Method and device for providing frequency and voltage support to flexible interconnected distribution network

Abstract

The method and device provided in the present application that can provide frequency and voltage support to a flexible interconnected distribution network, in order to assist the distributed power source connected via the inverter to provide frequency and voltage support to the flexible interconnected distribution network, can connect an energy storage unit in parallel at both ends of the inverter DC bus, and offset the impact of the change in the inverter's active power output on the DC bus voltage through its charge and discharge control. Specifically, the energy storage unit of the present application can be connected to the DC bus of the inverter via a bidirectional Buck / Boost circuit, and the charge and discharge power of the energy storage unit can be adjusted by controlling the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, thereby offsetting the imbalance between the DC bus input active power and the output active power, so that the inverter maintains the DC bus voltage stable in the process of providing frequency and voltage support to the flexible interconnected distribution network.

Description

Technical Field

[0001] The present application relates to the technical field of output control of distributed power sources in a flexible interconnected distribution network, and in particular to a method and device for providing frequency and voltage support to a flexible interconnected distribution network. Background Art

[0002] With the development of distributed power sources, the operation modes of distribution networks have become more diverse. In order to achieve flexible control of the operating status of the distribution network, flexible interconnected distribution networks have become an emerging architecture solution for distribution networks. In flexible interconnected distribution networks, distributed power sources are usually connected to the grid through inverters. Relying on the flexible output power control capability of the inverter, it can actively adjust its active power and reactive power output as a response when the flexible interconnected distribution network needs frequency and voltage support.

[0003] During this process, if the active power output of the inverter changes, an imbalance will occur between the active power input from the distributed power source into the inverter DC bus and the active power output by the inverter, which will cause the DC bus voltage to shift and affect the normal operation of the inverter. Summary of the invention

[0004] The purpose of the present application is to solve at least one of the above-mentioned technical defects, especially the technical defect in the prior art that the imbalance between the active power of the distributed power supply input into the inverter DC bus and the active power output by the inverter will cause the DC bus voltage to shift, thereby affecting the normal operation of the inverter.

[0005] The present application provides a method for providing frequency and voltage support to a flexible interconnected distribution network, wherein the flexible interconnected distribution network is connected to a distributed power source via an inverter, and an energy storage unit is connected to a DC bus of the inverter via a bidirectional Buck / Boost circuit, and the method comprises:

[0006] When it is detected that the inverter provides frequency and / or voltage support to the flexible interconnected distribution network, determining a current power control strategy of the inverter, and adjusting the output power of the inverter according to the current power control strategy;

[0007] During the process of adjusting the output power of the inverter, if it is detected that the charging and discharging active power of the DC bus capacitor of the inverter is unbalanced, the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit are obtained;

[0008] Calculating the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit;

[0009] According to the on-duty ratio of the IGBT switch control signal in the bidirectional Buck / Boost circuit, the charge and discharge state of the energy storage unit is adjusted to offset the imbalance between the output active power of the inverter and the input active power of the distributed power source.

[0010] Optionally, when detecting that the inverter provides frequency support to the flexible interconnected distribution network, determining a current power control strategy of the inverter includes:

[0011] When it is detected that the inverter provides frequency support to the flexible interconnected distribution network, determining the increased active power output of the inverter based on a first preset ramp rate, a first preset time period for increasing the active power output, and a second preset time period for maintaining the maximum active power output;

[0012] The active power output of the inverter is reduced to the power value at the initial moment after the second preset period ends based on the first preset down-slope rate.

[0013] Optionally, when detecting that the inverter provides voltage support to the flexible interconnected distribution network, determining a current power control strategy of the inverter includes:

[0014] When it is detected that the inverter provides voltage support to the flexible interconnected distribution network, determining the reactive power output increased by the inverter based on a second preset ramp rate, a third preset time period for increasing reactive power output, and a fourth preset time period for maintaining maximum reactive power output;

[0015] The reactive power output of the inverter is determined to be reduced to the power value at the initial moment after the fourth preset time period ends based on the second preset down-slope rate.

[0016] Optionally, the calculating the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and the unbalanced amount of the inverter, the initial voltage and the capacitance of the energy storage unit, includes:

[0017] Under the working condition that the output power of the inverter is not significantly adjusted, the difference between the DC bus voltage and its reference value is controlled by the DC bus voltage outer loop control link of the inverter through the proportional integral control link to obtain the adjustment amount of the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit;

[0018] Calculate the on-duty ratio reference setting value of the IGBT switch control signal according to the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit;

[0019] The on-duty ratio of the IGBT switch control signal is obtained by adding the adjustment amount of the on-duty ratio of the IGBT switch control signal to the on-duty ratio reference setting value.

[0020] Optionally, the method further comprises:

[0021] When it is detected that the inverter ends providing frequency support to the flexible interconnected distribution network, the voltage of the energy storage unit at the end time and the minimum allowable voltage value of the energy storage unit are obtained;

[0022] Determine the difference between the voltage at the end time and the minimum allowable voltage value;

[0023] If it is not less than, there is no need to modify the current power control strategy of the inverter;

[0024] If it is less than, the second preset time period is corrected according to the second preset time period in the current power control strategy, the capacitance of the energy storage unit, the voltage at the end time, the minimum allowable voltage value, the first preset time period, the first preset ramp rate, the input active power of the distributed power source, and the power value at the initial moment when the inverter outputs active power.

[0025] Optionally, the method further comprises:

[0026] When it is detected that the inverter ends providing voltage support to the flexible interconnected distribution network, the voltage of the energy storage unit at the end time and the maximum allowable voltage value of the energy storage unit are obtained;

[0027] Determine the difference between the voltage at the end time and the maximum allowable voltage value;

[0028] If the voltage at the end time is not greater than the maximum allowable voltage value, it means that the current power control strategy of the inverter will not cause the operation safety constraint of the energy storage unit to exceed the limit;

[0029] If the voltage at the end time is greater than the maximum allowable voltage value, the fourth preset time period is corrected based on the fourth preset time period in the current power control strategy, the capacitance of the energy storage unit, the voltage at the end time, the maximum allowable voltage value, the third preset time period, the second preset ramp rate, the input active power of the distributed power source, the initial power value when the inverter outputs reactive power, and the maximum allowable apparent power output.

