A multi-port optical storage hybrid power generation modulation method and system based on current ripple suppression

Abstract

The present application relates to the technical field of light storage hybrid power generation control, and particularly to a multi-port light storage hybrid power generation modulation method and system based on current ripple suppression. The method comprises obtaining grid-side voltage and current data; determining a space vector sector according to a reference voltage vector of the grid-side voltage and current data; constructing a clamping sequence based on a reference sector of the space vector sector; establishing a current ripple model according to the clamping sequence and selecting a minimum ripple clamping sequence; deriving a double modulation wave of the minimum ripple clamping sequence based on a volt-second balance; and performing carrier comparison and driving output based on the double modulation wave. The present application systematically gives all clamping switch sequences and determines the influence type of the clamping switch sequences on system power, so that dynamic power regulation among photovoltaic units, energy storage units and loads of a multi-port light storage hybrid power generation system can be realized on the basis of reducing switch loss and improving system efficiency.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic-storage hybrid power generation control technology, and in particular to a multi-port photovoltaic-storage hybrid power generation modulation method and system based on current ripple suppression. Background Technology

[0002] Due to its advantages such as being green, environmentally friendly, and pollution-free, photovoltaic (PV) power generation has developed rapidly. However, PV power generation is limited by the environment, exhibiting significant intermittency and randomness. Power generation and load often fail to reach a balance, further affecting the stability of the entire power grid system. PV energy storage systems can store excess electricity generated by the PV system during off-peak hours to fill the load gap; and release the stored energy during peak hours to compensate for the power difference between the PV system and the load, thus reducing peak load. Because it can reduce the peak-to-valley load difference in the power grid and balance power generation and consumption, PV energy storage systems have broad application prospects.

[0003] In photovoltaic energy storage systems, using a dual-DC-port inverter as a single power conversion stage is a feasible solution, with its DC side directly connected to the photovoltaic unit and the energy storage unit. However, in-depth research by the inventors revealed significant challenges to this approach: the photovoltaic output voltage and the energy storage unit voltage dynamically change with environmental conditions (such as light intensity, temperature, and state of charge). This inherent DC-side voltage fluctuation directly leads to increased current ripple. Furthermore, to balance system efficiency and control switching losses, measures such as limiting switching operations are often necessary, which further exacerbates current ripple under voltage fluctuations. Ultimately, increased current ripple degrades the system's current quality, adversely affecting overall operational stability and efficiency. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a multi-port photovoltaic-storage hybrid power generation modulation method and system based on current ripple suppression.

[0005] In a first aspect, the present invention provides a multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression, which adopts the following technical solution: A multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression includes: Acquire grid-side voltage and current data; The spatial vector sector is determined based on the reference voltage vector of the grid-side voltage and current data; A clamping sequence is constructed based on the reference sector of the spatial vector sector; A current ripple model is established based on the clamping sequence, and the minimum ripple clamping sequence is selected; Dual-modulated wave based on volt-second balance derivation of minimum ripple clamping sequence; Carrier comparison and output are based on dual-modulation waves.

[0006] Furthermore, determining the spatial vector sector based on the reference voltage vector of the grid-side voltage and current data includes placing the reference voltage vector in... αβ Represented in a stationary coordinate system, the sector located in the space voltage vector diagram is determined based on the phase angle of the reference voltage vector. When the sector is not the preset reference sector I, it is rotated and mirrored symmetrically mapped to the reference sector I for unified vector synthesis and sequence selection. Specifically, based on the collected three-phase power grid voltage data... αβ Transformation, to obtain αβ Grid voltage components in coordinate system u α , u β , is represented as: Then the reference voltage vector is obtained. V ref = u α + ju β Simultaneously, based on the balance between DC-side power and AC-side power, the target power of the energy storage unit is obtained, expressed as: ,in, P ac This refers to AC-side power and AC-side grid voltage. u x_RMS and the effective value of AC side grid current i x_RMS Decision, expressed as ; P pv It is the power of the photovoltaic unit, which is determined by the DC-side voltage of the photovoltaic unit. V pv With current i pv Decision, expressed as The actual power of the energy storage unit is determined by the DC-side voltage of the energy storage unit. V bat With current i bat Decision, expressed as DC bus voltage imbalance coefficient k Defined as the ratio of the voltage difference between the upper and lower capacitors to the DC bus voltage: .

[0007] Furthermore, the step of determining the space vector sector based on the reference voltage vector of the grid-side voltage and current data also includes determining the space vector sector based on the reference voltage vector. V ref exist αβ Grid voltage components in coordinate system uα , u β Perform phase angle calculation: The reference voltage vector is obtained based on the phase angle. V ref In sector N of the space voltage vector diagram: When sector N is not the preset reference sector I, the phase angle is processed as follows: The reference voltage vector is rotated and mirrored to map it to the reference sector I for unified vector synthesis and sequence selection.

[0008] Furthermore, the clamping sequence construction based on the space vector sector of the reference sector includes 16 types of clamping sequences based on the adaptive discontinuous pulse width modulation method within the reference sector I. These are classified according to clamping characteristics into P-type clamping sequence (PCM), N-type clamping sequence (NCM), and O-type clamping sequence (OCM). When sector I is the reference sector, the 16 clamping sequences are: 1) PCM-1: POO - PPO - PPP - PPO - POO; 2) PCM-2: PON - POO - PPO - POO - PON; 3) PCM-3: PON - PPN - PPO - PPN - PON; 4) PCM-4: POO - PON - PNN - PON - POO; 5) PCM-5: POO - PPO - PPN - PPO - POO; 6) PCM-6: POO - PON - PPN - PON - POO; 7) NCM-1: OON - ONN -NNN - ONN - OON; 8) NCM-2: ONN - OON - PON - OON - ONN; 9) NCM-3: OON - PON -PPN - PON - OON; 10) NCM-4: ONN - PNN - PON - PNN - ONN; 11) NCM-5: OON - ONN -PNN - ONN - OON; 12) NCM-6: OON - PON - PNN - PON - ONN; 13) OCM-1: OON - OOO -POO - OOO - OON; 14) OCM-2: OON - PON - POO - PON - OON; 15) OCM-3: ONN-OON-OOO-OON-ONN; 16) OCM-4: OOO-POO-PPO-POO-OOO; where PCM constitutes a candidate set of charging clamping sequences, NCM constitutes a candidate set of discharging clamping sequences, and OCM determines its power flow direction based on the relationship between the three-phase current direction and the vector duration, thereby determining whether it belongs to the charging candidate set or the discharging candidate set.

[0009] Furthermore, the step of establishing a current ripple model based on the clamping sequence and selecting the minimum ripple clamping sequence includes overlapping the applicable regions of multiple clamping sequences to obtain multiple overlapping regions; for any applicable region of a clamping sequence, the following condition must be met: when using the clamping sequence to synthesize a reference voltage vector, the dwell time of each phase level state corresponding to it should satisfy the non-negativity constraint and the summation constraint, that is: T xP ≥ 0, T xO ≥ 0, T xN ≥ 0, and T xP + T xO + T xN = T s , x∈{a,b,c}; where, T xP , T xO , T xN They are phases x In one PWM cycle T s The dwell time corresponds to the high-level state P, the zero-level state O, and the low-level state N. When dividing the overlapping area, a power control availability constraint is introduced, requiring that at least one charging clamping sequence and one discharging clamping sequence exist simultaneously in the same overlapping area.

