A multi-port modular ac-dc power supply simulator and control method

Abstract

This invention discloses a multi-port modular AC / DC power supply simulator and its control method, belonging to the field of electrical technology. The multi-port modular AC / DC power supply simulator consists of a three-phase AC power grid, a three-phase transformer, a three-phase bridge rectifier, a battery simulator, a photovoltaic simulator, and a power grid simulator, and can be modularly expanded. The three-phase bridge rectifier provides a stable DC bus voltage for the multi-port simulator. The battery simulator, photovoltaic simulator, and power grid simulator are each composed of multiple corresponding sub-modules and can be flexibly combined in series and parallel. This device has a high degree of modularity, integrates the simulation of multiple types of energy characteristics, can meet various application scenarios and different voltage levels, and is easy to use.

Description

Technical Field

[0001] This invention belongs to the field of electrical technology and relates to a multi-port modular AC / DC power supply simulator, specifically a multi-port modular AC / DC power supply simulator and its control method. Background Technology

[0002] In recent years, with the rapid development of new energy technologies, the demand for power simulators, as an essential component of these technologies, has surged, and their application scenarios have become more diversified. Therefore, power simulators need to meet the needs of DC / DC and DC / AC applications. In DC / DC scenarios, photovoltaic simulators and battery simulators are common, while in DC / AC scenarios, grid simulators are common. Existing power simulators suffer from two major problems: Firstly, current research shows that for multi-scenario applications, the modularity of the equipment is low, the number of ports is limited, the power supply method is singular, and the scalability is poor, leading to high equipment and electricity costs. Secondly, in DC / AC equipment, traditional control strategies are complex, with many steps in the control process, resulting in poor resilience of the control loop and reduced efficiency.

[0003] In response to the above problems, experts at home and abroad have proposed several methods, the main ones being:

[0004] The paper titled "A Non-Isolated Bidirectional Three-Port Buck-Buck Converter" (Proceedings of the CSEE, Vol. 34, No. 33, 2014) proposes a non-isolated bidirectional three-port buck-buck converter topology that can accommodate photovoltaic cell inputs and connect bidirectional DC / DC energy storage and loads at the output. It can reduce converter size and cost while increasing power density, but lacks capabilities for DC / AC scenarios. The paper titled "Research on High-Power Grid Simulator System" (Journal of Power Supply, Vol. 15, No. 3, 2017) proposes a topology and control strategy suitable for high-power grid simulators. It achieves good control performance by separating and independently controlling the fundamental and harmonic waves; however, its control method is overly complex and has significant room for improvement.

[0005] In summary, existing research findings all have shortcomings, specifically:

[0006] 1. Simulators for various energy types are independent, with low levels of integration and modularity. Building a simulation platform for multiple types of integrated energy is highly complex, has low scalability, is not convenient or flexible to use, and is not cost-effective.

[0007] 2. The control strategy is complex, the simulation accuracy for harmonic characteristics is not high, and the stability is poor. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the limitations of the above-mentioned technical solutions and provide a simulator with high integration, strong stability, strong scalability, and high simulation accuracy for harmonic characteristics.

[0009] The objective of this invention is achieved as follows: This invention provides a multi-port modular AC / DC power supply simulator, including a three-phase AC power grid, a three-phase transformer, a three-phase bridge rectifier, a battery simulator, a photovoltaic simulator, and a power grid simulator. The input terminal of the three-phase transformer is connected to the three-phase power grid, and the output terminal is connected in series with a three-phase input inductor L and then connected to the AC input terminal of the three-phase bridge rectifier. The DC output terminals of the three-phase bridge rectifier form a common DC bus, and a filter capacitor C is connected in parallel between the positive and negative DC bus of the common DC bus. The battery simulator, photovoltaic simulator, and power grid simulator are respectively connected to the common DC bus through their input terminals.

[0010] The battery simulator comprises N1 identical battery sub-modules, and each sub-module includes a Buck-Boost circuit and a single-phase DAB circuit. The Buck-Boost circuit includes switching transistors Q1 and Q2, a filter inductor L1, and a filter capacitor C1. The drain of switching transistor Q1 is connected to the filter inductor L1, and the other end of the filter inductor L1 is connected to the positive terminal of the filter capacitor C1. The source of switching transistor Q2 is connected to the line between the drain of switching transistor Q1 and the filter inductor L1, and the drain of switching transistor Q2 is connected to the negative terminal of the filter capacitor C1. The positive and negative terminals of the filter capacitor C1 constitute the output terminal of the Buck-Boost circuit. The single-phase DAB includes a primary-side H-bridge, a secondary-side H-bridge, a filter inductor L2, a filter capacitor C2, and a high-frequency transformer T1. The primary-side H-bridge contains four switching transistors. The primary H-bridge comprises four switching transistors: S1, S2, S3, and S4. The secondary H-bridge contains four switching transistors: S5, S6, S7, and S8. The DC input of the primary H-bridge is connected to the output of the Buck-Boost circuit. The AC output of the primary H-bridge is connected via inductor L2 and the primary side of high-frequency transformer T1. The secondary side of high-frequency transformer T1 is connected to the AC input of the secondary H-bridge. The DC output of the secondary H-bridge is connected in parallel to a filter capacitor C2. N1 filter capacitors C2 are cascaded, and the positive terminal of the filter capacitor C2 of the first battery submodule and the negative terminal of the filter capacitor C2 of the N1st battery submodule constitute the output of the battery simulator. The source of switching transistor Q1 and the drain of switching transistor Q2 constitute the input of the battery submodule. N1 battery submodules connected in parallel constitute the input of the battery simulator.

[0011] The photovoltaic simulator contains N2 identical Buck circuits, each of which includes a switching transistor V. T1 diode V D1, filter inductor L3 and filter capacitor C3, wherein the switching transistor V T1 The drain of the diode is connected to the filter inductor L3, and the other end of the filter inductor L3 is connected to the positive terminal of the filter capacitor C3. D1 The negative terminal is connected to the switching transistor V. T1 On the connection between the drain of diode V and the filter inductor L3, the diode V D1 The positive terminal is connected to the negative terminal of the filter capacitor C3, and the switching transistor V... T1 The source and diode V D1 The positive terminal of the first Buck circuit forms the input terminal of the Buck circuit. The input terminals of the N2 Buck circuits are connected in parallel to form the input terminal of the photovoltaic simulator. The N2 filter capacitors C3 are cascaded, and the positive terminal of the filter capacitor C3 of the first Buck circuit and the negative terminal of the filter capacitor C3 of the N2nd Buck circuit form the output terminal of the photovoltaic simulator.

[0012] The grid simulator comprises N3 identical full-bridge inverter submodules. Each full-bridge inverter submodule includes an inverter H-bridge, a filter inductor L4, and a filter capacitor C4. The inverter H-bridge contains four switching transistors, denoted as Z1, Z2, Z3, and Z4. A filter capacitor C4 is connected in parallel to the AC output of the inverter H-bridge, and a filter inductor L4 is connected in series between the AC output of the inverter H-bridge and the filter capacitor C4. The filter capacitor C4 constitutes the output of the full-bridge inverter submodule. The negative terminals of the filter capacitors C4 from the N3 full-bridge inverter submodules are connected together at a node denoted as N. O The positive terminal of the filter capacitor C4 of each of the N3 full-bridge inverter submodules serves as the N3 phase output of the grid simulator. This output simulates phases 1, 2, 3, ..., N3 of the grid simulator. Each of the N3 full-bridge inverter submodules is independently controlled, and the N3 phases are synchronized through communication, with a phase difference of θ between adjacent phases. phs θ phs =2π / N3; The input terminals of N3 inverter H-bridges are connected in parallel to form the input terminals of the power grid simulator.