[0030] Optionally, the method further comprises:

[0031] Determine a lower limit of a feasible range of a reference setting value of an on-duty cycle of the IGBT switch control signal that enables a current power control strategy of the inverter to provide frequency support to the flexible interconnected power distribution network;

[0032] Determine an upper limit of a feasible range of a reference setting value of an on-duty cycle of the IGBT switch control signal that enables a current power control strategy of the inverter to provide voltage support to the flexible interconnected power distribution network;

[0033] Determine the setting range of the on-duty cycle of the IGBT switch control signal of the energy storage unit under normal operating conditions so that the distributed power source has the ability to provide frequency and voltage support to the flexible interconnected distribution network within the operating safety constraint range.

[0034] The present application provides a device capable of providing frequency and voltage support to a flexible interconnected distribution network, wherein the flexible interconnected distribution network is connected to a distributed power source via an inverter, and an energy storage unit is connected to the DC bus of the inverter via a bidirectional Buck / Boost circuit, including:

[0035] an output power adjustment module, configured to determine a current power control strategy of the inverter when it is detected that the inverter provides frequency and / or voltage support to the flexible interconnected distribution network, and adjust the output power of the inverter according to the current power control strategy;

[0036] A parameter acquisition module, used for acquiring the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit if the charging and discharging active power of the DC bus capacitor of the inverter is detected to be unbalanced during the process of adjusting the output power of the inverter;

[0037] A conduction duty cycle calculation module, used to calculate the conduction duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit;

[0038] The charge and discharge state adjustment module is used to adjust the charge and discharge state of the energy storage unit according to the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit to offset the imbalance between the output active power of the inverter and the input active power of the distributed power source.

[0039] The present application provides a storage medium, which stores computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of a method for providing frequency and voltage support to a flexible interconnected distribution network as described in any of the above embodiments.

[0040] The present application provides a computer device, comprising: one or more processors, and a memory;

[0041] The memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the method for providing frequency and voltage support to a flexible interconnected distribution network as described in any of the above embodiments are performed.

[0042] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0043] The method and device provided in the present application that can provide frequency and voltage support to a flexible interconnected distribution network, in order to assist the distributed power source connected via the inverter to provide frequency and voltage support to the flexible interconnected distribution network, can connect an energy storage unit in parallel at both ends of the inverter DC bus, and offset the impact of the change in the inverter's active power output on the DC bus voltage through its charge and discharge control. Specifically, the energy storage unit of the present application can be connected to the DC bus of the inverter via a bidirectional Buck / Boost circuit, and the charge and discharge power of the energy storage unit can be adjusted by controlling the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, thereby offsetting the imbalance between the DC bus input active power and the output active power, so that the inverter maintains the DC bus voltage stable in the process of providing frequency and voltage support to the flexible interconnected distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0045] Figure 1 A flow chart of a method for providing frequency and voltage support to a flexible interconnected distribution network provided in an embodiment of the present application;

[0046] Figure 2 A topological structure diagram of a distributed power source including an energy storage unit provided in an embodiment of the present application being connected to a flexible interconnected distribution network;

[0047] Figure 3A topological structure diagram of an energy storage unit provided in an embodiment of the present application connected to an inverter DC bus via a bidirectional Buck / Boost circuit;

[0048] Figure 4 An inverter active power output curve diagram when providing frequency support to a flexible interconnected distribution network provided in an embodiment of the present application;

[0049] Figure 5 A power output curve diagram of an inverter when providing voltage support to a flexible interconnected distribution network provided in an embodiment of the present application;

[0050] Figure 6 A graph of operating parameters of an inverter and an energy storage unit in the process of providing frequency support to a flexible interconnected distribution network provided in an embodiment of the present application;

[0051] Figure 7 The embodiment of the present application provides a correction Δt 2,p The operating parameter curve diagram of the inverter and energy storage unit after parameters are changed;

[0052] Figure 8 A schematic diagram of the structure of a device that can provide frequency and voltage support to a flexible interconnected power distribution network provided in an embodiment of the present application;

[0053] Fig. 9 A schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] In one embodiment, Figure 1 As shown, Figure 1 A flow chart of a method for providing frequency and voltage support to a flexible interconnected distribution network provided in an embodiment of the present application; the present application provides a method for providing frequency and voltage support to a flexible interconnected distribution network, wherein the flexible interconnected distribution network is connected to a distributed power source via an inverter, and an energy storage unit is connected to the DC bus of the inverter via a bidirectional Buck / Boost circuit, and the method may include:

[0056] S110: When it is detected that the inverter provides frequency and / or voltage support to the flexible interconnected distribution network, determine the current power control strategy of the inverter, and adjust the output power of the inverter according to the current power control strategy.

[0057] In this step, since the flexible interconnected distribution network is connected to the distributed power source through the inverter, when the flexible interconnected distribution network needs frequency and / or voltage support, the active power and / or reactive power of the distributed power source can be transmitted to the flexible interconnected distribution network through the inverter to provide frequency and / or voltage support to the flexible interconnected distribution network.

[0058] Specifically, when the present application detects that the inverter provides frequency and / or voltage support to the flexible interconnected distribution network, the current power control strategy of the inverter can be determined. The current power control strategy refers to a power control strategy for regulating the output power of the inverter in the process of providing frequency and / or voltage support to the flexible interconnected distribution network, such as when to increase the output power, when to maintain the output power, when to reduce the output power, when to output active power, when to output reactive power, etc. The power control strategy can be updated according to the safety status of related equipment after each time the frequency and / or voltage support is provided to the flexible interconnected distribution network, so that when the inverter is detected again to provide frequency and / or voltage support to the flexible interconnected distribution network, the latest power control strategy can be used as the current power control strategy, and the output power of the inverter can be adjusted according to the current power control strategy, so as to provide frequency and / or voltage support to the flexible interconnected distribution network through the inverter.

