Control method, control device and readable storage medium of energy storage converter

Abstract

The present invention provides a control method, a control device and a readable storage medium for an energy storage converter, and relates to the field of power electronics technology. The control method for the energy storage converter includes obtaining a grid voltage and a grid current; obtaining active power and reactive power based on the grid voltage and the grid current; obtaining a first voltage based on active power, reactive power, a reference value of active power and a reference value of reactive power; generating a reference voltage based on the first voltage; inputting the reference voltage into a first voltage loop based on the reference voltage, obtaining a reference current based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter; obtaining a three-phase signal based on the reference current and the current loop; generating a PWM signal based on the three-phase signal and a pulse width modulation generator, so as to control the energy storage converter through the PWM signal, and ensure that the energy storage converter does not disconnect from the grid within a certain period of time.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a control method, a control device and a readable storage medium for an energy storage converter. Background Art

[0002] At present, in the related technology, in order to suppress the overcurrent caused by voltage drop, the grid-type energy storage converter adopts a method of comparing the AC voltage measurement value with the voltage amplitude that triggers the low voltage ride-through control, and then generating different limiting values. However, this method is only for traditional energy storage converters, and can only deal with the overcurrent problem caused by nonlinear limiting, and cannot improve the overcurrent problem caused by voltage drop of the grid-type energy storage converter. Summary of the invention

[0003] The present invention aims to at least solve the technical problem of overcurrent caused by voltage drop in grid-type energy storage inverters, in which the method of comparing the AC voltage measurement value with the voltage amplitude that triggers low voltage ride-through control and then generating different limiting values ​​in the prior art or related art is only applicable to traditional energy storage inverters and can only deal with overcurrent problems caused by nonlinear limiting, but cannot improve the overcurrent caused by voltage drop in grid-type energy storage inverters.

[0004] To this end, a first aspect of the present invention provides a control method for an energy storage converter.

[0005] A second aspect of the present invention provides a control device for an energy storage converter.

[0006] A third aspect of the present invention provides a readable storage medium.

[0007] In view of this, a first aspect of the present invention provides a control method for an energy storage inverter, which includes obtaining a grid voltage and a grid current; obtaining active power and reactive power based on the grid voltage and the grid current; obtaining a first voltage based on active power, reactive power, a reference value of active power and a reference value of reactive power; generating a reference voltage based on the first voltage; inputting the reference voltage into a first voltage loop based on the reference voltage, and obtaining a reference current based on the reference voltage, the grid voltage and a feedback voltage of the energy storage inverter; obtaining a three-phase signal based on the reference current and the current loop; generating a PWM signal based on the three-phase signal and a pulse width modulation (PWM) generator to control the energy storage inverter through the PWM signal.

[0008] The present invention proposes a control method for an energy storage converter. When a fault such as a voltage drop occurs, first, the energy storage converter obtains the grid voltage and grid current, and calculates the active power and reactive power through the grid voltage and grid current; the difference between the active power and the reference value of the active power, and the difference between the reactive power and the reference value of the reactive power are input into the virtual synchronous machine; the first voltage is output through the voltage regulation of the virtual synchronous machine; the reference voltage is obtained by comparing the output first voltage with the direct-axis (d, Direct-axis) component of the grid voltage and the quadrature-axis (q, Quadrature-axis) component of the grid voltage; the reference voltage is input into the first voltage loop, and the reference current is calculated based on the reference voltage, the grid voltage and the feedback voltage. The feedback voltage is obtained through the adaptive virtual impedance on the first voltage loop. The generated reference current is appropriately limited by the reference voltage, the grid voltage and the feedback voltage of the energy storage converter to ensure that the system can operate normally when a fault such as a voltage drop occurs, and does not disconnect from the grid within a certain period of time. Through current loop control, a three-phase signal is obtained, and a PWM signal is generated through the three-phase signal and a PWM generator to control the operation of the energy storage inverter. Among them, the energy storage inverter is a grid-type energy storage inverter. The present invention adopts the structure of low voltage ride-through control of the grid-type energy storage inverter, and the modulation mode of the energy storage inverter is pulse width modulation. The energy storage inverter can adopt a virtual synchronous machine mode and a voltage and current dual closed-loop control mode. By adding a virtual impedance based on the energy storage inverter side current, reference current and adaptive virtual impedance between the first voltage loop and the current loop, the energy storage inverter can suppress overcurrent caused by faults such as voltage drops, meet the fault ride-through requirements, and ensure that the grid-type energy storage inverter does not go off the grid for a certain period of time.

[0009] In addition, the control method of the energy storage converter in the above technical solution provided by the present invention may also have the following additional technical features:

[0010] In some technical schemes of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is a balanced voltage drop fault, then based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current and the q-axis component of the grid current, obtaining the active power and reactive power.

[0011] In this technical solution, after the grid voltage and grid current are obtained, it is determined whether the grid fault type is a balanced voltage drop fault or an unbalanced voltage drop fault. If the grid fault type is a balanced voltage drop fault, active power and reactive power are obtained based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current, and the q-axis component of the grid current, so as to compare with the reference value of the active power and the reference value of the reactive power to obtain the first voltage.

[0012] In some technical schemes of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is an unbalanced voltage drop fault, introducing adaptive positive and negative sequence separation control, using positive and negative sequence separation for the grid voltage and the grid current, and then obtaining active power and reactive power based on the d-axis component of the positive-sequence component and the q-axis component of the positive-sequence component.

[0013] In this technical solution, after the grid voltage and grid current are obtained, it is determined whether the fault type of the grid is a balanced voltage drop fault or an unbalanced voltage drop fault. If the fault type of the grid is an unbalanced voltage drop fault, an adaptive positive-negative sequence separation control is introduced, and the grid voltage and grid current are separated by positive-negative sequence, and then the active power and reactive power are obtained based on the d-axis component of the positive-sequence component and the q-axis component of the positive-sequence component, and then the first voltage is obtained by calculating the active power, reactive power, and the reference value of the active power and the reference value of the reactive power.

[0014] In some technical schemes of the present invention, optionally, adaptive positive and negative sequence separation control is introduced, and positive and negative sequence separation is adopted for the grid voltage and grid current, including converting the α-axis component and β-axis component of the positive sequence component of the grid voltage obtained by the positive and negative sequence separation control into the d-axis component of the grid voltage and the q-axis component of the grid voltage through coordinate transformation, inputting the q-axis component of the grid voltage into a phase-locked loop to obtain an angular velocity ω1, and feeding the angular velocity ω1 back to the positive and negative sequence separation control to obtain the d-axis component of the positive sequence component and the q-axis component of the positive sequence component.

[0015] Further, the α-axis of the α-axis component and the β-axis component represents the real part of the grid voltage, and the β-axis of the α-axis component and the β-axis component represents the imaginary part of the grid voltage.

[0016] In this technical solution, through positive and negative sequence separation control, the α-axis component and β-axis component of the positive sequence component of the grid voltage are converted into the d-axis component and q-axis component of the grid voltage through coordinate transformation, the q-axis component of the grid voltage is input into the phase-locked loop, and the obtained angular velocity ω1 is fed back to the positive and negative sequence separation control to obtain the d-axis component and the q-axis component of the positive sequence component, thereby obtaining active power and reactive power.

[0017] In some technical solutions of the present invention, optionally, a reference voltage is generated based on the first voltage, including obtaining the reference voltage based on the first voltage, a d-axis component of the grid voltage, and a q-axis component of the grid voltage.

[0018] In this technical solution, a reference voltage is generated based on the first voltage, including: obtaining a reference voltage based on the first voltage, the d-axis component of the grid voltage, and the q-axis component of the grid voltage, obtaining a reference voltage by comparing the first voltage with the d-axis component of the grid voltage and the q-axis component of the grid voltage, and inputting the reference voltage into a first voltage loop so as to calculate the reference voltage, the grid voltage and the feedback voltage through the first voltage loop to obtain a reference current.

