Control code switching and reuse method for emergency power supply reuse of bidirectional charging pile

Abstract

The present invention relates to the technical field of electric vehicle charging piles, and in particular to a control code switching and multiplexing method for bidirectional charging pile emergency power reuse, the method comprising the following steps: constructing a topology and control architecture for multiplexing the bidirectional charging pile as an emergency power supply for an area; based on the topology and control architecture, constructing a unified control algorithm architecture between the control method of the cascade power conversion system of the bidirectional charging pile when the power grid is normal and the control method of the cascade power conversion system during emergency power supply; and performing online switching of the control code of the cascade power conversion system according to the unified control algorithm architecture. Based on the proposed topology and control architecture, the present invention provides a unified control algorithm architecture between two different control methods of the cascade power conversion system, and the online switching of the control code of the cascade power conversion system can be achieved through a mode switching switch without the need for the main control chip to be powered off and restarted, thereby avoiding a large amount of repetitive embedded code caused by different control method codes.

Description

Technical Field

[0001] The invention relates to the technical field of electric vehicle charging piles, and in particular to a control code switching and multiplexing method for multiplexing emergency power supplies for bidirectional charging piles. Background Art

[0002] With the popularity of electric vehicles, the technical concept of vehicle-to-grid bidirectional power interaction (V2G) has emerged. Its core content is to use the battery units of new energy electric vehicles as large-scale distributed energy storage units of the power grid, and participate in the operation of the power system to achieve bidirectional interaction of energy between the power grid and the vehicle, with the aim of improving the power load curve of the power system and reducing the actual operating pressure of the power grid. Specifically, V2G can balance the load of the power system, charge electric vehicles during the valley power period at night based on time-of-use electricity prices, and feed back energy to the power grid according to demand during the peak power period during the day, thus achieving peak shifting and valley filling.

[0003] On the one hand, although the V2G bidirectional charging and discharging between electric vehicles and the power grid has completed successful demonstration operation in a series of national projects, it has encountered serious economic bottlenecks in its promotion and application. Specifically, it is intolerable for users of high-power fast charging piles to hang the car on the charging pile for a long time to charge and discharge during peak-filling periods. They all need to have a charging waiting time close to the experience of fast refueling of traditional cars. Moreover, compared with the expensive battery cost, the depreciation cost of the battery's charge and discharge cycle life caused by V2G cannot be recovered through the peak-valley price difference. These two major economic bottlenecks have severely restricted the real promotion of V2G. Therefore, vehicle-grid interaction requires other practical forms and corresponding technologies besides V2G.

[0004] On the other hand, in the existing emergency power supply scheme for urban substations, diesel generators or mobile power emergency vehicles are most commonly used. After a power outage occurs, the corresponding power staff usually disconnects the connection switch between the power supply substation and the mains in the distribution cabinet, and then starts the diesel generator or notifies the mobile power emergency vehicle to continue to supply power to the load of the power supply substation as a backup power supply. The time required for diesel generators or mobile power emergency vehicles to restore power is generally relatively long, and the area occupied by diesel generators is relatively large. In addition to the generator set, it is also necessary to consider the control, power distribution, fuel tank and other auxiliary equipment rooms, which have high requirements for plane and space. In addition, the oil storage room itself is a fire hazard, so it also needs to be fireproofed. Therefore, compared with V2G, reusing bidirectional charging piles as emergency power supplies to replace diesel generators has greater development prospects.

[0005] However, on the basis of reusing the bidirectional charging pile as an emergency power supply, there are also problems that need to be solved in the engineering implementation of new application scenarios. First of all, between the two different control modes of the cascade power conversion system control method of the bidirectional charging pile when the power grid is normal and the cascade power conversion system control method of the bidirectional charging pile during emergency power supply, it is necessary to power off and load to achieve mode switching. In addition, the two different control mode codes also bring about the problem of large amount of embedded code and low operating efficiency. Summary of the invention

[0006] In view of the defects in the prior art, the present invention provides a control code switching and multiplexing method for bidirectional charging pile emergency power reuse.