[0059] S120: During the process of adjusting the output power of the inverter, if it is detected that the charging and discharging active power of the DC bus capacitor of the inverter is unbalanced, the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit are obtained.

[0060] In this step, after the current power control strategy of the inverter is determined through S110 and the output power of the inverter is adjusted according to the current power control strategy, during the process of the inverter adjusting the output power, the present application can also continuously monitor the balance of the charging and discharging active power of the DC bus capacitor of the inverter. If an imbalance in the charging and discharging active power is detected, the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit can be obtained, and the imbalance can be adjusted according to the relevant parameters obtained.

[0061] It is understandable that in order to assist the distributed power source connected through the inverter to provide frequency and voltage support to the flexible interconnected distribution network, an energy storage unit can be connected in parallel at both ends of the inverter DC bus to offset the impact of the inverter active power output change on the DC bus voltage through its charge and discharge control. Figure 2 , Figure 2 A topological structure diagram of a distributed power source including an energy storage unit provided in an embodiment of the present application being connected to a flexible interconnected distribution network; Figure 2 In the present application, the energy storage unit can be a supercapacitor energy storage unit, which is connected to the DC bus of the inverter via a bidirectional Buck / Boost circuit. By controlling the duty cycle of the switch conduction signal in the bidirectional Buck / Boost circuit, the charging and discharging power of the supercapacitor energy storage unit can be adjusted to offset the imbalance between the input active power and the output active power of the DC bus, so that the inverter maintains the DC bus voltage stability while providing frequency and voltage support to the flexible interconnected distribution network.

[0062] Based on this, when the present application detects an imbalance in the charging and discharging active power of the DC bus capacitor of the inverter, it can control the charging and discharging state of the energy storage unit by obtaining the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit, so as to offset the imbalance between the DC bus input active power and the output active power.

[0063] S130: Calculate the on-duty ratio of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit.

[0064] In this step, after the relevant parameters are obtained through S120, the present application can calculate the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the obtained relevant parameters, and then adjust the charge and discharge state of the energy storage unit through the on-duty cycle.

[0065] Indicatively, Figure 3 As shown, Figure 3 A topological structure diagram of an energy storage unit provided in an embodiment of the present application connected to an inverter DC bus via a bidirectional Buck / Boost circuit; Figure 3In the figure, G2 is an IGBT switch connecting the inverter DC bus and the energy storage unit in the bidirectional Buck / Boost circuit, G1 and G2 are turned on alternately, and the energy storage unit is a supercapacitor energy storage unit. The present application calculates the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit through the DC bus voltage and imbalance of the inverter, the initial voltage and capacitance of the supercapacitor energy storage unit, and realizes the charging and discharging control of the supercapacitor energy storage unit by adjusting the on-duty cycle of the G2 switch control signal.

[0066] S140: According to the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, the charge and discharge state of the energy storage unit is adjusted to offset the imbalance between the output active power of the inverter and the input active power of the distributed power source.

[0067] In this step, after calculating the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit through S130, the present application can adjust the charge and discharge state of the energy storage unit according to the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit to offset the imbalance between the output active power of the inverter and the input active power of the distributed power source, thereby maintaining the DC bus voltage of the inverter stable in the process of providing frequency and voltage support to the flexible interconnected distribution network. Compared with the existing technical solution of maintaining the DC bus voltage stability of the inverter through the charge and discharge control of the energy storage unit, the present application can realize the direct control of the active power transmitted by the energy storage unit to the DC bus capacitor; and compared with the existing feedback control solution based on the DC bus voltage control deviation, the present application can achieve faster control response speed and higher control accuracy.

[0068] In the above embodiment, in order to assist the distributed power source connected through the inverter to provide frequency and voltage support to the flexible interconnected distribution network, an energy storage unit can be connected in parallel at both ends of the inverter DC bus, and the impact of the change in the inverter's active power output on the DC bus voltage can be offset by its charge and discharge control. Specifically, the energy storage unit of the present application can be connected to the DC bus of the inverter via a bidirectional Buck / Boost circuit, and the charge and discharge power of the energy storage unit can be adjusted by controlling the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, thereby offsetting the imbalance between the DC bus input active power and the output active power, so that the inverter maintains the DC bus voltage stable in the process of providing frequency and voltage support to the flexible interconnected distribution network.

[0069] In one embodiment, when it is detected that the inverter provides frequency support to the flexible interconnected distribution network, determining the current power control strategy of the inverter in S110 may include:

[0070] S111: When it is detected that the inverter provides frequency support to the flexible interconnected distribution network, the increased active power output of the inverter is determined based on a first preset ramp rate, a first preset time period for increasing the active power output, and a second preset time period for maintaining the maximum active power output.

[0071] S112: Determine, based on the first preset downslope rate, the active power output of the inverter that is reduced to the power value at the initial moment after the second preset period of time.

[0072] In this embodiment, when it is detected that the inverter provides frequency support to the flexible interconnected distribution network, the increased active power output of the inverter can be determined based on the first preset ramp rate, the first preset time period for increasing the active power output, and the second preset time period for maintaining the maximum active power output; then, the present application can determine the active power output of the inverter that is reduced to the power value at the initial moment after the second preset time period ends based on the first preset ramp rate, and use this to adjust the output power of the inverter.

