Low capacitance mmdtc-statcom control method based on carrier reconstruction

Abstract

This invention provides a low-capacitance MMDTC-STATCOM control method based on carrier reconstruction, relating to the field of power electronic converter control, which can simultaneously solve the problems of output voltage distortion and submodule capacitor voltage balance. The method includes: determining the capacitor voltage difference Δu of the submodule in the next sampling period k+1. c (k+1); based on the capacitor voltage reference value u c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_1 This is used to eliminate the influence of capacitor voltage ripple on the output voltage; based on the carrier u after the first carrier reconstruction. carry_1 capacitor voltage reference value u c * DC component U dc * Error proportionality coefficient ρ, and the direction of the bridge arm current sign(i) at time k+1. arm (k+1)), determine the carrier u after the second carrier reconstruction. carry_2 This is used to achieve capacitor voltage balancing in submodules; based on u carry_1 and u carry_2 Determine the carrier u after two reconstructions carry It is used for PWM modulation of each submodule.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion control, specifically to a low-capacitance MMDTC-STATCOM control method based on carrier reconstruction. Background Technology

[0002] A Static Synchronous Compensator (STATCOM) is a flexible AC transmission system (FACTS) device based on fully controlled power electronic devices (such as IGBTs and IGCTs). Its core function is to dynamically regulate reactive power, thereby quickly stabilizing grid voltage, improving power factor, and enhancing power quality.

[0003] With technological advancements, the low-capacitance modular multilevel DC-Link Based T-type converter (MMDTC) STATCOM has been introduced, employing fewer components and achieving higher conversion efficiency. The low-capacitance MMDTC-STATCOM utilizes the phase relationship between the submodule capacitor voltage and the bridge arm voltage (in phase for capacitive compensation, out phase for inductive compensation), allowing for larger ripple in the capacitor voltage.

[0004] However, submodule capacitor voltage balancing is a prerequisite for the stable operation of MMDTC-STATCOM, but the large capacitor voltage ripple under low capacitance operation is transmitted to the output voltage through pulse width modulation (PWM), causing harmonic distortion of the output voltage. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a low-capacity MMDTC-STATCOM control method based on carrier reconstruction.

[0006] This invention is achieved through the following technical solution:

[0007] This invention provides a low-capacitance MMDTC-STATCOM control method based on carrier reconfiguration. The low-capacitance MMDTC-STATCOM includes a bridge arm and a T-type structure. The bridge arm includes multiple cascaded sub-modules, and a capacitor is connected in parallel on the DC side of each sub-module. The method is characterized by including:

[0008] Determine the capacitor voltage difference Δu of the submodule in the next sampling period k+1. c (k+1), the Δu c (k+1) includes the AC component Δu c_ac (k+1) and DC component Δu c_dc(k+1), Δu c_ac (k+1) represents the voltage difference Δu between the capacitors of the submodules at time k+1. c The AC component, Δu c_dc (k+1) represents the voltage difference Δu between the capacitors of the submodules at time k+1. c DC component;

[0009] Based on the capacitor voltage reference value u c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_1 The carrier u after the first carrier reconstruction carry_1 Used to eliminate the impact of capacitor voltage fluctuations on the output voltage;

[0010] Based on the carrier u after the first carrier reconstruction carry_1 capacitor voltage reference value u c * DC component U dc * Error proportionality coefficient ρ, and the direction of the bridge arm current sign(i) at time k+1. arm (k+1)), determine the carrier u after the second carrier reconstruction. carry_2 This is to achieve balanced control of the capacitor voltage of the submodule;

[0011] Based on the carrier u after the first carrier reconstruction carry_1 and the carrier u after the second carrier reconstruction carry_2 Determine the carrier u after two reconstructions carry Through the reconstructed carrier u carry Determine the common modulation wave for the submodules.

[0012] Furthermore, the reference value u based on the capacitor voltage... c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_ 1. Includes:

[0013]

[0014] Among them, U dc * Represents the reference value of capacitor voltage u c *DC component, Δu c_ac (k+1) represents Δu at time k+1. c The exchange component, T c d(k+1) represents a carrier cycle, k0 represents the time corresponding to the amplitude symmetry center within a carrier cycle, k1 represents the time corresponding to the intersection of the modulated wave of the submodule with the right side of the initial carrier, and d(k+1) represents the derivative with respect to time k+1.

