Converter voltage support type network construction control method, equipment, terminal and medium

Abstract

The invention discloses a converter voltage support type network construction control method, which can realize a rapid voltage support function of a converter, and comprises the following steps: a pre-synchronization control module calculates and obtains d-axis and q-axis voltage initial values through voltage amplitudes and phases at two sides of a grid-connected circuit breaker, and pre-synchronization of the voltage amplitudes and phases of the converter is realized; the active power control module and the reactive power control module respectively calculate q-axis and d-axis reference values of the internal potential so as to control the output active power and reactive power of the converter; the virtual impedance calculation module automatically adjusts a virtual impedance value according to an internal potential reference value and a power grid voltage measurement value, so as to realize the functions that the virtual impedance is constant in a steady state and the virtual impedance is increased to limit short-circuit current after a fault; the virtual circuit module calculates virtual impedance voltage according to the relation of impedance, voltage and current under a d-axis coordinate system and a q-axis coordinate system; and the internal potential reference value and the virtual impedance voltage are added and then subjected to Park inverse transformation to obtain a three-phase voltage reference value of the converter, and finally, a trigger pulse of the converter is obtained through a PWM (Pulse Width Modulation) generation module.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method, equipment, terminal and medium for controlling a voltage-supported grid structure of a converter. Background Art

[0002] In the context of building a new power system, the large-scale application of power electronic equipment including new energy, energy storage, static var generator (SVG), etc. has led to the continuous deepening of the power electronics of the power system. Most traditional power electronic converters adopt the grid-following (GFL) control mode, which is equivalent to a current source. The active and reactive power flowing into the grid is controlled by controlling the output current of the converter, and a phase-locked loop is required to achieve synchronization between the converter voltage and the grid voltage. The characteristics of the grid-following control mode make it impossible to provide fast inertia and voltage support for the power system, which has caused a series of power grid failures and has become the focus of attention in the field of power systems and power electronics.

[0003] In order to solve the problems of reduced system inertia and insufficient voltage support caused by the application of large-scale power electronic equipment, some scholars have proposed the concept of grid-forming (GFM) converter by drawing on the physical principles of synchronous generators. It can achieve synchronization without sampling the external AC grid voltage and can be equivalent to a voltage source rather than a current source. The self-synchronization function ensures that the equivalent internal potential phase angle of the grid-forming converter does not change suddenly when the system is disturbed by frequency changes, providing short-term emergency active support for the system, that is, realizing the inertia support function; the voltage source property ensures that the equivalent internal potential amplitude does not change suddenly when the grid voltage changes, so that the converter has the ability to provide fast voltage support. The characteristics of grid-forming control enable the converter to establish AC voltage by itself, actively participate in grid regulation, be able to connect to extremely weak grids, and even operate in an isolated island, so it has received widespread attention in the industry.

[0004] Although there are many types of current grid-forming control methods, they are basically aimed at ensuring the general functions of grid-forming control, namely inertia support and voltage support. In some application scenarios, the converter may not have the ability to quickly support active power, such as new energy power generation devices that do not include spare capacity, SVG devices that do not include energy storage or supercapacitors on the DC side, etc., or the local power grid itself has strong active power support capabilities, and only requires the grid-forming converter to provide fast reactive power support functions. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a voltage support type grid control method for a converter, which abandons the active support function of conventional grid control, and enables the converter to have a fast voltage support capability similar to that of a synchronous machine in application scenarios where the power grid does not require active support from power electronic equipment or the power electronic equipment does not have active support capability.

[0006] According to a first aspect of the present invention, a method for controlling a voltage-supported grid-forming converter system is provided. The method is used to control a converter system, wherein the converter system comprises a pre-synchronization control module, an active power control module, a reactive power control module, a virtual impedance calculation module, a virtual circuit module, a power calculation module, a voltage calculation module, a phase-locked loop module, a Park transformation module, a Park inverse transformation module, and a PWM generation module. The method comprises:

[0007] The three-phase voltage u on the converter side of the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is connected to all the above modules to obtain the converter active power P s , Converter reactive power Q s , Circuit breaker side converter side voltage amplitude U s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , the d-axis component i of the converter current d and the q-axis component i q ;

[0008] The voltage amplitude U on the converter side of the circuit breaker side is s 、Voltage phase θ on the circuit breaker converter side s , the voltage amplitude of the circuit breaker grid side U g 、Circuit breaker grid side voltage phase θ g And AC voltage amplitude reference value U ref input to the pre-synchronization control module for voltage phase and amplitude pre-synchronization;

[0009] The active power reference value P ref and converter active power P s Input to the active power control module for controlling the active power output of the converter;

[0010] The input quantity of the reactive power control module is the reactive power reference value Q ref and converter reactive power Q s , used for controlling the reactive power output of the converter;

[0011] The virtual impedance calculation module calculates the value of the virtual impedance according to the steady-state virtual impedance and the current-limiting impedance;

[0012] The virtual circuit module is used to calculate the relationship between impedance, voltage and current in the d-axis and q-axis coordinate systems, and the d-axis component i of the converter current. d and the q-axis component i q , calculate the voltage d and q-axis component u on the virtual impedance vd 、u vq ;

[0013] The voltage d and q-axis components u on the virtual impedance vd 、u vq , plus the internal potential d and q-axis reference values ​​u output by the active control module and the reactive control module cd 、u cq , get the reference value u of the converter voltage d-axis and q-axis components dref 、u qref , after the Park inverse transformation module, the three-phase voltage reference value u of the converter is obtained abcref ;

[0014] The three-phase voltage reference value u of the converter abcref After the PWM generation module, a converter trigger pulse is obtained to complete the control.

