Joint compensation method, control method and device for grid-connected grid-connected energy storage system

Abstract

The present invention discloses a combined compensation method, control method, and device for grid-connected grid-type energy storage systems. The compensation method includes the following steps: obtaining the output angular frequency ω of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation; obtaining the output phase angle θ of the grid-type energy storage virtual synchronous machine through a combination of angular frequency feedforward compensation and phase angle feedforward compensation; and generating a drive signal for the inverter bridge switch tube of the grid-type energy storage converter based on the output phase angle θ of the grid-type energy storage virtual synchronous machine. The present invention improves the grid-connected active power and frequency response performance of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation and phase angle feedforward compensation. This can eliminate the dynamic oscillation and power overshoot of the grid-connected active power of the grid-type energy storage virtual synchronous machine, improve the dynamic response speed of its grid-connected output active power, and reduce the response overshoot amplitude of its output frequency. The grid-connected control method of the present invention is applicable to grid-connected operation scenarios of energy storage systems such as lithium batteries, lead-acid batteries, and supercapacitors.

Description

Technical Field

[0001] The present invention relates to a combined compensation method, a control method and a device for grid-connected energy storage systems, and belongs to the technical field of energy storage grid-connected control. Background Art

[0002] Traditional grid-connected virtual synchronous generators (VSGs) can provide a certain level of voltage and virtual inertia support for the connected grid during grid-connected operation. However, the virtual inertia control mechanism upgrades the VSG's grid-connected active power closed-loop control system to a second-order oscillation system. This results in dynamic oscillations and power overshoot in the grid-connected active power under disturbances in the active power reference command and grid frequency, slow dynamic response speed, and output frequency response overshoot. Furthermore, VSGs can effectively suppress dynamic oscillations and power overshoot in grid-connected active power by increasing the primary frequency modulation coefficient. However, due to the coupling between the primary frequency modulation coefficient and system damping, adjusting the VSG's primary frequency modulation coefficient and virtual inertia coefficient makes it difficult to ensure both good dynamic and steady-state response performance for the VSG's grid-connected active power.

[0003] To this end, people have conducted various studies, such as the article entitled "Analysis and Improvement Strategy of Grid-connected Damping Characteristics of Energy Storage Virtual Synchronous Generators", published in the Journal of Energetic Sciences, Vol. 44, No. 7, 2023, pp. 30-38. This article proposes adding an active first-order differential feedback compensation link to the feedback channel of the grid-connected active closed-loop control structure of the Traditional Grid-Forming Virtual Synchronous Generator (TGVSG), to increase the transient damping of the TGVSG grid-connected active closed-loop system and its ability to suppress grid-connected active dynamic oscillations and power overshoot. However, the differential operation will introduce high-frequency harmonic signals that affect the stability of the system, and the optimization of its active response speed and output frequency response is not considered.

[0004] An article entitled "Active Oscillation Suppression Strategy of VSG Parallel System Based on Transient Electromagnetic Power Compensation" is published in "Power System Technology" Volume 47, Issue 01, 2023, pages 23-33. Based on the control algorithm of the traditional grid-forming virtual synchronous generator (TGVSG), this article uses the first-order lag link of electromagnetic power as a differential operation compensation link, which enhances the transient damping of the TGVSG parallel system and its ability to suppress active dynamic oscillations, avoiding the active differential operation link. However, there are disadvantages such as the increase in the order of the TGVSG control system, the difficulty in system parameter design, the overshoot of the output frequency response, and the failure to consider the improvement of the active dynamic response speed.

[0005] The article entitled “A reference-feedforward-based damping method for virtual synchronous generator control”, YU Y, CHAUDHARY SK, TINAJERO GDA, et al, IEEE Transactions on Power Electronics, 2022, 37(7), 7566–7571 (“A virtual synchronous generator damping control strategy based on active reference command feedforward”, IEEE Journal of Power Electronics, Vol. 37, No. 7, 2022, pp. 7566–7571) proposes a damping control method based on active reference command feedforward, which has the advantages of no need for differential operation, simple and intuitive parameter design, and no dynamic oscillation of grid-connected active power under active reference command steps. However, there are problems such as high dependence of the algorithm implementation on the accuracy of system parameters, easy overshoot of output frequency response, slow dynamic response speed of grid-connected active power, and poor applicability to grid frequency disturbance conditions.

[0006] The article entitled “Phase feedforward damping control method for virtual synchronous generators”, LI MX, YU P, HU WH, et al., “IEEE Transactions on Power Electronics”, 2022, 37(8), 9790–9806 (“Phase feedforward damping control method for virtual synchronous generators”, IEEE Journal of Power Electronics, Vol. 37, No. 8, 2022, pp. 9790–9806); This article proposes a virtual synchronous generator damping optimization control method based on phase feedforward, which directly feeds the angular frequency deviation to the output phase angle of the virtual synchronous generator through a proportional link. It has the advantages of simple proportional feedforward parameter design and the ability to eliminate dynamic oscillations of grid-connected active power. However, the open-loop gain of the virtual synchronous generator control system has a small decreasing slope in the high frequency band, which significantly reduces its ability to resist high-frequency noise. In addition, there is a problem that the dynamic response performance of the virtual synchronous generator grid-connected active power still needs to be further optimized.