[0015] Furthermore, the reference value u based on the capacitor voltage... c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_1 After that, including:

[0016] The carrier u after the first carrier reconstruction carry_1 And the submodule turn-on time difference Δd between the first carrier reconstruction and the initial carrier, determine the amount to be added to the submodule output voltage u. arm Compensation variable voltage Δu arm ,

[0017]

[0018] Among them, S j The switch function representing the j-th submodule, γ j The variable d2 represents the rate of change of the j-th submodule relative to d1, where d1 represents the on-time of the submodule corresponding to the initial carrier; d2 represents the on-time of the submodule corresponding to the first carrier reconstruction, u cj This represents the capacitor voltage of the j-th submodule.

[0019] Furthermore, the carrier u reconstructed from the first carrier carry_1 capacitor voltage reference value u c * DC component U dc * Error proportionality coefficient ρ, and the direction of the bridge arm current sign(i) at time k+1. arm (k+1)), determine the carrier u after the second carrier reconstruction. carry_2 ,include:

[0020] u carry_2 =u carry_1 +ρΔu c_dc (k+1)*sign(i arm (k+1))

[0021]

[0022] Among them, u carry_1 The carrier wave represents the first reconstructed carrier, ρ represents the error scaling factor, and Δu c_dc (k+1) represents Δu at time k+1. c DC component, sign(i arm (k+1) represents the direction of the bridge arm current at time k+1, T c k represents a carrier cycle, and k0 represents the moment corresponding to the center of amplitude symmetry within a carrier cycle.

[0023] Furthermore, the carrier u reconstructed from the first carrier carry_1 capacitor voltage reference value u c * DC component U dc * Error proportionality coefficient ρ, and the direction of the bridge arm current sign(i) at time k+1. arm (k+1)), determine the carrier u after the second carrier reconstruction. carry_2 After that, including:

[0024] In determining Δu cj_dc When (k+1)=0, it is determined that the carrier u after the second carrier reconstruction is not needed. carry_2 ;

[0025] In determining Δu cj_dc (k+1)>0 or Δu cj_dc (k+1)<0, by constructing ρ, Δu cj_dc (k+1) and sign(i) arm The product of (k+1)) corrects the carrier signal, and dynamically compensates the carrier signal of the submodule.

[0026] Furthermore, the determination of Δu cj_dc (k+1)>0 or Δu cj_dc (k+1)<0, by constructing ρ, Δu cj_dc (k+1) and sign(i) arm The product of (k+1)) corrects the carrier signal, and performs dynamic compensation on the carrier signal, including:

[0027] When Δu c_dc Greater than 0 and sign(i) arm (k+1) is positive, and the carrier amplitude is increased by ρ to extend the conduction time of the submodule and accelerate the capacitor discharge.

[0028] Furthermore, the carrier u reconstructed from the first carrier carry_1 and the carrier u after the second carrier reconstruction carry_2Determine the carrier u after two reconstructions carry ,include:

[0029]

[0030] This embodiment provides a low-capacitance MMDTC-STATCOM control method based on carrier reconstruction. The method includes: determining the capacitor voltage difference Δu of the submodule in the next sampling period k+1. c (k+1); based on the capacitor voltage reference value u c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_1 Based on the carrier u after the first carrier reconstruction carry_1 capacitor voltage reference value u c * DC component U dc * Error proportionality coefficient ρ, and the direction of the bridge arm current sign(i) at time k+1. arm (k+1)), determine the carrier u after the second carrier reconstruction. carry_2 According to u carry_1 and u carry_2 Determine the carrier u after two reconstructions carry Through the reconstructed carrier u carry The common modulation waveform of the submodules is determined, thus avoiding harmonic distortion of the output voltage. Attached Figure Description

[0031] Figure 1(a) is a flowchart illustrating a low-capacity MMDTC-STATCOM control method based on carrier reconstruction according to an embodiment of the present invention;

[0032] Figure 1(b) is a topology diagram of MMDTC-STATCOM according to an embodiment of the present invention;