[0010] Furthermore, the step of establishing a current ripple model based on the clamping sequence and selecting the clamping sequence with minimum ripple also includes selecting a charging or discharging clamping sequence based on power hysteresis control, wherein the input of the power hysteresis comparator is the power regulation deviation Δ. P bat = P* bat - P bat The hysteresis bandwidth is h Its output H Satisfy: When Δ P bat > h hour, H= 1 and select the discharge-type clamping sequence of the current overlapping region to discharge the energy storage unit; when Δ P bat < - h hour, H = -1 and select the charging clamping sequence of the current overlapping region to charge the energy storage unit; when |Δ P bat | ≤ h hour, H To maintain the previous output and prevent the current sequence type from changing, thus Δ P bat Within the hysteresis bandwidth of the regulated loop; then, output current ripple modeling is performed for multiple clamping sequences of the same type. Within the action range of each voltage vector, the voltage across the filter inductor L is considered constant, causing the three-phase current ripple to change linearly with a slope; phase x Current ripple slope λ x Defined as: ,in, v xo ( x = a , b , c () represents the output voltage of the dual DC port inverter; i x ( x = a , b , c () represents the output current; u x ( x = a , b , c () is the AC side output base frequency voltage. u on Indicates the midpoint of a three-phase load. n With reference point o The voltage between them, taking into account the unbalance factor k right v xo The impact, that is, ,get λ x Will follow k change.

[0011] Furthermore, the step of establishing a current ripple model based on the clamping sequence and selecting the minimum ripple clamping sequence also includes using the root mean square of the three-phase current ripple as a ripple evaluation index. i x_ripThe effective value RMS within 1 / 2 carrier cycle ( i x_rip The calculation is as follows: ,in λ x1 , λ x2 , λ x3 ( x = a , b , c () represent the current ripple slopes of the first, second, and third voltage vectors in the clamping sequence, respectively. t 1. t 2. t 3 represents the duration of action of the first, second, and third voltage vectors in the clamping sequence, respectively. Finally, the selection... I RMS_rip The candidate clamping sequence with the smallest square value is taken as the current minimum ripple clamping sequence.

[0012] Furthermore, the dual-modulation wave derived from the minimum ripple clamping sequence based on volt-second balance includes establishing the equivalent vector action time relationship of the current minimum ripple clamping sequence within one PWM cycle, based on the volt-second balance between the DC and AC sides: The duration of different states in the clamping sequence was derived, and based on the three switch state transition types "O-P-O", "N-O-N", and "O-N-O" of 16 clamping sequences, the dwell time was mapped to a dual-modulation wave matching the clamping sequence. The dual-modulation wave is used to characterize the duty cycle relationship of the power switches of each bridge arm of the multi-port inverter.

[0013] Furthermore, the carrier comparison and drive output based on the dual-modulation wave includes obtaining a dual-modulation wave that matches the minimum ripple clamping sequence, and employing a triangular carrier wave with an amplitude variation following a 1-0-1 pattern. And triangular carrier waves that follow the amplitude variation pattern of (-1)-0-(-1). Compare the two modulated waves to synthesize a three-level switching state: (1) In each PWM cycle, the modulated wave m x1 With the upper triangular carrier Comparison: When m x1 ≥ At that time, a high-level drive signal is generated and applied to the switching transistor. S x1 Then, within each PWM cycle, when the modulated wave m x2When ≥0, it is related to the upper triangular carrier. When comparing, m x2 ≥ At that time, a high-level drive signal is generated and applied to the switching transistor. S x2 When the modulated wave m x2 When <0, it is related to the lower triangular carrier. When comparing, m x2 > At that time, a high-level drive signal is generated and applied to the switching transistor. S x2 This yields a PWM drive signal that satisfies the minimum ripple clamping sequence order and dwell time allocation.

[0014] Secondly, a multi-port photovoltaic-storage hybrid power generation modulation system based on current ripple suppression includes: The data acquisition module is configured as follows: Thirdly, the present invention provides a computer-readable storage medium storing a plurality of instructions adapted to be loaded and executed by a processor of a terminal device as described in the multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression.

[0015] Fourthly, the present invention provides a terminal device, including a processor and a computer-readable storage medium, wherein the processor is used to implement various instructions; the computer-readable storage medium is used to store multiple instructions, the instructions being adapted to be loaded and executed by the processor to provide the multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression.

[0016] In summary, the present invention has the following beneficial technical effects: 1. This invention systematically provides all clamping switch sequences and determines their impact on system power. It can realize dynamic power regulation among photovoltaic units, energy storage units and loads in a multi-port photovoltaic-storage hybrid power generation system while reducing switching losses and improving system efficiency.

[0017] 2. This invention addresses the inherent characteristics of DC voltage fluctuations in photovoltaic and energy storage units during system operation by establishing a specific mathematical model for current ripple. Based on this model, the clamping sequence that can achieve the minimum current ripple on the DC side is calculated and selected online in real time for application, thereby significantly reducing current ripple and improving grid-connected current quality.

[0018] 3. To address the complexity of allocating independent carrier signals for different clamping sequences, this invention proposes a dual-modulation wave driving strategy. This scheme requires only one pair of standardized carrier signals to generate driving signals for all clamping sequences, significantly simplifying the driving implementation process. The control algorithm is simple and easy to implement. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a typical photovoltaic-storage hybrid power generation system using a dual DC-port inverter as a separate power conversion stage, as provided in Embodiment 1 of the present invention. Figure 2 The following is a typical switching state and corresponding current path diagram of a dual-DC-port inverter provided in Embodiment 1 of the present invention; Figure 3 This is a typical space vector state diagram of a dual-DC-port inverter provided in Embodiment 1 of the present invention; Figure 4 This is the current path diagram corresponding to the space vector PPN provided in Embodiment 1 of the present invention; Figure 5 This is the current path diagram corresponding to the space vector OOO provided in Embodiment 1 of the present invention; Figure 6 This is the current path diagram corresponding to the space vector PPO provided in Embodiment 1 of the present invention; Figure 7 This is the current path diagram corresponding to the space vector OON provided in Embodiment 1 of the present invention; Figure 8 This is the current path diagram corresponding to the space vector PON provided in Embodiment 1 of the present invention; Figure 9 A diagram showing the applicable areas of PCM-1, 2, 3, 4 and OCM-4 provided in Embodiment 1 of the present invention; Figure 10 A diagram showing the applicable areas of NCM-1, 2, 3, 4 and OCM-3 provided in Embodiment 1 of the present invention; Figure 11 This is a diagram showing the applicable areas of OCM-1 and OCM-2 provided in Embodiment 1 of the present invention; Figure 12 This is a diagram showing the applicable areas of PCM-5 and 6 provided in Embodiment 1 of the present invention; Figure 13 This is a diagram showing the applicable areas of NCM-5 and 6 provided in Embodiment 1 of the present invention; Figure 14 This is a diagram of the overlapping region of the clamping sequence during low-profile regime provided in Embodiment 1 of the present invention; Figure 15 This is a diagram of the overlapping region of the clamping sequence during the mid-to-high modulation regime provided in Embodiment 1 of the present invention; Figure 16This is a diagram showing the overlapping region of the clamping sequence during low-frequency regimes provided in Embodiment 1 of the present invention. Figure 17 This is a diagram of the overlapping region of the high-modulation clamping sequence provided in Embodiment 1 of the present invention; Figure 18 This is a schematic diagram of the DC-side power hysteresis control method provided in Embodiment 1 of the present invention; Figure 19 This is the single-phase AC side equivalent circuit diagram of the dual DC port inverter provided in Embodiment 1 of the present invention; Figure 20 This is a schematic diagram of the three-phase inductor voltage and corresponding current ripple under different voltage vectors in the PCM-2 sequence provided in Embodiment 1 of the present invention; Figure 21 This is a schematic diagram of the generation of dual modulation waves and drive signals for the O-P-O switch state transition type provided in Embodiment 1 of the present invention; Figure 22 This is a schematic diagram of the generation of dual-modulation wave and drive signal for N-O-N switch state transition type provided in Embodiment 1 of the present invention; Figure 23 This is a schematic diagram of the generation of dual-modulation wave and drive signal of O-N-O switch state transition type provided in Embodiment 1 of the present invention; Figure 24 The switching transistor in the dual-modulation wave strategy provided in Embodiment 1 of the present invention S x1 and S x3 , S x2 and S x4 Flowchart of drive signal generation; Figure 25 This is a control block diagram of the multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression provided in Embodiment 1 of the present invention; Figure 26 This is a graph showing the variation of energy storage power ratio with imbalance coefficient and modulation index provided in Embodiment 1 of the present invention; Figure 27 This is a comparison diagram of the minimum current ripple between the traditional discontinuous pulse width modulation method and the proposed method provided in Embodiment 1 of the present invention; Figure 28 The above are simulation results of the energy storage unit power supply condition of the proposed method provided in Embodiment 1 of the present invention; Figure 29 The above are simulation results of the combined power supply conditions of the photovoltaic and energy storage units in the proposed method provided in Embodiment 1 of the present invention. Figure 30 The simulation results provided in Embodiment 1 of the present invention are for the photovoltaic power supply and energy storage unit supply conditions of the proposed method; Figure 31 The simulation results of the photovoltaic unit power supply condition provided in Embodiment 1 of the present invention are for the proposed method. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings.

