented by wind power and photovoltaic power are connected to the power system through power electronic converters, and the dynamic characteristics, stability mechanism and control requirements of the power system have undergone profound changes. The power system gradually evolves from the traditional "synchronous machine dominant type" to the "power electronic type". Under this background, the control strategy of the grid-connected converter becomes the core technology to ensure the safe operation of the power electronic grid. The current mainstream control methods can be divided into two categories: grid-following control and grid-forming control, including vector control based on phase-locked loop, virtual synchronous machine control, etc. Among them, the vector control can quickly track the grid parameters in transient disturbance and realize accurate active and reactive power regulation; the virtual synchronous machine control strategy can simulate the characteristics of synchronous machines and provide inertia support and frequency regulation capability for the grid, and has strong adaptability in weak grids.

[0003] However, the existing grid-connected converter control methods have the following problems:

[0004] (1) The phase-locked loop is not suitable for weak grid environment. The traditional control method relying on the phase-locked loop can realize relatively accurate synchronization and stable operation in strong grid, but in weak grid, the PLL is prone to large phase error, resulting in instability of the control system;

[0005] (2) There are limitations in simulating the operating characteristics of the synchronous machine. In strong grid environment, the inertia demand is low, and continuing to simulate its characteristics will increase the control complexity and implementation cost, limiting the advantages of fast dynamic response and flexible control of power electronic devices;

[0006] (3) The control structure is complex, and it is difficult to design and optimize parameters. In order to realize high-performance decoupling control and dynamic response, the current control method often needs a large number of complex algorithm designs, increasing the debugging and maintenance cost of the controller. SUMMARY

[0007] The present application is proposed to solve the above problems, and a transient complex power and complex frequency control method of a grid-connected converter is proposed, which can realize fast dynamic response and flexible control of power electronic devices and reduce the debugging and maintenance cost of the controller.

[0008] To solve the above technical problems, the present application provides the following technical scheme: a transient complex power and complex frequency control method of a grid-connected converter, comprising the following steps:

[0009] S1, based on the voltage complex vector u oαβand current complex vector i oαβ Calculate the actual value S of instantaneous complex power ο and instantaneous impedance Z ο S2, based on current complex vector i oαβ Calculate the actual value of the instantaneous complex frequency of the current.

[0010] S3, based on the reference value S of the instantaneous complex power. ο_ref0 The actual value of instantaneous complex power S ο and the conjugate of the instantaneous complex frequency reference value of the current Calculate the input signal of the complex power controller, and output the signal under the regulation of the complex power controller. The reference value of the instantaneous complex frequency of the current is then obtained through a conjugate process.

[0011] S4. Based on the actual value of the instantaneous complex frequency of the current in S2. The reference value of the instantaneous complex frequency of the current in S3 Error in calculating the instantaneous complex frequency of current The input current complex frequency controller, under its regulation, yields the instantaneous complex frequency ω of the converter output voltage reference value. ou_ref ;

[0012] S5, the instantaneous complex frequency ω of the converter output voltage reference value in S4. ou_ref The instantaneous complex phase angle θ of the converter output voltage reference value is obtained by performing integral calculations and feedback loops. ou_ref Therefore, the complex vector u of the converter output voltage reference value is calculated. oαβ_ref It is used for controlling the output voltage of grid-connected converters.

[0013] Furthermore, in the aforementioned step S1, the actual value S of the instantaneous complex power... ο The calculation process is as follows: Convert the voltage complex vector u... oαβ Multiply by the conjugate of the complex vector of the current Multiply by 1.5 to get the actual value of the instantaneous complex power. Where * denotes conjugate.

[0014] Furthermore, in the aforementioned step S1, the instantaneous impedance Z ο The result is obtained by calculating the following steps:

[0015] S101, Calculate the complex current vector i oαβ amplitude | i oαβ |, when |i oαβ When |>δ1, i oαβ unchanged; when |i oαβ When |≤δ1, take Obtain the current complex vector i after limiting oαβ_sat ,in For |i oαβ When |=δ1, the complex vector of current i oαβ The phase angle;

[0016] S102, convert the voltage complex vector u oαβ Divided by the current complex vector i after limiting oαβ_sat The instantaneous impedance Z is obtained. o Z o =u oαβ / i oαβ_sat .