[0033] Figure 2 This is a diagram of the submodule structure in Figure 1;

[0034] Figure 3 This is a schematic diagram of the AC / DC component decomposition of the capacitor voltage of a submodule according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the carrier reconstruction steps according to an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the first carrier reconfiguration process in an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the second carrier reconstruction process in one embodiment of the present invention;

[0038] Figure 7 This invention implements the modulation wave and the reconstructed carrier PWM modulation process. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0040] Figure 1(a) is a flowchart illustrating a low-capacitance MMDTC-STATCOM control method based on carrier reconfiguration according to an embodiment of the present invention; Figure 1(b) is a topology diagram of an MMDTC-STATCOM according to an embodiment of the present invention; as shown in Figure 1(b), the low-capacitance MMDTC-STATCOM includes a bridge arm and a T-structure. The bridge arm includes multiple cascaded sub-modules, with a capacitor connected in parallel on the DC side of each sub-module. The bridge arm is divided into an upper bridge arm and a lower bridge arm, both of which are cascaded from multiple half-bridge sub-modules HBSM and one full-bridge sub-module FBSM. See also Figure 2 The submodule structure diagrams are shown in Figure 1. (a) shows the structure diagram of the half-bridge submodule, and (b) shows the structure diagram of the full-bridge submodule. Both the DC side of the half-bridge submodule and the DC side of the full-bridge submodule are equipped with a capacitor C.

[0041] As shown in Figure 1(a), the low-capacity MMDTC-STATCOM control method based on carrier reconstruction includes the following steps:

[0042] Step 101: Determine the capacitor voltage difference Δu of the submodule in the next sampling period k+1. c (k+1).

[0043] The Δu in this embodiment c (k+1) includes the AC component Δu c_ac (k+1) and DC component Δu c_dc (k+1), Δu c_ac (k+1) represents the voltage difference Δu between the capacitors of the submodules at time k+1. c The AC component, Δu c_dc (k+1) represents the voltage difference Δu between the capacitors of the submodules at time k+1. c DC component;

[0044] like Figure 3 As shown, u c * U represents a reference value for the capacitor voltage. dc * Represents the reference value of capacitor voltage u c* DC component; u c U represents the measured value of the capacitor voltage; dc The measured value of capacitor voltage u c DC component; Δu c The DC component of the capacitor voltage represents the difference between the measured value and the reference value; therefore, Δu c_dc and Δu c_ac Representing Δu c The DC and AC components.

[0045] from Figure 3 It can be seen that when the capacitor voltages of the submodules are unbalanced, the essence is the DC component U in the measured value of the capacitor voltage. dc The DC component U in the capacitor voltage reference value dc * This resulted in a deviation. Therefore, U can be... dc * As a reference value, the DC component U in the measured capacitor voltage value is... dc Follow U dc * This allows for balanced capacitor voltage control.

[0046] Submodule capacitor voltage difference Δu c It can be represented as:

[0047]

[0048] When the submodule capacitor voltage deviates from the reference value, Δu c Contains a certain DC component Δu c_dc , i.e. Δu c This can be further expressed as:

[0049] Δuc=Δuc _dc +Δuc _ac (2)

[0050] However, Δu c_dc That is, U dc with U dc * The difference. As analyzed above, the pulse deviation of the submodule output voltage mainly originates from the AC component of the submodule capacitor voltage. Therefore, to compensate for the pulse deviation, only Δu needs to be considered. c_ac .

[0051] Based on the above analysis, the following conclusions can be drawn: through Δu c The AC component Δu c_ac Constructing a carrier wave can compensate for the effects of capacitor voltage fluctuations and eliminate Δu. c_dcThis allows for balanced capacitor voltage control. This demonstrates that the two control objectives can be decoupled and regulated independently.

[0052] Based on the above analysis, the carrier can be reconfigured twice to achieve independent control of both components. The first carrier reconfiguration targets the AC component Δu. c_ac This achieves output voltage pulse impulse compensation regulation; the second carrier reconstruction targets the DC component Δu. c_dc This enables balanced voltage control of the capacitors in the submodules.

