An energy management method and device applied to an electric vehicle charging and swapping station

Abstract

The application relates to an energy management method applied to an electric vehicle charging and replacing station, which comprises the following steps: when a charging and discharging machine is started, all the charging and discharging machines are started according to a master machine control method; when the phase angle of a load voltage is not equal to theta 0, the charging and discharging machine is identified as a slave machine, and the master machine control method is switched to a slave machine control method; after the charging and discharging machine is started, an energy management strategy of photovoltaic cell power supply priority or an energy management strategy of power equalization is selected. In the process of establishing the load voltage, the master machine and the slave machine are automatically determined, the stability and the reliability of starting are improved, the system has self-organizing ability, the starting success rate and the anti-interference ability of multi-machine parallel connection are obviously improved; according to the special requirements of the photovoltaic charging and storing integrated scene, in the photovoltaic priority mode, the energy of photovoltaic power generation can be maximally utilized, the light abandoning phenomenon of photovoltaic power generation is avoided, the overcharging and overdischarging of the power battery are prevented, the integration of the photovoltaic charging and storing is improved, and the real-time automatic adjustment of single-machine power is realized.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle charging and battery swapping technology, and in particular to an energy management method and equipment for electric vehicle charging and battery swapping stations. Background Technology

[0002] Currently, electric vehicle charging and battery swapping stations have evolved into comprehensive energy storage stations integrating photovoltaic charging and energy storage. The charging and discharging machines not only need to charge the power batteries, but also need to realize vehicle-to-grid (V2G) interaction and connect to the new energy power generation interface to provide power supplementation for local loads and backup energy for the power grid. This places higher demands on the multi-machine parallel control and multi-machine collaborative energy management strategies of the charging and discharging machines themselves.

[0003] Existing parallel multi-unit charging and discharging machines often employ droop control or master-slave control methods, requiring two independent parts: one part determines the power reference of each charging and discharging machine through energy management strategies, and the other part controls the output power of each charging and discharging machine to track the power reference. These control strategies all have a certain degree of lag and cannot be adjusted in real time according to the current load state. Furthermore, for integrated photovoltaic-charging-storage applications, they cannot flexibly utilize the energy generated by photovoltaic power generation; photovoltaic power generation and V2G charging and discharging are independent, failing to achieve true integration of photovoltaic, charging, and storage. Summary of the Invention

[0004] To address the issues of lag in response and lack of consideration for the integrated photovoltaic-charging-storage scenario in existing technologies, the primary objective of this invention is to provide an energy management method for electric vehicle charging and swapping stations that addresses the specific needs of integrated photovoltaic-charging-storage scenarios. Under photovoltaic priority mode, this method maximizes the utilization of photovoltaic power generation, improves the integration of photovoltaic, charging, and storage, and enables real-time automatic adjustment of single-unit power.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an energy management method applied to electric vehicle charging and swapping stations, the method comprising the following sequential steps:

[0006] (1) When the charge and discharge machine is started, all the charge and discharge machines are started according to the host control method, that is, the phase angle θ0 participating in the coordinate transformation is set, and the load voltage u is sampled at the same time. a0 u b0 and u c0 The phase angle of the load voltage is calculated by the phase-locked loop (PLL). When the phase angle of the load voltage is equal to θ0, the charger / discharger is identified as the master and the master control method remains unchanged. When the phase angle of the load voltage is not equal to θ0, the charger / discharger is identified as the slave and the master control method is switched to the slave control method.

[0007] (2) After the charger and discharger are started, select either the energy management strategy that prioritizes photovoltaic power supply or the energy management strategy that distributes power equally.

[0008] (3) If a photovoltaic cell power supply priority energy management strategy is adopted, the power required by the load will be provided by the photovoltaic cell first. When only the photovoltaic cell supplies power, the slave power is equal to the maximum power that the photovoltaic cell can provide. When the photovoltaic cell and the power battery supply power together, the slave power is equal to the sum of the maximum power that the photovoltaic cell can provide and the discharge power of the power battery.