[0017] Furthermore, in step S2 above, the actual value of the instantaneous complex frequency of the current... The following steps are used to calculate: S201, the complex vector of current i oαβ Multiply by e -jωNt Obtain the complex current vector i in a fixed rotating coordinate system odq : Where j is an imaginary number, ω N The frequency is the rated frequency, and t is time.

[0018] S202, fix the complex current vector i in the rotating coordinate system in step 201. odq Input controller G d (s) obtain i odq Approximate differential components

[0019] S203, Calculate the complex vector of current i odq amplitude | i odq |, when |i odq When |>δ2, i odq unchanged; when |i odq When |≤δ2, take in For |i odq When |=δ2, the complex vector of current i odq The phase angle;

[0020] S204, Approximate differential components Divided by the complex vector of current i odq The value i after limiting odq_sat Multiply by the negative imaginary unit -1j, and add the rated frequency ω. N Obtain the actual value of the instantaneous complex frequency of the current.

[0021] Furthermore, the input signal of the complex power controller in step S3 above is calculated as follows: the input signal of the complex power controller is the error amount of the instantaneous complex power. Equal to the reference value S of instantaneous complex power ο_ref0 Add complex damping term S D Subtract the actual value of instantaneous complex power S ο :

[0022] Furthermore, the aforementioned complex damping term S D The calculation method is as follows: Complex damping term S D Equals the deviation of the conjugate of the instantaneous complex frequency reference value of the current multiplied by the orthogonal complex power jS o Multiply by the correction factor K fw : Where j represents an imaginary number;

[0023] Furthermore, the adjustment process of the complex power controller in step S3 above is as follows:

[0024] S301, the error of instantaneous complex power. Input complex power controller G P (s), the output of the complex power controller divided by the quadrature complex power jS o get

[0025] S302, the instantaneous complex frequency ω of the converter output voltage reference value. ou_ref Subtract the steps in step S301 Obtain the conjugate of the instantaneous complex frequency reference value of the current calculate The conjugate of the current is used to obtain a reference value for the instantaneous complex frequency.

[0026] Furthermore, the adjustment process of the current complex frequency controller in step S4 above is as follows:

[0027] S401, The input signal of the current complex frequency controller is the error of the instantaneous complex frequency of the current. Equal to the reference value of the instantaneous complex frequency of the current Subtract the actual value of the instantaneous complex frequency of the current

[0028] S402, The error of the instantaneous complex frequency of the current in step S401. Input current complex frequency controller G ω (s), the output of the current complex frequency controller is

[0029] S403, The output of the current complex frequency controller in step S402 Dynamic sensing Dynamic impedance and instantaneous impedance Zo The error in calculating the instantaneous complex frequency of the converter output voltage reference value. Where L f For the filter inductor, R f This is the internal resistance of the filter inductor;

[0030] S404, Instantaneous complex frequency ω of the converter output voltage reference value ou_ref Equal to error amount Superimposed rated frequency ω N :

[0031]

[0032] Furthermore, the instantaneous complex phase angle θ of the aforementioned converter output voltage reference value... ou_ref Calculate as follows:

[0033] The instantaneous complex frequency ω of the converter output voltage reference value ou_ref Input the integrator controller and apply unity negative feedback to the imaginary part of the integrator controller output. Superimpose the final output of the integrator with the rated phase angle to obtain the instantaneous complex phase angle θ of the converter output voltage reference value. ou_ref .

[0034] Furthermore, the complex vector of the converter output voltage reference value in step S5 above is calculated according to the following steps:

[0035] S501, Instantaneous complex phase angle θ of the converter output voltage reference value ou_ref Multiply by the imaginary unit 1j, and treat the whole as an exponent with base e to obtain the exponential form of the converter output voltage reference value.

[0036] S502. Separate the real and imaginary parts of the exponent of e in step S501 to obtain... in Re(θ) is the magnitude of the complex vector of the converter output voltage reference value. ou_ref () represents the phase angle of the complex vector of the converter output voltage reference value;

[0037] S503, regarding step S502 Performing an inverse Euler transform, we obtain the complex vector form of the grid-connected converter output voltage reference value: The complex vector u oαβ_ref Used for controlling the output voltage of grid-connected converters.