[0019] In some technical solutions of the present invention, optionally, based on a reference voltage, a reference voltage is input into a first voltage loop, and based on the reference voltage, a grid voltage and a feedback voltage of an energy storage converter, a reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, a reference current is obtained through a proportional-integral controller.

[0020] In this technical solution, based on the reference voltage, the reference voltage is input into the first voltage loop, and based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter, the reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, the reference current is obtained through a proportional integral controller, the reference voltage is input into the first voltage loop, the reference voltage, the grid voltage and the feedback voltage are calculated by adjusting the first voltage loop, and the calculation result is passed through a proportional integral (PI) controller to obtain the reference current.

[0021] In some technical solutions of the present invention, optionally, obtaining the feedback voltage includes: obtaining an adaptive proportional parameter based on a peak value of a reference current and a current setting value; obtaining an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the current on the energy storage converter side; and obtaining the feedback voltage based on the adaptive virtual impedance and the current on the energy storage converter side.

[0022] In this technical solution, an adaptive proportional parameter can be obtained by referring to the current peak value and the current set value of the current loop. An adaptive virtual impedance can be obtained by the adaptive proportional parameter, the current set value and the current on the energy storage converter side. Finally, a feedback voltage can be obtained by the adaptive virtual impedance and the current on the energy storage converter side.

[0023] Furthermore, the current on the energy storage converter side is collected from the line on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation. The d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are used to obtain feedback voltage through adaptive virtual impedance. The feedback voltage, reference voltage and grid voltage are calculated, and the calculation result is passed through a proportional integral controller to obtain a reference current.

[0024] In some technical schemes of the present invention, optionally, a three-phase signal is obtained based on a reference current and a current loop, including obtaining a d-axis component of the reference current and a q-axis component of the reference current based on the reference current; the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through a proportional-integral controller.

[0025] In this technical solution, based on the reference current, the d-axis component of the reference current and the q-axis component of the reference current are obtained, and the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through the proportional integral controller. A PWM signal is generated through the three-phase signal and the PWM generator to control the energy storage converter through the PWM signal, so that the energy storage converter can suppress the overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not go off the grid for a certain period of time.

[0026] In some technical solutions of the present invention, optionally, the calculation formula of the adaptive ratio parameter is: k= I ref,peak / I th , where k is the adaptive scale parameter, I ref,peak is the peak value of the reference current, I th Set the current value.

[0027] In this technical solution, the adaptive proportional parameter is obtained by calculating the reference current peak value and the current setting value of the reference current.

[0028] In some technical solutions of the present invention, optionally, the calculation formula of the current setting value is: I th =1.1I g0 ,in I th is the current setting value, I g0 It is the peak value of steady-state current when there is no fault in the power grid.

[0029] Specifically, the calculation formula of the current setting value can be improved as follows: I th =1.3 I g0 .

[0030] In this technical solution, the current setting value is obtained by the peak value of the steady-state current when the power grid is free of faults.

[0031] In some technical solutions of the present invention, optionally, the calculation formula of the adaptive virtual impedance is: Zv=k( i L - I th ), where Zv is the adaptive virtual impedance, k is the adaptive ratio parameter, I th is the current setting value, i L is the current on the energy storage converter side.

[0032] In this technical solution, the adaptive virtual impedance is obtained by calculating the adaptive proportional parameter, the current setting value and the current on the energy storage converter side.

[0033] In some technical solutions of the present invention, optionally, the calculation formula of the feedback voltage is: v b = i L Zv, where Zv is the adaptive virtual impedance, i L is the current on the energy storage converter side.

[0034] In this technical solution, the feedback voltage is obtained by adaptively calculating the virtual impedance and the current on the energy storage converter side.

[0035] In some technical solutions of the present invention, further, the grid-type energy storage converter system includes: a DC power supply, an energy storage converter, a filter inductor 1, a filter capacitor, a filter inductor 2, a line inductor, and a power grid.

[0036] In some technical solutions of the present invention, further, the grid current is collected from the grid-side line, and the d-axis component of the grid current and the q-axis component of the grid current are obtained after coordinate transformation.

[0037] The grid voltage is collected from the grid side line, and the d-axis component of the grid voltage and the q-axis component of the grid voltage are obtained after coordinate transformation.

[0038] The current on the energy storage converter side is collected from the circuit on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation.

[0039] In some technical schemes of the present invention, further, the grid-type energy storage inverter defined by the present invention is a low voltage ride-through control structure, the modulation method of the energy storage inverter is pulse width modulation, and the energy storage inverter adopts a virtual synchronous machine method and a voltage and current dual closed-loop control method. Active power and reactive power are calculated by sampling the d-axis component and q-axis component of the grid voltage and grid current, and the difference is respectively made with the active power reference value and the reactive power reference value and the difference is input into the virtual synchronous machine to obtain the output first voltage of the virtual synchronous machine, which is converted into d-axis component and q-axis component through coordinate transformation, and the obtained d-axis and q-axis (direct-axis, quadrature-axis) components are made different from the d-axis component and q-axis component of the grid voltage and the d-axis component and q-axis component of the feedback voltage, and the d-axis component and q-axis component of the output reference current are made different from the d-axis component and q-axis component of the grid current through a proportional-integral controller, and the output quantity is calculated through a proportional-integral controller and input into a PWM generator, and the generated switching signal is input into the energy storage converter, so that the energy storage converter can suppress the overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not go off the grid within a certain period of time.

[0040] In some technical schemes of the present invention, further, in the adaptive virtual impedance control of the grid-type energy storage inverter, first, the peak value of the current reference value is compared with the current set value to obtain an adaptive proportional parameter, and then the current on the energy storage inverter side is subtracted from the current set value, and the obtained difference is multiplied by the adaptive proportional parameter to obtain the adaptive virtual impedance.

[0041] The second aspect of the present invention provides a control device for an energy storage converter, comprising: a first acquisition unit, a first calculation unit, a second calculation unit, a first generation unit, a third calculation unit, a second generation unit and a third generation unit. The first acquisition unit is used to acquire the grid voltage and the grid current; the first calculation unit is used to acquire the active power and the reactive power based on the grid voltage and the grid current; the second calculation unit is used to acquire the first voltage based on the active power, the reactive power, the reference value of the active power and the reference value of the reactive power; the first generation unit is used to generate a reference voltage based on the first voltage; the third calculation unit is used to input the reference voltage into the first voltage loop based on the reference voltage, and acquire the reference current based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter; the second generation unit is used to acquire the three-phase signal based on the reference current and the current loop; the third generation unit is used to generate the pulse width modulation signal based on the three-phase signal and the pulse width modulation generator, so as to control the energy storage converter through the pulse width modulation signal.

[0042] The present invention provides a control device for an energy storage converter, comprising: a first acquisition unit, a first calculation unit, a second calculation unit, a first generation unit, a third calculation unit, a second generation unit and a third generation unit. The first acquisition unit is used to acquire grid voltage and grid current; the first calculation unit is used to acquire active power and reactive power based on grid voltage and grid current; the second calculation unit is used to acquire a first voltage based on active power, reactive power, a reference value of active power and a reference value of reactive power; the first generation unit is used to generate a reference voltage based on the first voltage; the third calculation unit is used to input the reference voltage into a first voltage loop based on the reference voltage, and acquire a reference current based on the reference voltage, grid voltage and feedback voltage of the energy storage converter; the second generation unit is used to acquire a three-phase signal based on the reference current and the current loop; the third generation unit is used to generate a pulse width modulation signal based on the three-phase signal and a pulse width modulation generator, so as to control the energy storage converter through the pulse width modulation signal. By acquiring grid voltage and grid current; acquiring active power and reactive power based on the grid voltage and grid current; acquiring a first voltage based on active power, reactive power, a reference value of active power and a reference value of reactive power; generating a reference voltage based on the first voltage; inputting the reference voltage into a first voltage loop based on the reference voltage, acquiring a reference current based on the reference voltage, the grid voltage and a feedback voltage of an energy storage converter; acquiring a three-phase signal based on the reference current and the current loop; generating a PWM signal based on the three-phase signal and a pulse width modulation (PWM) generator to control the energy storage converter through the PWM signal.