[0009] (4) If the power sharing energy management strategy is adopted, the principle of consistent working power of each charging and discharging machine is followed. By cutting off the DC bus voltage outer loop of the slave control method, multiple charging and discharging machines without DC bus voltage outer loop are controlled in parallel. By detecting the current that the charging and discharging machine load, photovoltaic cell and power battery can provide, the active current reference value of the slave machine is adjusted in real time. Under the premise of meeting the input power supply capacity and load power supply requirements, the power sharing of each charging and discharging machine is realized.

[0010] In step (1), the host control method specifically refers to: sampling the three-phase voltage u of the load. a0 u b0 and u c0 The phase angle θ0 is used in the coordinate transformation to convert it into active voltage u in the dq coordinate system. d0 and reactive voltage u q0 The active voltage u d0 reactive voltage u q0 and active voltage reference value u d * reactive voltage reference value u q * In comparison, the obtained error signal is used by a PI controller to generate an active current reference value i. d0 * and reactive current reference value i q0 * Sample the three-phase current i of the load. a0 i b0 and i c0 The phase angle θ0 is used in the coordinate transformation to convert it into active current i in the dq coordinate system. d0 and reactive current i q0 The active current i d0 reactive current i q0 and active current reference value i d0 * Reactive current reference value i q0 *In comparison, the obtained error signal is fed into SVPWM space vector pulse width modulation after passing through a PI controller, generating the drive signal for the power switching transistors in the DC / AC converter.

[0011] The slave control method specifically refers to: sampling the three-phase voltage u of the load. a0 u b0 and u c0 The phase angle θ1 of the load voltage is calculated using a PLL (phase-locked loop); the DC bus voltage U between the DC / DC converter and the DC / AC converter is sampled. DC1 The DC bus voltage U DC1 With bus voltage reference U DC1 * In comparison, the obtained error signal is used by a PI controller to generate an active current reference value i. d1 * The reactive current reference value i q1 * Fixed at 0; sampled load three-phase current i a1 i b1 and i c1 Through coordinate transformation involving θ1, it is converted into active current i in the dq coordinate system. d1 and reactive current i q1 The active current i d1 reactive current i q1 and active current reference value i d1 * Reactive current reference value i q1 * In comparison, the obtained error signal is passed through a PI controller and then participates in SVPWM space vector pulse width modulation to generate the drive signal for the power switching transistors in the DC / AC converter.

[0012] Step (3) specifically refers to: U 0pv ...U N-1pv U represents the voltage of the photovoltaic cells connected to the DC side of N charge / discharge machines. 0bt ...U N-1bt The power battery connects to N charge / discharge machines. The photovoltaic cells and power batteries are electrically coupled through a multi-port DC / DC converter. The photovoltaic cells of each slave machine operate at the maximum power point. According to the slave machine control method, the slave machine controls the DC bus voltage. Therefore, the power of the slave machine is determined by the power supplied by the DC side.

[0013] When the charger supplies power to the local load, it prioritizes the photovoltaic cells. When the power supplied by the photovoltaic cells is less than the load power, u a0 u b0 and u c0 It will decrease, and the decrease can be measured; let the decrease be Δu.a0 , Δu b0 and Δu c0 The required additional power ΔP is calculated using the following formula:

[0014] ;

[0015] Among them, i aj Let i be the phase a current of the charge / discharger numbered j; bj Let i be the phase b current of the charge / discharger numbered j; cj Let Δu be the c-phase current of the charge / discharger numbered j; a0 , Δu b0 and Δu c0 This represents the decrease in the three-phase voltage on the load side.

[0016] The required additional power ΔP is provided by the slave device's power battery, corresponding to a voltage of U. 1bt ...U N-1bt And since each group of power batteries provides the same power, the discharge current of the slave power battery is:

[0017] ;

[0018] Among them, i jbt U represents the discharge current of the power battery of the charge / discharger numbered j, N is the total number of charge / dischargers, and U... jbt Let j be the voltage of the power battery of the charge / discharge machine.