[0013] The present invention also provides a control method for a multi-port modular AC / DC power supply simulator, comprising the following steps;

[0014] Step 1, Data Sampling and Command Value Setting

[0015] The sampled data is as follows: Buck-Boost circuit output instantaneous voltage U O_Buck-Boost And denoted as the first instantaneous voltage U O_Buck-Boost The instantaneous value of the current in the filter inductor L1 is recorded as the first instantaneous current I. L1_Buck-Boost Battery simulator output voltage U O_ES Battery simulator output current I O_ESThe instantaneous state of charge (SOC) of the battery simulator is recorded; the output voltage U of the photovoltaic simulator is recorded. O_PV and the output current I of the photovoltaic simulator O_PV The instantaneous voltage value output by the inverter H-bridge is recorded as the second instantaneous voltage U. OG The instantaneous value of the current in the filter inductor L4 is recorded as the second instantaneous current I. L4_G The output current of the inverter H-bridge in the power grid simulator is denoted as the inverter H-bridge output current I. o1 ;

[0016] The command value is set as follows: Inverter H-bridge voltage command value U of the power grid simulator. OG * And denoted as the inverter H-bridge voltage command value U. OG * The harmonic command value of the output voltage of the power grid simulator is denoted as the output voltage harmonic command value H. arm * ;

[0017] Step 2, Control of the battery simulator

[0018] Step 2.1, solve for the duty cycle D of switch Q1. Buck-Boost And single-phase DAB phase shift value P hs_DAB

[0019] Establish an equivalent circuit model and solve for the open-circuit voltage E0 of the battery simulator and the equivalent output voltage U of the battery under steady-state conditions. Batter ;

[0020] The battery simulator outputs current I. O_ES The instantaneous state of charge (SOC) is used as the input to the external characteristic equation, and the output of the external characteristic equation is the battery simulator output voltage command value U. O_ES * ;

[0021] The voltage command value U is output by the battery simulator. O_ES * Obtain the Buck-Boost circuit output voltage command value U O_Buck-Boost * ;

[0022] According to the first instantaneous voltage U O_Buck-Boost and Buck-Boost circuit output voltage command value U O_Buck-Boost * The calculated Buck-Boost circuit voltage error signal ΔU O_Buck-Boost and △U O_Buck-Boost As the input to the first PI controller, the output is the command value of the current of the filter inductor L1, which is denoted as the first current command value I. L1_Buck-Boost *;

[0023] According to the first current command value I L1_Buck-Boost * and the first instantaneous current I L1_Buck-Boost The first current error signal ΔI is calculated. L1_Buck-Boost The first current error signal △I L1_Buck-Boost As the input to the second PI controller, the output is the duty cycle D of the switching transistor Q1. Buck-Boost ;

[0024] According to the battery simulator output voltage U O_ES And the battery simulator output voltage command value U O_ES * The battery simulator output voltage error signal ΔU was calculated. O_ES The battery simulator outputs the voltage error signal △U O_ES As the input to the third PI controller, the single-phase DAB phase shift value P is obtained. hs_DAB ;

[0025] Step 2.2, Control of the battery simulator switching transistor

[0026] Based on the duty cycle D of switch Q1 Buck-Boost Based on the duty cycle modulation method, the drive signal PWM of the switching transistor Q1 is used. Q1 Based on this, a PWM drive signal for switching transistor Q2 is generated. Q2 And drive the corresponding switching transistor; based on the single-phase DAB phase shift value P hs_DAB Based on the phase-shift modulation method, the driving signal PWM of the switching transistor S1 is used. S1 Based on this, drive signals PWM are generated for switches S2, S3, S4, S5, S6, S7, and S8, respectively. S2 PWM S3 PWM S4 PWM S5 PWM S6 PWM S7 PWM S8 And drive the corresponding switching transistor;

[0027] Step 3, Control of the photovoltaic simulator

[0028] Step 3.1, solve for V of the switching transistor. T1 Duty cycle D PV

[0029] Determine the open-circuit voltage U of the photovoltaic simulator OC and the short-circuit current I of the photovoltaic simulator SC Construct the characteristic equation of the IU curve and solve for the simulated output current I of the photovoltaic simulator.O ;

[0030] The output voltage U of the photovoltaic simulator O_PV As the input to the volt-ampere converter, the output of the volt-ampere converter is the output current command value I of the photovoltaic simulator. O_PV * According to the photovoltaic simulator output current command value I O_PV * and the output current I of the photovoltaic simulator O_PV The current error signal ΔI of the photovoltaic simulator was calculated. O_PV The photovoltaic simulator current error signal ΔI O_PV As the input to the fourth PI controller, the output of the fourth PI controller is the switching transistor V. T1 Duty cycle D PV ;

[0031] Step 3.2, Control of the switching transistors in the photovoltaic simulator

[0032] According to the switching transistor V T1 Duty cycle D PV Based on the single-transistor modulation method, by controlling the switching transistor V T1 PWM drive signal VTI To control the switching transistor V T1 The switching on and off of the transistor; the single-transistor modulation method is as follows: switching transistor V T1 PWM drive signal VTI The frequency is f s ;

[0033] f s =1 / T S

[0034] Among them, T S For drive signal PWM VTI The cycle;

[0035] Step 4, Control of the power grid simulator

[0036] Step 4.1, Solve for the modulated wave m in the power grid simulator.

[0037] According to the second instantaneous voltage value U OG and inverter H-bridge voltage command value U OG * The inverter H-bridge voltage error signal ΔU is calculated. OG According to the inverter H-bridge voltage error signal △U OG The harmonic values ​​of the output voltage of the power grid simulator are calculated and denoted as the output voltage harmonic value H. arm ;

[0038] The inverter H-bridge voltage error signal △U OGAs the input to the fifth PI controller, the output of the fifth PI controller is the current command value of the filter inductor L4, which is recorded as the second instantaneous current command value I. L4_G * According to the second instantaneous current command value I L4_G * Second instantaneous current value I L4_G The current error signal of the filter inductor L4 is calculated and denoted as the second current error signal ΔI. L4_G The second current error signal △I L4_G and inverter H-bridge output current I o1 The sum of these values ​​is used as the input to the sixth PI controller to obtain the output ψ of the sixth PI controller;

[0039] According to the output voltage harmonic command value H arm * and output voltage harmonic value H arm The output voltage harmonic error signal ΔH of the power grid simulator was calculated. arm And denoted as the harmonic error signal ΔH arm The harmonic error signal ΔH arm As the input to the seventh PI controller and the second-order generalized differential harmonic compensator, the harmonic compensation output ψ1 is obtained;

[0040] The output ψ of the sixth PI controller and the inverter H-bridge voltage command value U OG * The harmonic compensation outputs ψ1 are added together and then proportionally transformed to obtain the modulated wave m of the power grid simulator.

[0041] Step 4.2, Control of the switching transistors in the power grid simulator

[0042] Based on the modulation wave m, and using the inverter H-bridge modulation method, the driving signal PWM of the switching transistor Z1 is used. Z1 Based on this, PWM drive signals corresponding to switches Z2, Z3, and Z4 are generated. Z2 PWM Z3 and PWM Z4 And drive the corresponding switching transistor to conduct.

[0043] Preferably, step 2.1 involves solving for the duty cycle D of the switch Q1. Buck-Boost And single-phase DAB phase shift value P hs_DAB The specific process is as follows:

[0044] An equivalent circuit model is established, consisting of a voltage source E0 and an equivalent internal resistance R, along with the battery simulator's open-circuit voltage E and the battery's equivalent output voltage U under steady-state conditions. Batter The expressions are as follows:

[0045] E = n1E cell

[0046] U Batter =EI Batter R

[0047] Where n1 is the number of individual battery cells, I Batter E is the battery output current. cell Let be the open-circuit voltage of a single battery cell, calculated as follows:

[0048]

[0049] In the formula, V eq K represents the equilibrium potential of the battery stack when SOC = 0.5. T The factor value is 0.1829 at room temperature;

[0050] The battery simulator outputs current I. O_ES The instantaneous state of charge (SOC) is used as the input to the external characteristic equation, and the output of the external characteristic equation is the battery simulator output voltage command value U. O_ES * Its expression is:

[0051]

[0052] According to the battery simulator output voltage command value U O_ES * Obtain the Buck-Boost circuit output voltage command value U O_Buck-Boost * U O_Buck-Boost * =U O_ES * / N1;

[0053] According to the first instantaneous voltage U O_Buck-Boost and Buck-Boost circuit output voltage command value U O_Buck-Boost * The voltage error signal ΔU of the Buck-Boost circuit was calculated. O_Buck-Boost ,△U O_Buck-Boost =U O_Buck-Boost * -U O_Buck-Boost ;

[0054] The Buck-Boost circuit voltage error signal ΔU O_Buck-Boost As the input to the first PI controller, the output of the first PI controller is the first current command value I. L1_Buck-Boost * Its expression is:

[0055]

[0056] Among them, K p1 K is the proportional coefficient of the first PI controller. i1 is the integral coefficient of the first PI controller, and s is the Laplace operator;

[0057] According to the first current command value I L1_Buck-Boost * and the first instantaneous current I L1_Buck-Boost The first current error signal ΔI is calculated. L1_Buck-Boost ,△I L1_Buck-Boost =I L1_Buck-Boost * -I L1_Buck-Boost The first current error signal △I L1_Buck-Boost As the input to the second PI controller, the output of the second PI controller is the duty cycle D of the switching transistor Q1. Buck-Boost Its expression is:

[0058]

[0059] Among them, K p2 K is the proportional coefficient of the second PI controller. i2 The integral coefficient of the second PI controller;

[0060] According to the battery simulator output voltage U O_ES And the battery simulator output voltage command value U O_ES * The battery simulator output voltage error signal ΔU was calculated. O_ES , △U O_ES =U O_ES * -U O_ES The battery simulator outputs the voltage error signal △U. O_ES As the input to the third PI controller, the output of the third PI controller is the single-phase DAB phase shift value P. hs_DAB Its expression is as follows:

[0061]

[0062] Among them, K p3 The proportional gain of the third PI controller, K i3 The integral coefficient of the third PI controller.