[0073] In a specific implementation, Figure 4 As shown, Figure 4 An inverter active power output curve diagram when providing frequency support to a flexible interconnected distribution network provided in an embodiment of the present application; Figure 4 In the case where the flexible interconnected distribution network needs frequency support, from the initial time t ini At the beginning, in the first preset period Δt 1,p Based on the first preset uphill rate r 1,p Increase the inverter active power output and maintain the maximum active power output for the second preset period Δt 2,p Then, based on the first preset downhill rate r 2,p Reduce the inverter active power output to the initial power value P inv,ini ; The active power output P of the inverter in the process of providing frequency support inv The expression is:

[0074]

[0075] Through the above formula, the active power output of the inverter can be adjusted directly according to the current moment, thereby effectively improving the control efficiency of the inverter.

[0076] In one embodiment, when it is detected that the inverter provides voltage support to the flexible interconnected power distribution network in S110, determining the current power control strategy of the inverter may include:

[0077] S113: When it is detected that the inverter provides voltage support to the flexible interconnected distribution network, the increased reactive power output of the inverter is determined based on a second preset ramp rate, a third preset time period for increasing reactive power output, and a fourth preset time period for maintaining maximum reactive power output.

[0078] S114: Determine, based on the second preset downslope rate, the reactive power output of the inverter that is reduced to the power value at the initial moment after the fourth preset time period ends.

[0079] In this embodiment, when it is detected that the inverter provides voltage support to the flexible interconnected distribution network, the increased reactive power output of the inverter can be determined based on the second preset ramp-up rate, the third preset time period for increasing the reactive power output, and the fourth preset time period for maintaining the maximum reactive power output; then, the present application can determine the reactive power output of the inverter that is reduced to the power value at the initial moment after the fourth preset time period ends based on the second preset ramp-down rate.

[0080] Indicatively, Figure 5 As shown, Figure 5 A power output curve diagram of an inverter when providing voltage support to a flexible interconnected distribution network provided in an embodiment of the present application; Figure 5 In the case where the flexible interconnected distribution network needs voltage support, from the initial time t ini At the beginning, in the third preset time period Δt 1,q Based on the second preset uphill rate r 1,q Increase the reactive power output of the inverter and maintain the maximum reactive power output for the fourth preset period Δt 2,q Then, based on the second preset downhill rate r 2,q Reduce the inverter reactive power output to the initial power value Q inv,ini ; The reactive power output Q of the inverter in the process of providing voltage support inv The expression is:

[0081]

[0082] Through the above formula, the reactive power output of the inverter can be adjusted directly according to the current moment, thereby effectively improving the control efficiency of the inverter.

[0083] Furthermore, when providing voltage support to the flexible interconnected distribution network, the inverter outputs reactive power first. Considering the capacity constraint of the inverter, the active power output of the inverter is calculated based on the following formula:

[0084]

[0085] In the formula, S inv,max It is the maximum allowable apparent power output of the inverter.

[0086] Figure 5 In the present invention, when providing voltage support to the flexible interconnected distribution network, considering the constraint of the maximum allowable apparent power output of the inverter, the active power output curve of the inverter will be lower than its initial active power output in the AB section under the action of the corresponding active power constraint curve, resulting in an imbalance between the input active power and the output active power of the inverter DC bus. Therefore, it is necessary to control the charging and discharging state of the energy storage unit to offset the active power imbalance.

[0087] In one embodiment, in S130, based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit, calculating the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit may include:

[0088] S131: Under the condition where the output power of the inverter is not significantly adjusted, the difference between the DC bus voltage and its reference value is controlled by a proportional-integral control link through a DC bus voltage outer loop control link of the inverter to obtain an adjustment amount of the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit.

[0089] S132: Calculate a reference setting value of the on-duty cycle of the IGBT switch control signal according to the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit.

[0090] S133: Adding the adjustment amount of the on-duty ratio of the IGBT switch control signal to the on-duty ratio reference setting value, to obtain the on-duty ratio of the IGBT switch control signal.

[0091] In this embodiment, when calculating the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, the adjustment amount of the on-duty cycle of the IGBT switch control signal under the condition that the output power of the inverter is not significantly adjusted can be obtained first, and then the on-duty cycle reference setting value of the IGBT switch control signal can be calculated. Finally, the two can be added together to obtain the on-duty cycle of the IGBT switch control signal.

[0092] It is understandable that when the inverter output power is not adjusted significantly, the inverter direct-axis active current reference value I gd,ref It is obtained by the DC voltage outer loop control; when the inverter output power is adjusted to provide frequency and voltage support, the inverter direct axis active current reference value I gd,refThe on-duty ratio of the IGBT switch control signal is obtained by the addition of the output of the DC voltage outer loop control and the on-duty ratio reference setting value d(t). The on-duty ratio d of the switch control signal acts on Figure 3 G2 in the figure can realize the charge and discharge control of the energy storage unit. Furthermore, after the process of providing frequency and support to the flexible interconnected distribution network is completed, it will return to the working condition where the inverter output power is not adjusted significantly. The on-duty cycle of the IGBT switch control signal follows the charging and discharging requirements of the DC bus voltage and is gradually adjusted to the set value d under its normal working condition. norm ,Under normal operating conditions, the DC bus voltage is controlled only by the inverter DC voltage outer loop.

[0093] Specifically, under the condition that the inverter output power is not adjusted significantly, that is, when the output power adjustment amplitude of the inverter is less than the preset amplitude threshold, the on-duty cycle of the IGBT switch control signal is obtained through the DC bus voltage outer loop control link. The input of the control link is the difference between the reference value of the DC bus voltage and the DC bus voltage. After the input of the control link is controlled by the proportional-integral control link, the adjustment amount of the on-duty cycle of the IGBT switch control signal can be obtained.