[0043] When a fault such as a voltage drop occurs, first, the energy storage converter obtains the grid voltage and grid current, and calculates the active power and reactive power through the grid voltage and grid current; the difference between the active power and the reference value of the active power, and the difference between the reactive power and the reference value of the reactive power are input into the virtual synchronous machine; the first voltage is output through the voltage regulation of the virtual synchronous machine; the reference voltage is obtained by comparing the output first voltage with the d-axis component of the grid voltage and the q-axis component of the grid voltage; the reference voltage is input into the first voltage loop, and the reference current is obtained by calculation based on the reference voltage, the grid voltage and the feedback voltage. The feedback voltage is obtained through the adaptive virtual impedance on the first voltage loop. The generated reference current is appropriately limited by the reference voltage, the grid voltage and the feedback voltage of the energy storage converter to ensure that the system can operate normally when a fault such as a voltage drop occurs, and does not disconnect from the grid within a certain period of time. Through the current loop control, a three-phase signal is obtained, and a PWM signal is generated through the three-phase signal and the PWM generator to control the operation of the energy storage converter. Among them, the energy storage converter is a grid-type energy storage converter. The present invention adopts the structure of low voltage ride-through control of the grid-type energy storage converter, the modulation mode of the energy storage converter is pulse width modulation, and the energy storage converter adopts a virtual synchronous machine mode and a voltage and current dual closed-loop control mode. By adding a virtual impedance based on the energy storage converter side current, reference current and adaptive virtual impedance between the first voltage loop and the current loop, the energy storage converter can suppress overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not go off the grid for a certain period of time.

[0044] In addition, the control device of the energy storage converter in the above technical solution provided by the present invention may also have the following additional technical features:

[0045] In some technical schemes of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is a balanced voltage drop fault, then based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current and the q-axis component of the grid current, obtaining the active power and reactive power.

[0046] In this technical solution, after the grid voltage and grid current are obtained, it is determined whether the grid fault type is a balanced voltage drop fault or an unbalanced voltage drop fault. If the grid fault type is a balanced voltage drop fault, active power and reactive power are obtained based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current, and the q-axis component of the grid current, so as to compare with the reference value of the active power and the reference value of the reactive power to obtain the first voltage.

[0047] In some technical schemes of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is an unbalanced voltage drop fault, introducing adaptive positive and negative sequence separation control, using positive and negative sequence separation for the grid voltage and the grid current, and then obtaining active power and reactive power based on the d-axis component of the positive-sequence component and the q-axis component of the positive-sequence component.

[0048] In this technical solution, after the grid voltage and grid current are obtained, it is determined whether the fault type of the grid is a balanced voltage drop fault or an unbalanced voltage drop fault. If the fault type of the grid is an unbalanced voltage drop fault, an adaptive positive-negative sequence separation control is introduced, and the grid voltage and grid current are separated by positive-negative sequence, and then the active power and reactive power are obtained based on the d-axis component of the positive sequence component and the q-axis component of the positive sequence component, and then the first voltage is obtained by comparing the active power and reactive power with the reference value of the active power and the reference value of the reactive power.

[0049] In some technical schemes of the present invention, optionally, adaptive positive and negative sequence separation control is introduced, and positive and negative sequence separation is adopted for the grid voltage and grid current, including converting the α-axis and β-axis components of the positive sequence component of the grid voltage obtained by the positive and negative sequence separation control into the d-axis component of the grid voltage and the q-axis component of the grid voltage through coordinate transformation, the q-axis component of the grid voltage is input into a phase-locked loop to obtain an angular velocity ω1, and the angular velocity ω1 is fed back to the positive and negative sequence separation control to obtain the d-axis component of the positive sequence component and the q-axis component of the positive sequence component.

[0050] In this technical solution, through positive and negative sequence separation control, the α-axis and β-axis components of the positive sequence component of the grid voltage are converted into the d-axis component of the grid voltage and the q-axis component of the grid voltage through coordinate transformation, and the q-axis component of the grid voltage is input into the phase-locked loop to obtain the angular velocity ω1, and fed back to the positive and negative sequence separation control to obtain the d-axis component of the positive sequence component and the q-axis component of the positive sequence component, thereby obtaining the active power and reactive power.

[0051] In some technical solutions of the present invention, optionally, a reference voltage is generated based on the first voltage, including obtaining the reference voltage based on the first voltage, a d-axis component of the grid voltage, and a q-axis component of the grid voltage.

[0052] In this technical solution, a reference voltage is generated based on the first voltage, including obtaining the reference voltage by comparing the first voltage with the d-axis component of the grid voltage and the q-axis component of the grid voltage, and inputting the reference voltage into the first voltage loop so that the reference voltage, the grid voltage and the feedback voltage are calculated through the first voltage loop to obtain a reference current.

[0053] In some technical solutions of the present invention, optionally, based on a reference voltage, a reference voltage is input into a first voltage loop, and based on the reference voltage, a grid voltage and a feedback voltage of an energy storage converter, a reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, a reference current is obtained through a proportional-integral controller.

[0054] In this technical solution, based on the reference voltage, the reference voltage is input into the first voltage loop, and based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter, the reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, the reference current is obtained through a proportional integral controller, and the first voltage loop can be used for adjustment to calculate the reference voltage, the grid voltage and the feedback voltage, and the calculation result is passed through a proportional integral (PI) controller to obtain the reference current.

[0055] In some technical solutions of the present invention, optionally, obtaining the feedback voltage includes: obtaining an adaptive proportional parameter based on a peak value of a reference current and a current setting value; obtaining an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the current on the energy storage converter side; and obtaining the feedback voltage based on the adaptive virtual impedance and the current on the energy storage converter side.

[0056] In this technical solution, an adaptive proportional parameter can be obtained by referring to the current peak value and the current set value of the current loop. An adaptive virtual impedance can be obtained by the adaptive proportional parameter, the current set value and the current on the energy storage converter side. Finally, a feedback voltage can be obtained by the adaptive virtual impedance and the current on the energy storage converter side.

[0057] Furthermore, the current on the energy storage converter side is collected from the line on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation. The d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are used to obtain feedback voltage through adaptive virtual impedance. The feedback voltage, reference voltage and grid voltage are calculated, and the calculation result is passed through a proportional integral controller to obtain a reference current.

[0058] In some technical schemes of the present invention, optionally, a three-phase signal is obtained based on a reference current and a current loop, including obtaining a d-axis component of the reference current and a q-axis component of the reference current based on the reference current; the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through a proportional-integral controller.

[0059] In this technical solution, based on the reference current, the d-axis component of the reference current and the q-axis component of the reference current are obtained, and the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through the proportional integral controller. A PWM signal is generated through the three-phase signal and the PWM generator to control the energy storage converter through the PWM signal, so that the energy storage converter can suppress the overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not go off the grid for a certain period of time.

[0060] In some technical solutions of the present invention, optionally, the calculation formula of the adaptive ratio parameter is: k= I ref,peak / I th , where k is the adaptive scale parameter, I ref,peak is the peak value of the reference current, I th Set the current value.

[0061] In this technical solution, the adaptive proportional parameter is obtained by calculating the reference current peak value and the current setting value of the reference current.

[0062] In some technical solutions of the present invention, optionally, the calculation formula of the current setting value is: I th =1.1 I g0 ,in I th is the current setting value, I g0 It is the peak value of steady-state current when there is no fault in the power grid.

[0063] In this technical solution, the current setting value is obtained by the peak value of the steady-state current when the power grid is free of faults.

[0064] In some technical solutions of the present invention, optionally, the calculation formula of the adaptive virtual impedance is: Zv=k( i L - I th ), where Zv is the adaptive virtual impedance, k is the adaptive ratio parameter, I th is the current setting value, i L is the current on the energy storage converter side.