[0021] Example 1 Reference Figure 1 This embodiment of a multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression includes: Acquire and process parameters. Acquire the three-phase voltage, three-phase current, and DC-side voltage parameters of the grid side, as well as the DC-side voltage and current parameters of the photovoltaic unit / energy storage unit, to obtain reference quantities for modulation and power control. These reference quantities include at least a reference voltage vector. V ref Energy storage unit target power P* bat and the actual power of the energy storage unit P bat Imbalance coefficient k ; The space vector sector is determined based on the reference voltage vector. The reference voltage vector is then... αβ Represented in a stationary coordinate system, and its sector in the space voltage vector diagram is determined based on the phase angle of the reference voltage vector; when the sector is not the preset reference sector I, it is mapped to the reference sector I by rotation or mirror symmetry to perform unified vector synthesis and sequence selection; A clamping sequence is constructed within a reference sector I. Within the reference sector I, 16 clamping switch sequences adapted to discontinuous pulse width modulation are constructed, and the applicable region of each clamping sequence within the sector is determined. Based on the applicable region of the clamping sequence, the overlapping region of power control is determined. Multiple overlapping regions are obtained by overlapping the applicable regions of multiple clamping sequences; among them, the overlapping regions that can be used for power control must satisfy the following condition: within the same overlapping region, there must be at least one charging clamping sequence and one discharging clamping sequence simultaneously, so as to achieve stable adjustment under different power directions; Power hysteresis control determines the current overlapping region and selects a set of charging / discharging clamping sequences. The power regulation deviation Δ is obtained based on the difference between the target power and the actual power of the energy storage unit. P bat and Δ P bat Input power hysteresis comparator; in Δ P bat When within the hysteresis bandwidth, the hysteresis comparator output remains unchanged, in Δ P batWhen the hysteresis bandwidth is exceeded, the hysteresis comparator output is flipped; based on the hysteresis comparator output, the current clamping sequence type to be selected is determined to be either charging or discharging, thereby determining the current candidate clamping sequence set within the power control overlap region; A current ripple model is established, and the minimum ripple clamping sequence is selected. For the determined set of current candidate clamping sequences, a corresponding three-phase current ripple model is established: within each voltage vector's effective range, the voltage across the inductor is treated as a constant, causing the three-phase current ripple to vary linearly with a slope; considering the unbalance coefficient... k Under dynamic conditions, the ripple evaluation index corresponding to the candidate clamping sequence is calculated, and the clamping sequence with the smallest ripple evaluation index is selected as the current minimum ripple clamping sequence to improve current quality. The dual-modulation wave of the minimum ripple sequence is derived based on the volt-second balance. Based on the obtained current minimum ripple clamping sequence, the equivalent vector action time relationship of the sequence within one PWM cycle is established, and the dual-modulation wave matching the clamping sequence is derived based on the volt-second balance. The dual-modulation wave is used to characterize the duty cycle relationship of the power switches of each bridge arm of the multi-port inverter. Carrier Comparison and Drive Output. The obtained dual-modulated wave is compared with a triangular carrier to generate a drive signal. The drive signals for the remaining power switches are obtained by utilizing the complementary drive relationship of the power switches in the same bridge arm. Finally, the gate drive pulse used to drive the inverter of the multi-port photovoltaic-storage hybrid power generation system is output.

[0022] Specifically, it includes the following steps: S1. Acquire and process parameters. These include system topology, switch states, current paths, space vector diagrams, and reference voltage vectors. V ref Energy storage unit target power P* bat and the actual power of the energy storage unit P bat Imbalance coefficient k This includes the following: 1) Switch state definition: such as Figure 1 As shown, this is the topology of a photovoltaic-storage hybrid power generation system using a dual-DC-port inverter as a separate power conversion stage. The dual-DC-port inverter can operate with variable voltages in both the photovoltaic unit and the energy storage unit. In each phase of the dual-DC-port inverter, S x1 , S x2 , S x3 and S x4 ( x = a , b , cThere are four power switching transistors. IGBTs can be used as the switching transistors. Their DC sides are connected to the photovoltaic unit and the energy storage unit, respectively. The midpoint of each phase arm is filtered. L Connected to the load. The photovoltaic unit voltage and the energy storage unit voltage are denoted as follows: V pv and V bat Each phase's output is represented by one of three switching states: [P], [O], and [N]. These three different switching states can be achieved by controlling the on and off states of the power switching transistors. With the positive terminal of the energy storage unit as the reference point, the output voltages are respectively... V pv - V bat 0 and - V bat The relationship between the switching state and the output phase voltage is shown in the following equation: , in, x = a , b , c ,express a , b , c Three phases, v xo This represents the output voltage of each phase of a dual DC-port inverter. V pv Indicates photovoltaic voltage. V bat This indicates the voltage of the energy storage unit.

[0023] 2) Current path definition: such as Figure 2 The diagram illustrates the current paths of a dual-DC port inverter under different switching states. When the switching state Sx = P, the corresponding current path is for the photovoltaic unit to supply power to the AC side; when the switching state Sx = O, there are two current paths: the energy storage unit supplies power to the AC side or the AC side charges the energy storage unit; when the switching state Sx = N, the system operates in freewheeling mode.

[0024] The relationship between the output phase voltage and the conduction of the power switch is shown in Table 1 below.

[0025] Table 1: Relationship between output phase voltage and power switch conduction of dual DC port inverter P <![CDATA[ S x1 , S x2 ]]> <![CDATA[ V pv - V bat ]]> O <![CDATA[ S x2 , S x3 ]]> 0 N <![CDATA[ S x3 , S x4 ]]> <![CDATA[- V bat ]]> 3) Definition of spatial vector map: using V PV - V Bat < V batFor example, Figure 3 The figure shows the space vector state diagram of a photovoltaic energy storage system using a dual-DC-port inverter as a separate power conversion stage. It can be seen that the dual-DC-port inverter has a total of 27 (3) 3 ( ) Switching states, by changing the power switching transistor S x1 ~ S x4 By controlling the on / off state, the dual-DC port inverter can output 27 different three-phase sinusoidal AC voltages. αβ In a coordinate system, using 27 switch states ( S a S b S c The space vectors corresponding to these 27 three-phase sinusoidal AC voltages are represented by , which yields the space vector state diagram. However, because the DC side of the dual-DC-port inverter is connected to both photovoltaic and energy storage units, its asymmetrical DC bus voltage characteristics make the space vector distribution of this topology significantly different from that of the traditional three-level inverter structure.