[0007] From the above, it can be seen that the existing technology can provide certain solutions and technical support for eliminating the dynamic oscillation and power overshoot problems of the grid-connected active power of the traditional grid-connected virtual synchronous machine under the step disturbance of its active power reference instruction. However, there are still disadvantages such as harmonic interference introduced by differential operation, output frequency response overshoot, increased system order, complex control parameter design, and the need to improve the dynamic response speed of the grid-connected active power. Summary of the Invention

[0008] In order to solve the above problems, the present invention proposes a joint compensation method, control method and device for the grid-connected grid-type energy storage system, which can not only eliminate the dynamic oscillation and power overshoot of the grid-connected active power of the grid-connected energy storage virtual synchronous machine, but also improve the dynamic response speed of its grid-connected output active power and reduce the response overshoot amplitude of its output frequency.

[0009] The technical solution adopted by the present invention to solve the technical problem is:

[0010] In a first aspect, an embodiment of the present invention provides a combined compensation method for grid-connected energy storage systems, which improves the grid-connected active power and frequency response performance of a grid-connected energy storage virtual synchronous machine through angular frequency feedforward compensation and phase angle feedforward compensation. The method includes the following steps:

[0011] Obtaining the output angular frequency of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation oh ;

[0012] The output phase angle of the grid-type energy storage virtual synchronous machine is obtained by combining angular frequency feedforward compensation and phase angle feedforward compensation. i ;

[0013] Output phase angle of virtual synchronous generator based on grid-type energy storage i Generate driving signals for inverter bridge switches of a grid-type energy storage converter.

[0014] As a possible implementation of this embodiment, the output angular frequency of the grid-type energy storage virtual synchronous machine is obtained by angular frequency feedforward compensation. oh ,include:

[0015] Grid-connected virtual synchronous generator with energy storage P e ;

[0016] According to the virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency oh 0, the angular frequency deviation Δ is obtained through the rotor motion equation oh ;

[0017] The angular frequency deviation Δ oh Plus the grid rated angular frequency oh 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine oh .

[0018] As a possible implementation of this embodiment, the output phase angle of the grid-type energy storage virtual synchronous machine is obtained by combining angular frequency feedforward compensation and phase angle feedforward compensation. i ,include:

[0019] The obtained angular frequency deviation Δ oh Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained oh b and phase angle feedforward compensation Δ i a ;

[0020] The angular frequency feedforward compensation value Δ oh b Output angular frequency of virtual synchronous machine with grid-type energy storage oh Sum, and then add the phase angle feedforward compensation Δ after the integral operation link i a Get the output phase angle of the grid-type energy storage virtual synchronous machine i .

[0021] In a second aspect, an embodiment of the present invention provides a combined compensation device for a grid-connected energy storage system, which improves the grid-connected active power and frequency response performance of a grid-connected energy storage virtual synchronous machine through angular frequency feedforward compensation and phase angle feedforward compensation. The device includes:

[0022] Angular frequency calculation module, used to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation oh ;

[0023] The joint compensation module is used to obtain the output phase angle of the grid-type energy storage virtual synchronous machine by combining angular frequency feedforward compensation and phase angle feedforward compensation. i ;

[0024] Drive signal generation module for output phase angle of virtual synchronous machine based on grid-type energy storage i Generate driving signals for inverter bridge switches of a grid-type energy storage converter.

[0025] In a third aspect, an embodiment of the present invention provides a grid-connected control method for a grid-connected energy storage system, comprising the following steps:

[0026] Collecting the grid-connected current of the grid-type energy storage converter i a 、 i b 、 i c and output voltage u a 、 u b 、 u c The output phase angle of the virtual synchronous machine based on the grid-type energy storage is obtained by single synchronous rotation coordinate transformation. i Directional dq components of grid current I d 、 I q and the dq components of the output voltage U d 、 U q Then, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is obtained through the power calculation equation. P e and grid-connected reactive power Q e ;

[0027] According to the obtained grid-connected reactive power of the virtual synchronous machine Q e Reactive power reference instructions for grid-connected energy storage virtual synchronous machines Q ref , primary voltage regulation coefficient kq , voltage reference instruction of grid-type energy storage virtual synchronous machine E 0, after a voltage regulation equation, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is obtained E d 、 E q ;

[0028] According to the grid-connected active power of the virtual synchronous machine P e and virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency oh 0, the angular frequency deviation Δ is obtained through the rotor motion equation oh , the angular frequency deviation Δ oh Plus the grid rated angular frequency oh 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine oh ;

[0029] The angular frequency deviation Δ oh Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained oh b and phase angle feedforward compensation Δ i a , the angular frequency feedforward compensation Δ oh b The grid-type energy storage virtual synchronous machine output angular frequency oh The sum is then added to the integral operation and the phase angle feedforward compensation Δ i a Get the output phase angle of the grid-type energy storage virtual synchronous machine i ;

[0030] According to the output phase angle of the grid-type energy storage virtual synchronous machine i , and the grid-type energy storage virtual synchronous machine dq axis output voltage reference instruction E d 、 E q , the three-phase bridge arm voltage modulation signal is obtained by single synchronous rotating coordinate inverse transformation E a 、 E b and E c , and then the three-phase bridge arm voltage modulation signal E a、 E b and E c The driving signal of the inverter bridge switch tube of the grid-type energy storage converter is generated through the SVPWM modulation link.

[0031] As a possible implementation of this embodiment, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is P e The calculation formula is:

[0032] ,

[0033] Grid-connected reactive power Q e The calculation formula is:

[0034] .

[0035] As a possible implementation of this embodiment, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is E d The calculation formula is:

[0036] ,

[0037] Output voltage reference command E q The calculation formula is:

[0038] .