[0007] In order to achieve the above-mentioned purpose, the present invention provides a control code switching and multiplexing method for bidirectional charging pile emergency power reuse, the method comprising the following steps: constructing a topology and control architecture for reusing the bidirectional charging pile vehicle pile unit as an emergency power supply for the substation; based on the topology and control architecture, constructing a unified control algorithm architecture between the control method of the cascade power conversion system of the bidirectional charging pile when the power grid is normal and the control method of the cascade power conversion system during emergency power supply; and performing online switching of the control code of the cascade power conversion system according to the unified control algorithm architecture. Based on the proposed topology and control architecture, the present invention provides a unified control algorithm architecture between two different control methods of the cascade power conversion system. The control code of the cascade power conversion system can be switched online through a mode switching switch without the need for the main control chip to be powered off and restarted, thereby avoiding a large amount of repetitive embedded code caused by different control method codes.

[0008] Optionally, the construction of a topology and control architecture for reusing the bidirectional charging pile vehicle pile unit as an emergency power supply for the station area includes the following steps:

[0009] Constructing a cascade power conversion system for a bidirectional charging pile, and constructing a power supply circuit for connecting the cascade power conversion system, the power grid and the load in the station area;

[0010] The power supply circuit is used to interconnect the cascade power conversion system, the power grid and the substation load to form the topology and control architecture.

[0011] Optionally, the cascade power conversion system includes a grid-side inverter and a pile-side converter of each of the bidirectional charging pile vehicle-pile units, and the power supply circuit includes a three-wire AC bus, an isolation transformer, a load switch, a switching switch, a four-wire AC bus, a grid-side switch and a load bus.

[0012] Optionally, the grid-side inverter and the pile-side converter are cascaded via a common DC bus;

[0013] The three-phase AC sides of the plurality of grid-side inverters are connected in parallel and connected to one side of the triangle of the isolation transformer;

[0014] The grid-side switch and the load switch are both three-phase four-wire, the two ends of the grid-side switch are respectively connected to the grid and the load bus, and the two ends of the load switch are respectively connected to the load bus and the three-phase four-wire of the star side of the isolation transformer;

[0015] The switching switch is a three-phase three-wire switch, and two ends of the switching switch are respectively connected to one side of the triangle of the isolation transformer and the load bus.

[0016] Optionally, the unified control algorithm architecture includes a networking control module, a first coordinate system transformation module, a second coordinate system transformation module, a voltage resonance controller module, a current resonance controller module, a phase-locked loop, a DC voltage PI module, a DC current PI module, a mode switching switch S1, a mode switching switch S2, a mode switching switch S3, a first PWM modulation module and a second PWM modulation module.

[0017] Optionally, the network control module is connected to the first coordinate system transformation module, the voltage resonance controller module is connected to the input I position of the mode switching switch S1, and the input of the voltage resonance controller module is the difference between the output of the first coordinate system transformation module and the output filter capacitor voltage feedback value of the grid-side inverter;

[0018] The output end of the current resonance controller module is connected to the first PWM modulation module, the first PWM modulation module is connected to the grid-side inverter, and the input of the current resonance controller module is the difference between the output signal of the mode switching switch S1 and the inverter-side current of the grid-side inverter;

[0019] The output I position of the mode switching switch S2 is connected to the input end of the second coordinate system transformation module, the output end of the second coordinate system transformation module is connected to the input II position of the mode switching switch S1, the input signal of the mode switching switch S2 is the output of the DC voltage PI module, and the input of the DC voltage PI module is the difference between the voltage command value and the voltage feedback value of the common DC bus between the grid-side inverter and the pile-side converter;

[0020] The output end of the DC current PI module is connected to the second PWM modulation module, the second PWM modulation module is connected to the pile-side converter, and the input of the DC current PI module is the difference between the output of the output II position of the mode switching switch S2 and the output current feedback value of the pile-side converter;

[0021] The input of the mode switching switch S3 is the output of the phase-locked loop, the output I position of the mode switching switch S3 is connected to the networking control module, and the output II position of the mode switching switch S3 is connected to the input end of the second coordinate system transformation module.

[0022] Optionally, when the power grid is out of power, the input of the mode switch S1 is switched to position I, the output of the mode switch S2 is switched to position II, and the output of the mode switch S3 is switched to position I.

[0023] Optionally, when the power grid operates normally, the input of the mode switching switch S1 is switched to position II, the output of the mode switching switch S2 is switched to position I, and the output of the mode switching switch S3 is switched to position II.

[0024] Optionally, the transfer functions of the voltage resonance controller module and the current resonance controller module sequentially satisfy the following relationship:

[0025]

[0026] Among them, G PRu represents the transfer function of the voltage resonant controller module, G PRi represents the transfer function of the current resonant controller module, K pu and K ru is the PI controller parameter of the voltage loop in the voltage resonance controller module, K pi and K ri is the PI controller parameter of the current loop in the voltage resonance controller module, ω c is the controller bandwidth, ω1 is the reference frequency, and s is the Laplace operator.