[0015] The voltage support type grid control method of the converter according to the embodiment of the present invention has at least the following beneficial effects: the control method of the embodiment of the present invention is composed of modules such as pre-synchronization control, active power control, reactive power control, virtual impedance calculation, and virtual circuit, which can realize the fast voltage support function of the converter; the voltage amplitude and phase on both sides of the grid-connected circuit breaker are obtained through PI control to obtain the initial values ​​of the d-axis and q-axis voltages, thereby realizing the pre-synchronization function of the converter voltage phase and amplitude; the virtual impedance value is automatically adjusted according to the internal potential reference value and the grid voltage measurement value, thereby realizing the function of constant virtual impedance in steady state and increased virtual impedance after a fault, thereby limiting the short-circuit current to below the converter tolerance capacity.

[0016] According to some embodiments of the present invention, the three-phase voltage u on the converter side based on the grid-connected circuit breaker B sa b c And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is connected to the above modules to obtain the converter active power P s , Converter reactive power Q s , Circuit breaker side converter side voltage amplitude U s , the voltage amplitude of the circuit breaker grid side U g、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , the d-axis component i of the converter current d and the q-axis component i q The steps include:

[0017] The three-phase voltage u sabc and the three-phase current i of the converter abc The power calculation module calculates the active power P of the converter. s and reactive power Q s ;

[0018] The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc The voltage calculation module is used to obtain the voltage amplitude U of the circuit breaker side and the converter side. s and the voltage amplitude U on the grid side of the circuit breaker g ;

[0019] The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc Through the phase-locked loop module, the voltage phase θ of the circuit breaker converter side is obtained respectively. s and the grid side voltage phase of the circuit breaker θ g ;

[0020] The three-phase voltage u sabc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component u of the converter side voltage is obtained. sd and the q-axis component u sq ;

[0021] The three-phase current i abc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component i of the converter current is obtained. d and the q-axis component i q .

[0022] According to some embodiments of the present invention, the mathematical expression of the function of the pre-synchronization control module is:

[0023]

[0024] Among them, K pθ and K iθ K is the proportional coefficient and integral coefficient of the phase pre-synchronization PI link, pU and K iUare the proportional coefficient and integral coefficient of the amplitude pre-synchronization PI link, and s is the differential operator.

[0025] According to some embodiments of the present invention, the active power reference value P ref and the measured value of the converter active power P s The step of inputting the active power control module to control the active power output of the converter also includes:

[0026] The active power control module will P ref and P s After the PI link, the initial value u of the q-axis voltage obtained by adding the pre-synchronization control is q0 , get the internal potential q-axis reference value u cq .

[0027] According to some embodiments of the present invention, the mathematical expression of the active power control module function is:

[0028]

[0029] Among them, K pp and K ip It is the proportional coefficient and integral coefficient of the active power control PI link.

[0030] According to some embodiments of the present invention, the active power reference value P ref and converter active power P s The step of inputting the active power control module to control the active power output of the converter also includes:

[0031] The reactive power control module will Q ref Add the reactive power-voltage droop control link output, and Q s After the PI link, the initial value u of the d-axis voltage obtained by adding the pre-synchronization control is d0 , get the internal potential d-axis reference value u cd .

[0032] According to some embodiments of the present invention, the mathematical expression of the reactive power control module function is:

[0033]

[0034] Where K is the reactive power-voltage droop coefficient, K pq and K iq It is the proportional coefficient and integral coefficient of reactive power control PI link.

[0035] According to some embodiments of the present invention, in the virtual impedance module, the calculation formula of the virtual impedance is:

[0036] Rv +jX v =(R v1 +R v2 )+j(X v1 +X v2 )

[0037] Among them, R v and X v is the virtual resistance and virtual reactance, R v1 and X v1 is the virtual impedance often added in steady state, R v2 and X v2 It is the current limiting impedance added after the fault;

[0038] R v2 and X v2 The calculation formula is:

[0039]

[0040] in, B=2[K v (R+R v1 )+X+X v1 ],

[0041] K v For R v2 and X v2 The proportionality coefficient is R and X, respectively, where R and X are the actual resistance and reactance between the converter and the grid, and I max is the maximum overcurrent capacity of the converter.

[0042] According to some embodiments of the present invention, the mathematical expression of the virtual circuit module is:

[0043]

[0044] Where ω is the rated angular frequency of the system.