[0053] The specific implementation mechanism of carrier reconfiguration is as follows: Figure 4 As shown. To better match the modulated wave, carrier reconstruction will reconstruct the carrier of the next cycle within this sampling period. The predicted value of the submodule capacitor voltage is:

[0054]

[0055] Among them, u c (k) represents the measured value of the submodule capacitor voltage at time k; u c (k+1) represents the voltage value of the submodule capacitor predicted for the next sampling period at time k; i arm (k) represents the bridge arm current corresponding to the submodule capacitor at time k; T s S represents a sampling period; S is a switching function. When the submodule is activated at time k, S(k) = 1, otherwise S(k) = 0.

[0056] Get u c After (k+1), Δu at time k+1 can be calculated. c (k+1), as follows:

[0057]

[0058] Further Δu c Signal separation at time (k+1) yields Δu at time k+1. c_ac (k+1) and Δu c_dc (k+1) is then used for the first carrier reconstruction and the second carrier reconstruction, respectively.

[0059] Step 102: Based on the capacitor voltage reference value u c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_1 .

[0060] The carrier u after the first carrier reconstruction in this embodiment carry_1Used to eliminate the impact of capacitor voltage fluctuations on the output voltage;

[0061] like Figure 5 As shown, the implementation mechanism of the first carrier reconfiguration is given, V ref The submodule modulation wave represents the first carrier wave; d1 represents the submodule conduction time corresponding to the initial carrier wave; d2 represents the submodule conduction time corresponding to the first carrier reconfiguration; Δd represents the conduction time difference between the first carrier reconfiguration and the initial carrier wave; T c It represents one carrier cycle.

[0062] from Figure 5 It can be observed that, based on the volt-second balance principle, by introducing Δu c_ac Adjusting the carrier wave by (k+1) can compensate for the submodule's output voltage. Using the similar triangle rule, this can be achieved from... Figure 4 The carrier after the first carrier reconstruction is derived from the derivation.

[0063] u carry_1 The mathematical expression:

[0064]

[0065] Among them, U dc * Represents the reference value of capacitor voltage u c * DC component; Δu c_ac (k+1) represents Δu at time k+1. c The exchange component; T c T C k represents one carrier cycle; k0 represents the time corresponding to the amplitude symmetry center within one carrier cycle, that is, the time point when the carrier waveform reaches its trough; k1 represents the time corresponding to the intersection point of the submodule modulation wave and the right side of the initial carrier.

[0066] Similarly, by the rule of similar triangles, we can... Figure 5 Conclusion:

[0067]

[0068] Here, Δd represents the turn-on time difference between the first carrier reconstruction and the initial carrier corresponding to the submodule.

[0069] Transforming equation (6) yields:

[0070]

[0071] Furthermore, we can conclude that:

[0072] d2=(1-γ)d1 (8)

[0073] wherein γ is the rate of change of d2 relative to d1. It can be concluded from the analysis that when Δu cj_ac (k+1)>0, γ>0 and d2<d1; when Δu cj_ac (k+1)=0, γ=0 and d2=d1; when Δu cj_ac (k+1)<0, γ<0 and d2>d1.

[0074] Through the first carrier reconstruction, the bridge arm output voltage u arm can be expressed as:

[0075]

[0076] wherein S j represents the switching function of the j-th submodule; γ represents the rate of change of d2 relative to d1 of the j-th submodule, u cj represents the capacitor voltage of the j-th submodule.

[0077] Let the above formula can be further expressed as:

[0078]

[0079] That is, Δu arm is a compensation variable added to u arm to eliminate the influence of capacitor voltage fluctuation on the output voltage.

[0080] In this embodiment, the first carrier reconstruction performs output voltage pulse amplitude compensation mainly for the AC component of the capacitor voltage ripple, so as to improve the quality of the output voltage waveform.

[0081] Step 103: Determine the carrier u after the second carrier reconstruction based on the carrier u after the first carrier reconstruction carry_1 , the capacitor voltage reference value u c * the DC component U dc * , the error proportional coefficient ρ, and the bridge arm current direction sign(i arm (k+1)) at time k+1, so as to realize the balance control of the submodule capacitor voltage; carry_2

[0082] For example, the second carrier reconstruction aims to eliminate Δu c_dc , since Δu c_dc will not be very large, Δu c_dc can be effectively eliminated by adjusting the error proportional coefficient ρ. Wherein, the specific value of ρ can be dynamically optimized according to the capacitor voltage equalization effect.