[0065] In this technical solution, the adaptive virtual impedance is obtained by calculating the adaptive proportional parameter, the current setting value and the current on the energy storage converter side.

[0066] In some technical solutions of the present invention, optionally, the calculation formula of the feedback voltage is: v b = i L Zv, where Zv is the adaptive virtual impedance, i L is the current on the energy storage converter side.

[0067] In this technical solution, the feedback voltage is obtained by adaptively calculating the virtual impedance and the current on the energy storage converter side.

[0068] In some technical solutions of the present invention, further, the grid-type energy storage converter system includes: a DC power supply, an energy storage converter, a filter inductor 1, a filter capacitor, a filter inductor 2, a line inductor, and a power grid.

[0069] In some technical solutions of the present invention, further, the grid current is collected from the grid-side line, and the d-axis component of the grid current and the q-axis component of the grid current are obtained after coordinate transformation.

[0070] The grid voltage is collected from the grid side line, and the d-axis component of the grid voltage and the q-axis component of the grid voltage are obtained after coordinate transformation.

[0071] The current on the energy storage converter side is collected from the circuit on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation.

[0072] In some technical schemes of the present invention, further, the grid-type energy storage inverter defined by the present invention is a low voltage ride-through control structure, the modulation method of the energy storage inverter is pulse width modulation, and the energy storage inverter adopts a virtual synchronous machine method and a voltage and current dual closed-loop control method. Active power and reactive power are calculated by sampling the d-axis component and q-axis component of the grid voltage and grid current, and the difference is respectively made with the active power reference value and the reactive power reference value and the difference is input into the virtual synchronous machine to obtain the output first voltage of the virtual synchronous machine, which is converted into d-axis component and q-axis component through coordinate transformation, and the obtained dq (direct-axis, quadrature-axis) component is made different from the d-axis component and q-axis component of the grid voltage and the d-axis component and q-axis component of the feedback voltage, and the d-axis component and q-axis component of the output reference current are made different from the d-axis component and q-axis component of the grid current through a proportional-integral controller, and the output quantity obtained through the proportional-integral controller is input into the switching signal generated in the PWM generator, and then the switching signal is input into the energy storage converter, so that the energy storage converter can suppress the overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not go off the grid for a certain period of time.

[0073] In some technical schemes of the present invention, further, in the adaptive virtual impedance control of the grid-type energy storage inverter, the peak value of the current reference value is first compared with the current set value to obtain an adaptive proportional parameter, and then the current on the energy storage inverter side is subtracted from the current set value, and the obtained difference is multiplied by the adaptive proportional parameter to obtain the adaptive virtual impedance.

[0074] A third aspect of the present invention provides a readable storage medium having a program or instruction stored thereon, which, when executed by a processor, implements the steps of a method for controlling an energy storage converter as described in any of the above technical solutions.

[0075] Since the readable storage medium proposed in the present invention stores a program or instruction thereon, and the program or instruction, when executed by the processor, implements the steps of the control method of the energy storage inverter as in any of the above-mentioned technical solutions, the readable storage medium has all the beneficial effects of the steps of the control method of the energy storage inverter as in any of the above-mentioned technical solutions, which will not be repeated here.

[0076] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0078] Figure 1 One of the schematic diagrams of a control method for an energy storage converter according to an embodiment of the present invention;

[0079] Figure 2 A system schematic diagram of an energy storage converter according to an embodiment of the present invention;

[0080] Figure 3 A schematic diagram of low voltage ride-through control of an energy storage converter according to an embodiment of the present invention;

[0081] Figure 4 A schematic diagram of adaptive virtual impedance control of an energy storage converter according to an embodiment of the present invention;

[0082] Figure 5 A second schematic diagram of a control method for an energy storage converter according to an embodiment of the present invention;

[0083] Figure 6 Schematic diagram of a control device for an energy storage converter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0084] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0085] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0086] Refer to the following Figures 1 to 6 A control method, a control device and a readable storage medium for an energy storage converter according to some embodiments of the present invention are described.

[0087] The present invention provides a control method for an energy storage converter, such as Figure 1 As shown, the control method of the energy storage converter includes:

[0088] Step 102: Obtaining grid voltage and grid current;

[0089] Step 104: Obtaining active power and reactive power based on the grid voltage and the grid current;

[0090] Step 106: acquiring a first voltage based on the active power, the reactive power, a reference value of the active power, and a reference value of the reactive power;

[0091] Step 108: Generate a reference voltage based on the first voltage;

[0092] Step 110: Based on the reference voltage, input the reference voltage into the first voltage loop, and obtain the reference current based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter;

[0093] Step 112: Acquire a three-phase signal based on the reference current and the current loop;

[0094] Step 114: Generate a pulse width modulation signal based on the three-phase signal and the pulse width modulation generator, so as to control the energy storage converter through the pulse width modulation signal.

[0095] The present invention proposes a control method for an energy storage converter. When a fault such as a voltage drop occurs, first, the energy storage converter obtains the grid voltage and grid current, and calculates the active power and reactive power through the grid voltage and grid current; the difference between the active power and the reference value of the active power, and the difference between the reactive power and the reference value of the reactive power are input into the virtual synchronous machine; the first voltage is output through the voltage regulation of the virtual synchronous machine; the reference voltage is obtained by comparing the output first voltage with the d-axis component of the grid voltage and the q-axis component of the grid voltage; the reference voltage is input into the first voltage loop, and the reference current is obtained by calculation based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter. The feedback voltage is obtained through the adaptive virtual impedance on the first voltage loop. The reference current is controlled by the current loop to obtain a three-phase signal, and the three-phase signal is input into the pulse width modulation generator, and then a pulse width modulation signal is generated to control the operation of the energy storage converter. The energy storage converter is a grid-type energy storage converter. The present invention uses a structure for low voltage ride-through control of a grid-type energy storage converter. The modulation mode of the energy storage converter is pulse width modulation. The energy storage converter can adopt a virtual synchronous machine mode and a voltage and current dual closed-loop control mode. By adding a virtual impedance based on the energy storage converter side current, reference current and adaptive virtual impedance between the first voltage loop and the current loop, the energy storage converter can suppress overcurrent caused by faults such as voltage drops, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not disconnect from the grid within a certain period of time.

[0096] In some embodiments of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is a balanced voltage drop fault, then based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current and the q-axis component of the grid current, obtaining active power and reactive power.

[0097] In this technical solution, after the grid voltage and grid current are obtained, it is determined whether the grid fault type is a balanced voltage drop fault or an unbalanced voltage drop fault. If the grid fault type is a balanced voltage drop fault, active power and reactive power are obtained based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current, and the q-axis component of the grid current, so as to compare with the reference value of the active power and the reference value of the reactive power to obtain the first voltage.

[0098] In some technical schemes of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is an unbalanced voltage drop fault, introducing adaptive positive and negative sequence separation control, using positive and negative sequence separation for the grid voltage and the grid current, and then obtaining active power and reactive power based on the d-axis component of the positive-sequence component and the q-axis component of the positive-sequence component.

[0099] In this embodiment, after the grid voltage and grid current are obtained, it is determined whether the fault type of the grid is a balanced voltage drop fault or an unbalanced voltage drop fault. If the fault type of the grid is an unbalanced voltage drop fault, an adaptive positive-negative sequence separation control is introduced, and the grid voltage and grid current are separated by positive-negative sequence, and then the active power and reactive power are obtained based on the d-axis component of the positive sequence component and the q-axis component of the positive sequence component, and then the first voltage is obtained by calculating the active power and reactive power with the reference value of the active power and the reference value of the reactive power.