[0039] As a possible implementation of this embodiment, the output angular frequency deviation Δ oh The calculation formula is:

[0040] ,

[0041] Output angular frequency oh The calculation formula is:

[0042] ,

[0043] Where, s is the Laplace operator.

[0044] As a possible implementation of this embodiment, the angular frequency feedforward compensation amount Δ oh b The calculation formula is:

[0045] ,

[0046] Phase angle feedforward compensation Δ i a The calculation formula is:

[0047] ,

[0048] The grid-type energy storage virtual synchronous machine output phase angle i The calculation formula used is:

[0049] ,

[0050] Where, s is the Laplace operator.

[0051] In a fourth aspect, an embodiment of the present invention provides a grid-connected control device for a grid-connected energy storage system, comprising:

[0052] Power calculation module, used to collect grid-connected current of grid-type energy storage converter i a 、 i b 、 i c and output voltage u a 、 u b 、 u c The output phase angle of the virtual synchronous machine based on the grid-type energy storage is obtained by single synchronous rotation coordinate transformation. i Directional dq components of grid current I d 、 I q and the dq components of the output voltage U d 、 U q Then, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is obtained through the power calculation equation. P e and grid-connected reactive power Q e ;

[0053] Voltage reference instruction acquisition module is used to obtain the grid-connected reactive power of the grid-connected virtual synchronous machine based on the obtained grid-connected reactive power of the grid-connected virtual synchronous machine. Q e Reactive power reference instructions for grid-connected energy storage virtual synchronous machines Q ref , primary voltage regulation coefficient k q , voltage reference instruction of grid-type energy storage virtual synchronous machine E 0, after a voltage regulation equation, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is obtained Ed 、 E q ;

[0054] Angular frequency acquisition module, used to connect the virtual synchronous machine to the grid according to the grid-type energy storage active power P e and virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency oh 0, the angular frequency deviation Δ is obtained through the rotor motion equation oh , the angular frequency deviation Δ oh Plus the grid rated angular frequency oh 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine oh ;

[0055] Feedforward compensation module is used to reduce the angular frequency deviation Δ oh Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained oh b and phase angle feedforward compensation Δ i a , the angular frequency feedforward compensation Δ oh b The grid-type energy storage virtual synchronous machine output angular frequency oh The sum is then added to the integral operation and the phase angle feedforward compensation Δ i a Get the output phase angle of the grid-type energy storage virtual synchronous machine i ;

[0056] Grid-connected control module, used to output phase angle according to grid-connected energy storage virtual synchronous machine i , and the grid-type energy storage virtual synchronous machine dq axis output voltage reference instruction E d 、 E q , the three-phase bridge arm voltage modulation signal is obtained by single synchronous rotating coordinate inverse transformation E a 、 E b and E c , and then the three-phase bridge arm voltage modulation signal E a 、 E b and E cThe driving signal of the inverter bridge switch tube of the grid-type energy storage converter is generated through the SVPWM modulation link.

[0057] The technical solution of the embodiment of the present invention can have the following beneficial effects:

[0058] The technical solution of the embodiment of the present invention is a combined compensation method for a grid-connected energy storage system, comprising the following steps: obtaining the output angular frequency of the grid-connected energy storage virtual synchronous machine by angular frequency feedforward compensation; oh By combining angular frequency feedforward compensation and phase angle feedforward compensation, the output phase angle of the grid-type energy storage virtual synchronous machine is obtained. i ; Output phase angle of virtual synchronous machine based on grid-type energy storage i Generates drive signals for the inverter bridge switches of the grid-connected energy storage converter. This invention improves the grid-connected active power and frequency response performance of the grid-connected energy storage virtual synchronous machine through angular frequency feedforward compensation and phase angle feedforward compensation. This eliminates dynamic oscillations and power overshoot in the grid-connected active power of the grid-connected energy storage virtual synchronous machine, improves the dynamic response speed of its grid-connected output active power, and reduces the amplitude of its output frequency response overshoot.

[0059] The technical solution of the embodiment of the present invention provides a grid-connected control method for a grid-connected energy storage system. Based on the traditional grid-connected energy storage virtual synchronous machine control algorithm, an angular frequency feedforward compensation and a phase angle feedforward compensation are added to improve the grid-connected active power and frequency response performance of the grid-connected energy storage virtual synchronous machine. The method solves the problems of dynamic oscillation and power overshoot of grid-connected active power, slow dynamic response speed of grid-connected active power, and output frequency response overshoot that exist in the process of traditional grid-connected energy storage virtual synchronous machines providing virtual inertia support for the connected power grid. The method has the advantages of not increasing the control system order and simple control parameter design, and is applicable to grid-connected operation scenarios of energy storage systems such as lithium batteries, lead-acid batteries, and supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a flow chart showing a joint compensation method for a grid-connected energy storage system according to an exemplary embodiment;

[0061] Figure 2 is a schematic diagram showing a combined compensation device for a grid-connected energy storage system according to an exemplary embodiment;

[0062] Figure 3 is a schematic diagram of a control structure of a grid-type energy storage virtual synchronous machine according to an exemplary embodiment;

[0063] Figure 4 This is a diagram showing a grid-connected active closed-loop equivalent control structure of a grid-connected energy storage virtual synchronous machine according to an exemplary embodiment;

[0064] Figure 5 is a schematic diagram of coordinate transformation and modulation according to an exemplary embodiment;

[0065] Figure 6 1 is a comparison diagram of simulation waveforms of a grid-type energy storage virtual synchronous machine before and after the present invention is adopted according to an exemplary embodiment;

[0066] Figure 7 The figure is a comparison diagram of experimental waveforms of a grid-type energy storage virtual synchronous machine before and after adopting the present invention according to an exemplary embodiment. DETAILED DESCRIPTION

[0067] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0068] In order to clearly illustrate the technical features of this solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings. The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. In addition, the present invention may repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. It should be noted that the components illustrated in the accompanying drawings are not necessarily drawn to scale. The present invention omits descriptions of well-known components and processing technologies and processes to avoid unnecessary limitations on the present invention.