[0063] Preferably, the duty cycle modulation method and phase shift modulation method described in step 2.2 are as follows:

[0064] Duty cycle modulation method: PWM driving signals corresponding to switching transistors Q1 and Q2 Q1 and drive signal PWM Q2The frequencies are all f s Switch Q1 and switch Q2 are complementary in conduction;

[0065] Phase-shift modulation method: PWM driving signals corresponding to switching transistors S1, S2, S3, S4, S5, S6, S7, and S8 S1 PWM S2 PWM S3 PWM S4 PWM S5 PWM S6 PWM S7 and PWM S8 The frequencies are all f S ; Drive signal PWM S1 and drive signal PWM S4 Same, drive signal PWM S2 and drive signal PWM S3 Same, drive signal PWM S5 and drive signal PWM S8 Same, drive signal PWM S6 and drive signal PWM S7 The same; switches S1 and S2 are complementary in conduction, switches S3 and S4 are complementary in conduction, switches S5 and S6 are complementary in conduction, and switches S7 and S8 are complementary in conduction; the drive signal PWM for switch S5 is... S5 The PWM signal lags behind the drive signal of the switching transistor S1. S1 The drive signal PWM of the switching transistor S6 S6 The PWM signal lags behind the drive signal of the switching transistor S2. S2 Lag time

[0066] Preferably, step 3.1 involves solving for the switching transistor V. T1 Duty cycle D PV The specific process is as follows:

[0067] Solve for the open-circuit voltage U of the photovoltaic simulator OC and the short-circuit current I of the photovoltaic simulator SC Its expression is:

[0068]

[0069]

[0070] Where A is the diode quality factor, K is the Popitzman constant, T is the photovoltaic cell junction temperature, q is the electron charge, and I... D For the current flowing through diode V D1 The current, Iph For photocurrent, R sh For equivalent parallel resistance, R s This is the equivalent series resistance;

[0071] The output voltage U of the photovoltaic simulator O_PV As the input to the volt-ampere converter, the output of the volt-ampere converter is the photovoltaic simulator's output current command value I. O_PV * ;

[0072]

[0073] Among them, A1 is the first impact factor. A2 is the second impact factor.

[0074] According to the photovoltaic simulator output current command value I O_PV * and the output current I of the photovoltaic simulator O_PV The current error signal ΔI of the photovoltaic simulator was calculated. O_PV , △I O_PV =I O_PV * -I O_PV ;

[0075] The photovoltaic simulator current error signal ΔI O_PV As the input to the fourth PI controller, the output of the fourth PI controller is the switching transistor V. T1 Duty cycle D PV Its expression is:

[0076]

[0077] Among them, K p4 The proportional gain of the fourth PI controller, K p4 is the integral coefficient of the fourth PI controller, and s is the Laplace operator.

[0078] Preferably, the specific process of solving for the modulated wave m in step 4.1 is as follows:

[0079] According to the second instantaneous voltage value U OG and inverter H-bridge voltage command value U OG * The inverter H-bridge voltage error signal ΔU is calculated. OG , △U OG =U OG * -U OG ;

[0080] Based on the inverter H-bridge voltage error signal △U OGThe output voltage harmonic value H was calculated. arm H arm =-△U OG : The inverter H-bridge voltage error signal △U OG As the input to the fifth PI controller, the output of the fifth PI controller is the second instantaneous current command value I. L4_G * Its expression is as follows:

[0081]

[0082] Among them, K p5 The proportional gain of the fifth PI controller, K i5 is the integral coefficient of the fifth PI controller, and s is the Laplace operator;

[0083] According to the second instantaneous current command value I L4_G * Second instantaneous current value I L4_G The second current error signal ΔI is calculated. L4_G , △I L4_G =I L4_G * -I L4_G : The second current error signal △I L4_G and inverter H-bridge output current I o1 The sum of these values ​​is used as the input to the sixth PI controller to obtain the output ψ of the sixth PI controller, which is expressed as follows:

[0084]

[0085] Among them, K p6 The proportional gain of the sixth PI controller, K i6 The integral coefficient of the sixth PI controller;

[0086] According to the output voltage harmonic command value H arm * and output voltage harmonic value H arm The harmonic error signal ΔH of the power grid simulator was calculated. arm , △H arm =H arm * -H arm ;

[0087] The harmonic error signal ΔH arm The inputs to the seventh PI controller and the second-order generalized differential harmonic compensator are then used. The resulting outputs of the seventh PI controller and the second-order generalized differential harmonic compensator are added together, and then compared with the harmonic command value H of the output voltage. arm *The two components are added together to obtain the harmonic compensation output ψ1. The expression for the harmonic compensation output ψ1 is:

[0088] ψ1=(H (s) +G (s) (H) arm * -H arm )+H arm *

[0089] Among them, H (s) For the control function of the seventh PI controller, G (s) The system function of the second-order generalized differential harmonic compensator is expressed as follows:

[0090]

[0091]

[0092] In the formula, K p7 The proportional gain of the seventh PI controller, K i7 The integral coefficient of the seventh PI controller, K h For the proportional coefficient and Q of the second-order generalized differential harmonic compensator h For the quality factor of the second-order generalized differential harmonic compensator, ω h This is the resonant angular frequency of the second-order generalized differential harmonic compensator;

[0093] The output ψ of the sixth PI controller and the inverter H-bridge voltage command value U are used. OG * The harmonic compensation outputs ψ1 are added together and then proportionally transformed to obtain the modulated wave m of the power grid simulator, whose expression is:

[0094]

[0095] Among them, U m U is the output voltage amplitude of the power grid simulator. dc This is the common DC bus voltage.

[0096] Preferably, the specific method of the inverter H-bridge modulation method in step 4.2 is as follows:

[0097] The PWM drive signals for switching transistors Z1, Z2, Z3, and Z4 are as follows: Z1 PWM Z2 PWM Z3 PWM Z4 The frequencies are all f S ; The drive signal PWM for switch Z1 Z1 and the drive signal PWM of the switching transistor Z4 Z4Similarly, the drive signal PWM for switch Z2 Z2 and the drive signal PWM of the switching transistor Z3 Z3 Same; switching transistors Z1 and Z2 are complementary in conduction, and switching transistors Z3 and Z4 are complementary in conduction; drive signal PWM Z1 With drive signal PWM Z4 The modulation system is M. Where |m| is the amplitude of the modulated wave m, and |m1| is the amplitude of the carrier wave.

[0098] Compared with the prior art, the beneficial effects of the present invention are:

[0099] 1. This invention proposes for the first time a multi-port modular AC / DC power supply simulator and control method concept. For new energy application scenarios, it has high integration, and one sampling device can replace three devices: battery simulator, photovoltaic simulator, and grid simulator. Compared with the three independent systems, it can save two sets of rectifier devices.

[0100] 2. Energy can be reused among the battery simulator, photovoltaic simulator, and grid simulator;

[0101] 3. This invention proposes for the first time a harmonic compensation control method based on a second-order generalized differentiator, and applies it to harmonic compensation. Compared with compensation methods such as pure differentiation and lead-lag, it has better high-frequency stability.

[0102] 4. It has good scalability and low overall cost. Attached Figure Description

[0103] Figure 1 This is a block diagram of a multi-port modular AC / DC power supply simulator according to the present invention.

[0104] Figure 2 This is a topology diagram of the battery simulator of the present invention.

[0105] Figure 3 This is a topology diagram of the photovoltaic simulator of the present invention.

[0106] Figure 4 This is a topology diagram of the power grid simulator of the present invention.

[0107] Figure 5 This is a control block diagram of the battery simulator of the present invention.