[0094] When the inverter DC bus capacitor has an unbalanced charge and discharge active power ΔP DC When the charging and discharging of the energy storage unit is used to offset the imbalance of the charging and discharging active power, after a period of time t, the change in the stored energy of the energy storage unit is ΔP DC t, the charging and discharging active power imbalance of the inverter DC bus capacitor ΔP DC The active power P of the distributed power supply input DG The inverter output active power P inv If the initial voltage of the energy storage unit is U SC,ini , after time t, the on-duty ratio reference setting value of the IGBT switch control signal should be adjusted to:

[0095]

[0096] In the formula, C SC is the capacitance of the energy storage unit, the DC bus voltage U DC and the energy storage unit voltage U connected via the bidirectional Buck / Boost circuit SC The relationship between them is expressed as U SC =dU DC .

[0097] In the process of the inverter providing frequency and voltage support to the flexible interconnected distribution network, in order to respond to the rapid change of the inverter output power in time, the on-duty ratio reference setting value of the IGBT switch control signal obtained by real-time solution can be added to the on-duty ratio adjustment amount of the IGBT switch control signal obtained through the DC bus voltage outer loop control link, and then the on-duty ratio of the IGBT switch control signal can be obtained. Its expression is as follows:

[0098] d=k p (U DC,ref -U DC )+k i ∫(U DC,ref -U DC )dt+d(t)

[0099] In the formula, k p is the gain of the proportional control link, k i is the gain of the integral control link, U DC,ref is the reference value of the DC bus voltage.

[0100] In one embodiment, the method may further include:

[0101] S150: When it is detected that the inverter ends providing frequency support to the flexible interconnected distribution network, the voltage of the energy storage unit at the end time and the minimum allowable voltage value of the energy storage unit are obtained.

[0102] S151: Determine the difference between the voltage at the end time and the minimum allowable voltage value.

[0103] S152: If it is not less than, there is no need to modify the current power control strategy of the inverter.

[0104] S153: If it is less than, the second preset time period is corrected according to the second preset time period in the current power control strategy, the capacitance of the energy storage unit, the voltage at the end time, the minimum allowable voltage value, the first preset time period, the first preset ramp rate, the input active power of the distributed power source, and the power value at the initial moment when the inverter outputs active power.

[0105] In this embodiment, when it is detected that the inverter has finished providing frequency support to the flexible interconnected distribution network, the present application can also obtain the voltage of the energy storage unit at the end time and the minimum allowable voltage of the energy storage unit. In this way, the size between the voltage of the energy storage unit at the end time and the minimum allowable voltage can be judged, and this can be used to determine whether the operating safety constraints of the energy storage unit have exceeded the limit.

[0106] For example, when the voltage U SC,end,p Not less than the minimum allowable voltage value USC,min When , it means that the current power control strategy of the inverter will not cause the operation safety constraint of the energy storage unit to exceed the limit; and when the voltage U SC,end,p Less than the minimum allowable voltage value U SC,min , it means that the current power control strategy of the inverter will cause the operation safety constraint of the energy storage unit to exceed the limit. At this time, it is necessary to adjust the Δt in the current power control strategy of the inverter. 2,p Parameters to meet the operational safety constraints of the energy storage unit; the modified Δt 2,p The parameter is expressed as Δt 2,p,c , its calculation expression is:

[0107]

[0108] At the end of the process of providing frequency support to the flexible interconnected distribution network, the voltage U SC,end,p The calculation formula can be expressed as follows:

[0109]

[0110] When this application is applied to Δt 2,p After the parameters are corrected, the corrected Δt can be used 2,p,c To calculate the end time voltage U of the energy storage unit SC,end,p .

[0111] In a specific example, Figure 6 As shown, Figure 6 A schematic diagram of the structure of the operating parameter curves of the inverter and the energy storage unit in the process of providing frequency support to the flexible interconnected distribution network provided in the embodiment of the present application; Figure 6 In the process, the inverter provides frequency support to the flexible interconnected power grid by increasing the active power output. The relevant parameter settings are: t ini =0.5s, Δt 1,p =0.5s, Δt 2,p =1s, r 1,p =300kW / s, r 2,p =150kW / s, the active power output of the inverter at the initial moment is 150kW; the rated voltage of the energy storage unit is 125V, the capacitance is 63F, the voltage range allowed during normal operation is 50V~100V, the voltage of the energy storage unit at the initial moment is 100V, based on the above formula, it can be calculated that the voltage of the energy storage unit at the end of the frequency support process is 40.82V, which is Figure 6 The voltage curve results of the energy storage unit are consistent. Figure 6 The inverter DC bus voltage curve in shows that the DC bus voltage of the inverter can be kept stable when the active power output of the inverter increases through the discharge control of the energy storage unit.

[0112] In addition, see Figure 6 The voltage curve of the energy storage unit in the frequency support process shows that the voltage of the energy storage unit is 40.82V at the end of the frequency support process, which is less than the voltage lower limit of 50V under normal operating conditions. At this time, based on the above formula, Δt is corrected. 2,p Parameter, its corrected parameter Δt 2,p,c The value is 0.825s. The operating parameter curves of the inverter and energy storage unit under this condition are as follows: Figure 7 As shown, Figure 7 The embodiment of the present application provides a correction Δt 2,p The operating parameter curve diagram of the inverter and energy storage unit after the parameters are changed; Figure 7 It can be seen from the energy storage unit voltage curve in that by correcting Δt 2,p Parameters can ensure that the energy storage unit operates within its safety constraints while the inverter increases its active power output to provide frequency support to the flexible interconnected distribution network.

[0113] In one embodiment, the method may further include:

[0114] S160: When it is detected that the inverter ends providing voltage support to the flexible interconnected distribution network, the voltage of the energy storage unit at the end time and the maximum allowable voltage value of the energy storage unit are obtained.

[0115] S161: Determine the difference between the voltage at the end time and the maximum allowable voltage value.

[0116] S162: If it is not greater than, there is no need to modify the current power control strategy of the inverter.