[0069] like Figure 1 As shown, an embodiment of the present invention provides a combined compensation method for grid-connected grid-type energy storage systems, which improves the grid-connected active power and frequency response performance of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation and phase angle feedforward compensation. The method includes the following steps:

[0070] Obtaining the output angular frequency of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation oh ;

[0071] The output phase angle of the grid-type energy storage virtual synchronous machine is obtained by combining angular frequency feedforward compensation and phase angle feedforward compensation. i ;

[0072] Output phase angle of virtual synchronous generator based on grid-type energy storage i Generate driving signals for inverter bridge switches of a grid-type energy storage converter.

[0073] As a possible implementation of this embodiment, the output angular frequency of the grid-type energy storage virtual synchronous machine is obtained by angular frequency feedforward compensation. oh ,include:

[0074] Grid-connected virtual synchronous generator with energy storageP e ;

[0075] According to the virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency oh 0, the angular frequency deviation Δ is obtained through the rotor motion equation oh ;

[0076] The angular frequency deviation Δ oh Plus the grid rated angular frequency oh 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine oh .

[0077] As a possible implementation of this embodiment, the output phase angle of the grid-type energy storage virtual synchronous machine is obtained by combining angular frequency feedforward compensation and phase angle feedforward compensation. i ,include:

[0078] The obtained angular frequency deviation Δ oh Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained oh b and phase angle feedforward compensation Δ i a ;

[0079] The angular frequency feedforward compensation value Δ oh b Output angular frequency of virtual synchronous machine with grid-type energy storage oh Sum, and then add the phase angle feedforward compensation Δ after the integral operation link i a Get the output phase angle of the grid-type energy storage virtual synchronous machine i .

[0080] like Figure 2 As shown, an embodiment of the present invention provides a combined compensation device for a grid-connected energy storage system, which improves the grid-connected active power and frequency response performance of a grid-connected energy storage virtual synchronous machine through angular frequency feedforward compensation and phase angle feedforward compensation. The device includes:

[0081] Angular frequency calculation module, used to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation oh ;

[0082] The joint compensation module is used to obtain the output phase angle of the grid-type energy storage virtual synchronous machine by combining angular frequency feedforward compensation and phase angle feedforward compensation. i ;

[0083] Drive signal generation module for output phase angle of virtual synchronous machine based on grid-type energy storage i Generate driving signals for inverter bridge switches of a grid-type energy storage converter.

[0084] An embodiment of the present invention provides a grid-connected control method for a grid-connected energy storage system, comprising the following steps:

[0085] Collecting the grid-connected current of the grid-type energy storage converter i a 、 i b 、 i c and output voltage u a 、 u b 、 u c The output phase angle of the virtual synchronous machine based on the grid-type energy storage is obtained by single synchronous rotation coordinate transformation. i Directional dq components of grid current I d 、 I q and the dq components of the output voltage U d 、 U q Then, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is obtained through the power calculation equation. P e and grid-connected reactive power Q e ;

[0086] According to the obtained grid-connected reactive power of the virtual synchronous machine Q e Reactive power reference instructions for grid-connected energy storage virtual synchronous machines Q ref , primary voltage regulation coefficient k q , voltage reference instruction of grid-type energy storage virtual synchronous machine E 0, after a voltage regulation equation, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is obtained E d 、 E q ;

[0087] According to the grid-connected active power of the virtual synchronous machine P eand virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency oh 0, the angular frequency deviation Δ is obtained through the rotor motion equation oh , the angular frequency deviation Δ oh Plus the grid rated angular frequency oh 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine oh ;

[0088] The angular frequency deviation Δ oh Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained oh b and phase angle feedforward compensation Δ i a , the angular frequency feedforward compensation Δ oh b The grid-type energy storage virtual synchronous machine output angular frequency oh The sum is then added to the integral operation and the phase angle feedforward compensation Δ i a Get the output phase angle of the grid-type energy storage virtual synchronous machine i ;

[0089] According to the output phase angle of the grid-type energy storage virtual synchronous machine i , and the grid-type energy storage virtual synchronous machine dq axis output voltage reference instruction E d 、 E q , the three-phase bridge arm voltage modulation signal is obtained by single synchronous rotating coordinate inverse transformation E a 、 E b and E c , and then the three-phase bridge arm voltage modulation signal E a 、 E b and E c The driving signal of the inverter bridge switch tube of the grid-type energy storage converter is generated through the SVPWM modulation link.

[0090] As a possible implementation of this embodiment, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is P e The calculation formula is:

[0091] ,

[0092] Grid-connected reactive power Q e The calculation formula is:

[0093] .

[0094] As a possible implementation of this embodiment, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is E d The calculation formula is:

[0095] ,

[0096] Output voltage reference command E q The calculation formula is:

[0097] .

[0098] As a possible implementation of this embodiment, the output angular frequency deviation Δ oh The calculation formula is:

[0099] ,

[0100] Output angular frequency oh The calculation formula is:

[0101] ,

[0102] Where, s is the Laplace operator.