[0026] It can be seen that due to the asymmetry of the DC bus voltage, some vectors corresponding to the 27 switching states of the dual DC port inverter will deviate from their original characteristics, and the phase angle and amplitude of the corresponding sinusoidal AC voltage output will no longer remain constant. Specifically, among these 27 switching states, the corresponding space vector categories include zero vector, negative small vector, positive small vector, medium vector, and large vector. The zero vectors include PPP, OOO, and NNN, whose corresponding sinusoidal AC voltage phase angle and amplitude remain unchanged, both being 0. The negative small vectors include ONN, NON, NNO, OON, NOO, and ONO, whose corresponding sinusoidal AC voltage phase angle remains unchanged, but the amplitude changes. The positive small vectors include POO, OPO, OOP, PPO, OPP, and POP, whose corresponding sinusoidal AC voltage phase angle remains unchanged, but the amplitude changes, and the trend is opposite to that of the negative small vectors. The medium vectors include PON, NPO, ONP, OPN, NOP, and PNO, whose corresponding sinusoidal AC voltage phase angle and amplitude both change. The large vectors include PNN, NPN, NNP, PPN, NPP, and PNP, whose corresponding sinusoidal AC voltage phase angle and amplitude remain unchanged.

[0027] 4) Reference voltage vector V ref : Based on the collected three-phase power grid voltage data αβ Transformation, to obtain αβ Grid voltage components in coordinate system u α , uβ , is represented as: Then the reference voltage vector is obtained. V ref = u α + ju β ; 5) Target power of energy storage unit P* bat and the actual power of the energy storage unit P bat : Simultaneously, based on the balance relationship between DC-side power and AC-side power, the target power of the energy storage unit can be obtained, expressed as: ,in, P ac This refers to AC-side power and AC-side grid voltage. u x_RMS and the effective value of AC side grid current i x_RMS Decision, expressed as ; P pv It is the power of the photovoltaic unit, which is determined by the DC-side voltage of the photovoltaic unit. V pv With current i pv Decision, expressed as The actual power of the energy storage unit is determined by the DC-side voltage of the energy storage unit. V bat With current i bat Decision, expressed as .

[0028] 6) Imbalance coefficient k DC bus voltage imbalance coefficient k It can be defined as the ratio of the voltage difference between the upper and lower capacitors to the DC bus voltage: .

[0029] S2. Determine the space vector sector based on the reference voltage vector.

[0030] Based on the collected three-phase power grid voltage data αβ After transformation, the obtained reference voltage vector V ref exist αβ Grid voltage components in coordinate system u α , u β Perform phase angle calculation: Based on the phase angle, the space vector state diagram can be divided into 6 equal sectors. Reference voltage vector. V refIn sector N of the space voltage vector diagram: , When sector N is not the preset reference sector I, the phase angle is processed as follows: The reference voltage vector can be rotated or mirrored and mapped to the reference sector I for unified vector synthesis and sequence selection.

[0031] In sector I, the zero vectors are PPP, OOO, and NNN; the negative small vectors are ONN and OON; the positive small vectors are POO and PPO; the medium vector is PON; and the large vectors are PNN and PPN. Further, as... Figures 4 to 8 As shown, based on the switching states and corresponding current paths, the vectors and their corresponding current paths are analyzed. It can be seen that, except for the large voltage vector and the zero vector, other vectors affect the energy storage unit current, thus further affecting the energy storage unit power. Specifically, since the large vector PPN is disconnected from the energy storage unit, it has no effect on the energy storage unit current. Although the zero vector OOO is connected to the energy storage unit, the total current is zero. Therefore, it does not affect the energy storage unit power. For the positive small vector PPO, since the three phases are connected between the positive DC link and the energy storage unit, current flows into the energy storage unit, and the surplus electrical energy generated by photovoltaic power generation is used to charge the energy storage unit. For the negative small vector OON, since the three phases are connected between the energy storage unit and the negative DC link, the deficit power demand is compensated by the energy storage unit. Similarly, the medium vector PON also affects the power flow of the energy storage unit; depending on the direction of the current connected to the energy storage unit, power either flows into or out of the energy storage unit.

[0032] As shown above, different vectors correspond to different energy storage unit currents. Therefore, given a fixed photovoltaic unit power, peak shaving and valley filling of the energy storage unit can be achieved by switching vectors.

[0033] S3: Construct the clamping sequence within the reference sector I.

[0034] In the traditional continuous pulse width modulation (PWM) method, each change in the switching state of a dual-DC-port inverter within one PWM cycle causes only one phase's switching state to change, resulting in a total of 6 changes in the switching state within one PWM cycle. In contrast, the discontinuous PWM method clamps one phase of the dual-DC-port inverter to a constant state within one PWM cycle, resulting in a total of 4 changes in the switching state within one PWM cycle, significantly reducing switching losses.

[0035] In sector I, there are 16 types of clamping sequences adapted to discontinuous pulse width modulation methods, which can be divided into P-type clamping sequences (PCM), N-type clamping sequences (NCM), and O-type clamping sequences (OCM). Details are shown below.

[0036] 1) PCM-1: POO - PPO - PPP - PPO - POO; 2) PCM-2: PON - POO - PPO - POO- PON; 3) PCM-3: PON - PPN - PPO - PPN - PON; 4) PCM-4: POO - PON - PNN - PON -POO; 5) PCM-5: POO - PPO - PPN - PPO - POO; 6) PCM-6: POO - PON - PPN - PON -POO; 7) NCM-1: OON - ONN - NNN - ONN - OON; 8) NCM-2: ONN - OON - PON - OON -ONN; 9) NCM-3: OON - PON - PPN - PON - OON; 10) NCM-4: ONN - PNN - PON - PNN -ONN; 11) NCM-5: OON - ONN - PNN-ONN- OON; 12) NCM-6: OON - PON - PNN - PON -ONN; 13) OCM-1: OON - OOO - POO - OOO - OON; 14) OCM-2: OON - PON - POO - PON -OON; 15) OCM-3: ONN-OON-OOO-OON-ONN; 16) OCM-4: OOO-POO-PPO-POO-OOO; Different types of clamping sequences utilize different vectors, resulting in significant differences in their power regulation effects. Specifically, P-type clamping sequences function when the photovoltaic unit's power generation exceeds the AC-side load power demand (i.e., there is a power surplus). As a charging sequence, its switching combination directs excess energy to the energy storage unit for charging. N-type clamping sequences are activated when photovoltaic power generation is below the load demand (i.e., there is a power deficit). As a discharging sequence, its switching combination activates the energy storage unit to discharge and supplement the load power. O-type clamping sequences determine their power flow direction based on the relationship between the direction of the three-phase current and the vector duration, thus identifying whether they are charging or discharging sequences. Based on this close correlation between clamping sequences and power flow direction, by dynamically switching between charging and discharging clamping sequences, precise control of system energy flow is achieved, ultimately fulfilling the core function of peak shaving and valley filling for the energy storage unit.

[0037] S4: Determine the overlapping area of ​​power control based on the applicable area of ​​the clamping sequence.

[0038] For any clamping sequence to be applicable, the following conditions must be met: when using this clamping sequence to synthesize a reference voltage vector, the dwell time of each phase level state should satisfy the non-negativity constraint and the summation constraint, that is: T xP ≥ 0, T xO ≥0, T xN ≥ 0, and T xP + T xO + T xN = T s , x∈{a,b,c}; where, T xP , T xO , T xN They are phases x In one PWM cycle T s The dwell time corresponding to the high-level state P, the zero state O, and the low-level state N.