[0083] Figure 6This demonstrates the mechanism for the second carrier reconstruction, which is performed based on the result of the first carrier reconstruction. The specific formula is as follows:

[0084] u carry_2 =u carry_1 +ρΔu c_dc (k+1)*sign(i arm (k+1))

[0085]

[0086] Among them, u carry_1 The carrier wave represents the first reconstruction; ρ represents the error scaling factor; Δu c_dc (k+1) represents Δu at time k+1. c DC component; sign(i arm (k+1) represents the direction of the bridge arm current at time k+1; T c k represents a carrier cycle; k0 represents the moment corresponding to the center of amplitude symmetry within a carrier cycle.

[0087] From the above equation, we can obtain that when Δu cj_dc When (k+1)=0, no secondary reconstruction is needed. If Δu cj_dc (k+1)>0 or Δu cj_dc (k+1)<0, by constructing ρ, Δu cj_dc (k+1) and sign(i) arm The carrier signal is dynamically compensated by multiplying the carrier voltage by (k+1), ultimately eliminating the DC deviation of the capacitor voltage. For example, the DC component deviation Δu of the submodule capacitor voltage is extracted in real time. c_dc (k+1) (i.e., the difference between the actual voltage and the reference value), using sign(i arm (k+1) detects the polarity of the bridge arm current to determine the charging or discharging state of the submodule. ρ serves as an adjustable gain to control the response speed and amplitude of dynamic correction. For example, when Δu c_dc Greater than 0 and sign(i) arm When (k+1) is positive, the capacitor needs to discharge. The carrier amplitude is increased by ρ, extending the conduction time of this submodule and accelerating capacitor discharge. The essence of dynamic equalization is to change the PWM pulse duty cycle by shifting the intersection point of the modulated wave and the corrected carrier, thereby directionally adjusting the input and output times of the submodule and achieving real-time compensation for voltage errors.

[0088] In this embodiment, the second carrier reconstruction mainly targets the DC component deviation of the capacitor voltage ripple to achieve precise capacitor voltage equalization control.

[0089] Step 104: Based on the carrier u after the first carrier reconstruction carry_1and the carrier u after the second carrier reconstruction carry_2 Determine the carrier u after two reconstructions carry , used for PWM modulation of submodules.

[0090] Specifically, the carrier wave after two reconstructions can be represented as:

[0091]

[0092] After obtaining the bridge arm output voltage reference value, the common modulation wave of the submodules can be determined. For example... Figure 7 As shown, the obtained modulated wave is modulated with the reconstructed carrier wave using PWM. When the modulated wave is greater than the reconstructed carrier wave, the submodule is activated; otherwise, the submodule is deactivated.

[0093] In this embodiment, the capacitor voltage difference Δu of the submodule in the next sampling period k+1 is determined. c (k+1), the Δu c (k+1) includes the AC component Δu c_ac (k+1) and DC component Δu c_dc (k+1), Δu c_ac (k+1) represents the voltage difference Δu between the capacitors of the submodules at time k+1. c The AC component, Δu c_dc (k+1) represents the voltage difference Δu between the capacitors of the submodules at time k+1. c The DC component; then, based on the capacitor voltage reference value u c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_1 The carrier u after the first carrier reconstruction carry_1 This is used to eliminate the impact of capacitor voltage fluctuations on the output voltage; then, based on the carrier u after the first carrier reconstruction... carry_1 capacitor voltage reference value u c * DC component U dc * Error proportionality coefficient ρ, and the direction of the bridge arm current sign(i) at time k+1. arm (k+1)), determine the carrier u after the second carrier reconstruction. carry_2 This is to achieve balanced control of the capacitor voltage of the submodule; then, based on the carrier u after the first carrier reconstruction... carry_1 and the carrier u after the second carrier reconstruction carry_2 Determine the carrier u after two reconstructions carryThrough the reconstructed carrier u carry Determine the common modulation waveform for each submodule. This can be achieved simply by upgrading the control algorithm, without adding sensors or changing the main circuit structure. It is unaffected by changes in capacitor values: maintaining stable waveform quality and capacitor voltage balance across different capacitance values.