[0117] S163: If it is greater than, the fourth preset time period is corrected according to the fourth preset time period in the current power control strategy, the capacitance of the energy storage unit, the voltage at the end time, the maximum allowable voltage value, the third preset time period, the second preset ramp rate, the input active power of the distributed power source, the initial power value when the inverter outputs reactive power, and the maximum allowable apparent power output.

[0118] In this embodiment, when it is detected that the inverter has finished providing voltage support to the flexible interconnected distribution network, the voltage of the energy storage unit at the end time and the maximum allowable voltage value of the energy storage unit can be obtained. In this way, the size between the voltage of the energy storage unit at the end time and the maximum allowable voltage value can be judged, and whether the operating safety constraints of the energy storage unit have exceeded the limit can be determined.

[0119] Specifically, when providing voltage support to the flexible interconnected distribution network, the voltage U SC,end,qThe maximum allowable voltage value U SC,max The size between them is used to determine whether the operation safety constraint of the energy storage unit exceeds the limit; if U SC,end,q ≤U SC,max , then the power control strategy of the inverter will not cause the operation safety constraints of the energy storage unit to exceed the limit; if U SC,end,q >U SC,max , the inverter's power control strategy will cause the energy storage unit's operating safety constraints to exceed the limit; at this time, the Δt in the inverter's current power control strategy can be adjusted 2,q Parameters to meet the operational safety constraints of the energy storage unit; the modified Δt 2,q The parameter is expressed as Δt 2,q,c , its calculation expression is:

[0120]

[0121] In one embodiment, the method may further include:

[0122] S170: Determine a lower limit of a feasible range of a reference setting value of an on-duty cycle of the IGBT switch control signal that enables a current power control strategy of the inverter to provide frequency support to the flexible interconnected power distribution network.

[0123] S171: Determine an upper limit of a feasible range of a reference setting value of the on-duty cycle of the IGBT switch control signal that enables the current power control strategy of the inverter to have the ability to provide voltage support to the flexible interconnected power distribution network.

[0124] S172: Determine a setting range of the on-duty cycle of the IGBT switch control signal of the energy storage unit under normal operating conditions so that the distributed power source has the ability to provide frequency and voltage support to the flexible interconnected distribution network within the operating safety constraint range.

[0125] In this embodiment, based on the current operating conditions of the energy storage unit and its operating safety constraints, a feasible output adjustment scheme for the inverter to provide frequency and voltage support to the flexible interconnected distribution network is determined, and a feasible range of the energy storage unit operating point under steady-state conditions can be further obtained to enable the grid-connected inverter to have the required frequency and voltage support capabilities. By regulating the steady-state operating state of the energy storage unit based on this range, it is possible to avoid the situation where the frequency and voltage support capabilities of the grid-connected inverter are limited due to the energy storage unit's own capacity constraints.

[0126] For example, in order to enable the inverter power control strategy to provide frequency support to the flexible interconnected distribution network, the lower limit of the feasible range of the set value of the on-duty cycle of the IGBT switch control signal can be set to d min , its calculation expression is:

[0127]

[0128] In order to enable the inverter power control strategy to provide voltage support to the flexible interconnected distribution network, the upper limit of the feasible range of the setting value of the on-duty cycle of the IGBT switch control signal is d max , and provides that:

[0129] like Then d max The value is 1;

[0130] like Then d max The calculation expression is:

[0131]

[0132] If the IGBT switch control signal conduction duty cycle is set at [d min ,d max ] within the range of operation safety constraints, the energy storage unit can enable the distributed power generation to provide frequency and voltage support to the flexible interconnected distribution network.

[0133] The following describes a device for providing frequency and voltage support to a flexible interconnected distribution network provided in an embodiment of the present application. The device for providing frequency and voltage support to a flexible interconnected distribution network described below and the method for providing frequency and voltage support to a flexible interconnected distribution network described above can be referenced to each other.

[0134] In one embodiment, Figure 8 As shown, Figure 8 A schematic diagram of a structure of a device that can provide frequency and voltage support to a flexible interconnected distribution network provided in an embodiment of the present application; the present application provides a device that can provide frequency and voltage support to a flexible interconnected distribution network, wherein the flexible interconnected distribution network is connected to a distributed power source via an inverter, and is connected to an energy storage unit via a bidirectional Buck / Boost circuit on the DC bus of the inverter, and may include an output power adjustment module 210, a parameter acquisition module 220, a conduction duty cycle calculation module 230, and a charge and discharge state adjustment module 240, specifically including the following:

[0135] The output power adjustment module 210 is used to determine the current power control strategy of the inverter when it is detected that the inverter provides frequency and / or voltage support to the flexible interconnected distribution network, and adjust the output power of the inverter according to the current power control strategy.

[0136] The parameter acquisition module 220 is used to obtain the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit if it is detected that the charging and discharging active power of the DC bus capacitor of the inverter is unbalanced during the process of adjusting the output power of the inverter.

[0137] The on-duty ratio calculation module 230 is used to calculate the on-duty ratio of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit.

[0138] The charge and discharge state adjustment module 240 is used to adjust the charge and discharge state of the energy storage unit according to the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit to offset the imbalance between the output active power of the inverter and the input active power of the distributed power source.

[0139] In the above embodiment, in order to assist the distributed power source connected through the inverter to provide frequency and voltage support to the flexible interconnected distribution network, an energy storage unit can be connected in parallel at both ends of the inverter DC bus, and the impact of the change in the inverter's active power output on the DC bus voltage can be offset by its charge and discharge control. Specifically, the energy storage unit of the present application can be connected to the DC bus of the inverter via a bidirectional Buck / Boost circuit, and the charge and discharge power of the energy storage unit can be adjusted by controlling the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, thereby offsetting the imbalance between the DC bus input active power and the output active power, so that the inverter maintains the DC bus voltage stable in the process of providing frequency and voltage support to the flexible interconnected distribution network.

[0140] In one embodiment, the present application provides a storage medium storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of a method for providing frequency and voltage support to a flexible interconnected distribution network as described in any of the above embodiments.