[0039] Based on the above, the boundary conditions for each clamping sequence can be specifically given. Table 2. Boundary conditions for clamping sequences PCM-1 POO-PPO-PPP-PPO-POO <![CDATA[√3 V α + V β <√3(1+ k ) / 2]]> PCM-2 PON-POO-PPO-POO-PON Except for PCM-1, 3, and 4 PCM-3 PON-PPN-PPO-PPN-PON <![CDATA[√3 kV α + V β >√3(1+ k ) 2 / 4]]> PCM-4 POO-PON-PNN-PON-POO <![CDATA[√3 V α - V β <√3(1+ k ) / 4]]> PCM-5 POO-PPO-PPN-PPO-POO <![CDATA[ V α >- kV β / √3+(1+ k ) / 2 and except for PCM-4]]> PCM-6 POO-PON-PPN-PON-POO <![CDATA[ V α <- kV β / √3+(1+ k ) / 2 and except for PCM-1]]> NCM-1 OON-ONN-NNN-ONN-OON <![CDATA[√3 V α + V β <√3(1- k ) / 2]]> NCM-2 ONN-OON-PON-OON-ONN Except for NCM-1, 3, and 4 NCM-3 OON-PON-PPN-PON-OON <![CDATA[ V β >√3(1- k ) / 4]]> NCM-4 ONN-PNN-PON-PNN-ONN <![CDATA[(2+6 k ) V β <√3(1- k )(2 V α -1+ k )]]> NCM-5 OON-ONN-PNN-ONN-OON <![CDATA[(3+ k ) V β <√3(1- k (1-) V α And except for NCM-1]]> NCM-6 OON-PON-PNN-PON ONN <![CDATA[(3+ k ) V β <√3(1- k (1-) V α In addition to NCM-3<!-- 9 --> ]]> OCM-1 OON-OOO-POO-OOO-OON <![CDATA[(2+6 k ) V β <-√3(1- k )(2 V α -1- k )]]> OCM-2 OON-PON-POO-PON-OON Except for PCM-4, NCM-3, and OCM-1 OCM-3 ONN-OON-OOO-OON-ONN <![CDATA[√3 V α + V β <√3(1- k ) / 2]]> OCM-4 OOO-POO-PPO-POO-OOO <![CDATA[√3 V α + V β <√3(1+ k ) / 2]]> like Figures 9 to 13 As shown, with the imbalance coefficient k Taking -0.2 as an example, the applicable regions of 16 clamping sequences are shown. It can be seen that overlapping the applicable regions of multiple clamping sequences results in multiple overlapping regions. Among these, the overlapping regions that can be used for power control must satisfy the following condition: within the same overlapping region, there must simultaneously exist at least one charging clamping sequence and one discharging clamping sequence, so that stable adjustment can be achieved under different power directions. For example... Figures 14 to 17 As shown, different overlapping regions that can be used for power control are presented.

[0040] S5: Power hysteresis control determines the current overlapping region and selects the set of charging / discharging clamping sequences.

[0041] It is important to note that the high-frequency switching between charging and discharging clamping sequences is detrimental to reducing switching losses and may even impair power quality. Therefore, as... Figure 18 As shown, a hysteresis control method for DC-side power is proposed, which reduces the switching frequency of the clamping sequence while satisfying power control requirements.

[0042] The hysteresis control formula is as follows: , in, h This represents the hysteresis bandwidth, which defines the permissible range of power regulation deviation for the energy storage unit. Reference value. The target power of the energy storage unit is the difference between the AC side power and the photovoltaic unit power.

[0043] When the difference between the actual power of the energy storage unit and the target power (i.e., the power regulation deviation Δ) P bat When the power deviation is less than the hysteresis bandwidth, the output H of the hysteresis comparator remains unchanged. At this time, the clamping sequence continues to operate in its current type, controlling the energy storage unit's absorption or release of energy. As the adjustment process continues, this power deviation may gradually increase until it exceeds the hysteresis bandwidth. Once the deviation exceeds the bandwidth, the hysteresis comparator changes its output state. The change in the hysteresis comparator output H triggers a clamping sequence update, thereby adjusting the power flow of the energy storage unit. When H = 1, a discharge-type clamping sequence is used, and the energy storage unit discharges; when H = -1, a charging-type clamping sequence is used, and the energy storage unit charges. This adjustment aims to bring the actual power deviation back to the hysteresis bandwidth. h Within the permissible range.

[0044] S6: Establish the current ripple model and select the minimum ripple clamping sequence.

[0045] After selecting the charging or discharging clamping sequence based on power hysteresis control, it is urgent to establish clear standards to determine the selection criteria for the specific clamping sequence. A strategy is proposed to select the clamping sequence from multiple clamping sequences based on improving current quality, as detailed below.

[0046] While the proposed strategy balances switching loss optimization and power control, vector selection introduces differentiated current ripple slope characteristics, resulting in specific output current ripple for different clamping sequences. Of particular note is the effect of varying imbalance coefficients... k During dynamic adjustment, the slope of the current ripple corresponding to the vector will change, which in turn will cause changes in the output current ripple of the clamping sequence. High-amplitude current ripple will significantly degrade current quality, forcing the filter inductor parameters to be upgraded, thereby reducing the system power density. Therefore, the imbalance coefficient... k Analyzing the slope of the dynamically adjusted vector current ripple and selecting a low-amplitude current ripple clamping sequence is crucial.

[0047] First, model the vector-based output current ripple. For example... Figure 19 As shown, the equivalent circuit of the single-phase AC side of a dual-DC-port inverter is represented by the following mathematical model: , in, v xo ( x = a , b , c () represents the output voltage of the dual DC port inverter; i x ( x = a , b , c () represents the output current; u x ( x = a , b , c () is the AC side output base frequency voltage. u on Indicates the midpoint of a three-phase load. n With reference point o The voltage between them. u on and u x The calculation is as follows: , in, ( x = a , b , c ) is the reference voltage vector.

[0048] Referring to the circuit model, the voltage across the filter inductor is expressed as: , Under each voltage vector, the voltage across the inductor is considered constant, while the corresponding current ripple varies linearly. The current ripple slope is... λ x ( x = a , b , c For the voltage vectors used in the 14 clamping sequences, based on the above formula, the corresponding three-phase current ripple slope is... λ x The calculations are shown in Table 3. It can be seen that for a dual-DC-port inverter, except for the three-phase current ripple slope corresponding to the zero vector which is the same, the three-phase current ripple slopes corresponding to the other voltage vectors are all different, and will vary with the unbalance coefficient. k Change for the sake of change.

[0049] Table 3: Three-phase current ripple slope of sector I OOO <![CDATA[( u b + u c -2 u a ) / (3 L )]]> <![CDATA[( u a + u c -2 u b ) / (3 L )]]> <![CDATA[( u a + u b -2 u c ) / (3 L )]]> PPP <![CDATA[( u b + u c -2 u a ) / (3 L )]]> <![CDATA[( u a + u c -2 u b ) / (3 L )]]> <![CDATA[( u a + u b -2 u c ) / (3 L )]]> NNN <![CDATA[( u b + u c -2 u a ) / (3 L )]]> <![CDATA[( u a + u c -2 u b ) / (3 L )]]> <![CDATA[( u a + u b -2 u c ) / (3 L )]]> POO <![CDATA[[(1+ k ) V pv / 3- u a ] / L ]]> <![CDATA[[-(1+ k ) V pv / 6- u b ] / L ]]> <![CDATA[[-(1+ k ) V pv / 6- u c ] / L ]]> ONN <![CDATA[[(1- k ) V pv / 3- u a ] / L ]]> <![CDATA[[-(1- k ) V pv / 6- u b ] / L ]]> <![CDATA[[-(1- k ) V pv / 6- u c ] / L ]]> PPO <![CDATA[[(1+ k ) V pv / 6- u a ] / L ]]> <![CDATA[[(1+ k ) V pv / 6- u b ] / L ]]> <![CDATA[[-(1+ k ) V pv / 3- u c ] / L ]]> OON <![CDATA[[(1- k ) V pv / 6- u a ] / L ]]> <![CDATA[[(1- k ) V pv / 6- u b ] / L ]]> <![CDATA[[-(1- k ) V pv / 3- u c ] / L ]]> PON <![CDATA[[(3- k ) V pv / 6- u a ] / L ]]> <![CDATA[[- kV pv / 3- u b ] / L ]]> <![CDATA[[(-3+ k ) V pv / 6- u c ] / L ]]> PPN <![CDATA[[(1+ k ) V pv / 3- u a ] / L ]]> <![CDATA[[(1+ k ) V pv / 3- u b ] / L ]]> <![CDATA[[-(2- k ) V pv / 3- u c ] / L ]]> PNN <![CDATA[[(2+ k ) V pv / 3- u a ] / L ]]> <![CDATA[[-(1- k ) V pv / 3- u b ] / L ]]> <![CDATA[[-(1- k ) V pv / 3- u c ] / L ]]>