[0103] As a possible implementation of this embodiment, the angular frequency feedforward compensation amount Δ oh b The calculation formula is:

[0104] ,

[0105] Phase angle feedforward compensation Δ i a The calculation formula is:

[0106] ,

[0107] The grid-type energy storage virtual synchronous machine output phase angle i The calculation formula used is:

[0108] ,

[0109] Where, s is the Laplace operator.

[0110] In a fourth aspect, an embodiment of the present invention provides a grid-connected control device for a grid-connected energy storage system, comprising:

[0111] Power calculation module, used to collect grid-connected current of grid-type energy storage converter i a 、 i b 、 i c and output voltage u a 、 u b 、 u c The output phase angle of the virtual synchronous machine based on the grid-type energy storage is obtained by single synchronous rotation coordinate transformation. i Directional dq components of grid current I d 、 I q and the dq components of the output voltage U d 、 U q Then, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is obtained through the power calculation equation. P e and grid-connected reactive power Q e ;

[0112] Voltage reference instruction acquisition module is used to obtain the grid-connected reactive power of the grid-connected virtual synchronous machine based on the obtained grid-connected reactive power of the grid-connected virtual synchronous machine. Q e Reactive power reference instructions for grid-connected energy storage virtual synchronous machines Q ref , primary voltage regulation coefficient k q , voltage reference instruction of grid-type energy storage virtual synchronous machine E 0, after a voltage regulation equation, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is obtained E d 、 E q ;

[0113] Angular frequency acquisition module, used to connect the virtual synchronous machine to the grid according to the grid-type energy storage active power P e and virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref, and the grid rated angular frequency oh 0, the angular frequency deviation Δ is obtained through the rotor motion equation oh , the angular frequency deviation Δ oh Plus the grid rated angular frequency oh 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine oh ;

[0114] Feedforward compensation module is used to reduce the angular frequency deviation Δ oh Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained oh b and phase angle feedforward compensation Δ i a , the angular frequency feedforward compensation Δ oh b The grid-type energy storage virtual synchronous machine output angular frequency oh The sum is then added to the integral operation and the phase angle feedforward compensation Δ i a Get the output phase angle of the grid-type energy storage virtual synchronous machine i ;

[0115] Grid-connected control module, used to output phase angle according to grid-connected energy storage virtual synchronous machine i , and the grid-type energy storage virtual synchronous machine dq axis output voltage reference instruction E d 、 E q , the three-phase bridge arm voltage modulation signal is obtained by single synchronous rotating coordinate inverse transformation E a 、 E b and E c , and then the three-phase bridge arm voltage modulation signal E a 、 E b and E c The driving signal of the inverter bridge switch tube of the grid-type energy storage converter is generated through the SVPWM modulation link.

[0116] like Figure 3 As shown, the process of optimizing the grid-connected active power and frequency response of the grid-connected energy storage system using the grid-connected control device of the present invention is as follows:

[0117] Step 1, power calculation part, first collect the grid-connected current of the grid-type energy storage converter i a ,i b , i c and output voltage u a , u b , u c The output phase angle of the virtual synchronous machine based on the grid-type energy storage is obtained by single synchronous rotation coordinate transformation. i Directional dq components of grid current I d , I q and the dq components of the output voltage U d , U q Then, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is obtained through the power calculation equation. P e and grid-connected reactive power Q e ;

[0118] That is, grid-connected active power P e The calculation formula used is:

[0119] ,

[0120] Grid-connected reactive power Q e The calculation formula used is:

[0121] .

[0122] Step 2, the primary voltage regulation part, according to the grid-connected reactive power of the grid-connected energy storage virtual synchronous machine obtained in step 1 Q e Reactive power reference instructions for grid-connected energy storage virtual synchronous machines Q ref , primary voltage regulation coefficient k q , voltage reference instruction of grid-type energy storage virtual synchronous machine E 0, after a voltage regulation equation, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is obtained E d , E q ;

[0123] That is, the output voltage reference instruction E d The calculation formula used is:

[0124] ,

[0125] Output voltage reference command E q The calculation formula used is:

[0126] .

[0127] Step 3, rotor motion equation part, according to the grid-connected active power of the grid-connected energy storage virtual synchronous machine obtained in step 1 P e and virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency oh 0, the angular frequency deviation Δ is obtained through the rotor motion equation oh , the angular frequency deviation Δ oh Plus the grid rated angular frequency oh 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine oh ;

[0128] That is, the angular frequency deviation Δ oh The calculation formula used is:

[0129] ,

[0130] Output angular frequency of grid-type energy storage virtual synchronous machine oh The calculation formula used is:

[0131] ,

[0132] Where, s is the Laplace operator.

[0133] Step 4, feedforward compensation part, the angular frequency deviation Δ obtained in step 3 is oh Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained oh b and phase angle feedforward compensation Δ i a , the angular frequency feedforward compensation Δ oh b The output angular frequency of the grid-type energy storage virtual synchronous machine obtained in step 3 is oh After the sum is calculated, the phase angle feedforward compensation Δ is added through the integral operation link. i a Get the output phase angle of the grid-type energy storage virtual synchronous machine i ;

[0134] That is, the angular frequency feedforward compensation amount Δ oh b The calculation formula used is:

[0135] ,

[0136] Phase angle feedforward compensation Δ i a The calculation formula used is:

[0137] ,

[0138] Output phase angle of grid-type energy storage virtual synchronous machine i The calculation formula used is:

[0139] ,

[0140] Where, s is the Laplace operator.