[0108] Figure 6 This is a control block diagram of the photovoltaic simulator of the present invention.

[0109] Figure 7 This is a control block diagram of the power grid simulator of the present invention. Detailed Implementation

[0110] The present invention will now be described in detail with reference to the accompanying drawings.

[0111] Figure 1 This is a block diagram of a multi-port modular AC / DC power supply simulator according to the present invention. Figure 2 This is a topology diagram of the battery simulator of the present invention. Figure 3 This is a topology diagram of the photovoltaic simulator of the present invention. Figure 4 This is a topology diagram of the power grid simulator of the present invention.

[0112] Depend on Figure 1 As can be seen, the present invention provides a multi-port modular AC / DC power supply simulator, including a three-phase AC power grid, a three-phase transformer, a three-phase bridge rectifier, a battery simulator, a photovoltaic simulator, and a power grid simulator. The input terminal of the three-phase transformer is connected to the three-phase power grid, and the output terminal is connected in series with a three-phase input inductor L and then connected to the AC input terminal of the three-phase bridge rectifier. The DC output terminal of the three-phase bridge rectifier forms a common DC bus, and a filter capacitor C is connected in parallel between the positive DC bus and the negative DC bus of the common DC bus. The battery simulator, photovoltaic simulator, and power grid simulator are respectively connected to the common DC bus through their input terminals.

[0113] In this embodiment, the AC input is 380V three-phase AC power, the three-phase transformer is connected in a 'Y-Y' configuration with a turns ratio of 1:1; the inductance of the three-phase input inductor L is 2mH, the capacitance of the filter capacitor C is 3000uF, and the common DC bus voltage is 700V. Additionally, in this embodiment, all switching frequencies are 20kHz; the operating frequency of the power grid simulator is 50Hz.

[0114] Depend on Figure 2As can be seen, the battery simulator contains N1 identical battery sub-modules, and each battery sub-module includes a Buck-Boost circuit and a single-phase DAB circuit. The Buck-Boost circuit includes switching transistors Q1 and Q2, a filter inductor L1, and a filter capacitor C1. The drain of switching transistor Q1 is connected to the filter inductor L1, and the other end of the filter inductor L1 is connected to the positive terminal of the filter capacitor C1. The source of switching transistor Q2 is connected to the line between the drain of switching transistor Q1 and the filter inductor L1, and the drain of switching transistor Q2 is connected to the negative terminal of the filter capacitor C1. The positive and negative terminals of the filter capacitor C1 constitute the output terminal of the Buck-Boost circuit. The single-phase DAB includes a primary-side H-bridge, a secondary-side H-bridge, a filter inductor L2, a filter capacitor C2, and a high-frequency transformer T1. The primary-side H-bridge contains four switching transistors. The primary H-bridge consists of four switching transistors, designated S1, S2, S3, and S4. The secondary H-bridge contains four switching transistors, designated S5, S6, S7, and S8. The DC input of the primary H-bridge is connected to the output of the Buck-Boost circuit. The AC output of the primary H-bridge is connected via inductor L2 and the primary side of high-frequency transformer T1. The secondary side of high-frequency transformer T1 is connected to the AC input of the secondary H-bridge. The DC output of the secondary H-bridge is connected in parallel to a filter capacitor C2. N1 filter capacitors C2 are cascaded, and the positive terminal of the filter capacitor C2 of the first battery submodule and the negative terminal of the filter capacitor C2 of the N1st battery submodule constitute the output of the battery simulator. The source of switching transistor Q1 and the drain of switching transistor Q2 constitute the input of the battery submodule. N1 battery submodules connected in parallel constitute the input of the battery simulator.

[0115] In this embodiment, N1 = 3, meaning the battery simulator consists of three battery sub-modules. Each sub-module has a rated power of 10KW, and the total rated power of the device is 30KW. The filter inductor L1 has a value of 200uH, the filter capacitor C1 has a value of 1000uF, the filter inductor L2 has a value of 277.8uH, the filter capacitor C2 has a value of 1000uF, the transformer T1 has a rated capacity of 10KVA, and the turns ratio is 1:1. The primary DC bus input voltage of the battery simulator is 700V, the output voltage range is 200V-2000V, and the output terminal is connected to the energy storage battery.

[0116] Depend on Figure 3 As can be seen, the photovoltaic simulator contains N2 identical Buck circuits, each of which includes a switching transistor V. T1 diode V D1 , filter inductor L3 and filter capacitor C3, wherein the switching transistor V T1 The drain of the diode is connected to the filter inductor L3, and the other end of the filter inductor L3 is connected to the positive terminal of the filter capacitor C3. D1 The negative terminal is connected to the switching transistor V.T1 On the connection between the drain of diode V and the filter inductor L3, the diode V D1 The positive terminal is connected to the negative terminal of the filter capacitor C3, and the switching transistor V... T1 The source and diode V D1 The positive terminal of the first Buck circuit forms the input terminal of the photovoltaic simulator. The input terminals of the N2 Buck circuits are connected in parallel to form the input terminal of the photovoltaic simulator. The N2 filter capacitors C3 are cascaded, and the positive terminal of the filter capacitor C3 of the first Buck circuit and the negative terminal of the filter capacitor C3 of the N2nd Buck circuit form the output terminal of the photovoltaic simulator.

[0117] In this embodiment, N2 = 3, the rated capacity of the photovoltaic simulator is 30KVA, the filter inductor L3 is 200uH, the filter capacitor C3 is 1000uF, the input voltage is 700V, and the output voltage is 0V. ～ A 2000V photovoltaic simulator output terminal is connected to a 133Ω resistor.

[0118] Depend on Figure 4 As can be seen, the power grid simulator contains N3 identical full-bridge inverter sub-modules. Each full-bridge inverter sub-module includes an inverter H-bridge, a filter inductor L4, and a filter capacitor C4. The inverter H-bridge contains four switching transistors, denoted as Z1, Z2, Z3, and Z4. A filter capacitor C4 is connected in parallel to the AC output of the inverter H-bridge, and a filter inductor L4 is connected in series between the AC output of the inverter H-bridge and the filter capacitor C4. The filter capacitor C4 constitutes the output of the full-bridge inverter sub-module. The negative terminals of the filter capacitors C4 from the N3 full-bridge inverter sub-modules are connected together, and the node is denoted as N. O The positive terminal of the filter capacitor C4 of each of the N3 full-bridge inverter submodules serves as the N3 phase output of the grid simulator. This output simulates phases 1, 2, 3, ..., N3 of the grid simulator. Each of the N3 full-bridge inverter submodules is independently controlled, and the N3 phases are synchronized through communication, with a phase difference of θ between adjacent phases. phs θ phs =2π / N3; The input terminals of N3 inverter H-bridges are connected in parallel to form the input terminals of the power grid simulator.

[0119] In this embodiment, N3 = 3. The rated power of the power grid simulator is 10KW, the filter inductor L4 is 100uH, the filter capacitor C4 is 60uF, the DC bus input voltage is 700V, the output voltage fundamental effective value is 220V, and the fundamental frequency is 50HZ.

[0120] Figure 5 This is a control block diagram of the battery simulator of the present invention. Figure 6 This is a control block diagram of the photovoltaic simulator of the present invention. Figure 7This is a control block diagram of the power grid simulator of the present invention. Figure 5 , Figure 6 and Figure 7 Therefore, the present invention also provides a control method for a multi-port modular AC / DC power supply simulator, comprising the following steps:

[0121] Step 1, Data Sampling and Command Value Setting

[0122] The sampled data is as follows: Buck-Boost circuit output instantaneous voltage U O_Buck-Boost And denoted as the first instantaneous voltage U O_Buck-Boost The instantaneous value of the current in the filter inductor L1 is recorded as the first instantaneous current I. L1_Buck-Boost Battery simulator output voltage U O_ES Battery simulator output current I O_ES The instantaneous state of charge (SOC) of the battery simulator is recorded; the output voltage U of the photovoltaic simulator is recorded. O_PV and the output current I of the photovoltaic simulator O_PV The instantaneous voltage value output by the inverter H-bridge is recorded as the second instantaneous voltage U. OG The instantaneous value of the current in the filter inductor L4 is recorded as the second instantaneous current I. L4_G The output current of the inverter H-bridge in the power grid simulator is denoted as the inverter H-bridge output current I. o1 ;

[0123] The command value is set as follows: Inverter H-bridge voltage command value U of the power grid simulator. OG * And denoted as the inverter H-bridge voltage command value U. OG * The harmonic command value of the output voltage of the power grid simulator is denoted as the output voltage harmonic command value H. arm * .