[0038] Compared with the prior art, the beneficial technical effects of the present invention using the above technical solution are as follows:

[0039] (1) Not dependent on the traditional phase-locked loop synchronization. Through the control of the current instantaneous complex frequency, the synchronization with the power grid is realized, the problem of PLL losing lock under the weak power grid is effectively avoided, and the robustness and stability of the system are improved;

[0040] (2) Get rid of the imitation of the synchronous machine characteristics. The instantaneous complex frequency control method realizes the grid synchronization and the fast calculation and control of the three-phase reference voltage of the converter through the direct adjustment of the real part (frequency) and the imaginary part (related to the voltage amplitude) of the complex frequency, and the advantages of flexible control of power electronic equipment are exerted;

[0041] (3) It has a simple control structure and parameter calculation method. The complex power outer ring integrates the traditional double variables (active / reactive) control into single complex variable control, without independent decoupling algorithm; the instantaneous complex frequency inner ring adjusts the frequency and amplitude through the complex dynamic model, and the controller design is simple and the structure is simple. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is the control block diagram of the application.

[0043] Figure 2 is the three-phase voltage reference value diagram of the converter output of the application.

[0044] Figure 3 is the waveform diagram of the real part of the corrected reference complex power and the actual complex power of the application.

[0045] Figure 4 is the waveform diagram of the imaginary part of the corrected reference complex power and the actual complex power of the application.

[0046] Figure 5 is the waveform diagram of the real part of the current reference complex frequency and the actual complex frequency of the application.

[0047] Figure 6 is the waveform diagram of the imaginary part of the current reference complex frequency and the actual complex frequency of the application. DETAILED DESCRIPTION

[0048] In order to better understand the technical content of the application, specific embodiments are described below with reference to the accompanying drawings.

[0049] Aspects of the application are described in this application with reference to the accompanying drawings, which show many illustrative embodiments. The embodiments of the application are not limited to the drawings described. It should be understood that the application is realized by any one of the above-mentioned concepts and embodiments, and the concepts and embodiments described in detail below, because the disclosed concepts and embodiments of the application are not limited to any embodiment. In addition, some aspects disclosed by the application can be used alone, or in any suitable combination with other aspects disclosed by the application.

[0050] The present application is based on the system architecture of three-phase grid-connected converter connected to the grid through a resistive-inductive load, and proposes a grid-connected converter control method based on instantaneous complex power and complex frequency control. The present application discloses a kind of instantaneous complex power and complex frequency control method of grid-connected converter, first, the three-phase voltage and current of grid-connected point are measured, voltage complex vector and current complex vector are constructed, the actual value of current instantaneous complex frequency and instantaneous complex power of grid are calculated;Second, the complex power error quantity is controlled in outer ring, the reference value of inner ring current complex frequency is obtained, the deviation of the reference value with rated frequency is constructed complex damping term, and the reference value of outer ring complex power is corrected;Subsequently, the current complex frequency error quantity is controlled in inner ring, and the reference voltage complex frequency of converter is obtained;Finally, the complex phase angle is obtained by integrating and feedback to voltage complex frequency, and thus the reference voltage complex vector of converter is calculated, which is used for the control of grid-connected converter output voltage.

[0051] Reference Figure 1 The present application provides a kind of instantaneous complex power and complex frequency control method of grid-connected converter, comprising the following steps:

[0052] S1, based on voltage complex vector u oαβ And current complex vector i oαβ The actual value S ο And instantaneous impedance Z ο Of instantaneous complex power are calculated, S2, based on current complex vector i oαβ The actual value of current instantaneous complex frequency is calculated

[0053] S3, according to the reference value S ο_ref0 Of instantaneous complex power, the actual value S ο Of instantaneous complex power and the conjugate of current instantaneous complex frequency reference value The input signal of complex power controller is calculated, and the reference value of current instantaneous complex frequency is obtained under the adjustment of complex power controller After passing through conjugate link, the reference value of current instantaneous complex frequency is obtained

[0054] S4, according to the actual value of current instantaneous complex frequency in S2 And the reference value of current instantaneous complex frequency in step S3 The error quantity of current instantaneous complex frequency is calculated The instantaneous complex frequency ω ou_ref Of converter output voltage reference value is obtained under the adjustment of current complex frequency controller

[0055] S5, the instantaneous complex frequency ω ou_ref Of converter output voltage reference value in S4 is integrated and feedback link to obtain the instantaneous complex phase angle θ ou_refTherefore, the complex vector u of the converter output voltage reference value is calculated. oαβ_ref It is used for controlling the output voltage of grid-connected converters.

[0056] Furthermore, as a preferred embodiment of the present invention, the grid-connected converter uses a filter inductor L f and the internal resistance R of the filter inductor f Connect to the power grid.