[0141] Combine Figure 3 The power transmission model and the above control can be obtained as follows: Figure 4 shown. Figure 4 middle, d is the power factor angle of the grid-type energy storage virtual synchronous machine; K is the synchronous voltage coefficient of the grid-type energy storage virtual synchronous machine;

[0142] That is, the power factor angle of the grid-type energy storage virtual synchronous machine is d The calculation formula used is:

[0143] ,

[0144] Synchronous voltage coefficient of grid-type energy storage virtual synchronous machine K The calculation formula used is:

[0145] ,

[0146] Where, oh g is the grid angular frequency, U g is the grid voltage amplitude, E is the output voltage amplitude of the grid-type energy storage virtual synchronous machine, X is the equivalent inductive reactance of the line.

[0147] Step 5, such as Figure 5 As shown, first according to the grid-type energy storage virtual synchronous machine output phase angle obtained in step 4 i, and the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine obtained in step 2 E d , E q , the three-phase bridge arm voltage modulation signal is obtained by single synchronous rotating coordinate inverse transformation E a , E b , E c , and then the three-phase bridge arm voltage modulation signal E a , E b , E c The driving signal of the inverter bridge switch tube of the grid-type energy storage converter is generated through the SVPWM modulation link.

[0148] In order to verify the implementation effect of the present invention, the control method of the grid-connected energy storage virtual synchronous machine (hereinafter referred to as GFVSG) proposed by the present invention, which adds an angular frequency feedforward compensation and a phase angle feedforward compensation link, is compared with the existing traditional grid-connected energy storage virtual synchronous machine (hereinafter referred to as TGVSG) control method (the TGVSG control method is mentioned in the background technology, entitled "Analysis and Improvement Strategy of Grid-Connected Damping Characteristics of Energy Storage Virtual Synchronous Machine", "Acta Energiae Solaris Sinica", Vol. 44, No. 7, 2023, pp. 30-38) by simulation and experiment. The main comparison is in response to the active reference instruction P ref Grid-connected active power under step disturbance conditions P e and its output frequency f Dynamic response performance. Details are as follows:

[0149] First, relevant parameters are set. In this embodiment, the relevant parameters in the GFVSG grid-connected active power and frequency response optimization method of the present invention are set as follows:

[0150] The rated capacity of the grid-type energy storage virtual synchronous machine is 100kVA, and the active reference instruction P ref 20kW, grid rated angular frequency oh 0 is 314.16rad / s, virtual inertia coefficient J 10kg·m 2 , primary frequency modulation coefficient k p is 15915.5J / rad, the grid voltage amplitude U g 311V, primary voltage regulation coefficient k q 1.4×10-4 V / var, output voltage amplitude of grid-type energy storage virtual synchronous machine E 311V, line equivalent inductive reactance X is 0.1Ω, then the synchronous voltage coefficient K =1.5 U g E / X 1450815. At the same time, combined Figure 2 After the formula derivation process, the damping ratio of the TGVSG grid-connected active closed-loop control system is is 0.12 less than 1, that is, the system is an underdamped system, and its natural oscillation angular frequency It is 21.49rad / s, which has a smaller value. Therefore, the grid-connected active power of TGVSG is P e Active reference instruction P ref Under step disturbance conditions, there will inevitably be problems such as dynamic oscillation, power overshoot and slow dynamic response.

[0151] In this embodiment, the GFVSG grid-connected active closed-loop control system is set as an over-damping system to ensure the grid-connected active power of the grid-connected virtual synchronous machine. P e In active reference instruction P ref Under step disturbance conditions, the effect of no dynamic oscillation and no power overshoot is achieved. At the same time, combined with Figure 2 After the formula derivation process, the damping ratio of the GFVSG grid-connected active closed-loop control system is , and its natural oscillation angular frequency , here we will a Set to 1.5, b If set to 8, , , so the grid-connected active power of GFVSG is P e Active reference instruction P ref Under step disturbance conditions, there will be no dynamic oscillation and power overshoot, and it will have a faster dynamic response speed than TGVSG.

[0152] Based on the above parameter settings, simulation and experimental comparison tests were carried out, as follows:

[0153] The simulation and experimental test conditions are as follows: at the initial moment, the grid-connected energy storage virtual synchronous machine stably outputs 20kW of grid-connected active power, and at 4.0s, the active power reference instruction P ref From 20kW to 60kW in steps.

[0154] According to the above working conditions, we can get Figure 6 and Figure 7 The comparison diagram between simulation and experimental test is shown in the figure, where Figure 6 、 Figure 7 GFVSG in the figure represents a method for optimizing the control of the grid-connected active power and frequency response of a grid-type energy storage system proposed in the present invention, and TGVSG represents an existing traditional method for controlling a virtual synchronous machine of a grid-type energy storage system. That is, the curve pointed to by TGVSG is a test waveform diagram before the present invention is adopted, specifically, a dynamic response test waveform diagram of the existing traditional method for controlling a virtual synchronous machine of a grid-type energy storage system. The curve pointed to by GFVSG is a test waveform diagram after the present invention is adopted, specifically, a dynamic response test waveform diagram of the method for optimizing the control of the grid-connected active power and frequency response of a grid-type energy storage system proposed in the present invention.