[0100] In some embodiments of the present invention, optionally, an adaptive positive-negative sequence separation control is introduced, and the positive-negative sequence separation is adopted for the grid voltage and the grid current, including converting the α-axis and β-axis components of the positive-sequence component of the grid voltage obtained by the positive-negative sequence separation control into the d-axis component of the grid voltage and the q-axis component of the grid voltage through coordinate transformation, the q-axis component of the grid voltage is input into a phase-locked loop to obtain an angular velocity ω1, and the angular velocity ω1 is fed back to the positive-negative sequence separation control to obtain the d-axis component of the positive-sequence component and the q-axis component of the positive-sequence component.

[0101] In this embodiment, through positive and negative sequence separation control, the α-axis component and β-axis component of the positive sequence component of the grid voltage are converted into the d-axis component and the q-axis component of the grid voltage through coordinate transformation, and the q-axis component of the grid voltage is input into the phase-locked loop to obtain the angular velocity ω1 and fed back to the positive and negative sequence separation control to obtain the d-axis component and the q-axis component of the positive sequence component, thereby obtaining the active power and reactive power.

[0102] In some embodiments of the present invention, optionally, generating a reference voltage based on the first voltage includes acquiring the reference voltage based on the first voltage, a d-axis component of the grid voltage, and a q-axis component of the grid voltage.

[0103] In this embodiment, a reference voltage is obtained by comparing the first voltage with the d-axis component of the grid voltage and the q-axis component of the grid voltage, and the reference voltage is input into the first voltage loop so that the reference voltage, the grid voltage and the feedback voltage are calculated through the first voltage loop to obtain a reference current.

[0104] In some embodiments of the present invention, optionally, based on a reference voltage, a reference voltage is input into a first voltage loop, and based on the reference voltage, a grid voltage and a feedback voltage of an energy storage converter, a reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, a reference current is obtained through a proportional-integral controller.

[0105] In this embodiment, based on the reference voltage, the reference voltage is input into the first voltage loop, and based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter, the reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, the reference current is obtained through a proportional-integral controller, the reference voltage is input into the first voltage loop, the reference voltage, the grid voltage and the feedback voltage are calculated, and the calculation result is input into the proportional-integral controller to obtain the reference current.

[0106] In some embodiments of the present invention, optionally, obtaining a feedback voltage includes: obtaining an adaptive proportional parameter based on a peak value of a reference current and a current setting value; obtaining an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the current on the energy storage converter side; and obtaining a feedback voltage based on the adaptive virtual impedance and the current on the energy storage converter side.

[0107] In this embodiment, obtaining the feedback voltage includes: obtaining an adaptive proportional parameter based on a reference current peak value and a current setting value; obtaining an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the energy storage converter side current; obtaining the feedback voltage based on the adaptive virtual impedance and the energy storage converter side current, and obtaining the adaptive proportional parameter through the current loop reference current peak value and the current setting value, and obtaining the adaptive virtual impedance through the adaptive proportional parameter, the current setting value and the energy storage converter side current, and finally obtaining the feedback voltage through the adaptive virtual impedance and the energy storage converter side current.

[0108] Furthermore, the current on the energy storage converter side is collected from the line on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation. The d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are used to obtain feedback voltage through adaptive virtual impedance. The feedback voltage, reference voltage and grid voltage are calculated, and the calculation result is passed through a proportional integral controller to obtain a reference current.

[0109] In some embodiments of the present invention, optionally, a three-phase signal is obtained based on a reference current and a current loop, including obtaining a d-axis component of the reference current and a q-axis component of the reference current based on the reference current; the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current, and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through a proportional-integral controller.

[0110] In this embodiment, based on the reference current and the current loop, a three-phase signal is obtained, including obtaining the d-axis component of the reference current and the q-axis component of the reference current based on the reference current; the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through a proportional-integral controller, and the reference current obtains the d-axis component of the reference current and the d-axis component of the grid current through coordinate transformation, and the difference calculated, as well as the difference calculated between the q-axis component of the reference current and the q-axis component of the grid current, and the three-phase signal is obtained through a proportional-integral controller. A PWM signal is generated through the three-phase signal and the PWM generator, so as to control the energy storage converter through the PWM signal, so that the energy storage converter can suppress the overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not disconnect from the grid within a certain period of time.

[0111] In some embodiments of the present invention, optionally, the calculation formula of the adaptive ratio parameter is: k= I ref,peak / I th , where k is the adaptive scale parameter, I ref,peak is the reference current i ref The peak value, I th Set the current value.

[0112] In this embodiment, the adaptive proportional parameter is obtained by calculating the reference current peak value and the current setting value of the reference current.

[0113] In some embodiments of the present invention, optionally, the calculation formula of the current setting value is: I th =1.1 I g0 ,in I th is the current setting value, I g0 It is the peak value of steady-state current when there is no fault in the power grid.

[0114] In this embodiment, the current setting value is obtained by the peak value of the steady-state current when the power grid is free of faults.

[0115] In some embodiments of the present invention, optionally, the calculation formula of the adaptive virtual impedance is: Zv=k( i L - I th ), where Zv is the adaptive virtual impedance, k is the adaptive ratio parameter, I th is the current setting value,i L is the current on the energy storage converter side.

[0116] In this embodiment, the adaptive virtual impedance is obtained by calculating the adaptive proportion parameter, the current setting value and the current on the energy storage converter side.

[0117] In some embodiments of the present invention, optionally, the calculation formula of the feedback voltage is: v b = i L Zv, where Zv is the adaptive virtual impedance, i L is the current on the energy storage converter side.

[0118] In this embodiment, the feedback voltage is obtained by calculating the adaptive virtual impedance and the current on the energy storage converter side.

[0119] In some embodiments of the present invention, further, Figure 2 As shown, the grid-type energy storage converter system includes: a DC power supply, an energy storage converter, a filter inductor 1, a filter capacitor, a filter inductor 2, a line inductor, and a power grid.

[0120] In this embodiment, the grid-type energy storage converter system includes, from left to right: a DC power supply V dc , energy storage converter, filter inductor L f1 、Filter capacitor C f 、Filter inductor L f2 , Line Inductance L g , power grid. The DC power supply provides a stable DC power input for the entire system; the energy storage converter can adjust the amplitude, frequency and phase of the output AC power according to the grid demand and energy storage status; the filter capacitor is used to filter and compensate for reactive power; the filter inductor is used to smooth the current, reduce the harmonic components in the current, and improve the power quality.

[0121] In some embodiments of the present invention, further, the grid current is collected from the grid-side line, and after coordinate transformation, a d-axis component of the grid current and a q-axis component of the grid current are obtained.

[0122] The grid voltage is collected from the grid side line, and the d-axis component of the grid voltage and the q-axis component of the grid voltage are obtained after coordinate transformation.

[0123] The current on the energy storage converter side is collected from the circuit on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation.

[0124] In some technical solutions of the present invention, further, Figure 3 As shown, the grid-type energy storage converter defined in the present invention is a low voltage ride-through control structure, the modulation mode of the energy storage converter is pulse width modulation, and the energy storage converter adopts a virtual synchronous machine mode and a voltage and current double closed-loop control mode. The grid voltage obtained by sampling v g and grid current i g The active power P and reactive power Q are calculated from the d-axis and q-axis components of the virtual synchronous machine, and the difference is respectively made with the active power reference value P* and the reactive power reference value Q*, and the difference is input into the virtual synchronous machine to obtain the output first voltage of the virtual synchronous machine. v vsg , transform it into d-axis and q-axis components through coordinate transformation abc / dq, and compare the obtained d-axis and q-axis components with the grid voltage v g The d-axis and q-axis components of v gd , v gq The d-axis and q-axis components of the feedback voltage are subtracted and passed through a proportional-integral controller to obtain the d-axis and q-axis components of the output reference current. i d_ref , i q_ref , and then with the grid current i g The d-axis and q-axis components of i gd , i gq The difference is then calculated by the proportional-integral controller to obtain the output, which is then input into the PWM generator. The generated switching signal is input into the energy storage converter, so that the energy storage converter can suppress overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not disconnect from the grid within a certain period of time. Among them, the feedback voltage is composed of the d-axis component of the current on the energy storage converter side i Ld and the q-axis component of the grid-side current i Lq Calculated by adaptive virtual impedance Zv.