[0094] This embodiment proposes a dual-objective carrier reconstruction control strategy, which can independently control both output waveform distortion compensation and capacitor voltage equalization. This resolves the contradictions and limitations arising from the coupling of control objectives in traditional methods.

[0095] In this embodiment, independent optimization control of voltage equalization and waveform quality is achieved through two-step carrier reconstruction. That is, a predictive model is used to predict the capacitor voltage of the next sampling period. Based on the predicted AC and DC components of the capacitor voltage ripple, the first and second carrier reconstruction amounts are calculated respectively, the carrier amplitude is dynamically adjusted, and the output voltage pulse distortion is compensated to achieve accurate capacitor voltage equalization.

[0096] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A low-capacitance MMDTC-STATCOM control method based on carrier reconfiguration, wherein the low-capacitance MMDTC-STATCOM includes a bridge arm and a T-structure, the bridge arm comprising multiple cascaded sub-modules, and a capacitor connected in parallel on the DC side of each sub-module, characterized in that, include: Determine the submodule in the next sampling period capacitor voltage difference The Including communication components and DC component , Representative at k +1 Time Submodule Capacitor Voltage Difference The amount of communication, Representative at k +1 Time Submodule Capacitor Voltage Difference DC component; Based on capacitor voltage reference value DC component , exchange quantity carrier period Determine the carrier after the first carrier reconstruction. ， The Used to eliminate the impact of capacitor voltage fluctuations on the output voltage; Based on the carrier after the first carrier reconstruction ， Capacitor voltage reference value DC component Error proportionality coefficient , k Direction of bridge arm current at time +1 Determine the carrier after the second carrier reconstruction. This is to achieve balanced control of the capacitor voltage of the submodule; Based on the carrier ucarry_1 after the first carrier reconstruction and the carrier ucarry_2 after the second carrier reconstruction, determine the carrier ucarry after the two reconstructions; where, The reference value of capacitor voltage DC component , exchange quantity carrier period Determine the carrier after the first carrier reconstruction. ,include: ； in, k 0 represents the moment corresponding to the center of amplitude symmetry within one carrier cycle. k 1 represents the time corresponding to the intersection point of the modulated wave of the submodule with the right side of the initial carrier wave. d ( k +1) represents the... k The differential at time +1; The reference value of capacitor voltage DC component , exchange quantity carrier period Determine the carrier after the first carrier reconstruction. After that, including: pass And the turn-on time difference between the first carrier reconstruction and the initial carrier corresponding to the submodule Determine the submodule output voltage to add. Compensation variable voltage , ， in, Representing the j The switch functions for each submodule, Representing the j Submodules d 2 relative to d The rate of change of 1 d 1 represents the on-time of the submodule corresponding to the initial carrier; d 2 represents the on-time of the submodule corresponding to the first carrier reconfiguration. Representing the j Individual module capacitor voltage; The carrier reconstructed from the first carrier capacitor voltage reference value DC component Error proportionality coefficient , k Direction of bridge arm current at time +1 Determine the carrier after the second carrier reconstruction. ,include: 。 2. The low-capacity MMDTC-STATCOM control method based on carrier reconfiguration according to claim 1, characterized in that, The carrier reconstructed from the first carrier capacitor voltage reference value DC component * Error proportionality coefficient , k Direction of bridge arm current at time +1 Determine the carrier after the second carrier reconstruction. After that, including: In determining When it is determined that the carrier reconstructed from the second carrier is not needed, ; In determining or By building , and The product of the carrier wave is used to dynamically compensate the carrier signal of the submodule.

3. The low-capacity MMDTC-STATCOM control method based on carrier reconfiguration according to claim 2, characterized in that, The determination or By building , and The product-corrected carrier performs dynamic compensation on the carrier signal, including: when Greater than 0 and For positive, through To increase the carrier amplitude and extend the conduction time of the submodule, thereby accelerating capacitor discharge.

Images