[0057] Furthermore, as a preferred embodiment of the present invention, the voltage complex vector u oαβ and current complex vector i oαβ The specific steps are as follows:

[0058] A-1. Acquire three-phase grid voltage u oa u ob u oc and three-phase grid current i oa i ob i oc The Clark transformation converts the voltage and current in the three-phase stationary coordinate system to the two-phase stationary coordinate system, i.e., the αβ coordinate system:

[0059]

[0060] Where the Clark transformation matrix T 3s-2s for:

[0061]

[0062] A-2. Construct a complex vector form of the electrical quantity using the α-axis component as the real part and the β-axis component as the imaginary part in the αβ coordinate system, and then use Euler transformation to convert the complex vector form into an exponential form:

[0063]

[0064] In the formula, j is an imaginary number, U om The magnitude of the voltage complex vector I om The magnitude of the complex vector of current Phase angle of the complex voltage vector Phase angle of the complex vector current

[0065] A-3, the exponent of e in equation (3) Instantaneous complex phase angle:

[0066]

[0067] In the formula, the real part of the instantaneous complex phase angle is the phase angle of the complex vector form of the electrical quantity, and the imaginary part is related to the amplitude of the complex vector; A-4, the derivative of the instantaneous complex phase angle with respect to time is called the instantaneous complex frequency:

[0068]

[0069] The real part of the instantaneous complex frequency is the frequency, and the imaginary part is related to the amplitude of the complex vector, and by deriving both sides of formula (3) with respect to time t and substituting formula (5), another calculation formula of the instantaneous complex frequency can be obtained:

[0070]

[0071] As a preferred embodiment of the present application, the differential equation of the three-phase grid-connected converter connected to the grid system through a resistive and inductive load is written according to Kirchhoff's law, and the instantaneous complex frequency formula is used to simplify it, to obtain the relationship between the instantaneous complex frequency of the current and the instantaneous complex frequency of the voltage, which specifically includes the following steps:

[0072] B-1, write the differential equation of the three-phase grid-connected converter connected to the grid system through a resistive and inductive load according to Kirchhoff's law, and substitute it into the instantaneous complex frequency formula:

[0073]

[0074] In the formula, u g represents the complex vector form of the three-phase voltage on the grid side, u o represents the complex vector form of the three-phase voltage output from the converter side, i o represents the current complex vector transmitted from the converter side to the grid side, and i o = u oαβ , L f represents the filter inductance, R f represents the internal resistance of the filter inductance.

[0075] B-2, divide both sides of formula (7) by the current complex vector i o to obtain a dynamic impedance model:

[0076]

[0077] In the formula, z g represents the dynamic impedance on the grid side z g = u g / i o , and z o represents the dynamic impedance on the converter side z o = u o / i o .

[0078] B-3, derive both sides of formula (7) with respect to time t, substitute into formula (6) and simplify, and divide both sides by current complex vector i o Get:

[0079]

[0080] Grid-side voltage instantaneous complex frequency is rated frequency ω N , and substitute formula (8) into formula (9) to eliminate z g , and simplify to get the relationship between current instantaneous complex frequency and voltage instantaneous complex frequency, which is used for subsequent inner loop current instantaneous complex frequency control:

[0081]

[0082] Further, as a preferred embodiment of the present application, in step S1, the actual value S ο of instantaneous complex power is calculated as follows: multiply voltage complex vector u oαβ by the conjugate of current complex vector , and then multiply by 1.5 times to get the actual value of instantaneous complex power:

[0083]

[0084] Where * represents conjugate,

[0085] Derive both sides of formula (11) with respect to time t to get the relationship between instantaneous complex power and instantaneous complex frequency, which is used for subsequent outer loop instantaneous complex power control:

[0086]

[0087] Further, as a preferred embodiment of the present application, in step S1, the instantaneous impedance Z ο is calculated according to the following steps:

[0088] S101, calculate the amplitude |i oαβ | of current complex vector i oαβ , when |i oαβ |> δ1, i oαβ is unchanged; when |i oαβ |≤ δ1, take to get the current complex vector i oαβ_sat after amplitude limiting:

[0089]

[0090] Where is the phase angle of current complex vector i oαβ when |i oαβ | = δ1.