[0141] In one embodiment, the present application provides a computer device, including: one or more processors, and a memory.

[0142] The memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the method for providing frequency and voltage support to a flexible interconnected distribution network as described in any of the above embodiments are performed.

[0143] Indicatively, Fig. 9 As shown, Fig. 9 This is a schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. The computer device 300 may be provided as a server. Fig. 9 The computer device 300 includes a processing component 302, which further includes one or more processors, and a memory resource represented by a memory 301 for storing instructions executable by the processing component 302, such as an application. The application stored in the memory 301 may include one or more modules, each corresponding to a set of instructions. In addition, the processing component 302 is configured to execute instructions to perform the method for providing frequency and voltage support to a flexible interconnected distribution network according to any of the above embodiments.

[0144] The computer device 300 may further include a power supply component 303 configured to perform power management of the computer device 300, a wired or wireless network interface 304 configured to connect the computer device 300 to a network, and an input / output (I / O) interface 305. The computer device 300 may operate based on an operating system stored in the memory 301, such as Windows Server TM, Mac OS X TM, Unix TM, Linux TM, Free BSD TM, or the like.

[0145] Those skilled in the art will understand that Fig. 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0146] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0147] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can refer to each other.

[0148] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for providing frequency and voltage support to a flexible interconnected distribution network, characterized in that: The flexible interconnected distribution network is connected to a distributed power source via an inverter, and is connected to an energy storage unit via a bidirectional Buck / Boost circuit on a DC bus of the inverter. The method includes: When it is detected that the inverter provides frequency and / or voltage support to the flexible interconnected distribution network, determining a current power control strategy of the inverter, and adjusting the output power of the inverter according to the current power control strategy; During the process of adjusting the output power of the inverter, if it is detected that the charging and discharging active power of the DC bus capacitor of the inverter is unbalanced, the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit are obtained; Calculating the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit; According to the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, the charge and discharge state of the energy storage unit is adjusted to offset the imbalance between the output active power of the inverter and the input active power of the distributed power source; Among them, when providing voltage support to the flexible interconnected distribution network, the inverter outputs reactive power first. Considering the capacity constraint of the inverter, the active power output size of the inverter is calculated based on the following formula: In the formula, S inv,max is the maximum allowable apparent power output of the inverter, Q inv is the reactive power output of the inverter in the process of providing voltage support, P inv is the active power output of the inverter in the process of providing frequency support, P inv,ini is the power value at the initial moment, t ini is the initial moment when the flexible interconnected distribution network needs frequency support, Δt 1,p is the first preset period, r 1,p is the first preset climbing rate, Δt 2,p is the second preset period, r 2,p is the first preset downhill slope rate, Δt 1,q is the third preset period, r 1,q is the second preset ascending slope rate, Δt 2,q is the fourth preset period, r 2,q is the second preset downhill slope rate, Q inv,ini is the power value at the initial moment; After time t, the change in stored energy of the energy storage unit is ΔP DC t, the charging and discharging active power imbalance of the inverter DC bus capacitor ΔP DC The active power P of the distributed power supply input DG The inverter output active power P inv If the initial voltage of the energy storage unit is U SC,ini , after time t, the on-duty ratio reference setting value of the IGBT switch control signal should be adjusted to: In the formula, C SC is the capacitance of the energy storage unit, the DC bus voltage U DC and the energy storage unit voltage U connected via the bidirectional Buck / Boost circuit SC The relationship between them is expressed as U SC =dU DC ; The on-duty ratio reference setting value of the IGBT switch control signal obtained by real-time solution is added to the on-duty ratio adjustment amount of the IGBT switch control signal obtained through the DC bus voltage outer loop control link, and then the on-duty ratio of the IGBT switch control signal is obtained, and its expression is as follows: d=k p (U DC,ref -U DC )+k i ∫(U DC,ref -U DC )dt+d(t) In the formula, k p is the gain of the proportional control link, k i is the gain of the integral control link, U DC,ref is the reference value of the DC bus voltage.

2. The method for providing frequency and voltage support to a flexible interconnected distribution network according to claim 1, characterized in that: The determining of the current power control strategy of the inverter when detecting that the inverter provides frequency support to the flexible interconnected distribution network includes: When it is detected that the inverter provides frequency support to the flexible interconnected distribution network, determining the increased active power output of the inverter based on a first preset ramp rate, a first preset time period for increasing the active power output, and a second preset time period for maintaining the maximum active power output; The active power output of the inverter is reduced to the power value at the initial moment after the second preset period ends based on the first preset down-slope rate.

3. The method for providing frequency and voltage support to a flexible interconnected distribution network according to claim 1 or 2, characterized in that: The determining of the current power control strategy of the inverter when detecting that the inverter provides voltage support to the flexible interconnected distribution network comprises: When it is detected that the inverter provides voltage support to the flexible interconnected distribution network, determining the reactive power output increased by the inverter based on a second preset ramp rate, a third preset time period for increasing reactive power output, and a fourth preset time period for maintaining maximum reactive power output; The reactive power output of the inverter is determined to be reduced to the power value at the initial moment after the fourth preset time period ends based on the second preset down-slope rate.

4. The method for providing frequency and voltage support to a flexible interconnected distribution network according to claim 1, characterized in that: The step of calculating the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit, comprises: Under the working condition that the output power of the inverter is not significantly adjusted, the difference between the DC bus voltage and its reference value is controlled by the DC bus voltage outer loop control link of the inverter through the proportional integral control link to obtain the adjustment amount of the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit; Calculate the on-duty ratio reference setting value of the IGBT switch control signal according to the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit; The on-duty ratio of the IGBT switch control signal is obtained by adding the adjustment amount of the on-duty ratio of the IGBT switch control signal to the on-duty ratio reference setting value.