[0019] In step (4), the parallel control of multiple charge / discharge machines without a DC bus voltage outer loop specifically refers to: disconnecting the DC bus voltage outer loop of the slave control method, and at the initial moment after startup, the slave current setpoint i d1 * to i dN-1 * It is no longer obtained through the outer loop of the DC bus voltage, but is equal to the host's current reference i. d0 * ;

[0020] Simultaneously calculate the maximum power P that all master and slave devices can provide on the DC side. PV_BAT_j For j=0,1,...N-1, the formula is as follows:

[0021] ;

[0022] Among them, P jpv P represents the maximum power of the photovoltaic cells in the j-th charge / discharge machine. N_BATj The rated power of the power battery for the j-th charge / discharge machine; SOP j Let P be the state of power of the power battery of the j-th charge / discharge machine; then PPV_BAT_j Active current i mapped to the DC / AC converter PV_BAT_j for:

[0023] ;

[0024] Among them, u AC This is the effective value of the load voltage.

[0025] In step (4), the power-sharing energy management strategy specifically includes the following steps: (4a) Let j=0, calculate the active current i jointly provided by the photovoltaic cell and the power battery of the host. PV_BAT_0 If the active current reference value i d0 * Less than i PV_BAT_0 The rated current i of the charge / discharger N The minimum value min(i) PV_BAT_0 i N This indicates that the master unit can provide the currently required power, and the slave unit's i in the initial state... d1 * ...i dN-1 * It should be equal to i d0 * Then, the slave device i is compared in a loop. d1 * ...i dN-1 * i PV_BAT_ 1...i PV_BAT_N-1 and i N Specifically, the loop compares i d1 * i PV_BAT_1 and i N i d2 *、i PV_BAT_2 and i N i d3 *、i PV_BAT_3 and i N And so on, until comparing i dN-1 * and i PV_BAT_N-1 Each charger and discharger has the same rated current, which is i. N ;

[0026] (4a1) if i d1 * ...i dN-1 * Less than i N Then compare i d1 * ...i dN-1 * and i PV_BAT_1 ...iPV_BAT_N-1 size:

[0027] If the active current i provided by the photovoltaic cell and power battery of the i-th slave device is... PV_BAT_i Greater than the active current reference value i di * This means that the i-th slave device can provide the currently required power. di * Remain unchanged;

[0028] If the i-th slave device's i PV_BAT_i Less than i di * Then the i-th slave device di * It should be changed to i PV_BAT_i The active current reference value of other slave devices is changed to i dj *’ :

[0029] ;

[0030] In the formula, i dj *’ The updated first active current reference value for slave device j;

[0031] That is, the insufficient current sent by the i-th slave device is evenly supplemented to the other slave devices;

[0032] (4a2) If i d1 * ...i dN-1 * Greater than i N This indicates that the slave device, after the supplementary current is applied, has exceeded its rated operating power. Therefore, i d1 * ...i dN-1 * Change to i N And issue a request to increase the number of parallel charging and discharging machines, that is, to increase N;

[0033] (4b) If the host's i PV_BAT_0 Less than i d0 * Then, the master voltage loop current limiting is applied, and the system is changed to slave mode, selecting i. PV_BAT_x The largest slave-to-master voltage loop becomes the master, and the master and slave numbers are swapped. The current reference value of the slave that was transformed from the master becomes i. PV_BAT_x 'x' represents the changed slave device number, and the current reference value for other slave devices becomes 'i'. dj *’’ :

[0034] ;

[0035] In the formula, i dj *’’ The updated second active current reference value for slave device j; the average current difference before and after the change is added to the other slave devices;

[0036] (4c) Repeat (4a) until the user requests a shutdown.

[0037] Another object of the present invention is to provide an electronic device comprising:

[0038] Processor; and

[0039] A memory storing computer program instructions that, when executed by the processor, cause the processor to perform the energy management method described above for electric vehicle charging and swapping stations.

[0040] The present invention also provides a computer-readable storage medium having stored thereon computer program instructions, which, when executed by a processor, cause the processor to perform the energy management method applied to an electric vehicle charging and swapping station as described above.