[0155] according to Figure 6 It can be seen that, firstly, the grid-connected active power corresponding to the GFVSG proposed in the present invention has neither dynamic oscillation nor power overshoot, while the grid-connected active power corresponding to the existing TGVSG has large dynamic oscillation and power overshoot; secondly, the grid-connected active power adjustment time corresponding to the GFVSG proposed in the present invention is 0.08s, which is much shorter than the 1.8s corresponding to the existing TGVSG; thirdly, the output frequency of the grid-connected energy storage virtual synchronous machine corresponding to the GFVSG proposed in the present invention is 0.08s. f The overshoot amplitude is 0.02Hz, which is lower than the 0.14Hz corresponding to the existing TGVSG. P ref The step from 20kW to 60kW has smaller power overshoot, faster response speed and smaller output frequency overshoot amplitude.

[0156] according to Figure 7 It can be concluded that: first, the grid-connected active power corresponding to the GFVSG proposed in the present invention has neither dynamic oscillation nor power overshoot, while the grid-connected active power corresponding to the existing TGVSG has large dynamic oscillation and power overshoot; second, the grid-connected active power adjustment time corresponding to the GFVSG proposed in the present invention is 0.16s, which is much shorter than the 1.96s corresponding to the existing TGVSG; third, the output frequency of the grid-connected energy storage virtual synchronous machine corresponding to the GFVSG proposed in the present invention is 0.16s. f The overshoot amplitude is 0.05Hz, which is lower than the 0.17Hz corresponding to the existing TGVSG. Figure 5 We can see that the grid-connected active power of the GFVSG proposed in this invention is better than that of the existing TGVSG in terms of active power reference instruction. P ref Under step disturbance, it has smaller power overshoot, faster response speed and smaller output frequency overshoot amplitude.

[0157] Will Figure 7 and Figure 6 After comparing the results of Figure 7 The experimental test results can be compared with Figure 6 The simulation test comparison results in the paper keep one-to-one correspondence, and both fully demonstrate that the GFVSG proposed in this invention is better than the existing TGVSG in active reference instruction. P ref Under step disturbance, the GFVSG proposed in the present invention has the advantages of faster grid-connected active power response speed, smaller active power overshoot and smaller output frequency overshoot amplitude. Therefore, compared with the existing TGVSG, the control effect of the GFVSG proposed in the present invention is better.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A combined compensation method for grid-connected energy storage systems, characterized in that: The grid-connected active power and frequency response performance of a grid-connected energy storage virtual synchronous machine are improved by angular frequency feedforward compensation and phase angle feedforward compensation. The method comprises the following steps: Obtaining the output angular frequency of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation ω ; The output phase angle of the grid-type energy storage virtual synchronous machine is obtained by combining angular frequency feedforward compensation and phase angle feedforward compensation. θ ; Output phase angle of virtual synchronous generator based on grid-type energy storage θ Generate drive signals for inverter bridge switches of a grid-type energy storage converter; The output angular frequency of the grid-type energy storage virtual synchronous machine is obtained by angular frequency feedforward compensation. ω ,include: Grid-connected virtual synchronous generator with energy storage P e ; According to the virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency ω 0, the angular frequency deviation Δ is obtained through the rotor motion equation ω ; The angular frequency deviation Δ ω Plus the grid rated angular frequency ω 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine ω ; The output phase angle of the grid-type energy storage virtual synchronous machine is obtained by combining angular frequency feedforward compensation and phase angle feedforward compensation. θ ,include: The angular frequency deviation Δ ω Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained ω b and phase angle feedforward compensation Δ θ a ; The angular frequency feedforward compensation value Δ ω b Output angular frequency of virtual synchronous machine with grid-type energy storage ω Sum, and then add the phase angle feedforward compensation Δ after the integral operation link θ a Get the output phase angle of the grid-type energy storage virtual synchronous machine θ .

2. A combined compensation device for a grid-connected energy storage system, characterized in that: The grid-connected active power and frequency response performance of a grid-connected energy storage virtual synchronous machine are improved by angular frequency feedforward compensation and phase angle feedforward compensation. The device includes: Angular frequency calculation module, used to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine through angular frequency feedforward compensation ω ; The joint compensation module is used to obtain the output phase angle of the grid-type energy storage virtual synchronous machine by combining angular frequency feedforward compensation and phase angle feedforward compensation. θ ; Drive signal generation module for output phase angle of virtual synchronous machine based on grid-type energy storage θ Generate drive signals for inverter bridge switches of a grid-type energy storage converter; The output angular frequency of the grid-type energy storage virtual synchronous machine is obtained by angular frequency feedforward compensation. ω ,include: Grid-connected virtual synchronous generator with energy storage P e ; According to the virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency ω 0, the angular frequency deviation Δ is obtained through the rotor motion equation ω ; The angular frequency deviation Δ ω Plus the grid rated angular frequency ω 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine ω ; The output phase angle of the grid-type energy storage virtual synchronous machine is obtained by combining angular frequency feedforward compensation and phase angle feedforward compensation. θ ,include: The angular frequency deviation Δ ω Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained ω b and phase angle feedforward compensation Δ θ a ; The angular frequency feedforward compensation value Δ ω b Output angular frequency of virtual synchronous machine with grid-type energy storage ω Sum, and then add the phase angle feedforward compensation Δ after the integral operation link θ a Get the output phase angle of the grid-type energy storage virtual synchronous machine θ .