[0027] Optionally, the transfer functions of the DC voltage PI module and the DC current PI module sequentially satisfy the following relationship:

[0028]

[0029] Among them, G PI_dcu represents the transfer function of the DC voltage PI module, G PI_dci represents the transfer function of the DC current PI module, k pdcu and k idcu is the PI controller parameter of the voltage loop in the DC voltage PI module, k pdci and k idci is the PI controller parameter of the current loop in the DC voltage PI module, and s is the Laplace operator.

[0030] In summary, the present invention breaks the application bottleneck of bidirectional charging pile vehicle-grid interaction V2G limited to peak shifting and valley filling by transforming the bidirectional charging pile into a multifunctional multiplexing device that provides emergency power supply. When the power grid is out of power, any electric vehicle can be mobilized to connect to the bidirectional charging pile for emergency power supply to the substation, so that the emergency diesel generator set does not need to be installed to greatly improve the disaster prevention capacity of the urban power supply substation. At the same time, based on the proposed topology and control architecture, the present invention provides a unified control algorithm architecture between two different control methods of the cascade power conversion system. The control code of the cascade power conversion system can be switched online through the mode switching switch without the need for the main control chip to be powered off and restarted, avoiding a large amount of repetitive embedded code caused by different control method codes. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a flow chart of a control code switching and multiplexing method for multiplexing a bidirectional charging pile emergency power supply according to an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the topology and control architecture of an embodiment of the present invention;

[0034] Figure 3 Schematic diagram of a control strategy for constructing a network using multiple vehicles and multiple piles according to an embodiment of the present invention;

[0035] Figure 4 This is a block diagram of the control of the common DC bus voltage by the grid-side inverter when the power grid is operating normally according to an embodiment of the present invention;

[0036] Figure 5 is a block diagram of a current controller according to an embodiment of the present invention;

[0037] Figure 6 4 is a block diagram of a unified control algorithm architecture of an embodiment of the present invention.

[0038] Among them: 1-power grid, 2-bidirectional charging pile vehicle-pile unit, 3-pile-side converter, 4-grid-side inverter, 5-three-wire AC bus, 6-isolation transformer, 7-load switch, 8-load bus, 9-switching switch, 10-station load, 11-four-wire AC bus, 12-grid-side switch, 13-multi-vehicle multi-pile structure, 14-multi-mechanism network control structure, 15-first coordinate system transformation module, 16-voltage resonance controller module, 17-DC voltage PI module, 18-second coordinate system transformation module, 19-current resonance controller module, 20-DC current PI module, 21-first PWM modulation module, 22-second PWM modulation module. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0040] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0041] It should be noted in advance that, in an optional embodiment, except for independent explanations, the same symbols or letters appearing in all formulas have the same meanings and values.

[0042] In an alternative embodiment, see Figure 1 The present invention provides a control code switching and multiplexing method for bidirectional charging pile emergency power multiplexing, the method comprising the following steps:

[0043] T1. Construct a topology and control architecture that reuses the bidirectional charging pile unit as an emergency power supply for the station area.

[0044] Among them, T1 specifically includes the following steps:

[0045] T11. Construct a cascade power conversion system for a bidirectional charging pile, and at the same time construct a power supply circuit for connecting the cascade power conversion system, the power grid and the load in the substation.

[0046] Specifically, in this embodiment, see Figure 2 The bidirectional charging pile vehicle pile unit 2 includes a grid-side inverter 4 and a pile-side converter 3. The cascade power conversion system includes multiple bidirectional charging pile vehicle pile units 2, and the three-phase AC sides of multiple grid-side inverters 4 are connected in parallel. The power supply circuit includes a three-wire AC bus 5, an isolation transformer 6, a load switch 7, the switching switch 9, a four-wire AC bus 11, a grid-side switch 12 and a load bus 8.

[0047] Furthermore, the pile-side converter 3 is a DC / DC converter, and the grid-side inverter 4 is an AC / DC converter, both of which are components of the bidirectional charging pile. The cascade power conversion system of this embodiment is a prior art and will not be described in detail here.

[0048] In other optional embodiments, the bidirectional charging pile vehicle pile unit 2 may also include an electric car connected to the bidirectional charging pile.

[0049] T12. Use the power supply circuit to interconnect the cascade power conversion system, the power grid and the substation load to form the topology and control architecture.