[0045] The embodiment of the second aspect of the present invention provides a device, which is connected to the converter, and includes a pre-synchronization control module, an active power control module, a reactive power control module, a virtual impedance calculation module, a virtual circuit module, a power calculation module, a voltage calculation module, a phase-locked loop module, a Park transformation module, a Park inverse transformation module, and a PWM generation module; wherein,

[0046] The three-phase voltage u on the converter side of the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is input into all the above modules to obtain the converter active power P s, Converter reactive power Q s , Circuit breaker side converter side voltage amplitude U s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , the d-axis component i of the converter current d and the q-axis component i q ;

[0047] The voltage amplitude U on the converter side of the circuit breaker side s 、Voltage phase θ on the circuit breaker converter side s , the voltage amplitude of the circuit breaker grid side U g 、Circuit breaker grid side voltage phase θ g And AC voltage amplitude reference value U ref input to the pre-synchronization control module for voltage phase and amplitude pre-synchronization;

[0048] The active power reference value P ref and the measured value of the converter active power P s Input to the active power control module for controlling the active power output of the converter;

[0049] The input quantity of the reactive power control module is the reactive power reference value Q ref and converter reactive power Q s , used for controlling the reactive power output of the converter;

[0050] The virtual impedance calculation module calculates the value of the virtual impedance according to the steady-state virtual impedance and the current-limiting impedance;

[0051] The virtual circuit module is based on the relationship between impedance, voltage and current in the d-axis and q-axis coordinate systems, and the d-axis component i of the converter current. d and the q-axis component i q , calculate the voltage d and q-axis component u on the virtual impedance vd 、u vq ;

[0052] The voltage d and q-axis components u on the virtual impedance vd 、u vq , plus the internal potential d and q-axis reference values ​​u output by the active control module and the reactive control module cd 、u cq , get the reference value u of the converter voltage d-axis and q-axis components dref 、u qref , after the Park inverse transformation module, the three-phase voltage reference value u of the converter is obtained abcref ;

[0053] The converter three-phase voltage reference value u abcref After the PWM generation module, a converter trigger pulse is obtained to complete the control.

[0054] Furthermore, the three-phase voltage u on the converter side based on the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is connected to the above modules to obtain the converter active power P s , Converter reactive power Q s , Circuit breaker side converter side voltage amplitude U s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , the d-axis component i of the converter current d and the q-axis component i q The process includes:

[0055] The three-phase voltage u sabc and the three-phase current i of the converter abc The power calculation module calculates the active power P of the converter. s and reactive power Q s ;

[0056] The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc The voltage calculation module is used to obtain the voltage amplitude U of the circuit breaker side and the converter side. s and the voltage amplitude U on the grid side of the circuit breaker g ;

[0057] The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc Through the phase-locked loop module, the voltage phase θ of the circuit breaker converter side is obtained respectively. s and the grid side voltage phase of the circuit breaker θ g ;

[0058] The three-phase voltage u sabc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component u of the converter side voltage is obtained. sd and the q-axis component u sq ;

[0059] The three-phase current i abc and the voltage phase θ on the converter side of the circuit breaker sAfter the Park transformation module, the d-axis component i of the converter current is obtained. d and the q-axis component i q .

[0060] Furthermore, the mathematical expression of the function of the pre-synchronization control module is:

[0061]

[0062] Among them, K pθ and K iθ K is the proportional coefficient and integral coefficient of the phase pre-synchronization PI link, pU and K iU are the proportional coefficient and integral coefficient of the amplitude pre-synchronization PI link, and s is the differential operator.

[0063] Furthermore, the active power reference value P ref and converter active power P s The process of inputting the active power control module to control the active power output of the converter also includes:

[0064] The active power control module will P ref and P s After the PI link, the initial value u of the q-axis voltage obtained by adding the pre-synchronization control is q0 , get the internal potential q-axis reference value u cq .

[0065] Furthermore, the mathematical expression of the active power control module function is:

[0066]

[0067] Among them, K pp and K ip It is the proportional coefficient and integral coefficient of the active power control PI link.

[0068] Furthermore, the active power reference value P ref and converter active power P s The step of inputting the active power control module to control the active power output of the converter also includes:

[0069] The reactive power control module will Q ref Add the reactive power-voltage droop control link output, and Q s After the PI link, the initial value u of the d-axis voltage obtained by adding the pre-synchronization control is d0 , get the internal potential d-axis reference value u cd .

[0070] Furthermore, the mathematical expression of the reactive power control module function is:

[0071]

[0072] Where K is the reactive power-voltage droop coefficient, K pq and K iq It is the proportional coefficient and integral coefficient of reactive power control PI link.

[0073] Furthermore, in the virtual impedance module, the calculation formula of the virtual impedance is:

[0074] R v +jX v =(R v1 +R v2 )+j(X v1 +X v2 )

[0075] Among them, R v and X v is the virtual resistance and virtual reactance, R v1 and X v1 is the virtual impedance often added in steady state, R v2 and X v2 It is the current limiting impedance added after the fault;

[0076] R v2 and X v2 The calculation formula is:

[0077]

[0078] in, B=2[K v (R+R v1 )+X+X v1 ],

[0079] K v For R v2 and X v2 The proportionality coefficient is R and X, respectively, where R and X are the actual resistance and reactance between the converter and the grid, and I max is the maximum overcurrent capacity of the converter.

[0080] Furthermore, the mathematical expression of the virtual circuit module is:

[0081]

[0082] Where ω is the rated angular frequency of the system.

[0083] An embodiment of the third aspect of the present invention provides a terminal, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the above-mentioned converter voltage-supported network control method is implemented.

[0084] An embodiment of the fourth aspect of the present invention provides a computer-readable storage medium, which stores computer-executable instructions for executing the above-mentioned converter voltage-supported grid control method.