[0041] As can be seen from the above technical solution, the beneficial effects of the present invention are as follows: First, the present invention automatically determines the master and slave units during the load voltage establishment process, improving the stability and reliability of startup, enabling the system to have self-organizing capabilities, and significantly improving the startup success rate and anti-interference capability of multi-unit parallel operation; Second, in response to the special needs of integrated photovoltaic-charging-storage scenarios, under the photovoltaic priority mode, it can maximize the utilization of photovoltaic power generation energy, avoiding both the curtailment of photovoltaic power generation and the overcharging and over-discharging of power batteries, improving the integration of photovoltaic-charging-storage, and realizing real-time automatic adjustment of single-unit power; Third, it can balance the working power of each charging and discharging unit, dynamically adjust the active current distribution by real-time monitoring of the photovoltaic-battery combined power supply capability of each unit, and ensure that the output power deviation of each unit is minimized; The designed current redistribution mechanism can evenly distribute the power margin of a single unit to other units, improving the stability and real-time performance of parallel operation; By deeply integrating photovoltaic power generation, power battery energy storage, and V2G services, it is suitable for scenarios with stringent power supply reliability requirements, such as urban integrated photovoltaic-storage-charging stations and fast charging networks in highway service areas. Attached Figure Description

[0042] Figure 1 A parallel control method for multiple charge / discharge machines with an outer loop of DC bus voltage;

[0043] Figure 2 A parallel control method for multiple charge / discharge machines without an outer loop of DC bus voltage. Detailed Implementation

[0044] like Figure 1 As shown, an energy management method for electric vehicle charging and swapping stations includes the following sequential steps:

[0045] (1) When the charge and discharge machine is started, all the charge and discharge machines are started according to the host control method, that is, the phase angle θ0 participating in the coordinate transformation is set, and the load voltage u is sampled at the same time. a0 u b0 and u c0 The phase angle of the load voltage is calculated by the phase-locked loop (PLL). When the phase angle of the load voltage is equal to θ0, the charger / discharger is identified as the master and the master control method remains unchanged. When the phase angle of the load voltage is not equal to θ0, the charger / discharger is identified as the slave and the master control method is switched to the slave control method.

[0046] (2) After the charger and discharger are started, select either the energy management strategy that prioritizes photovoltaic power supply or the energy management strategy that distributes power equally.

[0047] (3) If a photovoltaic cell power supply priority energy management strategy is adopted, the power required by the load will be provided by the photovoltaic cell first. When only the photovoltaic cell supplies power, the slave power is equal to the maximum power that the photovoltaic cell can provide. When the photovoltaic cell and the power battery supply power together, the slave power is equal to the sum of the maximum power that the photovoltaic cell can provide and the discharge power of the power battery.

[0048] (4) If a power-sharing energy management strategy is adopted, the principle of consistent operating power of each charge / discharger is followed. By cutting off the DC bus voltage outer loop of the slave control method, parallel control of multiple charge / dischargers without a DC bus voltage outer loop is implemented. By detecting the current available from the load of the charge / discharger, photovoltaic cells, and power batteries, the active current reference value of the slave is adjusted in real time. Under the premise of meeting the input power supply capacity and load power supply requirements, power sharing of each charge / discharger is achieved. Figure 1 In the diagram, dashed box 1 shows the master control method, while dashed boxes 2 and 3 are identical and represent the slave control method.

[0049] In step (1), the host control method specifically refers to: sampling the three-phase voltage u of the load. a0 u b0 and u c0 The phase angle θ0 is used in the coordinate transformation to convert it into active voltage u in the dq coordinate system. d0 and reactive voltage u q0 The active voltage u d0 reactive voltage u q0 and active voltage reference value u d * reactive voltage reference value u q *In comparison, the obtained error signal is used by a PI controller to generate an active current reference value i. d0 * and reactive current reference value i q0 * Sample the three-phase current i of the load. a0 i b0 and i c0 The phase angle θ0 is used in the coordinate transformation to convert it into active current i in the dq coordinate system. d0 and reactive current i q0 The active current i d0 reactive current i q0 and active current reference value i d0 * Reactive current reference value i q0 * In comparison, the obtained error signal is fed into SVPWM space vector pulse width modulation after passing through a PI controller, generating the drive signal for the power switching transistors in the DC / AC converter.