[0050] Specifically, in this embodiment, see Figure 2 , the grid-side inverter 4 and the pile-side converter 3 are cascaded through a common DC bus, the pile-side converter 3 is connected to the bidirectional charging pile vehicle pile unit 2 by a cable, and the three-phase AC sides of multiple grid-side inverters 4 are connected in parallel and connected to the delta side of the isolation transformer 6. The grid-side switch 12 and the load switch 7 are both three-phase four-wire, and the two ends of the grid-side switch 12 are respectively connected to the power grid 1 and the load bus 8, and the two ends of the load switch 7 are respectively connected to the load bus 8 and the three-phase four-wire on the star side of the isolation transformer 6. The switching switch 9 is three-phase three-wire, and the two ends of the switching switch 9 are respectively connected to the delta side of the isolation transformer 6 and the load bus 8. Multiple load feeders are used to connect the load bus 8 and the substation load 10.

[0051] The topology and control architecture of reusing bidirectional charging piles as emergency power sources for substations can also be called the substation emergency power supply system of bidirectional charging piles. By constructing a topology and control architecture that reuses bidirectional charging piles as emergency power sources for substations, bidirectional charging piles are transformed into multifunctional multiplexing devices that provide emergency power supply, breaking the application bottleneck of bidirectional charging pile vehicle-grid interaction V2G limited to shifting peaks and filling valleys. When the power grid 1 is out of power, any electric vehicle can be mobilized to connect to the bidirectional charging pile for emergency power supply to the substation, so that there is no need to install emergency diesel generator sets to greatly improve the disaster prevention capabilities of urban power supply substations, and at the same time relieve the pressure on emergency power supply vehicles.

[0052] For more details, switch to emergency power supply mode when power grid 1 fails. Figure 2 and Figure 3 , turn off the load switch 7, disconnect the grid-side switch 12 and the switch 9, and then use the electric vehicle battery pack to provide off-grid emergency power supply to the load in the substation. At this time, in the multi-vehicle multi-pile structure 13, the current i2 of the input isolation transformer 6 and the output filter capacitor voltage u of the grid-side inverter 4 are c Sampling is performed and the sampling results are input into the multi-mechanism network control structure 14. The sampling results are transformed by abc / dq to obtain the d-axis component i of i2 in the dq coordinate system. 2d and the q-axis component i 2q and u c In the dq coordinate system, the d-axis component u c_d and the q-axis component u c_q , then i 2d 、i 2q 、u c_d and u c_q The input instantaneous power calculation module performs instantaneous power calculation, thereby obtaining instantaneous active power P and instantaneous reactive power Q. The instantaneous power calculation module for calculating instantaneous power is a prior art, and will not be described in detail here.

[0053] The instantaneous active power and instantaneous reactive power are input into the network control module, and the network control module outputs the voltage amplitude and angle signal to the voltage generation module. The angle signal θ output by the network control module and the instantaneous active power P satisfy the following relationship:

[0054]

[0055] Among them, θ i is the phase angle of the voltage vector of the i-th bidirectional charging pile vehicle pile unit 2, s is the Laplace operator, P outi is the instantaneous active power corresponding to the i-th bidirectional charging pile vehicle pile unit 2, J 0i is the frequency time constant of the i-th bidirectional charging pile vehicle pile unit 2, ω0 is the rated angular frequency of the bidirectional charging pile vehicle pile unit 2, D i is the damping coefficient of the i-th bidirectional charging pile vehicle pile unit 2, i=1,2,3,...,N, and N is the total number of the bidirectional charging pile vehicle pile units 2.

[0056] The voltage amplitude U output by the network control module and the instantaneous reactive power Q satisfy the following relationship:

[0057]

[0058] Among them, U iis the voltage amplitude output by the network control module corresponding to the i-th bidirectional charging pile vehicle pile unit 2, K i is the voltage regulation coefficient of the i-th bidirectional charging pile vehicle pile unit 2, D qi is the reactive power regulation coefficient of the i-th bidirectional charging pile vehicle pile unit 2, Q outi is the instantaneous reactive power corresponding to the i-th bidirectional charging pile vehicle pile unit 2.