[0124] Step 2, Control of the battery simulator

[0125] Step 2.1, solve for the duty cycle D of switch Q1. Buck-Boost And single-phase DAB phase shift value P hs_DAB

[0126] Establish an equivalent circuit model and solve for the open-circuit voltage E0 of the battery simulator and the equivalent output voltage U of the battery under steady-state conditions. Batter ;

[0127] The battery simulator outputs current I. O_ES The instantaneous state of charge (SOC) is used as the input to the external characteristic equation, and the output of the external characteristic equation is the battery simulator output voltage command value U. O_ES * ;

[0128] The voltage command value U is output by the battery simulator. O_ES * Obtain the Buck-Boost circuit output voltage command value U O_Buck-Boost * ;

[0129] According to the first instantaneous voltage U O_Buck-Boost and Buck-Boost circuit output voltage command value U O_Buck-Boost * The calculated Buck-Boost circuit voltage error signal ΔU O_Buck-Boost and △U O_Buck-Boost As the input to the first PI controller, the output is the command value of the current of the filter inductor L1, which is denoted as the first current command value I. L1_Buck-Boost * ;

[0130] According to the first current command value I L1_Buck-Boost * and the first instantaneous current I L1_Buck-Boost The first current error signal ΔI is calculated. L1_Buck-Boost The first current error signal △I L1_Buck-Boost As the input to the second PI controller, the output is the duty cycle D of the switching transistor Q1. Buck-Boost ;

[0131] According to the battery simulator output voltage U O_ES And the battery simulator output voltage command value U O_ES * The battery simulator output voltage error signal ΔU was calculated. O_ES The battery simulator outputs the voltage error signal △U O_ES As the input to the third PI controller, the single-phase DAB phase shift value P is obtained. hs_DAB .

[0132] In this embodiment, the duty cycle D of the switching transistor Q1 Buck-Boost And single-phase DAB phase shift value P hs_DAB The solution process is as follows:

[0133] An equivalent circuit model is established, consisting of a voltage source E0 and an equivalent internal resistance R, along with the battery simulator's open-circuit voltage E and the battery's equivalent output voltage U under steady-state conditions. Batter The expressions are as follows:

[0134] E = n1E cell

[0135] U Batter =EI Batter R

[0136] Where n1 is the number of individual battery cells, I Batter E is the battery output current. cell Let be the open-circuit voltage of a single battery cell, calculated as follows:

[0137]

[0138] In the formula, V eq K represents the equilibrium potential of the battery stack when SOC = 0.5. T The factor value is 0.1829 at room temperature;

[0139] The battery simulator outputs current I. O_ES The instantaneous state of charge (SOC) is used as the input to the external characteristic equation, and the output of the external characteristic equation is the battery simulator output voltage command value U. O_ES * Its expression is:

[0140]

[0141] According to the battery simulator output voltage command value U O_ES * Obtain the Buck-Boost circuit output voltage command value U O_Buck-Boost * U O_Buck-Boost * =U O_ES * / N1;

[0142] According to the first instantaneous voltage U O_Buck-Boost and Buck-Boost circuit output voltage command value U O_Buck-Boost * The voltage error signal ΔU of the Buck-Boost circuit was calculated. O_Buck-Boost ,△U O_Buck-Boost =U O_Buck-Boost * -U O_Buck-Boost ;

[0143] The Buck-Boost circuit voltage error signal ΔU O_Buck-Boost As the input to the first PI controller, the output of the first PI controller is the first current command value I. L1_Buck-Boost * Its expression is:

[0144]

[0145] Among them, K p1 K is the proportional coefficient of the first PI controller. i1 is the integral coefficient of the first PI controller, and s is the Laplace operator;

[0146] According to the first current command value I L1_Buck-Boost * and the first instantaneous current I L1_Buck-Boost The first current error signal ΔI is calculated. L1_Buck-Boost ,△I L1_Buck-Boost =I L1_Buck-Boost * -I L1_Buck-Boost The first current error signal △I L1_Buck-Boost As the input to the second PI controller, the output of the second PI controller is the duty cycle D of the switching transistor Q1. Buck-Boost Its expression is:

[0147]

[0148] Among them, K p2 K is the proportional coefficient of the second PI controller. i2 The integral coefficient of the second PI controller;

[0149] According to the battery simulator output voltage U O_ES And the battery simulator output voltage command value U O_ES * The battery simulator output voltage error signal ΔU was calculated. O_ES , △U O_ES =U O_ES * -U O_ES The battery simulator outputs the voltage error signal △U. O_ES As the input to the third PI controller, the output of the third PI controller is the single-phase DAB phase shift value P. hs_DAB Its expression is as follows:

[0150]

[0151] Among them, K p3 The proportional gain of the third PI controller, K i3 The integral coefficient of the third PI controller.

[0152] In this embodiment, K P1 =0.02, K i1 =1,K P2 =0.015, K i2 =30, K P3 =0.0015, K i3 =0.03; Calculation yields: D Buck-Boost =0.9524, At this time, the output voltage of the battery simulator is 2000V.

[0153] Step 2.2, Control of the battery simulator switching transistor

[0154] Based on the duty cycle D of switch Q1 Buck-Boost Based on the duty cycle modulation method, the drive signal PWM of the switching transistor Q1 is used. Q1 Based on this, a PWM drive signal for switching transistor Q2 is generated. Q2 And drive the corresponding switching transistor; based on the single-phase DAB phase shift value P hs_DAB Based on the phase-shift modulation method, the driving signal PWM of the switching transistor S1 is used. S1 Based on this, drive signals PWM are generated for switches S2, S3, S4, S5, S6, S7, and S8, respectively. S2 PWM S3 PWM S4 PWM S5 PWM S6 PWM S7 PWM S8 And drive the corresponding switching transistor.

[0155] In this embodiment, the duty cycle modulation method; the drive signals PWM corresponding to switching transistors Q1 and Q2. Q1 and drive signal PWM Q2 The frequencies are all f S Switch Q1 and switch Q2 are complementary in conduction;

[0156] The phase-shift modulation method includes the PWM driving signals corresponding to switches S1, S2, S3, S4, S5, S6, S7, and S8. S1 PWM S2 PWM S3 PWM S4 PWM S5 PWM S6 PWM S7 and PWM S8 The frequencies are all f S ; Drive signal PWM S1 and drive signal PWM S4 Same, drive signal PWM S2 and drive signal PWM S3 Same, drive signal PWM S5 and drive signal PWM S8 Same, drive signal PWM S6 and drive signal PWM S7The same; switches S1 and S2 are complementary in conduction, switches S3 and S4 are complementary in conduction, switches S5 and S6 are complementary in conduction, and switches S7 and S8 are complementary in conduction; the drive signal PWM for switch S5 is... S5 The PWM signal lags behind the drive signal of the switching transistor S1. S1 The drive signal PWM of the switching transistor S6 S6 The PWM signal lags behind the drive signal of the switching transistor S2. S2 Lag time

[0157] Step 3, Control of the photovoltaic simulator

[0158] Step 3.1, solve for V of the switching transistor. T1 Duty cycle D PV

[0159] Determine the open-circuit voltage U of the photovoltaic simulator OC and the short-circuit current I of the photovoltaic simulator SC Construct the characteristic equation of the IU curve and solve for the simulated output current I of the photovoltaic simulator. O ;

[0160] The output voltage U of the photovoltaic simulator O_PV As the input to the volt-ampere converter, the output of the volt-ampere converter is the output current command value I of the photovoltaic simulator. O_PV * According to the photovoltaic simulator output current command value I O_PV * and the output current I of the photovoltaic simulator O_PV The current error signal ΔI of the photovoltaic simulator was calculated. O_PV The photovoltaic simulator current error signal ΔI O_PV As the input to the fourth PI controller, the output of the fourth PI controller is the switching transistor V. T1 Duty cycle D PV .

[0161] In this embodiment, the solution for the switching transistor V T1 Duty cycle D PV The specific process is as follows:

[0162] Solve for the open-circuit voltage U of the photovoltaic simulator OC and the short-circuit current I of the photovoltaic simulator SC Its expression is:

[0163]

[0164]

[0165] Where A is the diode quality factor, K is the Popitzman constant, T is the photovoltaic cell junction temperature, q is the electron charge, and I... D For the current flowing through diode V D1 The current, I ph For photocurrent, R sh For equivalent parallel resistance, R s This is the equivalent series resistance;

[0166] The output voltage U of the photovoltaic simulator O_PV As the input to the volt-ampere converter, the output of the volt-ampere converter is the photovoltaic simulator's output current command value I. O_PV * ;

[0167]

[0168] Among them, A1 is the first impact factor. A2 is the second impact factor.