3. A grid-connected control method for a grid-connected energy storage system, characterized in that: The following steps are involved: Collecting the grid-connected current of the grid-type energy storage converter i a 、 i b 、 i c and output voltage u a 、 u b 、 u c The output phase angle of the virtual synchronous machine based on the grid-type energy storage is obtained by single synchronous rotation coordinate transformation. θ Directional dq components of grid current I d 、 I q and the dq components of the output voltage U d 、 U q Then, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is obtained through the power calculation equation. P e and grid-connected reactive power Q e ; According to the obtained grid-connected reactive power of the virtual synchronous machine Q e Reactive power reference instructions for grid-connected energy storage virtual synchronous machines Q ref , primary voltage regulation coefficient k q , voltage reference instruction of grid-type energy storage virtual synchronous machine E 0, after a voltage regulation equation, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is obtained E d 、 E q ; According to the grid-connected active power of the virtual synchronous machine P e and virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency ω 0, the angular frequency deviation Δ is obtained through the rotor motion equation ω , the angular frequency deviation Δ ω Plus the grid rated angular frequency ω 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine ω ; The angular frequency deviation Δ ω Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained ω b and phase angle feedforward compensation Δ θ a , the angular frequency feedforward compensation Δ ω b The grid-type energy storage virtual synchronous machine output angular frequency ω The sum is then added to the integral operation and the phase angle feedforward compensation Δ θ a Get the output phase angle of the grid-type energy storage virtual synchronous machine θ ; According to the output phase angle of the grid-type energy storage virtual synchronous machine θ , and the grid-type energy storage virtual synchronous machine dq axis output voltage reference instruction E d 、 E q , the three-phase bridge arm voltage modulation signal is obtained by single synchronous rotating coordinate inverse transformation E a 、 E b and E c , and then the three-phase bridge arm voltage modulation signal E a 、 E b and E c The driving signal of the inverter bridge switch tube of the grid-type energy storage converter is generated through the SVPWM modulation link.

4. The grid-connected control method of a grid-connected energy storage system according to claim 3, characterized in that: The grid-connected active power of the grid-connected energy storage virtual synchronous machine P e The calculation formula is: ， Grid-connected reactive power Q e The calculation formula is: 。 5. The grid-connected control method of the grid-connected energy storage system according to claim 3, characterized in that: The dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine E d The calculation formula is: ， Output voltage reference command E q The calculation formula is: 。 6. The grid-connected control method of a grid-connected energy storage system according to claim 3, characterized in that: The output angular frequency deviation Δ of the grid-type energy storage virtual synchronous machine ω The calculation formula is: ， Output angular frequency ω The calculation formula is: ， Where, s is the Laplace operator.

7. The grid-connected control method of a grid-connected energy storage system according to claim 3, characterized in that: The angular frequency feedforward compensation amount Δ ω b The calculation formula is: ， Phase angle feedforward compensation Δ θ a The calculation formula is: ， The grid-type energy storage virtual synchronous machine output phase angle θ The calculation formula used is: ， Where, s is the Laplace operator.

8. A grid-connected control device for a grid-connected energy storage system, characterized in that: include: Power calculation module, used to collect grid-connected current of grid-type energy storage converter i a 、 i b 、 i c and output voltage u a 、 u b 、 u c The output phase angle of the virtual synchronous machine based on the grid-type energy storage is obtained by single synchronous rotation coordinate transformation. θ Directional dq components of grid current I d 、 I q and the dq components of the output voltage U d 、 U q Then, the grid-connected active power of the grid-connected energy storage virtual synchronous machine is obtained through the power calculation equation. P e and grid-connected reactive power Q e ; Voltage reference instruction acquisition module is used to obtain the grid-connected reactive power of the grid-connected virtual synchronous machine based on the obtained grid-connected reactive power of the grid-connected virtual synchronous machine. Q e Reactive power reference instructions for grid-connected energy storage virtual synchronous machines Q ref , primary voltage regulation coefficient k q , voltage reference instruction of grid-type energy storage virtual synchronous machine E 0, after a voltage regulation equation, the dq axis output voltage reference instruction of the grid-type energy storage virtual synchronous machine is obtained E d 、 E q ; Angular frequency acquisition module, used to connect the virtual synchronous machine to the grid according to the grid-type energy storage active power P e and virtual inertia coefficient J , primary frequency modulation coefficient k p , Active reference instruction P ref , and the grid rated angular frequency ω 0, the angular frequency deviation Δ is obtained through the rotor motion equation ω , the angular frequency deviation Δ ω Plus the grid rated angular frequency ω 0 to obtain the output angular frequency of the grid-type energy storage virtual synchronous machine ω ; Feedforward compensation module is used to reduce the angular frequency deviation Δ ω Multiply by the angular frequency feedforward compensation coefficient b and phase angle feedforward compensation coefficient a Then the angular frequency feedforward compensation Δ is obtained ω b and phase angle feedforward compensation Δ θ a , the angular frequency feedforward compensation Δ ω b The grid-type energy storage virtual synchronous machine output angular frequency ω The sum is then added to the integral operation and the phase angle feedforward compensation Δ θ a Get the output phase angle of the grid-type energy storage virtual synchronous machine θ ; Grid-connected control module, used to output phase angle according to grid-connected energy storage virtual synchronous machine θ , and the grid-type energy storage virtual synchronous machine dq axis output voltage reference instruction E d 、 E q , the three-phase bridge arm voltage modulation signal is obtained by single synchronous rotating coordinate inverse transformation E a 、 E b and E c , and then the three-phase bridge arm voltage modulation signal E a 、 E b and E c The driving signal of the inverter bridge switch tube of the grid-type energy storage converter is generated through the SVPWM modulation link.

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