[0059] At this time, the output active power change of the bidirectional charging pile vehicle pile unit 2 and the rated active power change should satisfy the following relationship:

[0060]

[0061] Among them, ΔP outi is the output active power change of the i-th bidirectional charging pile vehicle pile unit 2, ΔP seti is the rated active power change of the i-th bidirectional charging pile vehicle pile unit 2, ΔP load is the load power variation in the entire multi-vehicle multi-pile structure 13, G iP and G iω They represent the active power command P of the i-th bidirectional charging pile vehicle pile unit 2 respectively. ref The transfer function of the frequency disturbance to its output power is expressed as follows:

[0062]

[0063] Among them, U0 is the output phase voltage of the multi-vehicle multi-pile structure 13, U g is the voltage amplitude at the PCC in the multi-vehicle multi-pile structure 13, X gi is the grid-side equivalent impedance of the i-th bidirectional charging pile vehicle pile unit 2.

[0064] The voltage generation module is used to generate the dq axis voltage control command, and the dq axis voltage control command is subtracted from the dq coordinate system transformation result of the output filter capacitor voltage and then input into the voltage and current inner loop. The dq axis voltage control command generated by the voltage generation module includes the d axis voltage control command u c_dref and q-axis voltage control command u c_qref The dq coordinate system transformation result of the output filter capacitor voltage includes u c_d and u c_q . will u c_dref and u c_d Do poorly, u c_qref and u c_qThe difference is made, and the difference result is input into the voltage and current inner loop. The voltage and current inner loop generates the output voltage dq coordinate axis instruction of the grid-side inverter 4, and the output voltage dq coordinate axis instruction generated by the voltage and current inner loop is converted into the output voltage instruction of the three-phase coordinate system after dq / abc transformation. Then, the output voltage instruction is input into the PWM modulation module to generate the high-frequency switching signal of the grid-side inverter, which is a prior art method.

[0065] exist Figure 3 In, L f and C f are the filter inductance and filter capacitance of the output filter of the grid-side inverter 4, respectively, c That is C f Voltage across L g and R g are line inductance and resistance respectively, i1 represents the output current of the grid-side converter 4, Q ref is the reactive power command, C dc It is the DC capacitor between the two-stage cascade of the grid-side inverter 4 and the pile-side converter 3.

[0066] In other optional embodiments, when the power grid 1 operates normally, see Figure 2 , the load switch 7 is opened, the grid-side switch 12 and the switching switch 9 are closed, the three-phase AC side of the grid-side inverter 4 is directly connected to the three-phase line of the load bus 8, and the power grid 1 directly supplies power to the substation load 10.

[0067] For further information, see Figure 4 The grid-side inverter 4 adopts the grid-connected current source control to stabilize the common DC bus between the grid-side inverter 4 and the pile-side converter 3. When the grid 1 is operating normally, the outer loop of the grid-side inverter 4 is a DC voltage loop, and the sampling C dc The voltage V dc As the feedback value and the voltage command value V of the common DC bus dref Compare and V ddc With V dref The difference is input into the DC voltage controller, and then the current command value i of the AC side d axis of the grid-side inverter 4 is obtained respectively. dref and the q-axis current command value i qref , since the DC side demand of the grid-side inverter 4 is active power, i dref Take zero, i dref Enter the current controller. At the same time, the three-phase inductor current i on the grid-side inverter 4 is sampled L,abc ,i L,abc After abc / dq transformation, the current components i of the d-axis are obtained respectively. Ld and the current component i on the q axis Lq , and iLd and i Lq Enter the current controller.

[0068] See also Figure 5 , the current controller will i dref with i Ld The difference input transfer function is The PI controller obtains the control voltage of the d-axis k p_d and k i_d is the control parameter of the current loop of the PI controller; i qref with i Lq The difference input transfer function is The PI controller obtains the control voltage of the q axis k p_q and k i_q is the control parameter of the PI controller current loop. and After dq / abc conversion, the signal is input into the PWM modulation module to obtain the on / off signal of the grid-side inverter 4 .

[0069] When the power grid 1 operates normally, the bidirectional power flow of the electric vehicle is controlled by directly controlling the output current of the pile-side converter 3. This is a prior art and will not be described in detail here.

[0070] T2. Based on the topology and control architecture, a unified control algorithm architecture is constructed between the control method of the cascade power conversion system of the bidirectional charging pile when the power grid is normal and the control method of the cascade power conversion system during emergency power supply.

[0071] Specifically, in this embodiment, see Figure 6 The unified control algorithm architecture includes a network control module, a first coordinate system transformation module 15, a second coordinate system transformation module 18, a voltage resonance controller module 16, a current resonance controller module 19, a phase-locked loop, a DC voltage PI module 17, a DC current PI module 20, a mode switching switch S1, a mode switching switch S2, a mode switching switch S3, a first PWM modulation module 21 and a second PWM modulation module 22. The mode switching switch S1, the mode switching switch S2 and the mode switching switch S3 are all dual-input single-output switches.