[0050] The slave control method specifically refers to: sampling the three-phase voltage u of the load. a0 u b0 and u c0 The phase angle θ1 of the load voltage is calculated using a PLL (phase-locked loop); the DC bus voltage U between the DC / DC converter and the DC / AC converter is sampled. DC1 The DC bus voltage U DC1 With bus voltage reference U DC1 * In comparison, the obtained error signal is used by a PI controller to generate an active current reference value i. d1 * The reactive current reference value i q1 * Fixed at 0; sampled load three-phase current i a1 i b1 and i c1 Through coordinate transformation involving θ1, it is converted into active current i in the dq coordinate system. d1 and reactive current i q1 The active current i d1 reactive current i q1 and active current reference value i d1 * Reactive current reference value i q1 * In comparison, the obtained error signal is passed through a PI controller and then participates in SVPWM space vector pulse width modulation to generate the drive signal for the power switching transistors in the DC / AC converter.

[0051] like Figure 1As shown, step (3) specifically refers to: U 0pv ...U N-1pv U represents the voltage of the photovoltaic cells connected to the DC side of N charge / discharge machines. 0bt ...U N-1bt The power battery connects to N charge / discharge machines. The photovoltaic cells and power batteries are electrically coupled through a multi-port DC / DC converter. The photovoltaic cells of each slave machine operate at the maximum power point. According to the slave machine control method, the slave machine controls the DC bus voltage. Therefore, the power of the slave machine is determined by the power supplied by the DC side.

[0052] When the charger supplies power to the local load, it prioritizes the photovoltaic cells. When the power supplied by the photovoltaic cells is less than the load power, u a0 u b0 and u c0 It will decrease, and the decrease can be measured; let the decrease be Δu. a0 , Δu b0 and Δu c0 The required additional power ΔP is calculated using the following formula:

[0053] ;

[0054] Among them, i aj Let i be the phase a current of the charge / discharger numbered j; bj Let i be the phase b current of the charge / discharger numbered j; cj Let Δu be the c-phase current of the charge / discharger numbered j; a0 , Δu b0 and Δu c0 This represents the decrease in the three-phase voltage on the load side.

[0055] The required additional power ΔP is provided by the slave device's power battery, corresponding to a voltage of U. 1bt ...U N-1bt And since each group of power batteries provides the same power, the discharge current of the slave power battery is:

[0056] ;

[0057] Among them, i jbt U represents the discharge current of the power battery of the charge / discharger numbered j, N is the total number of charge / dischargers, and U... jbt Let j be the voltage of the power battery of the charge / discharge machine.

[0058] like Figure 2 As shown, in step (4), the parallel control of multiple charge / discharge machines without a DC bus voltage outer loop specifically refers to: disconnecting the DC bus voltage outer loop of the slave control method, and at the initial moment after startup, the current setpoint i of the slave machine. d1* to i dN-1 * It is no longer obtained through the outer loop of the DC bus voltage, but is equal to the host's current reference i. d0 * ;

[0059] Simultaneously calculate the maximum power P that all master and slave devices can provide on the DC side. PV_BAT_j For j=0,1,...N-1, the formula is as follows:

[0060] ;

[0061] Among them, P jpv P represents the maximum power of the photovoltaic cells in the j-th charge / discharge machine. N_BATj The rated power of the power battery for the j-th charge / discharge machine; SOP j Let P be the state of power of the power battery of the j-th charge / discharge machine; then P PV_BAT_j Active current i mapped to the DC / AC converter PV_BAT_j for:

[0062] ;

[0063] Among them, u AC This is the effective value of the load voltage.

[0064] In step (4), the power-sharing energy management strategy specifically includes the following steps: (4a) Let j=0, calculate the active current i jointly provided by the photovoltaic cell and the power battery of the host. PV_BAT_0 If the active current reference value i d0 * Less than i PV_BAT_0 The rated current i of the charge / discharger N The minimum value min(i) PV_BAT_0 i N This indicates that the master unit can provide the currently required power, and the slave unit's i in the initial state... d1 * ...i dN-1 * It should be equal to i d0 * Then, the slave device i is compared in a loop. d1 * ...i dN-1 * i PV_BAT_ 1...i PV_BAT_N-1 and i N Specifically, the loop compares i d1 * i PV_BAT_1 and i N i d2*、i PV_BAT_2 and i N i d3 *、i PV_BAT_3 and i N And so on, until comparing i dN-1 * and i PV_BAT_N-1 Each charger and discharger has the same rated current, which is i. N ;