[0085] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0087] Figure 1 A method block diagram of a voltage-supported grid-forming control method for a converter according to an embodiment of the present invention;

[0088] Figure 2 for Figure 1 The functional schematic diagram of the pre-synchronization control module of the voltage support type grid control method shown;

[0089] Figure 3 for Figure 1 The functional schematic diagram of the active power control module of the voltage support type grid control method shown;

[0090] Figure 4 for Figure 1 The functional schematic diagram of the reactive power control module of the voltage support type grid control method shown;

[0091] Figure 5 for Figure 1 The functional schematic diagram of the virtual circuit module of the voltage support type network control method is shown;

[0092] Figure 6 A schematic diagram of simulation comparison between the present invention and conventional network control when a grid voltage mutation occurs in an embodiment of the present invention;

[0093] Figure 7 A schematic diagram of simulation comparison between the present invention and conventional network control when the power grid frequency suddenly changes provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0094] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0095] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only 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 operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0096] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0097] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0098] In some application scenarios, the converter may not have the ability to quickly support active power, such as new energy power generation devices that do not include spare capacity, SVG devices that do not include energy storage or supercapacitors on the DC side, etc., or the local power grid itself has strong active support capabilities, and only requires the grid-forming converter to provide fast reactive power support functions. In these scenarios, designing a simplified grid-forming control method that only provides voltage support but does not include inertia support functions, so that it has voltage source properties and can quickly compensate for the reactive power of the grid, has become a practical problem that needs to be solved.

[0099] Embodiment 1

[0100] The embodiment of the present invention provides a method for controlling a voltage-supported grid structure of a converter, which mainly includes modules such as pre-synchronization control, reactive power control, active power control, virtual impedance calculation, virtual circuit, etc. In addition, it also includes necessary modules such as power calculation, voltage calculation, phase-locked loop (PLL), Park transformation, Park inverse transformation, PWM generation, etc. The control block diagram of the present invention is shown in FIG. Figure 1 shown.

[0101] The present invention needs to collect the three-phase voltage u of the converter side of the converter grid-connected circuit breaker Bsabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc as control input.

[0102] u sabc and i abc Through the power calculation module, the converter active power P is calculated. s and reactive power Q s .

[0103] u sabc and u gabc Through the voltage calculation module, the voltage amplitude U on the converter side of circuit breaker B can be obtained. s and the grid voltage amplitude U g .

[0104] u sabc and u gabc Through the PLL module, the respective phase θ is obtained s and θ g .

[0105] u sabc and θ s After the park transformation module, the d-axis component u of the voltage on the converter side of circuit breaker B is obtained. sd and the q-axis component u sq .

[0106] i abc and θ s After the park conversion module, the d-axis component i of the converter current is obtained. d and the q-axis component i q .

[0107] The function of the pre-synchronization control module is to realize the voltage phase and amplitude pre-synchronization function, ensuring that the output voltage phase and amplitude of the converter are the same as the grid voltage, so that the converter can be smoothly connected to the grid. Its input quantity is U s ,θ s , U g ,θ g and U ref , U ref is the reference value of AC voltage amplitude.

[0108] Phase pre-synchronization sets the grid side voltage phase θ g and the voltage phase θ on the converter side s The initial value of the q-axis voltage u is obtained by making a difference and passing through the PI controller. q0 ; Amplitude pre-synchronization sets the grid side voltage amplitude U g and the voltage amplitude U on the converter side and the circuit breaker side s The difference is then passed through the PI controller and the AC voltage reference value U is added.ref , get the initial value of d-axis voltage u d0 The mathematical expression of presynchronization control is:

[0109]

[0110] Among them, K pθ and K iθ K is the proportional coefficient and integral coefficient of the phase pre-synchronization PI link, pU and K iU are the proportional coefficient and integral coefficient of the amplitude pre-synchronization PI link, and s is the differential operator.

[0111] The corresponding block diagram of pre-synchronization control is as follows Figure 2 shown.

[0112] The active power control module realizes the control of the active power output of the converter, and its input is the active power reference value P ref and the measured value of the converter active power P s The specific method is: ref and P s After the PI link, the initial value u of the q-axis voltage obtained by adding the pre-synchronization control is q0 , get the internal potential q-axis reference value u cq The active power reference value can be determined according to the actual application of the converter, such as constant DC capacitor voltage control output, or new energy maximum power point tracking control output, etc.

[0113] The mathematical expression of active power control is:

[0114]

[0115] Among them, K pp and K ip It is the proportional coefficient and integral coefficient of the active power control PI link.

[0116] The block diagram of active power control is as follows Figure 3 shown.

[0117] The reactive power control module realizes the control of the reactive power output of the converter, and its input is the reactive power reference value Q ref and the measured value of the converter reactive power Q s The specific method is to convert Q ref Add the reactive power-voltage droop control link output, and Q s After the PI link, the initial value u of the d-axis voltage obtained by adding the pre-synchronization control is d0 , get the internal potential d-axis reference value u cd .

[0118] The mathematical expression of reactive power control is:

[0119]

[0120] Where K is the reactive power-voltage droop coefficient, K pq and K iq The proportional coefficient and integral coefficient of the reactive power control PI link

[0121] The block diagram of reactive power control is as follows: Figure 4 shown.

[0122] From the perspective of network control, the potential amplitude in the converter is This value will not change suddenly during the operation of the converter, reflecting the voltage source properties of the converter.