[0072] The network control module is connected to the first coordinate system transformation module 15, and the voltage amplitude and angle signal output by the network control module are used as the input of the first coordinate system transformation module 15. After the dq / αβ coordinate transformation, the output filter capacitor voltage command value of the grid-side inverter 4 is obtained. The voltage resonance controller module 16 is connected to the input I position of the mode switching switch S1. The input of the voltage resonance controller module 16 is the output of the first coordinate system transformation module 15. The output filter capacitor voltage feedback value V cap The difference, where V cap =u c The transfer function of the voltage resonance controller module 16 satisfies the following relationship:

[0073]

[0074] Among them, G PRu Denotes the transfer function of the voltage resonance controller module 16, K pu and K ru is the resonant controller parameter of the voltage loop in the voltage resonant controller module 16, ω c is the controller bandwidth, ω1 is the reference frequency, and ω1 is generally 50Hz.

[0075] The control equation of the network control module is as follows:

[0076]

[0077] Q ref -Q=D q (E-E0)

[0078] Among them, D p is the active damping coefficient of the bidirectional charging pile vehicle pile unit 2, ω is the output angular frequency of the bidirectional charging pile vehicle pile unit 2, J is the frequency time constant of the bidirectional charging pile vehicle pile unit 2, D q is the reactive damping coefficient of the bidirectional charging pile vehicle pile unit 2, E is the output voltage amplitude of the bidirectional charging pile vehicle pile unit 2, and E0 is the rated voltage amplitude of the bidirectional charging pile vehicle pile unit 2.

[0079] The output end of the current resonance controller module 19 is connected to the first PWM modulation module 21, the first PWM modulation module 21 is connected to the grid-side inverter 4, and the input of the current resonance controller module 19 is the output signal of the mode switching switch S1 The inverter side current i of the grid-side inverter 4 inv The first PWM modulation module 21 performs PWM modulation on the output of the current resonance controller module 19 to generate a PWM control signal for the grid-side inverter 4. The transfer function of the current resonance controller module 19 satisfies the following relationship:

[0080]

[0081] Among them, G PRi represents the transfer function of the current resonant controller module 19, Kpi and K ri is the resonant controller parameter of the current loop in the voltage resonant controller module 21.

[0082] The output I position of the mode switching switch S2 is connected to the input end of the second coordinate system transformation module 18, and the output end of the second coordinate system transformation module 18 is connected to the input II position of the mode switching switch S1. The input signal of the mode switching switch S2 is the output of the DC voltage PI module 17, and the input of the DC voltage PI module 17 is the voltage command value of the common DC bus between the grid-side inverter 4 and the pile-side converter 3. and voltage feedback value V dc The transfer function of the DC voltage PI module 17 satisfies the following relationship:

[0083]

[0084] Among them, G PI_dcu represents the transfer function of the DC voltage PI module 17, k pdcu and k idcu are the PI controller parameters of the voltage loop in the DC voltage PI module 17.

[0085] The output end of the DC current PI module 20 is connected to the second PWM modulation module 22, and the second PWM modulation module 22 is connected to the pile-side converter 3. The input of the DC current PI module 24 is the output of the output II position of the mode switching switch S2 and the output current feedback value i of the pile-side converter 3. dc The output of the DC current PI module 20 is PWM modulated by the second PWM modulation module 22 to generate a PWM control signal for the pile-side converter 3. The output of the output II position of the mode switching switch S2 is the output current command value of the pile-side converter 3. The transfer function of the DC current PI module 20 satisfies the following relationship:

[0086]

[0087] Among them, G PI_dci represents the transfer function of the DC current PI module 20, k pdci and k idci are the PI controller parameters of the current loop in the DC voltage PI module 22.

[0088] The input of the mode switching switch S3 is the output of the phase-locked loop. The output I position of the mode switching switch S3 is connected to the network control module, and the output II position of the mode switching switch S3 is connected to the input end of the second coordinate system transformation module 18.

[0089] T3. Perform online switching of the control code of the cascade power conversion system according to the unified control algorithm architecture.