[0125] In some embodiments of the present invention, further, Figure 4 As shown in the figure, the grid-type energy storage converter adaptive virtual impedance control first refers to the peak value of the current I ref,peak With current setting value I th Compared with the adaptive proportional parameter k, the current on the energy storage converter side is I LWith current setting value I th Make a difference, and multiply the difference by the adaptive proportional parameter k to obtain the adaptive virtual impedance Zv.

[0126] In some embodiments of the present invention, further, Figure 5 As shown in the figure, the low voltage ride-through control process of the grid-type energy storage converter includes:

[0127] Step 202: determining, based on the grid voltage, whether the grid fault type is a balanced voltage drop fault or an unbalanced voltage drop fault;

[0128] Step 204: when an unbalanced voltage drop fault occurs, an adaptive positive-negative sequence separation control is introduced, the grid voltage and grid current are separated by positive-negative sequence, and the dq components of the grid voltage and grid current are used for power calculation;

[0129] Step 206: When a balanced voltage drop fault occurs, power calculation is performed using the dq components of the grid voltage and grid current;

[0130] Step 208: Calculate the active power and reactive power, make a difference between the active power reference value and the reactive power reference value, and input the difference into the virtual synchronous machine control to obtain v vsg ;

[0131] Step 210: Voltage Reference v ref Input to the improved voltage loop, the voltage reference is combined with the grid voltage and the feedback voltage to calculate the reference current of the current loop, wherein the feedback voltage is calculated by the adaptive proportional parameter obtained by calculating the peak value of the current loop reference current and the current setting value, and the adaptive virtual impedance and the converter side current;

[0132] Step 212: The current reference is transformed into its dq components by coordinate transformation. d_ref and i q_ref The value obtained by subtracting the dq components generated by the coordinate transformation of the grid current is input into the current loop, and finally generates a three-phase signal after passing through PI;

[0133] Step 214: Generate a PWM signal.

[0134] Furthermore, the calculation formula of the adaptive ratio parameter k is:

[0135] k= I ref,peak / I th ;

[0136] Where k is the adaptive scale parameter, I ref,peakis the reference current i ref The peak value, I th Set the current value.

[0137] Furthermore, the current setting value I th for:

[0138] I th =1.1 I g0 ;

[0139] in I th is the current setting value, I g0 It is the peak value of steady-state current when there is no fault in the power grid.

[0140] Furthermore, the calculation formula of the virtual impedance Zv is:

[0141] Zv=k( i L - I th );

[0142] Where Zv is the virtual impedance, k is the adaptive proportional parameter, I th is the current setting value, i L is the current on the energy storage converter side.

[0143] Furthermore, the feedback voltage v b The calculation formula is:

[0144] v b = i L Zv;

[0145] Where Zv is the virtual impedance, i L is the current on the energy storage converter side.

[0146] Specifically, the dq components of the grid voltage and the grid current refer to the d-axis component and the q-axis component of the grid voltage and the grid current.

[0147] Specifically, the voltage reference v ref Refers to the voltage reference value. The current on the converter side is the current on the energy storage converter side.

[0148] The present invention provides a control device 300 for an energy storage converter, such as Figure 6As shown, the control device 300 of the energy storage converter includes: a first acquisition unit 302 , a first calculation unit 304 , a second calculation unit 306 , a first generation unit 308 , a third calculation unit 310 , a second generation unit 312 and a third generation unit 314 . The first acquisition unit 302 is used to acquire the grid voltage and the grid current; the first calculation unit 304 is used to acquire the active power and the reactive power based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current and the q-axis component of the grid current; the second calculation unit 306 is used to acquire the first voltage based on the active power, the reactive power, the reference value of the active power and the reference value of the reactive power; the first generation unit 308 is used to generate a reference voltage based on the first voltage; the third calculation unit 310 is used to input the reference voltage into the first voltage loop based on the reference voltage, and acquire the reference current based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter; the second generation unit 312 is used to acquire the three-phase signal based on the reference current and the current loop; the third generation unit 314 is used to generate a pulse width modulation signal based on the three-phase signal and the pulse width modulation generator, so as to control the energy storage converter through the pulse width modulation signal.

[0149] The present invention proposes a control device 300 for an energy storage converter, comprising obtaining a grid voltage and a grid current; obtaining active power and reactive power based on the grid voltage and the grid current; obtaining a first voltage based on active power, reactive power, a reference value of active power and a reference value of reactive power; generating a reference voltage based on the first voltage; inputting the reference voltage into a first voltage loop based on the reference voltage, and obtaining a reference current based on the reference voltage, the grid voltage and a feedback voltage of the energy storage converter; obtaining a three-phase signal based on the reference current and the current loop; generating a PWM signal based on the three-phase signal and a pulse width modulation (PWM) generator to control the energy storage converter through the PWM signal.

[0150] The present invention proposes a control device 300 for an energy storage converter. When a fault such as a voltage drop occurs, first, the energy storage converter obtains the grid voltage and grid current, and calculates the active power and reactive power through the grid voltage and grid current; the difference between the active power and the reference value of the active power, and the difference between the reactive power and the reference value of the reactive power are input into the virtual synchronous machine; the first voltage is output through the voltage regulation function of the virtual synchronous machine; the reference voltage is obtained by comparing the output first voltage with the d-axis component of the grid voltage and the q-axis component of the grid voltage; the reference voltage is input into the first voltage loop, and the reference current is obtained by calculation based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter. The feedback voltage is obtained through the adaptive virtual impedance on the first voltage loop. The generated reference current is appropriately limited by the reference voltage, the grid voltage and the feedback voltage to ensure that the system can operate normally when a fault such as a voltage drop occurs, and does not disconnect from the grid within a certain period of time. Through the current loop control, a three-phase signal is obtained, and a PWM signal is generated through the three-phase signal and the PWM generator to control the operation of the energy storage converter. Among them, the energy storage converter is a grid-type energy storage converter. The present invention adopts the structure of low voltage ride-through control of the grid-type energy storage converter, the modulation mode of the energy storage converter is pulse width modulation, and the energy storage converter adopts a virtual synchronous machine mode and a voltage and current dual closed-loop control mode. By adding a virtual impedance based on the energy storage converter side current, reference current and adaptive virtual impedance between the first voltage loop and the current loop, the energy storage converter can suppress overcurrent caused by faults such as voltage drops, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not go off the grid for a certain period of time.

[0151] In some embodiments of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is a balanced voltage drop fault, then based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current and the q-axis component of the grid current, obtaining active power and reactive power.

[0152] In this technical solution, after the grid voltage and grid current are obtained, it is determined whether the grid fault type is a balanced voltage drop fault or an unbalanced voltage drop fault. If the grid fault type is a balanced voltage drop fault, active power and reactive power are obtained based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current, and the q-axis component of the grid current, so as to compare with the reference value of the active power and the reference value of the reactive power to obtain the first voltage.

[0153] In some technical schemes of the present invention, optionally, after obtaining the grid voltage and the grid current, it also includes judging, based on the grid voltage, whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; if the type of grid fault is an unbalanced voltage drop fault, introducing adaptive positive and negative sequence separation control, using positive and negative sequence separation for the grid voltage and the grid current, and then obtaining active power and reactive power based on the d-axis component of the positive-sequence component and the q-axis component of the positive-sequence component.

[0154] In this embodiment, after the grid voltage and grid current are obtained, it is determined whether the fault type of the grid is a balanced voltage drop fault or an unbalanced voltage drop fault. If the fault type of the grid is an unbalanced voltage drop fault, an adaptive positive-negative sequence separation control is introduced, and the grid voltage and grid current are separated by positive-negative sequence, and then the active power and reactive power are obtained based on the d-axis component of the positive sequence component and the q-axis component of the positive sequence component, and then the first voltage is obtained by calculating the active power and reactive power with the reference value of the active power and the reference value of the reactive power.