[0123] The function of the virtual impedance calculation module is to calculate the value of the virtual impedance, which is used by the virtual circuit module for corresponding calculations. The calculation formula of the virtual impedance is as follows:

[0124] R v +jX v =(R v1 +R v2 )+j(X v1 +X v2 ) (4)

[0125] Among them, R v and X v is the virtual resistance and virtual reactance, R v1 and X v1 is the virtual impedance often added in steady state, R v2 and X v2 It is the current limiting impedance added after the fault.

[0126] R v1 and X v1 The inverter can be adjusted according to the grid parameters in steady state to ensure the stability of system operation. v2 and X v2 It needs to be adjusted according to the system operating status to ensure that the short-circuit current can be effectively limited after a system failure. v2 and X v2 Satisfies the relationship:

[0127] R v2 =K v X v2 (5)

[0128] Among them, K v For R v2 and X v2 The proportional coefficient can be adjusted as needed.

[0129] The total impedance Z between the converter equivalent internal potential and the power grid sum for

[0130]

[0131] Among them, R and X are the actual resistance and reactance between the converter and the grid, such as the impedance of the new energy AC filter or the impedance of the SVG connection reactor.

[0132] According to the maximum overcurrent capacity of the converter I max , the total system impedance Z sum The following formula must be satisfied:

[0133]

[0134] At the same time, X v2 Must be greater than or equal to 0.

[0135] Combining equations (4) to (7), we can get

[0136]

[0137] in,

[0138]

[0139] When the system is running in steady state, X v2 and R v2 0, no impact on system operation. When a fault occurs, X v2 and R v2 The calculated result is automatically positive and added to the virtual impedance to limit the short-circuit current to no more than I max .

[0140] The virtual circuit module is used to calculate the voltage on the virtual impedance. The specific method is to calculate the voltage d and q axis components u on the virtual impedance through the relationship between impedance, voltage and current in the d and q axis coordinate system. vd 、u vq , the calculation formula and block diagram are as follows: Figure 5 As shown, where ω is the rated angular frequency of the system.

[0141]

[0142] The output u of the virtual impedance module vd 、u vq , plus the output u of the active control module and the reactive control module cd 、u cq , get the reference value u of the converter voltage d-axis and q-axis components dref 、u qref, and then through Park inverse transformation, the three-phase voltage reference value u of the converter is obtained abcref , where the angle used by the Park inverse transformation is the collected voltage phase θ s Therefore, the present invention does not have a self-synchronization function and will not provide active support to the power grid.

[0143] u abcref After the PWM generation module, the converter trigger pulse is obtained.

[0144] Embodiment 2

[0145] Another aspect of the present invention provides simulation analysis results of the control method in the first embodiment.

[0146] Figure 6 This is a comparison between the present invention and conventional network control when the grid voltage suddenly changes. It can be seen that the response speed of the present invention to reactive power is almost the same as that of the conventional network control, indicating that the voltage support capability of the present invention meets the requirements of network control.

[0147] Figure 7 The comparison between the present invention and conventional network control when the grid frequency changes suddenly shows that, compared with the conventional network control, the active power of the present invention changes very little, indicating that the present invention does not reflect the active support capability and achieves the purpose of the present invention.

[0148] Embodiment 3

[0149] Another embodiment of the present invention provides a converter voltage support type grid control device, which, as described in the first embodiment, includes a pre-synchronization control module, an active power control module, a reactive power control module, a virtual impedance calculation module, a virtual circuit module, a power calculation module, a voltage calculation module, a phase-locked loop module, a Park transformation module, a Park inverse transformation module, and a PWM generation module; wherein,

[0150] The three-phase voltage u on the converter side of the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is input into all the above modules to obtain the converter active power P s , Converter reactive power Q s , Circuit breaker side converter side voltage amplitude U s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , d-axis component u of the converter side voltage sd and the q-axis component u sq , the d-axis component i of the converter currentd and the q-axis component i q ;

[0151] The voltage amplitude U on the converter side of the circuit breaker side s 、Voltage phase θ on the circuit breaker converter side s , the voltage amplitude of the circuit breaker grid side U g 、Circuit breaker grid side voltage phase θ g And AC voltage amplitude reference value U ref input to the pre-synchronization control module for voltage phase and amplitude pre-synchronization;

[0152] The active power reference value P ref and the measured value of the converter active power P s Input to the active power control module for controlling the active power output of the converter;

[0153] The input quantity of the reactive power control module is the reactive power reference value Q ref and converter reactive power Q s , used for controlling the reactive power output of the converter;

[0154] The virtual impedance calculation module calculates the value of the virtual impedance according to the steady-state virtual impedance and the current-limiting impedance;

[0155] The virtual circuit module is based on the relationship between impedance, voltage and current in the d-axis and q-axis coordinate systems, and the d-axis component i of the converter current. d and the q-axis component i q , calculate the voltage d and q-axis component u on the virtual impedance vd 、u vq :

[0156] The voltage d and q-axis components u on the virtual impedance vd 、u vq , plus the internal potential d and q-axis reference values ​​u output by the active control module and the reactive control module cd 、u cq , get the reference value u of the converter voltage d-axis and q-axis components dref 、u qre f , after the Park inverse transformation module, the three-phase voltage reference value u of the converter is obtained abcref ;

[0157] The converter three-phase voltage reference value u abcref After the PWM generation module, a converter trigger pulse is obtained to complete the control.