[0090] Specifically, in this embodiment, see Figure 6 When the power grid 1 is out of power, the first control mode of the cascade power conversion system is adopted, specifically: the input of the mode switching switch S1 is switched to the I position, the output of the mode switching switch S2 is switched to the II position, and the output of the mode switching switch S3 is switched to the I position.

[0091] When the power grid 1 is out of power, the network control module and the first coordinate system transformation module 15 are first used to obtain Then With V cap The difference is input to the voltage resonance controller module 16 to obtain And output through the mode switching switch S1, and then combined with the inverter side current i of the grid side inverter 4 inv After the difference is made, it is used as the input of the current resonance controller module 19 to output the PWM control signal of the grid-side inverter 4. The phase-locked loop is connected to the grid control module through the mode switching switch S3. However, when the grid 1 is out of power, the phase angle information of the phase-locked loop is only used during the pre-synchronization of the multi-mechanism network. With V dc The difference is input into the DC voltage PI module 17, and its output After switching mode switch S2 and i dc The difference is made, and the difference result is input into the DC current PI module 20, and the output of the DC current PI module 20 is PWM modulated to obtain the PWM control signal of the pile-side converter 3.

[0092] Furthermore, when the power grid 1 is operating normally, the second control mode of the cascade power conversion system is adopted, specifically: the input of the mode switching switch S1 is switched to the II position, the output of the mode switching switch S2 is switched to the I position, and the output of the mode switching switch S3 is switched to the II position.

[0093] When the power grid 1 is operating normally, With V dc The difference is input to the DC voltage PI module 17, and the output of the DC voltage PI module 17 is input to the second coordinate system transformation module 18 through the mode switching switch S2. The phase information corresponding to the output of the DC voltage PI module 17 is given by the phase-locked loop after passing through the mode switching switch S3. After the mode switch S1 and i inv The difference is used as the input of the current resonance controller module 19, and the output of the current resonance controller module 19 is PWM modulated to obtain the PWM control signal of the grid-side inverter 4.

[0094] Furthermore, the two different control modes, the cascade power conversion system control method for bidirectional charging piles when the power grid is normal and the cascade power conversion system control method for bidirectional charging piles when emergency power supply is in use, require power off and loading to achieve mode switching. In addition, the two different control mode codes also bring about the problem of large amount of embedded code and low operating efficiency.

[0095] When switching between the control code of the first control mode and the control code of the second control mode, there is no need to power off and restart the main control chip and reload the code. Instead, it is only necessary to stop running the control algorithm of the grid-side inverter 4 and the pile-side converter 3 and stop their PWM signal output, and then send instructions through the host computer to switch the mode switching switches S1, S2 and S3 online, so as to switch to the control code corresponding to another control mode. At the same time, under the unified control algorithm architecture, most of the modules are shared between the first control mode and the second control mode, avoiding a large amount of repetitive embedded code caused by loading two sets of control mode codes, thereby improving the efficiency of mode switching.

[0096] It should be noted that, in some cases, the actions described in the specification can be performed in a different order and still achieve the desired results. In this embodiment, the order of steps given is only to make the embodiment appear clearer and easier to explain, rather than to limit it.