[0065] (4a1) if i d1 * ...i dN-1 * Less than i N Then compare i d1 * ...i dN-1 * and i PV_BAT_1 ...i PV_BAT_N-1 size:

[0066] If the active current i provided by the photovoltaic cell and power battery of the i-th slave device is... PV_BAT_i Greater than the active current reference value i di * This means that the i-th slave device can provide the currently required power. di * Remain unchanged;

[0067] If the i-th slave device's i PV_BAT_i Less than i di * Then the i-th slave device di * It should be changed to i PV_BAT_i The active current reference value of other slave devices is changed to i dj *’ :

[0068] ;

[0069] In the formula, i dj *’ The updated first active current reference value for slave device j;

[0070] That is, the insufficient current sent by the i-th slave device is evenly supplemented to the other slave devices;

[0071] (4a2) If i d1 * ...i dN-1 * Greater than i N This indicates that the slave device, after the supplementary current is applied, has exceeded its rated operating power. Therefore, i d1 * ...idN-1 * Change to i N And issue a request to increase the number of parallel charging and discharging machines, that is, to increase N;

[0072] (4b) If the host's i PV_BAT_0 Less than i d0 * Then, the master voltage loop current limiting is applied, and the system is changed to slave mode, selecting i. PV_BAT_x The largest slave-to-master voltage loop becomes the master, and the master and slave numbers are swapped. The current reference value of the slave that was transformed from the master becomes i. PV_BAT_x 'x' represents the changed slave device number, and the current reference value for other slave devices becomes 'i'. dj *’’ :

[0073] ;

[0074] In the formula, i dj *’’ The updated second active current reference value for slave device j; the average current difference before and after the change is added to the other slave devices;

[0075] (4c) Repeat (4a) until the user requests a shutdown.

[0076] In summary, this invention automatically determines the master and slave units during the load voltage establishment process, improving startup stability and reliability, enabling the system to have self-organizing capabilities, and significantly enhancing the startup success rate and anti-interference ability of multi-unit parallel operation. Addressing the specific needs of integrated photovoltaic-charging-storage scenarios, in photovoltaic priority mode, it maximizes the utilization of photovoltaic power generation energy, avoiding both photovoltaic curtailment and overcharging / over-discharging of power batteries, improving the integration of photovoltaic-charging-storage and real-time automatic adjustment of single-unit power. It can balance the operating power of each charger and discharger, dynamically adjusting the active current distribution by real-time monitoring of the photovoltaic-battery combined power supply capability of each unit, ensuring minimal output power deviation among units. The designed current redistribution mechanism can evenly distribute the power margin of a single unit to other units, improving the stability and real-time performance of parallel operation. By deeply integrating photovoltaic power generation, power battery energy storage, and V2G services, it is suitable for scenarios with stringent power supply reliability requirements, such as urban integrated photovoltaic-storage-charging stations and highway service area fast charging networks.