[0091] S102, convert the voltage complex vector u oαβ Divided by the current complex vector i after limiting oαβ_sat The instantaneous impedance Z is obtained. o :

[0092]

[0093] Furthermore, as a preferred embodiment of the present invention, the actual value of the instantaneous complex frequency of the current in step 2 is... The following steps were used to calculate the result:

[0094] S201, convert the complex vector of current i oαβ Multiply Obtain the complex current vector i in a fixed rotating coordinate system odq :

[0095]

[0096] S202, fix the complex current vector i in the rotating coordinate system in step S201. odq Input controller G d (s) obtain i odq Approximate differential components

[0097]

[0098] S203, Calculate the complex current vector i in S201. odq amplitude | i odq |, when |i odq When |>δ2, i odq unchanged; when |i odq When |≤δ2, take Obtain the current complex vector i after limiting odq_sat :

[0099]

[0100] in For |i odq When |=δ2, the complex vector of current i odq The phase angle;

[0101] S204, the approximate differential components in S202 Divide by the current complex vector i after limiting the current complex vector in a fixed rotating coordinate system odq_sat Multiply by the unit negative imaginary number -1j, and add the rated angular frequency ω. N The actual value of the instantaneous complex frequency of the current is obtained.

[0102]

[0103] Further, as a preferred embodiment of the present invention, the input signal of the complex power controller in step S3 is calculated as follows: the unit imaginary number 1j is multiplied by the actual value of the instantaneous complex power in S303 to obtain the orthogonal actual instantaneous complex power jS. o The adjustment amount of the complex power controller is the error amount of the instantaneous complex power. This error is equal to the reference value S of the instantaneous complex power. ο_ref0 Adding the orthogonal complex power jS o Conjugate of instantaneous complex frequency reference value of current and correction factor K fw Calculated complex damping term S D Subtract the actual value of instantaneous complex power S ο ::

[0104]

[0105] Complex damping term S D The deviation equal to the conjugate of the instantaneous complex frequency reference value of the current Multiplied by orthogonal complex power jS o Multiply by the correction factor K fw :

[0106]

[0107] Furthermore, as a preferred embodiment of the present invention, the adjustment process of the complex power controller in step S3 is as follows: S301, adjust the amount of the complex power controller... Input controller G P (s), divided by the orthogonal complex power jS o get

[0108]

[0109] In the formula, K pz K is the outer ring proportionality coefficient. pi These are the integral coefficients of the outer loop;

[0110] S302, the instantaneous complex frequency ω of the converter output voltage reference value. ou_ref Subtract S301 Obtain the conjugate of the instantaneous complex frequency reference value of the current

[0111]

[0112] Then calculate S302. The conjugate of the current is used to obtain a reference value for the instantaneous complex frequency.

[0113] Further, as a preferred embodiment of the present application, the adjustment process of the current complex frequency controller in step S4 is as follows:

[0114] S401, the adjustment amount of the complex frequency controller is the error amount of the current instantaneous complex frequency equal to the reference value of the current instantaneous complex frequency minus the actual value of the current instantaneous complex frequency

[0115]

[0116] S402, the actual value of the current instantaneous complex frequency is multiplied by the unit imaginary number and the filter inductance value, the grid dynamic inductance

[0117] the internal resistance R of the filter inductance f is added to the grid dynamic inductance to obtain the grid dynamic impedance the adjustment amount of the complex frequency controller input controller G ω (s), the output of the current complex frequency controller is

[0118] S403, the output of the controller is added to the actual value of the current instantaneous complex frequency is multiplied by the dynamic inductance of the grid minus the rated frequency ω N , multiplied by the dynamic impedance of the grid and the whole is divided by the instantaneous impedance Z o to obtain the error amount of the instantaneous complex frequency of the converter output voltage reference value

[0119]

[0120] In the formula, L f is the filter inductance, R f is the internal resistance of the filter inductance;

[0121] The controller G ω (s) in this example is a PI controller:

[0122]

[0123] In the formula, K pi is the inner loop proportional coefficient, K ii is the inner loop integral coefficient;

[0124] S404, the instantaneous complex frequency ω of the converter output voltage reference value ou_ref The error quantity equal to the instantaneous complex frequency of the converter output voltage reference value The superimposed rated frequency ω N :

[0125]

[0126] Further, as a preferred embodiment of the present application, the instantaneous complex phase angle θ of the converter output voltage reference value ou_ref is calculated as follows:

[0127] The instantaneous complex frequency ω of the converter output voltage reference value ou_ref is input into an integral controller, the imaginary part output by the integral controller is subjected to unit negative feedback, and the final output of the integrator is superimposed with the rated phase angle θ N to obtain the instantaneous complex phase angle θ of the reference voltage ou_ref :