[0050] like Figure 20 As shown, taking the P-type clamping sequence PCM-2: PON - POO - PPO - POO - PON as an example, the three-phase inductor voltage and corresponding current ripple under different voltage vectors are given. Among them, i x_ref ( x = a , b , c () indicates the output current i x The ideal value; i x_rip ( x = a , b , c The value represents the output current ripple, which is calculated as follows: , Current ripple i x_rip The current ripple varies periodically within one carrier cycle. Therefore, this patent uses the current ripple within half a carrier cycle. i x_rip To quantitatively calculate the effective value of current ripple within one carrier cycle. For x Phase current, current ripple i x_rip The effective value RMS within 1 / 2 carrier cycle ( i x_rip The calculation is as follows.

[0051] , in λ x1 , λ x2 , λ x3 ( x = a , b , c See Table 2, which represents the current ripple slopes of the first, second, and third voltage vectors in the clamping sequence, respectively.

[0052] Based on the above formula, the effective value of the three-phase current ripple RMS ( i a_rip ) , RMS i b_rip ) , RMS i c_rip The average effective value of ) I RMS_ripThe following calculation can be performed. To reduce computational complexity, let... I RMS_rip The square value is used to reflect the magnitude of the three-phase current ripple.

[0053] , Based on the above formula, we can select the one with the smallest... I RMS_rip The clamping sequence of the square value is used to reduce current ripple and improve current quality.

[0054] S7: Derive the dual-modulation wave of the minimum ripple sequence based on volt-second balance.

[0055] Based on the obtained minimum ripple clamping sequence, the modulation wave will be analytically derived to simplify the implementation of the clamping sequence. A dual modulation wave driving different switches is designed, where modulation wave 1 is compared with the upper carrier of alternating inverted stacked carriers to generate the modulation wave for the switching transistors. S x1 and S x3 The driving signal; while the modulated wave 2 is compared with the alternating anti-phase stacked carrier wave to generate the driving signal for... S x2 and S x4 The driving signal. Thus, 16 clamping sequences can be achieved via a carrier wave without the need to pre-store a large number of voltage vector states.

[0056] Based on the volt-second balance between the DC and AC sides, the duration of different states in the clamping sequence can be determined, specifically: , in, u x ( x = a , b , c () is the AC side output base frequency voltage; T xP , T xO and T xN ( x = a , b , c The dwell time for the "P", "O" and "N" states, respectively. Taking the P-type clamping sequence PCM-2: PON - POO - PPO - POO - PON as an example, it can be seen that, , Substituting the above equation into the volt-second balance formula, we can obtain... , Analysis of 16 clamping sequences revealed three switch-state transition types: "O - P - O", "N - O - N", and "O - N - O". Traditional methods typically require three carriers with specific amplitude characteristics: the first follows a "1 - 0 - 1" amplitude variation pattern, the second "0 - (-1) - 0" pattern, and the third "(-1) - 0 - (-1)" pattern. This approach has a significant drawback—different clamping sequences require modulation on different carriers, necessitating the simultaneous maintenance of multiple drive signal generation mechanisms. This significantly increases the complexity of the control system and incurs additional hardware resource consumption. To address this bottleneck, this invention innovatively proposes a dual-modulation wave control strategy. While maintaining the ability to generate full-sequence drive signals, it reduces the required number of carriers by 33%, effectively simplifying the system architecture and improving control efficiency. Figures 21 to 23 As shown, the generation of dual-modulation waves and drive signals for these three types of switch state transitions is explained.

[0057] The formulas for the dual-modulation waves with the three switching state transition types are as follows: , For the P-type clamping sequence PCM-2, which satisfies the "O - P - O" and "N - O - N" switching state transition types, the dual modulation wave formula of PCM-2 is: , Furthermore, we can see that t1, t2, and t3 in PCM-2 are respectively: , This results in a dual-modulation wave that matches the clamping sequence, which is used to characterize the duty cycle relationship of the power switches of each arm of the multi-port inverter.

[0058] S8: Carrier Comparison and Drive Output.

[0059] The obtained dual-modulated wave is compared with a triangular carrier wave to generate a drive signal, due to the switching transistor. S x1 and S x3 , S x2 and S x4 The driving signals have complementary characteristics, therefore only need to generate S x1 , Sx2 The drive signal is sufficient to fully control the bridge arm. For example... Figure 24 As shown, the switching transistors in the dual-modulation wave strategy are given. S x1 and S x3 , S x2 and S x4 The drive signal generation process follows these specific rules: (1) In each PWM cycle, the modulated wave m x1 With the upper triangular carrier Comparison: When m x1 ≥ At that time, a high-level drive signal is generated and applied to the switching transistor. S x1 .

[0060] (2) During each PWM cycle, when the modulated wave m x2 When ≥0, it is related to the upper triangular carrier. When comparing, m x2 ≥ At that time, a high-level drive signal is generated and applied to the switching transistor. S x2 When the modulated wave m x2 When <0, it is related to the lower triangular carrier. When comparing, m x2 > At that time, a high-level drive signal is generated and applied to the switching transistor. S x2 The final output is the gate drive pulse used to drive the inverter of the multi-port photovoltaic-storage hybrid power generation system.

[0061] like Figure 25 As shown, the control process of this invention includes: collecting the DC voltage and current of the photovoltaic port and the energy storage port, as well as the three-phase voltage and current on the grid-connected side, and calculating the photovoltaic power, energy storage power, AC power, and imbalance coefficient, respectively. k The power deviation Δ at the energy storage port is generated based on the power balance relationship and power command. P bat And determine the appropriate charging / discharging clamping sequence type through power hysteresis control; αβThe phase angle of the reference voltage vector is calculated in the coordinate system, and the spatial vector sector is determined. After mapping the non-reference sector to sector I, a clamping switch sequence adapted to discontinuous pulse width modulation is constructed, and the power control overlap region is divided. In the overlap region, a three-phase current ripple mathematical model is established for the candidate clamping sequences, and the ripple evaluation index is calculated online. The clamping sequence with the smallest ripple is selected as the current optimal sequence. Based on the vector dwell time of the optimal clamping sequence and the volt-second balance, the corresponding dual modulation wave is derived. The dual modulation wave is compared with the carrier to generate the gate drive signal, and the complementary drive relationship of the bridge arm switches is used to output the drive pulses of the remaining switches. Thus, by changing the dwell time of the switch state coupled with the energy storage port, the charging and discharging power of the energy storage port can be continuously controlled, while reducing the current ripple.

[0062] like Figure 26 As shown, the energy storage power ratio is given. P bat / P ac With the unbalance coefficient k And the modulation index change graph. When P bat / P ac When <0, the system is in a photovoltaic-energy storage (charging) combined working mode; when P bat / P ac When =0, the system is in photovoltaic-only operation mode; when P bat / P ac When the value is greater than 0, the system operates in a photovoltaic-energy storage (discharge) combined mode; while when... P bat / P ac When =1, the system is in energy storage only operation mode.