[0158] Furthermore, the three-phase voltage u on the converter side based on the grid-connected circuit breaker B sa bc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is connected to the above modules to obtain the converter active power P s , Converter reactive power Q s , Circuit breaker side converter side voltage amplitude U s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , d-axis component u of the converter side voltage sd and the q-axis component u sq , the d-axis component i of the converter current d and the q-axis component i q The process includes:

[0159] The three-phase voltage u sabc and the three-phase current i of the converter abc The power calculation module calculates the active power P of the converter. s and reactive power Q s ;

[0160] The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc The voltage calculation module is used to obtain the voltage amplitude U of the circuit breaker side and the converter side. s and the voltage amplitude U on the grid side of the circuit breaker g ;

[0161] The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc Through the phase-locked loop module, the voltage phase θ of the circuit breaker converter side is obtained respectively. s and the grid side voltage phase of the circuit breaker θ g ;

[0162] The three-phase voltage u sabc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component u of the converter side voltage is obtained. sd and the q-axis component u sq ;

[0163] The three-phase current i abc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component i of the converter current is obtained. d and the q-axis component i q .

[0164] Furthermore, the mathematical expression of the function of the pre-synchronization control module is:

[0165]

[0166] Among them, K pθ and K iθ K is the proportional coefficient and integral coefficient of the phase pre-synchronization PI link, pU and K iU are the proportional coefficient and integral coefficient of the amplitude pre-synchronization PI link, and s is the differential operator.

[0167] Furthermore, the active power reference value P ref and converter active power P s The process of inputting the active power control module to control the active power output of the converter also includes:

[0168] The active power control module will P ref and P s After the PI link, the initial value u of the q-axis voltage obtained by adding the pre-synchronization control is q0 , get the internal potential q-axis reference value u cq .

[0169] Furthermore, the mathematical expression of the active power control module function is:

[0170]

[0171] Among them, K pp and K ip It is the proportional coefficient and integral coefficient of the active power control PI link.

[0172] Furthermore, the active power reference value P ref and converter active power P s The step of inputting the active power control module to control the active power output of the converter also includes:

[0173] The reactive power control module will Q ref Add the reactive power-voltage droop control link output, and Q s After the PI link, the initial value u of the d-axis voltage obtained by adding the pre-synchronization control is d0 , get the internal potential d-axis reference value u cd .

[0174] Furthermore, the mathematical expression of the reactive power control module function is:

[0175]

[0176] Where K is the reactive power-voltage droop coefficient, K pq and K iq It is the proportional coefficient and integral coefficient of reactive power control PI link.

[0177] Furthermore, in the virtual impedance module, the calculation formula of the virtual impedance is:

[0178] R v +jX v =(R v1 +R v2 )+j(X v1 +X v2 ) (13)

[0179] Among them, R v and X v is the virtual resistance and virtual reactance, R v1 and X v1 is the virtual impedance often added in steady state, R v2 and X v2 It is the current limiting impedance added after the fault;

[0180] R v2 and X v2 The calculation formula is:

[0181]

[0182] in, B=2[K v (R+R v1 )+X+X v1 ],

[0183] K v For R v2 and X v2 The proportionality coefficient is R and X, respectively, where R and X are the actual resistance and reactance between the converter and the grid, and I max is the maximum overcurrent capacity of the converter.

[0184] Furthermore, the mathematical expression of the virtual circuit module is:

[0185]

[0186] Where ω is the rated angular frequency of the system.

[0187] Embodiment 4:

[0188] Another embodiment of the present invention provides a terminal, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned converter voltage support type network control method when executing the computer program.

[0189] Specifically, the processor may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, a transistor logic device, a hardware component or any combination thereof. It may implement or execute various exemplary logic blocks, modules and circuits described in conjunction with the disclosure of the present invention. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0190] Specifically, the processor is connected to the memory via a bus, and the bus may include a path for transmitting information. The bus may be a PCI bus or an EISA bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc.

[0191] The memory can be a ROM or other type of static storage device that can store static information and instructions, a RAM or other type of dynamic storage device that can store information and instructions, or an EEPROM, CD-ROM or other optical disk storage, optical disk storage (including compressed optical disk, laser disk, optical disk, digital versatile disk, Blu-ray disk, etc.), magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited to this.

[0192] Optionally, the memory is used to store the code of the computer program for executing the solution of the present invention, and the execution is controlled by the processor. The processor is used to execute the application program code stored in the memory to implement Figure 1 The illustrated embodiment provides the functions of the converter voltage support type grid control method.

[0193] Embodiment 4:

[0194] Another aspect of the present invention provides a computer-readable storage medium storing computer-executable instructions for executing the above-mentioned Figure 1 The illustrated embodiment provides the functions of the converter voltage support type grid control method.