[0169]

[0170] According to the photovoltaic simulator output current command value I O_PV * and the output current I of the photovoltaic simulator O_PV The current error signal ΔI of the photovoltaic simulator was calculated. O_PV , △I O_PV =I O_PV * -I O_PV ;

[0171] The photovoltaic simulator current error signal ΔI O_PV As the input to the fourth PI controller, the output of the fourth PI controller is the switching transistor V. T1 Duty cycle D PV Its expression is:

[0172]

[0173] Among them, K p4 The proportional gain of the fourth PI controller, K p4 is the integral coefficient of the fourth PI controller, and s is the Laplace operator.

[0174] In this embodiment, U OC =2000V, I SC =15A, load resistance R=133Ω. K P4 =0.002, K i4 =0.025, when the voltage return value is U 0_PVAt 1500V, A1 = 0.5 and A2 = 0.91 are calculated; by referring to the curve, the maximum power point at this time is (1500V, 7.5A); the calculated D... PV =0.67.

[0175] Step 3.2, Control of the switching transistors in the photovoltaic simulator

[0176] According to the switching transistor V T1 Duty cycle D PV Based on the single-transistor modulation method, by controlling the switching transistor V T1 PWM drive signal VTI To control the switching transistor V T1 The switching on and off of the transistor; the single-transistor modulation method is as follows: switching transistor V T1 PWM drive signal VTI The period is T S .

[0177] Step 4, Control of the power grid simulator

[0178] Step 4.1, Solve for the modulated wave m in the power grid simulator.

[0179] According to the second instantaneous voltage value U OG and inverter H-bridge voltage command value U OG * The inverter H-bridge voltage error signal ΔU is calculated. OG According to the inverter H-bridge voltage error signal △U OG The harmonic values ​​of the output voltage of the power grid simulator are calculated and denoted as the output voltage harmonic value H. arm ;

[0180] The inverter H-bridge voltage error signal △U OG As the input to the fifth PI controller, the output of the fifth PI controller is the current command value of the filter inductor L4, which is recorded as the second instantaneous current command value I. L4_G * According to the second instantaneous current command value I L4_G * Second instantaneous current value I L4_G The current error signal of the filter inductor L4 is calculated and denoted as the second current error signal ΔI. L4_G The second current error signal △I L4_G and inverter H-bridge output current I o1 The sum of these values ​​is used as the input to the sixth PI controller to obtain the output ψ of the sixth PI controller;

[0181] According to the output voltage harmonic command value H arm * and output voltage harmonic value H armThe output voltage harmonic error signal ΔH of the power grid simulator was calculated. arm And denoted as the harmonic error signal ΔH arm The harmonic error signal ΔH arm As the input to the seventh PI controller and the second-order generalized differential harmonic compensator, the harmonic compensation output ψ1 is obtained;

[0182] The output ψ of the sixth PI controller and the inverter H-bridge voltage command value U OG * The harmonic compensation output ψ1 is added together and then proportionally transformed to obtain the modulated wave m of the power grid simulator.

[0183] In this embodiment, the specific process of solving for the modulated wave m in the power grid simulator is as follows:

[0184] According to the second instantaneous voltage value U OG and inverter H-bridge voltage command value U OG * The inverter H-bridge voltage error signal ΔU is calculated. OG , △U OG =U OG * -U OG ;

[0185] Based on the inverter H-bridge voltage error signal △U OG The output voltage harmonic value H was calculated. arm H arm =-△U OG : The inverter H-bridge voltage error signal △U OG As the input to the fifth PI controller, the output of the fifth PI controller is the second instantaneous current command value I. L4_G * Its expression is as follows:

[0186]

[0187] Among them, K p5 The proportional gain of the fifth PI controller, K i5 is the integral coefficient of the fifth PI controller, and s is the Laplace operator;

[0188] According to the second instantaneous current command value I L4_G * Second instantaneous current value I L4_G The second current error signal ΔI is calculated. L4_G , △I L4_G =I L4_G * -I L4_G : The second current error signal △I L4_G and inverter H-bridge output current Io1 The sum of these values ​​is used as the input to the sixth PI controller to obtain its output ψ, which is expressed as:

[0189]

[0190] Among them, K p6 The proportional gain of the sixth PI controller, K i6 The integral coefficient of the sixth PI controller;

[0191] According to the output voltage harmonic command value H arm * and output voltage harmonic value H arm The harmonic error signal ΔH of the power grid simulator was calculated. arm , △H arm =H arm * -H arm ;

[0192] The harmonic error signal ΔH arm The inputs to the seventh PI controller and the second-order generalized differential harmonic compensator are then used. The resulting outputs of the seventh PI controller and the second-order generalized differential harmonic compensator are added together, and then compared with the harmonic command value H of the output voltage. arm * The two components are added together to obtain the harmonic compensation output ψ1. The expression for the harmonic compensation output ψ1 is:

[0193] ψ1=(H (s) +G (s) (H) arm * -H arm )+H arm *

[0194] Among them, H (s) For the control function of the seventh PI controller, G (s) The system function of the second-order generalized differential harmonic compensator is expressed as follows:

[0195]

[0196]

[0197] In the formula, K p7 The proportional gain of the seventh PI controller, K i7 The integral coefficient of the seventh PI controller, K h For the proportional coefficient and Q of the second-order generalized differential harmonic compensator h For the quality factor of the second-order generalized differential harmonic compensator, ω hThis is the resonant angular frequency of the second-order generalized differential harmonic compensator;

[0198] The output ψ of the sixth PI controller and the inverter H-bridge voltage command value U are used. OG * The harmonic compensation outputs ψ1 are added together and then proportionally transformed to obtain the modulated wave m of the power grid simulator, whose expression is:

[0199]

[0200] Among them, U m U is the output voltage amplitude of the power grid simulator. dc This is the common DC bus voltage.

[0201] In this implementation example: there are three phases, each connected to a 10Ω resistor, and the command voltage is... In this embodiment, the compensated harmonic is the 9th harmonic, and for an amplitude of 0.2 times the fundamental amplitude, the harmonic command... K P5 =0.05, K i5 =1000, K P6 =0.05, K i6 =0,K P7 =0.5, K i7 =0;K h =1, Q h =0.015, ω h =2827, The output phase difference between two adjacent phases is

[0202] Step 4.2, Control of the switching transistors in the power grid simulator

[0203] Based on the modulation wave m, and using the inverter H-bridge modulation method, the driving signal PWM of the switching transistor Z1 is used. Z1 Based on this, PWM drive signals corresponding to switches Z2, Z3, and Z4 are generated. Z2 PWM Z3 and PWM Z4 And drive the corresponding switching transistor to conduct.

[0204] The specific method of the inverter H-bridge modulation method is as follows:

[0205] The PWM drive signals for switching transistors Z1, Z2, Z3, and Z4 are as follows: Z1 PWM Z2 PWM Z3 PWM Z4 The period is T. S ; The drive signal PWM for switch Z1Z1 and the drive signal PWM of the switching transistor Z4 Z4 Similarly, the drive signal PWM for switch Z2 Z2 and the drive signal PWM of the switching transistor Z3 Z3 Same; switching transistors Z1 and Z2 are complementary in conduction, and switching transistors Z3 and Z4 are complementary in conduction; drive signal PWM Z1 With drive signal PWM Z4 The modulation system is M. Where |m| is the amplitude of the modulated wave m, and |m1| is the amplitude of the carrier wave.