5. The method for providing frequency and voltage support to a flexible interconnected distribution network according to claim 2, characterized in that: The method further comprises: When it is detected that the inverter ends providing frequency support to the flexible interconnected distribution network, the voltage of the energy storage unit at the end time and the minimum allowable voltage value of the energy storage unit are obtained; Determine the difference between the voltage at the end time and the minimum allowable voltage value; If it is not less than, there is no need to modify the current power control strategy of the inverter; If it is less than, the second preset time period is corrected according to the second preset time period in the current power control strategy, the capacitance of the energy storage unit, the voltage at the end time, the minimum allowable voltage value, the first preset time period, the first preset ramp rate, the input active power of the distributed power source, and the power value at the initial moment when the inverter outputs active power.

6. The method for providing frequency and voltage support to a flexible interconnected distribution network according to claim 3, characterized in that: The method further comprises: When it is detected that the inverter ends providing voltage support to the flexible interconnected distribution network, the voltage of the energy storage unit at the end time and the maximum allowable voltage value of the energy storage unit are obtained; Determine the difference between the voltage at the end time and the maximum allowable voltage value; If it is not greater than, there is no need to modify the current power control strategy of the inverter; If it is greater, the fourth preset time period is corrected according to the fourth preset time period in the current power control strategy, the capacitance of the energy storage unit, the voltage at the end time, the maximum allowable voltage value, the third preset time period, the second preset ramp rate, the input active power of the distributed power source, the initial power value when the inverter outputs reactive power, and the maximum allowable apparent power output.

7. The method for providing frequency and voltage support to a flexible interconnected distribution network according to claim 4, characterized in that: The method further comprises: Determine a lower limit of a feasible range of a reference setting value of an on-duty cycle of the IGBT switch control signal that enables a current power control strategy of the inverter to provide frequency support to the flexible interconnected power distribution network; Determine an upper limit of a feasible range of a reference setting value of an on-duty cycle of the IGBT switch control signal that enables a current power control strategy of the inverter to provide voltage support to the flexible interconnected power distribution network; Determine the setting range of the on-duty cycle of the IGBT switch control signal of the energy storage unit under normal operating conditions so that the distributed power source has the ability to provide frequency and voltage support to the flexible interconnected distribution network within the operating safety constraint range.

8. A device capable of providing frequency and voltage support to a flexible interconnected distribution network, characterized in that: The flexible interconnected distribution network is connected to the distributed power source via an inverter, and is connected to the energy storage unit via a bidirectional Buck / Boost circuit on the DC bus of the inverter, including: an output power adjustment module, configured to determine a current power control strategy of the inverter when it is detected that the inverter provides frequency and / or voltage support to the flexible interconnected distribution network, and adjust the output power of the inverter according to the current power control strategy; A parameter acquisition module, used for acquiring the imbalance between the output active power of the inverter and the input active power of the distributed power source, the DC bus voltage of the inverter, and the voltage of the energy storage unit at the initial moment when the inverter is unbalanced and the capacitance of the energy storage unit if the charging and discharging active power of the DC bus capacitor of the inverter is detected to be unbalanced during the process of adjusting the output power of the inverter; A conduction duty cycle calculation module, used to calculate the conduction duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit based on the DC bus voltage and unbalance of the inverter, the initial voltage and capacitance of the energy storage unit; A charge and discharge state adjustment module, used to adjust the charge and discharge state of the energy storage unit according to the on-duty cycle of the IGBT switch control signal in the bidirectional Buck / Boost circuit, so as to offset the imbalance between the output active power of the inverter and the input active power of the distributed power source; Among them, when providing voltage support to the flexible interconnected distribution network, the inverter outputs reactive power first. Considering the capacity constraint of the inverter, the active power output size of the inverter is calculated based on the following formula: In the formula, S inv,max is the maximum allowable apparent power output of the inverter, Q inv is the reactive power output of the inverter in the process of providing voltage support, P inv is the active power output of the inverter in the process of providing frequency support, P inv,ini is the power value at the initial moment, t ini is the initial moment when the flexible interconnected distribution network needs frequency support, Δt 1,p is the first preset period, r 1,p is the first preset climbing rate, Δt 2,p is the second preset period, r 2,p is the first preset downhill slope rate, Δt 1,q is the third preset period, r 1,q is the second preset ascending slope rate, Δt 2,q is the fourth preset period, r 2,q is the second preset downhill slope rate, Q inv,ini is the power value at the initial moment; After time t, the change in stored energy of the energy storage unit is ΔP DC t, the charging and discharging active power imbalance of the inverter DC bus capacitor ΔP DC The active power P of the distributed power supply input DG The inverter output active power P inv If the initial voltage of the energy storage unit is U SC,ini , after time t, the on-duty ratio reference setting value of the IGBT switch control signal should be adjusted to: In the formula, C SC is the capacitance of the energy storage unit, the DC bus voltage U DC and the energy storage unit voltage U connected via the bidirectional Buck / Boost circuit SC The relationship between them is expressed as U SC =dU DC ; The on-duty ratio reference setting value of the IGBT switch control signal obtained by real-time solution is added to the on-duty ratio adjustment amount of the IGBT switch control signal obtained through the DC bus voltage outer loop control link, and then the on-duty ratio of the IGBT switch control signal is obtained, and its expression is as follows: d=k p (U DC,ref -U DC )+k i ∫(U DC,ref -U DC )dt+d(t) In the formula, k p is the gain of the proportional control link, k i is the gain of the integral control link, U DC,ref is the reference value of the DC bus voltage.

9. A storage medium, characterized in that: The storage medium stores computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to execute the steps of the method for providing frequency and voltage support to a flexible interconnected distribution network as described in any one of claims 1 to 7.

10. A computer device, characterized in that: include: one or more processors, and memory; The memory stores computer-readable instructions, which, when executed by the one or more processors, perform the steps of the method for providing frequency and voltage support to a flexible interconnected distribution network as described in any one of claims 1 to 7.

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