[0195] The device embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0196] It will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed method above may be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that may be used to store desired information and may be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0197] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present invention. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A method for controlling a voltage-supported grid structure of a converter, characterized in that: The method is used to control a converter system, the converter system comprising a pre-synchronization control module, an active power control module, a reactive power control module, a virtual impedance calculation module, a virtual circuit module, a power calculation module, a voltage calculation module, a phase-locked loop module, a Park transformation module, a Park inverse transformation module, and a PWM generation module; the method comprises: The three-phase voltage u on the converter side of the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is connected to all the above modules to obtain the converter active power P s , Converter reactive power Q s , the voltage amplitude U on the circuit breaker side and the converter side s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , the d-axis component i of the converter current d and the q-axis component i q ; The voltage amplitude U on the converter side of the circuit breaker side is s 、Voltage phase θ on the circuit breaker converter side s , the voltage amplitude of the circuit breaker grid side U g 、Circuit breaker grid side voltage phase θ g And AC voltage amplitude reference value U ref input to the pre-synchronization control module for voltage phase and amplitude pre-synchronization; The active power reference value P ref and converter active power P s Input to the active power control module for controlling the active power output of the converter; The input quantity of the reactive power control module is the reactive power reference value Q ref and converter reactive power Q s , used for controlling the reactive power output of the converter; The virtual impedance calculation module calculates the value of the virtual impedance according to the steady-state virtual impedance and the current-limiting impedance; The virtual circuit module is used to calculate the relationship between impedance, voltage and current in the d-axis and q-axis coordinate systems, and the d-axis component i of the converter current. d and the q-axis component i q , calculate the voltage d and q-axis component u on the virtual impedance vd 、u vq ; The voltage d and q-axis components u on the virtual impedance vd 、u vq , plus the internal potential d and q-axis reference values ​​u output by the active control module and the reactive control module c d.u cq , get the reference value u of the converter voltage d-axis and q-axis components dref 、u qref , after the Park inverse transformation module, the three-phase voltage reference value u of the converter is obtained abcref ; The three-phase voltage reference value u of the converter abcref After the PWM generation module, a converter trigger pulse is obtained to complete the control.

2. The method according to claim 1, characterized in that The three-phase voltage u on the converter side based on the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is connected to all the above modules to obtain the converter active power P s , Converter reactive power Q s , the voltage amplitude U on the circuit breaker side and the converter side s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , the d-axis component i of the converter current d and the q-axis component i q The steps include: The three-phase voltage u sabc and the three-phase current i of the converter abc The power calculation module calculates the active power P of the converter. s and reactive power Q s ; The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc The voltage calculation module is used to obtain the voltage amplitude U of the circuit breaker side and the converter side. s and the voltage amplitude U on the grid side of the circuit breaker g ; The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc Through the phase-locked loop module, the voltage phase θ of the circuit breaker converter side is obtained respectively. s and the grid side voltage phase of the circuit breaker θ g ; The three-phase voltage u sabc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component u of the converter side voltage is obtained. sd and the q-axis component u sq ; The three-phase current i abc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component i of the converter current is obtained. d and the q-axis component i q .

3. The network control method according to claim 1, characterized in that: The mathematical expression of the function of the pre-synchronization control module is: Among them, K pθ and K iθ K is the proportional coefficient and integral coefficient of the phase pre-synchronization PI link, pU and K iU are the proportional coefficient and integral coefficient of the amplitude pre-synchronization PI link, and s is the differential operator.

4. The network control method according to claim 1, characterized in that: The active power reference value P ref and the measured value of the converter active power P s The step of inputting the active power control module to control the active power output of the converter also includes: The active power control module will P ref and P s After the PI link, the initial value u of the q-axis voltage obtained by adding the pre-synchronization control is q0 , get the internal potential q-axis reference value u cq .

5. The network control method according to claim 4, characterized in that: The mathematical expression of the active power control module function is: Among them, K pp and K ip It is the proportional coefficient and integral coefficient of the active power control PI link.

6. The network control method according to claim 1, characterized in that: The active power reference value P ref and converter active power P s The step of inputting the active power control module to control the active power output of the converter also includes: The reactive power control module will Q ref Add the reactive power-voltage droop control link output, and Q s After the PI link, the initial value u of the d-axis voltage obtained by adding the pre-synchronization control is d0 , get the internal potential d-axis reference value u cd .

7. The network control method according to claim 6, characterized in that: The mathematical expression of the reactive power control module function is: Where K is the reactive power-voltage droop coefficient, K pq and K iq It is the proportional coefficient and integral coefficient of reactive power control PI link.

8. The network control method according to claim 1, characterized in that: In the virtual impedance module, the calculation formula of the virtual impedance is: R v +jX v =(R v1 +R v2 )+j(X v1 +X v2 ) Among them, R v and X v is the virtual resistance and virtual reactance, R v1 and X v1 is the virtual impedance often added in steady state, R v2 and X v2 It is the current limiting impedance added after the fault; R v2 and X v2 The calculation formula is: in, B=2[K v (R+R v1 )+X+X v1 ], K v For R v2 and X v2 The proportionality coefficient, R and X are the actual resistance and reactance between the converter and the grid, I max is the maximum overcurrent capacity of the converter.

9. The network control method according to claim 1, characterized in that: The mathematical expression of the virtual circuit module is: Where ω is the rated angular frequency of the system.