[0077] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. An energy management method applied to electric vehicle charging and swapping stations, characterized in that: The method includes the following steps in sequence: (1) When the charge and discharge machine is started, all the charge and discharge machines are started according to the host control method, that is, the phase angle θ0 participating in the coordinate transformation is set, and the load voltage u is sampled at the same time. a0 u b0 and u c0 The phase angle of the load voltage is calculated by the phase-locked loop (PLL). When the phase angle of the load voltage is equal to θ0, the charger / discharger is identified as the master and the master control method remains unchanged. When the phase angle of the load voltage is not equal to θ0, the charger / discharger is identified as the slave and the master control method is switched to the slave control method. (2) After the charger and discharger are started, select either the energy management strategy that prioritizes photovoltaic power supply or the energy management strategy that distributes power equally. (3) If a photovoltaic cell power supply priority energy management strategy is adopted, the power required by the load will be provided by the photovoltaic cell first. When only the photovoltaic cell supplies power, the slave power is equal to the maximum power that the photovoltaic cell can provide. When the photovoltaic cell and the power battery supply power together, the slave power is equal to the sum of the maximum power that the photovoltaic cell can provide and the discharge power of the power battery. (4) If the power sharing energy management strategy is adopted, the principle of consistent working power of each charging and discharging machine is followed. By cutting off the DC bus voltage outer loop of the slave control method, multiple charging and discharging machines without DC bus voltage outer loop are controlled in parallel. By detecting the current that the charging and discharging machine load, photovoltaic cell and power battery can provide, the active current reference value of the slave machine is adjusted in real time. Under the premise of meeting the input power supply capacity and load power supply requirements, the power sharing of each charging and discharging machine is realized. In step (4), the power-sharing energy management strategy specifically includes the following steps: (4a) Let j=0, calculate the active current i jointly provided by the photovoltaic cell and the power battery of the host. PV_BAT_0 If the active current reference value i d0 * Less than i PV_BAT_0 The rated current i of the charge / discharger N The minimum value min(i) PV_BAT_0 i N This indicates that the master unit can provide the currently required power, and the slave unit's i in the initial state... d1 * ...i dN-1 * It should be equal to i d0 * Then, the slave device i is compared in a loop. d1 * ...i dN-1 * i PV_BAT_1 ...i PV_BAT_N-1 and i N Specifically, the loop compares i d1 * i PV_BAT_1 and i N i d2 *、i PV_BAT_2 and i N i d3 *、i PV_BAT_3 and i N And so on, until comparing i dN-1 * and i PV_BAT_N-1 Each charger and discharger has the same rated current, which is i. N ; (4a1) if i d1 * ...i dN-1 * Less than i N Then compare i d1 * ...i dN-1 * and i PV_BAT_1 ...i PV_BAT_N-1 size: If the active current i provided by the photovoltaic cell and power battery of the i-th slave device is... PV_BAT_i Greater than the active current reference value i di * This means that the i-th slave device can provide the currently required power. di * Remain unchanged; If the i-th slave device's i PV_BAT_i Less than i di * Then the i-th slave device di * It should be changed to i PV_BAT_i The active current reference value of other slave devices is changed to i dj *’ : ； In the formula, i dj *’ The updated first active current reference value for slave device j; That is, the insufficient current sent by the i-th slave device is evenly supplemented to the other slave devices; (4a2) If i d1 * ...i dN-1 * Greater than i N This indicates that the slave device, after the supplementary current is applied, has exceeded its rated operating power. Therefore, i d1 * ...i dN-1 * Change to i N And issue a request to increase the number of parallel charging and discharging machines, that is, to increase N; (4b) If the host's i PV_BAT_0 Less than i d0 * Then, the master voltage loop current limiting is applied, and the system is changed to slave mode, selecting i. PV_BAT_x The largest slave-to-master voltage loop becomes the master, and the master and slave numbers are swapped. The current reference value of the slave that was transformed from the master becomes i. PV_BAT_x 'x' represents the changed slave device number, and the current reference value for other slave devices becomes 'i'. dj *’’ : ； In the formula, i dj *’’ The updated second active current reference value for slave device j; the average current difference before and after the change is added to the other slave devices; (4c) Repeat (4a) until the user requests a shutdown.