Claims

1. A multi-port modular AC / DC power supply simulator, characterized in that, The system includes a three-phase AC power grid, a three-phase transformer, a three-phase bridge rectifier, a battery simulator, a photovoltaic simulator, and a power grid simulator. The input terminal of the three-phase transformer is connected to the three-phase power grid, and the output terminal is connected in series with a three-phase input inductor L and then connected to the AC input terminal of the three-phase bridge rectifier. The DC output terminals of the three-phase bridge rectifier form a common DC bus, and a filter capacitor C is connected in parallel between the positive and negative DC bus of the common DC bus. The battery simulator, photovoltaic simulator, and power grid simulator are each connected to the common DC bus through their input terminals. The battery simulator comprises N1 identical battery sub-modules, and each sub-module includes a Buck-Boost circuit and a single-phase DAB circuit. The Buck-Boost circuit includes switching transistors Q1 and Q2, a filter inductor L1, and a filter capacitor C1. The drain of switching transistor Q1 is connected to the filter inductor L1, and the other end of the filter inductor L1 is connected to the positive terminal of the filter capacitor C1. The source of switching transistor Q2 is connected to the line between the drain of switching transistor Q1 and the filter inductor L1, and the drain of switching transistor Q2 is connected to the negative terminal of the filter capacitor C1. The positive and negative terminals of the filter capacitor C1 constitute the output terminal of the Buck-Boost circuit. The single-phase DAB includes a primary-side H-bridge, a secondary-side H-bridge, a filter inductor L2, a filter capacitor C2, and a high-frequency transformer T1. The primary-side H-bridge contains four switching transistors, denoted as switching transistors. The primary H-bridge consists of four transistors: S1, S2, S3, and S4. The secondary H-bridge contains four transistors: S5, S6, S7, and S8. The DC input of the primary H-bridge is connected to the output of the Buck-Boost circuit. The AC output of the primary H-bridge is connected via inductor L2 and the primary side of high-frequency transformer T1. The secondary side of high-frequency transformer T1 is connected to the AC input of the secondary H-bridge. The DC output of the secondary H-bridge is connected in parallel to a filter capacitor C2. The filter capacitors C2 of N1 battery sub-modules are cascaded in series. The positive terminal of the filter capacitor C2 of the first battery sub-module and the negative terminal of the filter capacitor C2 of the N1th battery sub-module constitute the output of the battery simulator. The source of transistor Q1 and the drain of transistor Q2 constitute the input of the battery sub-module. The N1 battery sub-modules connected in parallel constitute the input of the battery simulator. The photovoltaic simulator contains N2 identical Buck circuits, each of which includes a switching transistor V. T1 diode V D1 , filter inductor L3 and filter capacitor C3, where the switching transistor V T1 The drain of the diode is connected to the filter inductor L3, and the other end of the filter inductor L3 is connected to the positive terminal of the filter capacitor C3. D1 The negative terminal is connected to the switching transistor V. T1 On the connection between the drain of diode V and the filter inductor L3, the diode V D1 The positive terminal is connected to the negative terminal of the filter capacitor C3, and the switching transistor V... T1 The source and diode V D1 The positive terminal forms the input terminal of the Buck circuit. The input terminals of N2 Buck circuits are connected in parallel to form the input terminal of the photovoltaic simulator. The capacitors C3 of N2 Buck circuits are cascaded, and the positive terminal of the filter capacitor C3 of the first Buck circuit and the negative terminal of the filter capacitor C3 of the N2 Buck circuit form the output terminal of the photovoltaic simulator. The grid simulator comprises N3 identical full-bridge inverter submodules. Each full-bridge inverter submodule includes an inverter H-bridge, a filter inductor L4, and a filter capacitor C4. The inverter H-bridge contains four switching transistors, denoted as Z1, Z2, Z3, and Z4. A filter capacitor C4 is connected in parallel to the AC output of the inverter H-bridge, and a filter inductor L4 is connected in series between the AC output of the inverter H-bridge and the filter capacitor C4. The filter capacitor C4 constitutes the output of the full-bridge inverter submodule. The negative terminals of the filter capacitors C4 from the N3 full-bridge inverter submodules are connected together at a node denoted as N. O Point N3: The positive terminal of the filter capacitor C4 of the N3 full-bridge inverter submodules serves as the N3 phase output of the grid simulator. This output simulates phases 1, 2, and 3 of the grid simulator, respectively. ..., The N3 phases and N3 full-bridge inverter submodules are controlled independently. The N3 phases are synchronized through communication, and the output phases of adjacent phases differ by a certain amount. , =2π / N3; The input terminals of N3 inverter H-bridges are connected in parallel to form the input terminals of the power grid simulator.

2. A control method for a multi-port modular AC / DC power supply simulator, employing the multi-port modular AC / DC power supply simulator as described in claim 1, characterized in that, Includes the following steps: Step 1, Data Sampling and Command Value Setting The sampled data is as follows: Instantaneous output voltage of the Buck-Boost circuit. And denoted as the first instantaneous voltage The instantaneous value of the current in the filter inductor L1 is recorded as the first instantaneous current. Battery simulator output voltage Battery simulator output current The instantaneous state of charge (SOC) of the battery simulator is recorded; the output voltage of the photovoltaic simulator is recorded. and photovoltaic simulator output current ; Inverter The bridge outputs the instantaneous voltage value and records it as the second instantaneous voltage. The instantaneous value of the current in the filter inductor L4 is recorded as the second instantaneous current. Grid simulator inverter The output current of the bridge is denoted as the inverter. Bridge output current ; The command values ​​are set as follows: Inverter H-bridge voltage command values ​​for the power grid simulator. And recorded as the inverter H-bridge voltage command value. The harmonic command value of the output voltage of the power grid simulator is recorded as the output voltage harmonic command value. ; Step 2, Control of the battery simulator Step 2.1, solve for the duty cycle of switch Q1. and single-phase DAB phase shift value Establish an equivalent circuit model and solve for the open-circuit voltage of the battery simulator. Equivalent output voltage of battery under steady state ; Output current from the battery simulator The instantaneous state of charge (SOC) is used as the input to the external characteristic equation, and the output of the external characteristic equation is the voltage command value output by the battery simulator. ; Voltage command value output by battery simulator Obtain the output voltage command value of the Buck-Boost circuit. ; Based on the first instantaneous voltage and Buck-Boost circuit output voltage command value Calculated Buck-Boost circuit voltage error signal and will As the input to the first PI controller, the output is the command value of the current of the filter inductor L1, which is recorded as the first current command value. ; According to the first current command value and the first instantaneous current The first current error signal was calculated. The first current error signal As the input to the second PI controller, the output is the duty cycle of the switching transistor Q1. ; According to the output voltage of the battery simulator and the battery simulator output voltage command value The battery simulator output voltage error signal was calculated. The battery simulator outputs a voltage error signal. As input to the third PI controller, the single-phase DAB phase shift value is obtained. ; Step 2.2, Control of the battery simulator switching transistor Based on the duty cycle of switch Q1 Based on the duty cycle modulation method, the drive signal PWM of the switching transistor Q1 is used. Q1 Based on this, the drive signal PWM for the switching transistor Q2 is generated. Q2 And drive the corresponding switching transistor; based on the single-phase DAB phase shift value Based on the phase-shift modulation method, the driving signal PWM of the switching transistor S1 is used. S1 Based on this, drive signals PWM are generated for switches S2, S3, S4, S5, S6, S7, and S8, respectively. S2 PWM S3 PWM S4 PWM S5 PWM S6 PWM S7 PWM S8 And drive the corresponding switching transistor; Step 3, Control of the photovoltaic simulator Step 3.1, solve for V of the switching transistor. T1 duty cycle Determine the open-circuit voltage U of the photovoltaic simulator OC and the short-circuit current I of the photovoltaic simulator SC , build The characteristic equation of the curve is used to solve for the simulated output current I of the photovoltaic simulator. O ; Output voltage of the photovoltaic simulator As the input to the volt-ampere converter, the output of the volt-ampere converter is the output current command value of the photovoltaic simulator. ; According to the output current command value of the photovoltaic simulator and photovoltaic simulator output current The current error signal of the photovoltaic simulator was calculated. ; to convert the photovoltaic simulator current error signal As the input to the fourth PI controller, the output of the fourth PI controller is the switching transistor V. T1 duty cycle ; Step 3.2, Control of the switching transistors in the photovoltaic simulator According to the switching transistor V T1 duty cycle Based on the single-transistor modulation method, by controlling the switching transistor V T1 PWM drive signal VTI To control the switching transistor V T1 The switching on and off of the transistor; the single-transistor modulation method is as follows: switching transistor V T1 PWM drive signal VTI The frequency is f s ; f s =1 / T S Among them, T S For drive signal PWM VTI The cycle; Step 4, Control of the power grid simulator Step 4.1, Solve for the modulated wave m in the power grid simulator. Based on the second instantaneous voltage value and inverter H-bridge voltage command value The inverter H-bridge voltage error signal was calculated. Based on the inverter H-bridge voltage error signal The harmonic values ​​of the output voltage of the power grid simulator are calculated and recorded as the output voltage harmonic values. ; Inverter H-bridge voltage error signal As the input to the fifth PI controller, the output of the fifth PI controller is the current command value of the filter inductor L4, which is recorded as the second instantaneous current command value. According to the second instantaneous current command value Second instantaneous current value The current error signal of the filter inductor L4 is calculated and denoted as the second current error signal. The second current error signal and invert Bridge output current The sum of these values ​​is used as the input to the sixth PI controller to obtain the output ψ of the sixth PI controller; Based on the output voltage harmonic command value and output voltage harmonic values The output voltage harmonic error signal of the power grid simulator was calculated. And denoted as harmonic error signal. Harmonic error signal As the input to the seventh PI controller and the second-order generalized differential harmonic compensator, the harmonic compensation output ψ1 is obtained; The output ψ of the sixth PI controller and the inverter H-bridge voltage command value The harmonic compensation outputs ψ1 are added together and then proportionally transformed to obtain the modulated wave m of the power grid simulator. Step 4.2, Control of the switching transistors in the power grid simulator Based on the modulation wave m, and using the inverter H-bridge modulation method, the driving signal PWM of the switching transistor Z1 is used. Z1 Based on this, PWM drive signals corresponding to switches Z2, Z3, and Z4 are generated. Z2 PWM Z3 and PWM Z4 And drive the corresponding switching transistor to conduct.