[0155] In some embodiments of the present invention, optionally, adaptive positive and negative sequence separation control is introduced, including converting the α-axis component and β-axis component of the positive sequence component of the grid voltage obtained by the positive and negative sequence separation control into the d-axis component of the grid voltage and the q-axis component of the grid voltage through coordinate transformation, and the q-axis component of the grid voltage is input into a phase-locked loop to obtain an angular velocity ω1, and is fed back to the positive and negative sequence separation control.

[0156] In this embodiment, through positive and negative sequence separation control, the α-axis component and β-axis component of the positive sequence component of the grid voltage are converted into the d-axis component and the q-axis component of the grid voltage through coordinate transformation, and the q-axis component of the grid voltage is input into the phase-locked loop to obtain the angular velocity ω1, and is fed back to the positive and negative sequence separation control to obtain the d-axis component and the q-axis component of the positive sequence component, thereby obtaining the active power and reactive power.

[0157] In some embodiments of the present invention, optionally, generating a reference voltage based on the first voltage includes acquiring the reference voltage based on the first voltage, a d-axis component of the grid voltage, and a q-axis component of the grid voltage.

[0158] In this embodiment, a reference voltage is generated based on the first voltage, including obtaining a reference voltage based on the first voltage, a d-axis component of the grid voltage, and a q-axis component of the grid voltage, and obtaining the reference voltage by comparing the first voltage with the d-axis component of the grid voltage and the q-axis component of the grid voltage. The reference voltage is input into the first voltage loop so that the reference voltage, the grid voltage and the feedback voltage are calculated through the first voltage loop to obtain a reference current.

[0159] In some embodiments of the present invention, optionally, based on a reference voltage, a reference voltage is input into a first voltage loop, and based on the reference voltage, a grid voltage and a feedback voltage of an energy storage converter, a reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, a reference current is obtained through a proportional-integral controller.

[0160] In this embodiment, based on the reference voltage, the reference voltage is input into the first voltage loop, and based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter, the reference current is obtained, including: based on the reference voltage, the grid voltage and the feedback voltage, the reference current is obtained through a proportional integral controller, and the reference voltage, the grid voltage and the feedback voltage are calculated by adjusting the first voltage loop, and the calculation result is brought into a proportional integral (PI) controller to obtain the reference current.

[0161] In some embodiments of the present invention, optionally, obtaining a feedback voltage includes: obtaining an adaptive proportional parameter based on a peak value of a reference current and a current setting value; obtaining an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the current on the energy storage converter side; and obtaining a feedback voltage based on the adaptive virtual impedance and the current on the energy storage converter side.

[0162] In this embodiment, obtaining the feedback voltage includes: obtaining an adaptive proportional parameter based on a reference current peak value and a current setting value; obtaining an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the energy storage converter side current; obtaining the feedback voltage based on the adaptive virtual impedance and the energy storage converter side current, and obtaining the adaptive proportional parameter through the current loop reference current peak value and the current setting value, and obtaining the adaptive virtual impedance through the adaptive proportional parameter, the current setting value and the energy storage converter side current, and finally obtaining the feedback voltage through the adaptive virtual impedance and the energy storage converter side current.

[0163] Furthermore, the current on the energy storage converter side is collected from the line on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation. The d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are used to obtain feedback voltage through adaptive virtual impedance. The feedback voltage, reference voltage and grid voltage are calculated, and the calculation result is passed through a proportional integral controller to obtain a reference current.

[0164] In some embodiments of the present invention, optionally, a three-phase signal is obtained based on a reference current and a current loop, including obtaining a d-axis component of the reference current and a q-axis component of the reference current based on the reference current; the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current, and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through a proportional-integral controller.

[0165] In this embodiment, based on the reference current and the current loop, a three-phase signal is obtained, including obtaining the d-axis component of the reference current and the q-axis component of the reference current based on the reference current; the d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through a proportional-integral controller. The reference current can obtain the d-axis component of the reference current and the d-axis component of the grid current through coordinate transformation, and the difference is calculated, as well as the difference between the q-axis component of the reference current and the q-axis component of the grid current, and the three-phase signal is obtained through a proportional-integral controller. A PWM signal is generated through the three-phase signal and the PWM generator, so as to control the energy storage converter through the PWM signal, so that the energy storage converter can suppress the overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not disconnect from the grid within a certain period of time.

[0166] In some embodiments of the present invention, optionally, the calculation formula of the adaptive ratio parameter is: k= I ref,peak / I th , where k is the adaptive scale parameter, I ref,peak is the reference current i ref The peak value, I th Set the current value.

[0167] In this embodiment, the adaptive proportional parameter is obtained by calculating the reference current peak value and the current setting value of the reference current.

[0168] In some embodiments of the present invention, optionally, the calculation formula of the current setting value is: I th =1.1 I g0 ,in I th is the current setting value, I g0 It is the peak value of steady-state current when there is no fault in the power grid.

[0169] Specifically, the calculation formula of the current setting value can be improved as follows: I th =1.3 I g0 .

[0170] In this embodiment, the current setting value is obtained by the peak value of the steady-state current when the power grid is free of faults.

[0171] In some embodiments of the present invention, optionally, the calculation formula of the adaptive virtual impedance is: Zv=k( i L - I th ), where Zv is the adaptive virtual impedance, k is the adaptive ratio parameter, I th is the current setting value, i L is the current on the energy storage converter side.

[0172] In this embodiment, the adaptive virtual impedance is obtained by calculating the adaptive proportion parameter, the current setting value and the current on the energy storage converter side.

[0173] In some embodiments of the present invention, optionally, the calculation formula of the feedback voltage is: v b = i L Zv, where Zv is the adaptive virtual impedance, i L is the current on the energy storage converter side.

[0174] In this embodiment, the feedback voltage is obtained by calculating the adaptive virtual impedance and the current on the energy storage converter side.

[0175] In some embodiments of the present invention, further, the grid-type energy storage converter system includes: a DC power supply, an energy storage converter, a filter inductor 1, a filter capacitor, a filter inductor 2, a line inductor, and a power grid.

[0176] In some embodiments of the present invention, further, the grid current is collected from the grid-side line, and after coordinate transformation, a d-axis component of the grid current and a q-axis component of the grid current are obtained.

[0177] The grid voltage is collected from the grid side line, and the d-axis component of the grid voltage and the q-axis component of the grid voltage are obtained after coordinate transformation.

[0178] The current on the energy storage converter side is collected from the circuit on the energy storage converter side, and the d-axis component of the current on the energy storage converter side and the q-axis component of the current on the energy storage converter side are obtained after coordinate transformation.

[0179] In some embodiments of the present invention, further, the grid-type energy storage inverter defined by the present invention is a low voltage ride-through control structure, the modulation method of the energy storage inverter is pulse width modulation, and the energy storage inverter adopts a virtual synchronous machine method and a voltage and current dual closed-loop control method. Active power and reactive power are calculated by sampling the d-axis component and q-axis component of the grid voltage and grid current, and the difference is respectively made with the active power reference value and the reactive power reference value and the difference is input into the virtual synchronous machine to obtain the output first voltage of the virtual synchronous machine, which is converted into d-axis component and q-axis component through coordinate transformation, and the obtained dq (direct-axis, quadrature-axis) component is made different from the d-axis component and q-axis component of the grid voltage and the d-axis component and q-axis component of the feedback voltage, and the d-axis component and q-axis component of the output reference current are made different from the d-axis component and q-axis component of the grid current after passing through the proportional-integral controller, and the output quantity obtained by the proportional-integral controller is input into the PWM generator, and the generated switching signal is input into the energy storage converter, so that the energy storage converter can suppress the overcurrent caused by faults such as voltage drop, meet the fault ride-through requirements, and ensure that the grid-type energy storage converter does not go off the grid for a certain period of time.