[0063] like Figure 27 As shown, a comparison of the minimum current ripple between the traditional discontinuous pulse width modulation method and the proposed method is presented. It can be seen that the proposed method significantly reduces the current ripple, indicating an effective improvement in current quality.

[0064] like Figures 28 to 31 The figure shown is a simulation result diagram of the multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression in this embodiment. From top to bottom, it records the simulated waveforms of photovoltaic power, energy storage unit power, A-phase current, line voltage, and three-phase voltage under four operating conditions. The main parameters are as follows: Photovoltaic voltage... V pv =120V; Energy storage unit voltage V bat=72V / 90V; AC side load resistance =10Ω; AC side reference current i d =5A; Switching frequency f s =10kHz; Filter inductor L = 2.5mH. Simulation results show that when the photovoltaic voltage... V pv 120V and energy storage unit voltage V bat At 90V, the system can stably achieve a single energy storage power supply mode at night, with the energy storage unit providing 375W of power to the load and the photovoltaic unit having no output. When the photovoltaic voltage... V pv Maintaining 120V while energy storage voltage V bat When the voltage drops to 72V, the system precisely implements multiple daytime power regulation modes: the energy storage unit can selectively supply power (100W), absorb power (i.e., charge, 100W), or remain idle (neither charging nor discharging); correspondingly, the output power of the photovoltaic unit is flexibly adjusted to 275W, 475W, or 375W. This precise allocation of multiple power states fully covers the core requirements of peak shaving and valley filling in photovoltaic-energy storage systems, effectively verifying the superior capabilities of the control strategy of this invention in dynamic power regulation and allocation among photovoltaic units, energy storage units, and loads. The total harmonic distortion (THD) of the grid-connected current corresponding to these four operating states is as low as 3.14%, 2.34%, 2.09%, and 2.45%, respectively. These excellent current quality indicators further corroborate the effectiveness of the modulation method of this invention in suppressing ripple and improving waveform accuracy. Furthermore, the phase voltage waveform exhibits obvious clamping phenomena under different operating conditions (some switching transistors remain in the same state). This directly reflects the key role played by the clamp sequence optimization strategy and hysteresis control method proposed in this invention in actively reducing switching actions, reducing the switching losses of the system, and verifying its contribution to improving the overall efficiency of the system.

[0065] Thus far, Example 1 has systematically presented the present invention from the aspects of system topology and parameter acquisition, reference quantity calculation, and... αβ The complete implementation process includes transformation, spatial vector sector discrimination, construction of clamping sequence within sector, determination of power control overlapping region, DC-side power hysteresis decision charging / discharging sequence, establishment of candidate sequence current ripple model and online selection of minimum ripple sequence, analytical derivation of dual modulation wave based on volt-second balance, carrier comparison and gate drive output; the above constitutes a detailed implementation method that expresses the core technical contributions of this invention in a "patented, step-by-step, and engineering-oriented" manner.

[0066] Example 2 This embodiment provides a multi-port photovoltaic-storage hybrid power generation modulation system based on current ripple suppression, presented in a modular form to facilitate engineering implementation, software encapsulation, and patent claim drafting. The system includes, but is not limited to, the following functional modules: The parameter acquisition and processing module is configured to: collect the three-phase voltage and three-phase current of the grid side, the DC bus voltage, the DC side voltage and current of the photovoltaic unit, and the DC side voltage and current of the energy storage unit, and calculate the reference voltage vector, the target power of the energy storage unit, the actual power of the energy storage unit, and the imbalance coefficient based on the sampled data; The sector discrimination module is configured to: represent the reference voltage vector as... αβ A stationary coordinate system is used, and the spatial voltage vector sector to which it belongs is determined according to the phase angle. When the sector is not the reference sector I, the reference voltage vector is rotated or mirrored to the reference sector I. The clamp sequence construction module is configured to: construct multiple clamp switch sequences adapted to discontinuous pulse width modulation within the reference sector I, and calculate the applicable region of each clamp sequence.

[0067] The overlapping region determination module is configured to: obtain the overlapping region by intersecting the applicable regions of each clamping sequence, and determine the overlapping region that can be used for power control according to the constraint that the same overlapping region contains at least one charging clamping sequence and one discharging clamping sequence; The power hysteresis control module is configured to: obtain the power deviation based on the difference between the target power and the actual power of the energy storage unit; keep the current sequence type unchanged within the hysteresis bandwidth; and switch the hysteresis output when it exceeds the hysteresis bandwidth to determine whether the charging or discharging clamping sequence set should be selected in the current overlapping area. The current ripple modeling and minimum ripple sequence selection module is configured to: establish a three-phase current ripple piecewise linear model for the clamping sequence set and calculate the ripple evaluation index, and select the clamping sequence with the smallest ripple evaluation index from the candidate clamping sequences as the current minimum ripple sequence; The dual modulation wave derivation module is configured to: derive the corresponding dual modulation wave based on the vector action time relationship of the minimum ripple sequence and the volt-second balance, and use it to determine the duty cycle relationship of each bridge arm of the dual DC port inverter in one PWM cycle; The PWM carrier comparison and drive output module is configured to: compare the dual-modulated wave with the triangular carrier to generate a drive pulse for the switching transistors, and generate drive signals for the remaining switching transistors by utilizing the complementary drive relationship of the power switches in the same bridge arm to output the gate drive signal.

[0068] A computer-readable storage medium storing a plurality of instructions adapted for loading and execution by a processor of a terminal device of the multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression.

[0069] A terminal device includes a processor and a computer-readable storage medium, the processor being used to implement various instructions; the computer-readable storage medium being used to store multiple instructions, the instructions being adapted to be loaded and executed by the processor to provide a multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression.

[0070] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression, characterized in that, include: Acquire grid-side voltage and current data; The spatial vector sector is determined based on the reference voltage vector of the grid-side voltage and current data; A clamping sequence is constructed based on the reference sector of the spatial vector sector; A current ripple model is established based on the clamping sequence, and the minimum ripple clamping sequence is selected; Dual-modulated wave based on volt-second balance derivation of minimum ripple clamping sequence; Carrier comparison and output drive are based on dual modulation waves; The clamping sequence construction based on the reference sector of the space vector sector includes 16 types of clamping sequences based on the adaptive discontinuous pulse width modulation method within the reference sector I. These are classified according to clamping characteristics into P-type clamping sequence (PCM), N-type clamping sequence (NCM), and O-type clamping sequence (OCM). When sector I is the reference sector, the 16 clamping sequences are: 1) PCM-1: POO - PPO - PPP - PPO - POO; 2) PCM-2: PON - POO - PPO - POO - PON; 3) PCM-3: PON - PPN - PPO - PPN - PON; 4) PCM-4: POO - PON - PNN - PON - POO; 5) PCM-5: POO - PPO - PPN - PPO - POO; 6) PCM-6: POO - PON - PPN - PON - POO; 7) NCM-1: OON - ONN - NNN -ONN - OON; 8) NCM-2: ONN - OON - PON - OON - ONN; 9) NCM-3: OON - PON - PPN -PON - OON; 10) NCM-4: ONN - PNN - PON - PNN - ONN; 11) NCM-5: OON - ONN - PNN -ONN - OON; 12) NCM-6: OON - PON - PNN - PON - ONN; 13) OCM-1: OON - OOO - POO -OOO - OON; 14) OCM-2: OON - PON - POO - PON - OON; 15) OCM-3: ONN-OON-OOO-OON-ONN; 16) OCM-4: OOO-POO-PPO-POO-OOO; Among them, PCM constitutes a candidate set of charging clamping sequence, NCM constitutes a candidate set of discharging clamping sequence, and OCM determines its power flow direction based on the relationship between the three-phase current direction and the vector duration, thereby determining whether it belongs to the charging candidate set or the discharging candidate set. The process of establishing a current ripple model based on the clamping sequence and selecting the minimum ripple clamping sequence includes overlapping the applicable regions of multiple clamping sequences to obtain multiple overlapping regions. For any applicable region of a clamping sequence, the following condition must be met: when using the clamping sequence to synthesize a reference voltage vector, the dwell time of each phase level state should satisfy the non-negativity constraint and the summation constraint, i.e.: T xP ≥ 0, T xO ≥ 0, T xN ≥ 0, and T xP + T xO +T xN = T s , x∈{a,b,c}; where, T xP T xO T xN Each phase x is a PWM period T. s The dwell time corresponds to the high-level state P, the zero-level state O, and the low-level state N. When dividing the overlapping area, a power control availability constraint is introduced, requiring that at least one charging clamping sequence and one discharging clamping sequence exist simultaneously in the same overlapping area.