[0128] θ ou_ref = Re(∫ω ou dt) + θ N (27)

[0129] Further, as a preferred embodiment of the present application, the complex vector of the converter output voltage reference value in step S5 is calculated as follows:

[0130] S501, the instantaneous complex phase angle θ of the reference voltage ou_ref is multiplied by the unit imaginary number 1j, and the whole is taken as the exponential with e as the base to obtain the exponential form of the reference voltage:

[0131]

[0132] S502, the exponential θ of e ou_ref is subjected to separation of real and imaginary parts to obtain:

[0133]

[0134] wherein is the amplitude of the complex vector of the converter output voltage reference value, and Re(θ ou_ref ) is the phase angle of the complex vector of the converter output voltage reference value;

[0135] S503, Euler inverse transformation is performed on to obtain the complex vector form of the grid-connected converter output voltage reference value:

[0136]

[0137] The complex vector u oαβ_ref is used for control of the grid-connected converter output voltage.

[0138] The method is further described below in combination with the results of specific embodiments, and Table 1 shows key simulation parameters of a grid-connected converter model based on the instantaneous complex power and complex frequency control method:

[0139] Table 1

[0140]

[0141] A disturbance is applied to the reference value of the instantaneous complex power: Figure 1 The overall control block diagram includes the calculation of the instantaneous complex frequency, the instantaneous complex power and the instantaneous impedance, and the instantaneous complex power outer loop and the current instantaneous complex frequency inner loop structure; Figure 2 When the reference value of the instantaneous complex power suddenly changes, the partial amplification diagram of the change of the converter output voltage reference value can be seen, and it can be seen that the converter output voltage reference value can quickly respond when the system state suddenly changes, and the final amplitude and frequency tend to be stable; Figure 3 and Figure 4 The waveform diagram of the corrected reference instantaneous complex power and the actual instantaneous complex power can be seen, and it can be seen that the controller effectively detects the change of the instantaneous complex power, quickly adjusts the reference value of the instantaneous complex power, and the response rate is fast, and the actual instantaneous complex power can effectively track the reference value; Figure 5 and Figure 6 The waveform diagram of the reference value of the current instantaneous complex frequency and the actual current instantaneous complex frequency can be seen, and it can be seen that the control system can make the current instantaneous complex frequency fluctuation recover to the reference level in a short time, the fluctuation is small, and the dynamic response speed is fast.

[0142] Although the present application has been described above with reference to a preferred embodiment, it is not intended to limit the present application. Those skilled in the art, without departing from the spirit and scope of the present application, can make various modifications and improvements. Therefore, the scope of protection of the present application shall be subject to the scope defined by the claims.

Claims

1. A method of instantaneous complex power and complex frequency control of a grid connected converter, characterized in that, The method comprises the following steps: S1, the actual value of the instantaneous complex power S is calculated from the voltage complex vector u oαβ and the current complex vector i oαβ ο and the instantaneous impedance Z ο ,​ S2, according to the current complex vector i oαβ calculating the actual value of the current instantaneous complex frequency S3, the reference value of the instantaneous complex power S ο_ref0 S, the actual value of the instantaneous complex power ο and the conjugate of the reference value of the instantaneous complex frequency of the current calculating the input signal of the complex power controller, outputting the reference value of the instantaneous complex frequency of the current through the conjugate element S4, the actual value of the current instantaneous complex frequency in S2 and the reference value of the current instantaneous complex frequency in S3 calculating the error amount of the current instantaneous complex frequency inputting the current complex frequency, and obtaining the instantaneous complex frequency ω of the output voltage reference value of the current converter under the regulation of the current complex frequency controller ou_ref ; S5, the instantaneous complex frequency ω of the converter output voltage reference value in S4 is calculated ou_ref The integral operation and feedback link are performed to obtain the instantaneous complex phase angle θ of the converter output voltage reference value ou_ref , the complex vector u of the converter output voltage reference value is calculated oαβ_ref , for the control of the grid-connected converter output voltage.