2. The energy management method applied to electric vehicle charging and swapping stations according to claim 1, characterized in that: In step (1), the host control method specifically refers to: sampling the three-phase voltage u of the load. a0 u b0 and u c0 The phase angle θ0 is used in the coordinate transformation to convert it into active voltage u in the dq coordinate system. d0 and reactive voltage u q0 The active voltage u d0 reactive voltage u q0 and active voltage reference value u d * reactive voltage reference value u q * In comparison, the obtained error signal is used by a PI controller to generate an active current reference value i. d0 * and reactive current reference value i q0 * Sample the three-phase current i of the load. a0 i b0 and i c0 The phase angle θ0 is used in the coordinate transformation to convert it into active current i in the dq coordinate system. d0 and reactive current i q0 The active current i d0 reactive current i q0 and active current reference value i d0 * Reactive current reference value i q0 * In comparison, the obtained error signal is fed into SVPWM space vector pulse width modulation after passing through a PI controller, generating the drive signal for the power switching transistors in the DC / AC converter. The slave control method specifically refers to: sampling the three-phase voltage u of the load. a0 u b0 and u c0 The phase angle θ1 of the load voltage is calculated using a PLL (phase-locked loop); the DC bus voltage U between the DC / DC converter and the DC / AC converter is sampled. DC1 The DC bus voltage U DC1 With bus voltage reference U DC1 * In comparison, the obtained error signal is used by a PI controller to generate an active current reference value i. d1 * The reactive current reference value i q1 * Fixed at 0; sampled load three-phase current i a1 i b1 and i c1 Through coordinate transformation involving θ1, it is converted into active current i in the dq coordinate system. d1 and reactive current i q1 The active current i d1 reactive current i q1 and active current reference value i d1 * Reactive current reference value i q1 * In comparison, the obtained error signal is passed through a PI controller and then participates in SVPWM space vector pulse width modulation to generate the drive signal for the power switching transistors in the DC / AC converter.

3. The energy management method applied to electric vehicle charging and swapping stations according to claim 1, characterized in that: Step (3) specifically refers to: U 0pv ...U N-1pv U represents the voltage of the photovoltaic cells connected to the DC side of N charge / discharge machines. 0bt ...U N-1bt The power battery connects to N charge / discharge machines. The photovoltaic cells and power batteries are electrically coupled through a multi-port DC / DC converter. The photovoltaic cells of each slave machine operate at the maximum power point. According to the slave machine control method, the slave machine controls the DC bus voltage. Therefore, the power of the slave machine is determined by the power supplied by the DC side. When the charger supplies power to the local load, it prioritizes the photovoltaic cells. When the power supplied by the photovoltaic cells is less than the load power, u a0 u b0 and u c0 It will decrease, and the decrease can be measured; let the decrease be Δu. a0 , Δu b0 and Δu c0 The required additional power ΔP is calculated using the following formula: ； Among them, i aj Let i be the phase a current of the charge / discharger numbered j; bj Let i be the phase b current of the charge / discharger numbered j; cj Let Δu be the c-phase current of the charge / discharger numbered j; a0 , Δu b0 and Δu c0 This represents the decrease in the three-phase voltage on the load side. The required additional power ΔP is provided by the slave device's power battery, corresponding to a voltage of U. 1bt ...U N-1bt And since each group of power batteries provides the same power, the discharge current of the slave power battery is: ； Among them, i jbt U represents the discharge current of the power battery of the charge / discharger numbered j, N is the total number of charge / dischargers, and U... jbt Let j be the voltage of the power battery of the charge / discharge machine.

4. The energy management method applied to electric vehicle charging and swapping stations according to claim 1, characterized in that: In step (4), the parallel control of multiple charge / discharge machines without a DC bus voltage outer loop specifically refers to: disconnecting the DC bus voltage outer loop of the slave control method, and at the initial moment after startup, the slave current setpoint i d1 * to i dN-1 * It is no longer obtained through the outer loop of the DC bus voltage, but is equal to the host's current reference i. d0 * ; Simultaneously calculate the maximum power P that all master and slave devices can provide on the DC side. PV_BAT_j For j=0,1,...N-1, the formula is as follows: ； Among them, P jpv P represents the maximum power of the photovoltaic cells in the j-th charge / discharge machine. N_BATj The rated power of the power battery for the j-th charge / discharge machine; SOP j Let P be the state of power of the power battery of the j-th charge / discharge machine; then P PV_BAT_j Active current i mapped to the DC / AC converter PV_BAT_j for: ； Among them, u AC This is the effective value of the load voltage.

5. An electronic device, comprising: processor; as well as A memory storing computer program instructions, which, when executed by the processor, cause the processor to perform the energy management method for electric vehicle charging and swapping stations as described in any one of claims 1-4.

6. A computer-readable storage medium having stored thereon computer program instructions, which, when executed by a processor, cause the processor to perform an energy management method for an electric vehicle charging and swapping station as described in any one of claims 1-4.

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