[0180] In some technical schemes of the present invention, further, in the adaptive virtual impedance control of the grid-type energy storage inverter, first, the peak value of the current reference value is compared with the current set value to obtain an adaptive proportional parameter, and then the current on the energy storage inverter side is subtracted from the current set value, and the obtained difference is multiplied by the adaptive proportional parameter to obtain the adaptive virtual impedance.

[0181] The present invention provides a readable storage medium on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the control method of the energy storage converter as described in any of the above technical solutions are implemented.

[0182] Since the readable storage medium proposed in the present invention stores a program or instruction thereon, and the program or instruction, when executed by the processor, implements the steps of the control method of the energy storage inverter as in any of the above-mentioned technical solutions, the readable storage medium has all the beneficial effects of the steps of the control method of the energy storage inverter as in any of the above-mentioned technical solutions, which will not be repeated here.

[0183] In the claims, specification and drawings of the present invention, the term "multiple" refers to two or more than two. Unless otherwise clearly defined, the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the drawings, which is only for the purpose of more conveniently describing the present invention and making the description process simpler, rather than indicating or implying that the device or element referred to must have the specific orientation described, be constructed and operated in a specific orientation, so these descriptions cannot be understood as limiting the present invention; the terms "connect", "install", "fix" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection between multiple objects, or a detachable connection between multiple objects, or an integral connection; it can be a direct connection between multiple objects, or an indirect connection between multiple objects through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood based on the specific circumstances of the above data.

[0184] In the claims, specification and drawings of the present invention, the description of the terms "one embodiment", "some embodiments", "specific embodiments" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In the claims, specification and drawings of the present invention, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0185] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A control method for an energy storage converter, characterized in that: The control method of the energy storage converter comprises: Obtain grid voltage and grid current; Based on the grid voltage and the grid current, obtaining active power and reactive power; acquiring a first voltage based on the active power, the reactive power, a reference value of active power, and a reference value of reactive power; generating a reference voltage based on the first voltage; Based on the reference voltage, inputting the reference voltage into a first voltage loop, and acquiring a reference current based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter; The first voltage is converted into a d-axis component and a q-axis component through coordinate transformation, and the d-axis component and the q-axis component of the first voltage are respectively subtracted from the d-axis component and the q-axis component of the grid voltage and the d-axis component and the q-axis component of the feedback voltage, and the d-axis component and the q-axis component of the reference current are obtained through a proportional-integral controller; Based on the reference current and the current loop, obtaining a three-phase signal; Based on the three-phase signal and the pulse width modulation generator, a pulse width modulation signal is generated to control the energy storage converter through the pulse width modulation signal; Acquiring the feedback voltage includes: Based on the peak value of the reference current and the current setting value, an adaptive proportional parameter is obtained; Acquire an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the energy storage converter side current; Based on the adaptive virtual impedance and the current on the energy storage converter side, obtaining the feedback voltage; Among them, the current setting value is determined according to the steady-state current peak value when the power grid is fault-free; the adaptive proportional parameter is the ratio of the peak value of the reference current to the current setting value, the adaptive virtual impedance is the product of the difference between the current on the energy storage converter side and the current setting value and the adaptive proportional parameter; the feedback voltage is the product of the adaptive virtual impedance and the current on the energy storage converter side.

2. The control method of the energy storage converter according to claim 1, characterized in that: After obtaining the grid voltage and grid current, the control method of the energy storage converter further includes: Based on the grid voltage, determining whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; If the fault type of the power grid is a balanced voltage drop fault, the active power and the reactive power are obtained based on the d-axis component of the grid voltage, the q-axis component of the grid voltage, the d-axis component of the grid current, and the q-axis component of the grid current.

3. The control method of the energy storage converter according to claim 1, characterized in that: After obtaining the grid voltage and grid current, the control method of the energy storage converter further includes: Based on the grid voltage, determining whether the type of grid fault is a balanced voltage drop fault or an unbalanced voltage drop fault; If the fault type of the power grid is an unbalanced voltage drop fault, adaptive positive and negative sequence separation control is introduced, and positive and negative sequence separation is used for the grid voltage and the grid current, and then the active power and the reactive power are obtained based on the d-axis component of the positive sequence component and the q-axis component of the positive sequence component.

4. The control method of the energy storage converter according to claim 3, characterized in that: The introducing of adaptive positive-negative sequence separation control and the use of positive-negative sequence separation for the grid voltage and the grid current comprises: The α-axis component and the β-axis component of the positive-sequence component of the grid voltage obtained by the positive-negative sequence separation control are converted into the d-axis and q-axis components of the grid voltage through coordinate transformation, the q-axis component of the grid voltage is input into a phase-locked loop to obtain an angular velocity ω1, and the angular velocity ω1 is fed back to the positive-negative sequence separation control to obtain the d-axis component of the positive-sequence component and the q-axis component of the positive-sequence component.

5. The control method of the energy storage converter according to claim 1, characterized in that: The step of generating a reference voltage based on the first voltage comprises: A reference voltage is acquired based on the first voltage, a d-axis component of the grid voltage, and a q-axis component of the grid voltage.

6. The control method of the energy storage converter according to claim 1, characterized in that: The step of inputting the reference voltage into a first voltage loop based on the reference voltage, and acquiring a reference current based on the reference voltage, the grid voltage, and the feedback voltage of the energy storage converter comprises: Based on the reference voltage, the grid voltage and the feedback voltage, the reference current is obtained through a proportional-integral controller.

7. The control method of the energy storage converter according to claim 1, characterized in that: The obtaining of a three-phase signal based on the reference current and the current loop includes: Based on the reference current, obtaining a d-axis component of the reference current and a q-axis component of the reference current; The d-axis component of the reference current, the q-axis component of the reference current, the d-axis component of the grid current and the q-axis component of the grid current are input into the current loop, and the three-phase signal is obtained through a proportional-integral controller.

8. A control device for an energy storage converter, characterized in that: include: A first acquisition unit, used for acquiring a grid voltage and a grid current; A first calculation unit, configured to obtain active power and reactive power based on the grid voltage and the grid current; a second calculation unit, configured to obtain a first voltage based on the active power, the reactive power, a reference value of active power, and a reference value of reactive power; A first generating unit, configured to generate a reference voltage based on the first voltage; A third calculation unit is used to input the reference voltage into a first voltage loop based on the reference voltage, and obtain a reference current based on the reference voltage, the grid voltage and the feedback voltage of the energy storage converter; The first voltage is converted into a d-axis component and a q-axis component through coordinate transformation, and the d-axis component and the q-axis component of the first voltage are respectively subtracted from the d-axis component and the q-axis component of the grid voltage and the d-axis component and the q-axis component of the feedback voltage, and the d-axis component and the q-axis component of the reference current are obtained through a proportional-integral controller; A second generating unit, configured to obtain a three-phase signal based on the reference current and the current loop; a third generating unit, configured to generate a pulse width modulation signal based on the three-phase signal and the pulse width modulation generator, so as to control the energy storage converter through the pulse width modulation signal; Acquiring the feedback voltage includes: Based on the peak value of the reference current and the current setting value, an adaptive proportional parameter is obtained; Acquire an adaptive virtual impedance based on the adaptive proportional parameter, the current setting value and the energy storage converter side current; Based on the adaptive virtual impedance and the current on the energy storage converter side, obtaining the feedback voltage; Among them, the current setting value is determined according to the steady-state current peak value when the power grid is fault-free; the adaptive proportional parameter is the ratio of the peak value of the reference current to the current setting value, the adaptive virtual impedance is the product of the difference between the current on the energy storage converter side and the current setting value and the adaptive proportional parameter; the feedback voltage is the product of the adaptive virtual impedance and the current on the energy storage converter side.

9. A readable storage medium having a program or instruction stored thereon, characterized in that: When the program or the instruction is executed by a processor, the steps of the method for controlling the energy storage converter according to any one of claims 1 to 7 are implemented.

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