2. The method of claim 1, wherein, In step S1, the actual value S of the instantaneous complex power is calculated as follows: the voltage complex vector u ο is multiplied by the conjugate of the current complex vector oαβ and by the factor 1.5 to obtain the actual value of the instantaneous complex power where * denotes the conjugate, ​ 3. The method of claim 1, wherein, The instantaneous impedance Z in step S1 ο is calculated according to the following steps: S101, Calculate the complex current vector i oαβ amplitude | i oαβ |, when |i oαβ When |>δ1, i oαβ unchanged; when |i oαβ When |≤δ1, take Obtain the current complex vector i after limiting oαβ_sat ,in For |i oαβ When |=δ1, the complex vector of current i oαβ The phase angle; S102, convert the voltage complex vector u oαβ Divided by the current complex vector i after limiting oαβ_sat The instantaneous impedance Z is obtained. o Z o =u oαβ / i oαβ_sat .

4. The method of claim 1, wherein, In step S2, the actual value ω of the current transient complex frequency is determined io is calculated according to the following steps: S201, convert the complex vector of current i oαβ Multiply Obtain the complex current vector i in a fixed rotating coordinate system odq : Where j is an imaginary number, ω N The frequency is the rated frequency, and t is time. S202, fix the complex current vector i in the rotating coordinate system in step 201. odq Input controller G d (s) obtain i odq Approximate differential components S203, calculating the current complex vector i odq the amplitude |i odq |, when |i odq | > δ2, i odq is unchanged; when |i odq |≤δ2, take where is the phase angle of the current complex vector i odq | = δ2; and odq the phase angle of the current complex vector i S204, the approximate differential quantity divide by the complex current vector i odq the amplitude-limited value i odq_sat , multiplied by the negative unit imaginary number -1j, and superimposed with the rated frequency ω N to obtain the actual value of the current instantaneous complex frequency 5. The method of claim 1, wherein, The input signal of the complex power controller is calculated as follows: the input signal of the complex power controller is the error ε of the instantaneous complex power So , equal to the reference value S ο_ref0 of the instantaneous complex power plus the complex damping term S D , minus the actual value S ο of the instantaneous complex power:

6. The method of claim 5, wherein, S D is calculated as follows: S D is equal to the deviation of the instantaneous complex frequency reference value of the current multiplied by the orthogonal complex power jS o again multiplied by the correction factor K fw : where j represents the imaginary number.

7. The method of claim 5, wherein, The regulating process of the complex power controller in step S3 is as follows: S301, the error amount of the instantaneous complex power is calculated input complex power controller G P (s), the output of the complex power controller is divided by the quadrature complex power jS o obtained S302, the instantaneous complex frequency ω of the converter output voltage reference value is obtained ou_ref Subtracting the value of step S301 The conjugate of the current instantaneous complex frequency reference value is obtained The conjugate of the value of The conjugate of the value of 8. The method of claim 5, wherein, The regulating process of the current complex frequency controller in step S4 is as follows: S401, the input signal of the current complex frequency controller is the error amount of the current instantaneous complex frequency is equal to the reference value of the current instantaneous complex frequency subtracts the actual value of the current instantaneous complex frequency S402, The error of the instantaneous complex frequency of the current in step S401. Input current complex frequency controller G ω (s), the output of the current complex frequency controller is S403, output from the current complex frequency controller in step S402 dynamic inductance dynamic impedance and instantaneous impedance Z o , an error amount of the instantaneous complex frequency of the converter output voltage reference value where L f is the filter inductance, R f is the internal resistance of the filter inductance; S404, the instantaneous complex frequency ω of the converter output voltage reference value ou_ref is equal to the error amount superimposed rated frequency ω N :

9. The method of claim 1, wherein, the instantaneous complex phase angle θ of the converter output voltage reference value ou_ref is calculated as follows: The instantaneous complex frequency ω of the converter output voltage reference value is calculated as ou_ref The instantaneous complex phase angle θ of the converter output voltage reference value is calculated as ou_ref .

10. The method of claim 1, wherein, The complex vector of the converter output voltage reference value in step S5 is calculated according to the following steps: The regulating process of the complex power controller in step S3 is as follows: S501, the instantaneous complex phase angle θ of the converter output voltage reference value ou_ref multiplying by the unit imaginary number 1j and taking the whole as an exponential with base e, the exponential form of the converter output voltage reference value is obtained S502, separating the index e in step S501 into real part and imaginary part, to obtain wherein is the amplitude of the complex vector of the converter output voltage reference value, Re(θ ou_ref ) is the phase angle of the complex vector of the converter output voltage reference value; S503、performing Euler inverse transformation on the complex vector u oαβ_ref for the control of the output voltage of the grid-connected converter.​​

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