2. The multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression according to claim 1, characterized in that, The process of determining the spatial vector sector based on the reference voltage vector of the grid-side voltage and current data includes representing the reference voltage vector in the αβ stationary coordinate system and determining the sector located in the spatial voltage vector diagram based on the phase angle of the reference voltage vector. When the sector is not a preset reference sector I, it is rotated and mirrored symmetrically mapped to the reference sector I for unified vector synthesis and sequence selection. Specifically, the αβ transformation is performed based on the collected three-phase grid voltage data to obtain the grid voltage component u in the αβ coordinate system. α u β , is represented as: , where u a u b u c These represent the phase voltages of phase a, phase b, and phase c on the grid side, respectively; then, the reference voltage vector V is obtained. ref = u α + ju β Simultaneously, based on the balance between DC-side power and AC-side power, the target power of the energy storage unit is obtained, expressed as: , where P ac This refers to the AC-side power and the AC-side grid voltage u. x_RMS and the effective value i of the AC side grid current x_RMS Decision, expressed as ;P pv It is the power of the photovoltaic unit, which is determined by the DC-side voltage V of the photovoltaic unit. pv With current i pv Decision, expressed as The actual power of the energy storage unit is determined by the DC-side voltage V of the energy storage unit. bat With current i bat Decision, expressed as The unbalance coefficient k of the DC bus voltage is defined as the ratio of the voltage difference between the upper and lower capacitors to the DC bus voltage: .

3. The multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression according to claim 2, characterized in that, The step of determining the spatial vector sector based on the reference voltage vector of the grid-side voltage and current data also includes determining the spatial vector sector based on the reference voltage vector V. ref The grid voltage component u in the αβ coordinate system α u β Phase angle calculation: θ = mod (atan2(u β ,u α ), 2π); The reference voltage vector V is obtained based on the phase angle. ref In sector N of the space voltage vector diagram: When sector N is not the preset reference sector I, the phase angle is processed as follows: The reference voltage vector is rotated and mirrored to map it to the reference sector I for unified vector synthesis and sequence selection.

4. The multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression according to claim 3, characterized in that, The step of establishing a current ripple model based on the clamping sequence and selecting the clamping sequence with minimum ripple also includes selecting a charging or discharging clamping sequence based on power hysteresis control, wherein the input of the power hysteresis comparator is the power regulation deviation. The hysteresis bandwidth is h, and its output H satisfies: when ΔP bat When ΔP > h, H = 1 and the discharge-type clamping sequence of the current overlapping region is selected to discharge the energy storage unit; when ΔP bat When < -h, H = -1 and the charging clamping sequence of the current overlapping region is selected to charge the energy storage unit; when |ΔP bat When | ≤ h, H keeps the output from the previous time step unchanged to maintain the current sequence type without switching, thus allowing ΔP to remain unchanged. bat Within the hysteresis bandwidth of the regulated loop; then, output current ripple modeling is performed for multiple clamping sequences of the same type. Within the action interval of each voltage vector, the voltage across the filter inductor L is considered constant, causing the three-phase current ripple to change linearly with a slope; the current ripple slope λ of phase x. x Defined as: , where v xo (x=a,b,c) represents the output voltage of the dual DC-port inverter; i x (x=a,b,c) represents the output current; u x (x=a,b,c) is the AC side output fundamental frequency voltage, u on This represents the voltage between the neutral point n and the reference point o of a three-phase load, considering the unbalance factor k on v. xo The impact, that is, , thus obtaining λ x It will change with k.

5. A multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression according to claim 4, characterized in that, The step of establishing a current ripple model based on the clamping sequence and selecting the minimum ripple clamping sequence also includes using the root mean square of the three-phase current ripple as a ripple evaluation index, where the current ripple i x_rip The effective value RMS(i) within 1 / 2 carrier cycle x_rip The calculation is as follows: , where λ x1 , λ x2 , λ x3 (x=a,b,c) represent the current ripple slopes of the first, second, and third voltage vectors in the clamping sequence, respectively, and t1, t2, and t3 represent the durations of the first, second, and third voltage vectors in the clamping sequence, respectively. Finally, I is selected. RMS_rip The candidate clamping sequence with the smallest square value is taken as the current minimum ripple clamping sequence.

6. The multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression according to claim 5, characterized in that, The dual-modulation wave derived from the minimum ripple clamping sequence based on volt-second balance includes establishing the equivalent vector action time relationship of the current minimum ripple clamping sequence within one PWM cycle, based on the volt-second balance between the DC and AC sides: The duration of different states in the clamping sequence was derived, and based on the three switch state transition types "O-P-O", "N-O-N", and "O-N-O" of 16 clamping sequences, the dwell time was mapped to a dual-modulation wave matching the clamping sequence. , where m x1 m x2 These represent the first and second modulation waves corresponding to the xth wave, respectively; the dual modulation waves are used to characterize the duty cycle relationship of the power switches of each arm of the multi-port inverter.

7. A multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression according to claim 6, characterized in that, The carrier comparison and drive output based on dual-modulation waves includes obtaining a dual-modulation wave that matches the minimum ripple clamping sequence, and using a triangular carrier wave with amplitude variation following a 1-0-1 pattern. And triangular carrier waves that follow the amplitude variation pattern of (-1)-0-(-1). Compare the two modulated waves to synthesize the three-level switching state: (1) In each PWM cycle, the modulated wave m x1 With the upper triangular carrier Comparison: When m x1 ≥ At that time, a high-level drive signal is generated and applied to the switching transistor S. x1 Then, within each PWM cycle, when the modulated wave m x2 When ≥0, it is related to the upper triangular carrier. Comparison, when m x2 ≥ At that time, a high-level drive signal is generated and applied to the switching transistor S. x2 When the modulated wave m x2 When <0, it is related to the lower triangular carrier. Comparison, when m x2 > At that time, a high-level drive signal is generated and applied to the switching transistor S. x2 This yields a PWM drive signal that satisfies the minimum ripple clamping sequence order and dwell time allocation.

8. A multi-port photovoltaic-storage hybrid power generation modulation system based on current ripple suppression, executing the multi-port photovoltaic-storage hybrid power generation modulation method based on current ripple suppression as described in claim 1, characterized in that, include: The data acquisition module is configured to acquire grid-side voltage and current data; The vector module is configured to determine the space vector sector based on the reference voltage vector of the grid-side voltage and current data. The clamping sequence module is configured to construct a clamping sequence based on the reference sector of the space vector sector; The current ripple module is configured to build a current ripple model based on the clamping sequence and select the minimum ripple clamping sequence. The dual-modulation wave module is configured to generate a dual-modulation wave based on the volt-second balance derivation of the minimum ripple clamping sequence. The driver module is configured to perform carrier comparison and drive output based on dual-modulation waves.

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