3. The control method for a multi-port modular AC / DC power supply simulator according to claim 2, characterized in that, Step 2.1 involves solving for the duty cycle of switch Q1. and single-phase DAB phase shift value The specific process is as follows: An equivalent circuit model is established, consisting of a voltage source E0 and an equivalent internal resistance R. The open-circuit voltage of the battery simulator is... Battery equivalent output voltage under steady-state conditions The expressions are as follows: Where n1 is the number of individual battery cells, E is the battery output current. cell Let be the open-circuit voltage of a single battery cell, calculated as follows: In the formula, K represents the equilibrium potential of the battery stack when SOC = 0.

5. T The factor value is 0.1829 at room temperature; Output current from the battery simulator The instantaneous state of charge (SOC) is used as the input to the external characteristic equation, and the output of the external characteristic equation is the voltage command value output by the battery simulator. Its expression is: According to the output voltage command value of the battery simulator Obtain the output voltage command value of the Buck-Boost circuit. , = / N1; Based on the first instantaneous voltage and Buck-Boost circuit output voltage command value The voltage error signal of the Buck-Boost circuit was calculated. , ; Buck-Boost circuit voltage error signal As the input to the first PI controller, the output of the first PI controller is the first current command value. Its expression is: in, The proportional gain of the first PI controller. is the integral coefficient of the first PI controller, and s is the Laplace operator; According to the first current command value and the first instantaneous current The first current error signal was calculated. , ; the first current error signal As the input to the second PI controller, the output of the second PI controller is the duty cycle of the switching transistor Q1. Its expression is: in, The proportional gain of the second PI controller. The integral coefficient of the second PI controller; According to the output voltage of the battery simulator and the battery simulator output voltage command value The battery simulator output voltage error signal was calculated. , The battery simulator outputs a voltage error signal. As the input to the third PI controller, the output of the third PI controller is the single-phase DAB phase shift value. Its expression is as follows: in, The proportional gain of the third PI controller, The integral coefficient of the third PI controller.

4. The control method for a multi-port modular AC / DC power supply simulator according to claim 2, characterized in that, The specific methods of duty cycle modulation and phase shift modulation described in step 2.2 are as follows: Duty cycle modulation method: PWM driving signals corresponding to switching transistors Q1 and Q2 Q1 and drive signal PWM Q2 The frequencies are all f s Switch Q1 and switch Q2 are complementary in conduction; Phase-shift modulation method: PWM driving signals corresponding to switching transistors S1, S2, S3, S4, S5, S6, S7, and S8 S1 PWM S2 PWM S3 PWM S4 PWM S5 PWM S6 PWM S7 and PWM S8 The frequencies are all f S ; Drive signal PWM S1 and drive signal PWM S4 Same, drive signal PWM S2 and drive signal PWM S3 Same, drive signal PWM S5 and drive signal PWM S8 Same, drive signal PWM S6 and drive signal PWM S7 The same; switches S1 and S2 are complementary in conduction, switches S3 and S4 are complementary in conduction, switches S5 and S6 are complementary in conduction, and switches S7 and S8 are complementary in conduction; the drive signal PWM for switch S5 is... S5 The PWM signal lags behind the drive signal of the switching transistor S1. S1 The drive signal PWM of the switching transistor S6 S6 The PWM signal lags behind the drive signal of the switching transistor S2. S2 Lag time .

5. The control method for a multi-port modular AC / DC power supply simulator according to claim 2, characterized in that, Step 3.1 involves solving for the switching transistor V. T1 duty cycle The specific process is as follows: Solve for the open-circuit voltage U of the photovoltaic simulator OC and the short-circuit current I of the photovoltaic simulator SC Its expression is: in, For diode quality factor, Popitzmann's constant, For the junction temperature of photovoltaic cells, For electron charge, For the current flowing through diode V D1 The current, For photocurrent, For equivalent parallel resistance, This is the equivalent series resistance; Output voltage of the photovoltaic simulator As the input to the volt-ampere converter, the output of the volt-ampere converter is the output current command value of the photovoltaic simulator. ; Among them, A1 is the first impact factor. A2 is the second impact factor. ; According to the output current command value of the photovoltaic simulator and photovoltaic simulator output current The current error signal of the photovoltaic simulator was calculated. , ; Photovoltaic simulator current error signal As the input to the fourth PI controller, the output of the fourth PI controller is the switching transistor V. T1 duty cycle Its expression is: in, The proportional gain of the fourth PI controller, is the integral coefficient of the fourth PI controller, and s is the Laplace operator.

6. The control method for a multi-port modular AC / DC power supply simulator according to claim 2, characterized in that, The specific process of solving for the modulated wave m in step 4.1 is as follows: Based on the second instantaneous voltage value and inverter H-bridge voltage command value The inverter H-bridge voltage error signal was calculated. , ; Based on the inverter H-bridge voltage error signal The output voltage harmonic values ​​were calculated. , : Inverter H-bridge voltage error signal As the input to the fifth PI controller, the output of the fifth PI controller is the second instantaneous current command value. Its expression is as follows: in, The proportional gain of the fifth PI controller, is the integral coefficient of the fifth PI controller, and s is the Laplace operator; According to the second instantaneous current command value Second instantaneous current value The second current error signal was calculated. , : The second current error signal and invert Bridge output current The sum of these values ​​is used as the input to the sixth PI controller to obtain its output. Its expression is; in, The proportional gain of the sixth PI controller, The integral coefficient of the sixth PI controller; Based on the output voltage harmonic command value and output voltage harmonic values The harmonic error signal of the power grid simulator was calculated. , ; harmonic error signal The inputs to the seventh PI controller and the second-order generalized differential harmonic compensator are then used as inputs. The resulting outputs of the seventh PI controller and the second-order generalized differential harmonic compensator are then added together, and finally compared with the harmonic command value of the output voltage. Add them together to obtain the harmonic compensation output. Harmonic compensation output The expression is: in, For the control function of the seventh PI controller, The system function of the second-order generalized differential harmonic compensator is expressed as follows: In the formula, The proportional gain of the seventh PI controller, The integral coefficient of the seventh PI controller, For the proportional coefficient of the second-order generalized differential harmonic compensator, For the quality factor of the second-order generalized differential harmonic compensator, This is the resonant angular frequency of the second-order generalized differential harmonic compensator; The output of the sixth PI controller Inverter H-bridge voltage command value Harmonic compensation output After addition and proportional transformation, the modulated wave m of the power grid simulator is obtained, and its expression is: in, The output voltage amplitude for the power grid simulator. This is the common DC bus voltage.

7. The control method for a multi-port modular AC / DC power supply simulator according to claim 2, characterized in that, The specific method of the inverter H-bridge modulation method described in step 4.2 is as follows: The PWM drive signals for switching transistors Z1, Z2, Z3, and Z4 are as follows: Z1 PWM Z2 PWM Z3 PWM Z4 The frequencies are all f S ; The drive signal PWM for switch Z1 Z1 and the drive signal PWM of the switching transistor Z4 Z4 Similarly, the drive signal PWM for switch Z2 Z2 and the drive signal PWM of the switching transistor Z3 Z3 Same; switching transistors Z1 and Z2 are complementary in conduction, and switching transistors Z3 and Z4 are complementary in conduction; drive signal PWM Z1 With drive signal PWM Z4 The modulation scheme is M. ,in, Let m be the amplitude of the modulating wave. This represents the amplitude of the carrier wave.

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