10. A converter voltage support type grid control device, characterized in that: The device is connected to the converter, and includes a pre-synchronization control module, an active power control module, a reactive power control module, a virtual impedance calculation module, a virtual circuit module, a power calculation module, a voltage calculation module, a phase-locked loop module, a Park transformation module, a Park inverse transformation module, and a PWM generation module; wherein, The three-phase voltage u on the converter side of the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is input into all the above modules to obtain the converter active power P s , Converter reactive power Q s , the voltage amplitude U on the circuit breaker side and the converter side s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , the d-axis component i of the converter current d and the q-axis component i q ; The voltage amplitude U on the converter side of the circuit breaker side s 、Voltage phase θ on the circuit breaker converter side s , the voltage amplitude of the circuit breaker grid side U g 、Circuit breaker grid side voltage phase θ g And AC voltage amplitude reference value U ref input to the pre-synchronization control module for voltage phase and amplitude pre-synchronization; The active power reference value P ref and the measured value of the converter active power P s Input to the active power control module for controlling the active power output of the converter; The input quantity of the reactive power control module is the reactive power reference value Q ref and converter reactive power Q s , used for controlling the reactive power output of the converter; The virtual impedance calculation module calculates the value of the virtual impedance according to the steady-state virtual impedance and the current-limiting impedance; The virtual circuit module is based on the relationship between impedance, voltage and current in the d-axis and q-axis coordinate systems, and the d-axis component i of the converter current. d and the q-axis component i q , calculate the voltage d and q-axis component u on the virtual impedance vd 、u vq ; The voltage d and q-axis components u on the virtual impedance vd 、u vq , plus the internal potential d and q-axis reference values ​​u output by the active control module and the reactive control module c d.u cq , get the reference value u of the converter voltage d-axis and q-axis components dre f、u qref , after the Park inverse transformation module, the three-phase voltage reference value u of the converter is obtained abcref ; The converter three-phase voltage reference value u abcref After the PWM generation module, a converter trigger pulse is obtained to complete the control.

11. The device according to claim 10, characterized in that The three-phase voltage u on the converter side based on the grid-connected circuit breaker B sabc And the three-phase voltage u on the grid side gabc , and the three-phase current i of the converter abc As the control input, it is connected to all the above modules to obtain the converter active power P s , Converter reactive power Q s , the voltage amplitude U on the circuit breaker side and the converter side s , the voltage amplitude of the circuit breaker grid side U g 、Voltage phase θ on the circuit breaker converter side s 、Circuit breaker grid side voltage phase θ g , d-axis component u of the converter side voltage sd and the q-axis component u sq , the d-axis component i of the converter current d and the q-axis component i q The process includes: The three-phase voltage u sabc and the three-phase current i of the converter abc The power calculation module calculates the active power P of the converter. s and reactive power Q s ; The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc The voltage calculation module is used to obtain the voltage amplitude U of the circuit breaker side and the converter side. s and the voltage amplitude U on the grid side of the circuit breaker g ; The three-phase voltage u sabc And the three-phase voltage u on the grid side gabc Through the phase-locked loop module, the voltage phase θ of the circuit breaker converter side is obtained respectively. s and the grid side voltage phase of the circuit breaker θ g ; The three-phase voltage u sabc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component u of the converter side voltage is obtained. sd and the q-axis component u sq ; The three-phase current i abc and the voltage phase θ on the converter side of the circuit breaker s After the Park transformation module, the d-axis component i of the converter current is obtained. d and the q-axis component i q .

12. The network control device according to claim 10, characterized in that: The mathematical expression of the function of the pre-synchronization control module is: Among them, K pθ and K iθ K is the proportional coefficient and integral coefficient of the phase pre-synchronization PI link, pU and K iU are the proportional coefficient and integral coefficient of the amplitude pre-synchronization PI link, and s is the differential operator.

13. The network control device according to claim 10, characterized in that: The active power reference value P ref and converter active power P s The process of inputting the active power control module to control the active power output of the converter also includes: The active power control module will P ref and P s After the PI link, the initial value u of the q-axis voltage obtained by adding the pre-synchronization control is q0 , get the internal potential q-axis reference value u cq .

14. The network control device according to claim 13, characterized in that: The mathematical expression of the active power control module function is: Among them, K pp and K ip It is the proportional coefficient and integral coefficient of the active power control PI link.

15. The network control device according to claim 10, characterized in that: The active power reference value P ref and converter active power P s The step of inputting the active power control module to control the active power output of the converter also includes: The reactive power control module will Q ref Add the reactive power-voltage droop control link output, and Q s After the PI link, the initial value u of the d-axis voltage obtained by adding the pre-synchronization control is d0 , get the internal potential d-axis reference value u cd .

16. The network control device according to claim 15, characterized in that: The mathematical expression of the reactive power control module function is: Where K is the reactive power-voltage droop coefficient, K pq and K iq It is the proportional coefficient and integral coefficient of reactive power control PI link.

17. The network control device according to claim 1, characterized in that: In the virtual impedance module, the calculation formula of the virtual impedance is: R v +jX v =(R v1 +R v2 )+j(X v1 +X v2 ) Among them, R v and X v is the virtual resistance and virtual reactance, R v1 and X v1 is the virtual impedance often added in steady state, R v2 and X v2 It is the current limiting impedance added after the fault; R v2 and X v2 The calculation formula is: in, B=2[K v (R+R v1 )+X+X v1 ], K v For R v2 and X v2 The proportionality coefficient, R and X are the actual resistance and reactance between the converter and the grid, I max is the maximum overcurrent capacity of the converter.

18. The network control device according to claim 10, characterized in that: The mathematical expression of the virtual circuit module is: Where ω is the rated angular frequency of the system.

19. A terminal, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method according to any one of claims 1 to 9.

20. A computer-readable storage medium, characterized in that: Computer executable instructions are stored, and the computer executable instructions are used to execute the method according to any one of claims 1 to 9.

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