[0097] In summary, the present invention breaks the application bottleneck of bidirectional charging pile vehicle-grid interaction V2G limited to peak shifting and valley filling by transforming the bidirectional charging pile into a multifunctional multiplexing device that provides emergency power supply. When the power grid is out of power, any electric vehicle can be mobilized to connect to the bidirectional charging pile for emergency power supply to the substation, so that the emergency diesel generator set does not need to be installed to greatly improve the disaster prevention capacity of the urban power supply substation. At the same time, the present invention provides a unified control algorithm architecture between two different control methods of the cascade power conversion system on the basis of the proposed topology and control architecture. The control code of the cascade power conversion system can be switched online through the mode switching switch without the need for the main control chip to be powered off and restarted, avoiding a large amount of repetitive embedded code caused by different control method codes, thereby improving the efficiency of mode switching.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A control code switching and multiplexing method for bidirectional charging pile emergency power supply multiplexing, characterized in that: The steps include: Construct a topology and control architecture that reuses the bidirectional charging pile vehicle pile unit as an emergency power supply for the station area; Based on the topology and control architecture, a unified control algorithm architecture is constructed between the control method of the cascade power conversion system of the bidirectional charging pile when the power grid is normal and the control method of the cascade power conversion system during emergency power supply; Performing online switching of control codes of the cascade power conversion system according to the unified control algorithm architecture; The topology and control architecture for reusing the bidirectional charging pile vehicle pile unit as an emergency power supply for the station area includes the following steps: Constructing a cascade power conversion system for a bidirectional charging pile, and constructing a power supply circuit for connecting the cascade power conversion system, the power grid and the load in the station area; Using the power supply circuit to interconnect the cascade power conversion system, the power grid and the load in the substation area to form the topology and control architecture; The cascade power conversion system includes a grid-side inverter and a pile-side converter of each of the bidirectional charging pile vehicle pile units, and the power supply circuit includes a three-wire AC bus, an isolation transformer, a load switch, a switching switch, a four-wire AC bus, a grid-side switch and a load bus; The grid-side inverter and the pile-side converter are cascaded via a common DC bus; The three-phase AC sides of the plurality of grid-side inverters are connected in parallel and connected to one side of the triangle of the isolation transformer; The grid-side switch and the load switch are both three-phase four-wire, the two ends of the grid-side switch are respectively connected to the grid and the load bus, and the two ends of the load switch are respectively connected to the load bus and the three-phase four-wire of the star side of the isolation transformer; The switching switch is a three-phase three-wire switch, and the two ends of the switching switch are respectively connected to one side of the triangle of the isolation transformer and the load bus; The unified control algorithm architecture includes a network control module, a first coordinate system transformation module, a second coordinate system transformation module, a voltage resonance controller module, a current resonance controller module, a phase-locked loop, a DC voltage PI module, a DC current PI module, a mode switching switch S1, a mode switching switch S2, a mode switching switch S3, a first PWM modulation module and a second PWM modulation module; The network control module is connected to the first coordinate system transformation module, the voltage resonance controller module is connected to the input I position of the mode switching switch S1, and the input of the voltage resonance controller module is the difference between the output of the first coordinate system transformation module and the output filter capacitor voltage feedback value of the grid-side inverter; The output end of the current resonance controller module is connected to the first PWM modulation module, the first PWM modulation module is connected to the grid-side inverter, and the input of the current resonance controller module is the difference between the output signal of the mode switching switch S1 and the inverter-side current of the grid-side inverter; The output I position of the mode switching switch S2 is connected to the input end of the second coordinate system transformation module, the output end of the second coordinate system transformation module is connected to the input II position of the mode switching switch S1, the input signal of the mode switching switch S2 is the output of the DC voltage PI module, and the input of the DC voltage PI module is the difference between the voltage command value and the voltage feedback value of the common DC bus between the grid-side inverter and the pile-side converter; The output end of the DC current PI module is connected to the second PWM modulation module, the second PWM modulation module is connected to the pile-side converter, and the input of the DC current PI module is the difference between the output of the output II position of the mode switching switch S2 and the output current feedback value of the pile-side converter; The input of the mode switching switch S3 is the output of the phase-locked loop, the output I position of the mode switching switch S3 is connected to the networking control module, and the output II position of the mode switching switch S3 is connected to the input end of the second coordinate system transformation module.

2. The control code switching and multiplexing method for bidirectional charging pile emergency power reuse according to claim 1 is characterized in that: When the power grid is out of power, the input of the mode switch S1 is switched to position I, the output of the mode switch S2 is switched to position II, and the output of the mode switch S3 is switched to position I.

3. The control code switching and multiplexing method for bidirectional charging pile emergency power reuse according to claim 1 is characterized in that: When the power grid operates normally, the input of the mode switching switch S1 is switched to position II, the output of the mode switching switch S2 is switched to position I, and the output of the mode switching switch S3 is switched to position II.

4. The control code switching and multiplexing method for bidirectional charging pile emergency power reuse according to claim 1 is characterized in that: The transfer functions of the voltage resonance controller module and the current resonance controller module satisfy the following relationship in sequence: in, represents the transfer function of the voltage resonance controller module, represents the transfer function of the current resonant controller module, and are the PI controller parameters of the voltage loop in the voltage resonance controller module, and are the PI controller parameters of the current loop in the voltage resonance controller module, is the controller bandwidth, is the reference frequency, and s is the Laplace operator.

5. The control code switching and multiplexing method for bidirectional charging pile emergency power reuse according to claim 1 is characterized in that: The transfer functions of the DC voltage PI module and the DC current PI module satisfy the following relationship in sequence: in, represents the transfer function of the DC voltage PI module, represents the transfer function of the DC current PI module, and are the PI controller parameters of the voltage loop in the DC voltage PI module, and is the PI controller parameter of the current loop in the DC voltage PI module, and s is the Laplace operator.

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