Autonomous synchronous networking control method for parallel operation of networking type energy storage converters

Abstract

The invention provides an autonomous synchronous network construction control method for parallel operation of a network construction type energy storage converter. The method comprises the following steps: collecting a grid-connected point voltage and a grid-side current of the energy storage converter; performing active power adjustment according to the grid-connected point voltage, the grid-side current and an active power instruction to obtain an output voltage phase; determining an adjustment deviation according to the grid-side current, the energy storage filter parameter, the first voltage instruction and the second voltage instruction; adjusting the adjustment deviation to obtain a virtual internal potential amplitude; and according to the virtual internal potential amplitude, the output voltage phase, the grid-connected point voltage and the grid-side current, voltage regulation, current regulation, coordinate system transformation and space vector modulation are carried out in sequence, and a driving signal required by control of the grid-forming type energy storage converter is generated. According to the method provided by the invention, the output voltage is adjusted by depending on the output capability of the energy storage converter, and the voltage adjusting capability is improved while the stable operation of the energy storage converter is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of converter control, and in particular to an autonomous synchronous networking control method for parallel operation of networking type energy storage converters. Background Art

[0002] With the access of a large number of renewable energy sources to the power grid, the resilience of the power grid has been reduced, posing great challenges to the frequency and voltage stability of the power grid. However, the access of energy storage systems to support the power grid can enhance the resilience of the power grid and safeguard the access of a large number of renewable energy sources.

[0003] The support capacity of the energy storage system for the power grid is mainly achieved through the control of the converter. The use of a grid-type control converter allows the energy storage system to simulate the operation of a synchronous machine, so that when the power grid is disturbed, it can actively respond to the disturbance suppression requirements like the synchronous machine in the traditional power system. While improving the energy storage's own adaptability to the power grid, it can further improve the grid support capacity of the energy storage. However, the output characteristics of the grid-type energy storage voltage source are prone to circulating current problems when multiple machines are running in parallel. To solve this problem, it is usually weakened by weakening its AC voltage regulation capability, such as using a voltage reactive power droop control method; it is also possible to introduce an energy regulation device in the station where multiple parallel energy storage converters are located, and to adjust the voltage by issuing reactive power instructions through the station energy regulation device.

[0004] However, when the voltage and reactive power droop control method is adopted, it is necessary to enhance the voltage and reactive power droop control strength of each energy storage inverter to enhance the voltage regulation capability of the grid-type multi-machine parallel system, which will increase the risk of unstable operation of the energy storage inverter; when the energy regulation device is introduced, on the one hand, the cost will be increased, and on the other hand, due to the difference in line impedance from the grid connection point of the parallel unit to the station outlet, the effect of the station voltage regulation may not be consistent with the voltage regulation target of the grid connection point of the energy storage unit in the station, which may cause the problem of excessive voltage regulation caused by excessive reactive power output of individual units; thirdly, this voltage regulation method has a certain dependence on the communication between the energy storage unit and the energy regulation device. Once there is a problem with the communication, the voltage regulation will fail. Summary of the invention

[0005] The present invention provides an autonomous synchronous networking control method for parallel operation of networking type energy storage converters, which relies on the output capacity of the energy storage converter itself to adjust the output voltage, thereby maintaining the stable operation of the energy storage converter and improving the voltage regulation capability.

[0006] According to a first aspect of an embodiment of the present invention, there is provided an autonomous synchronous networking control method for parallel operation of a networking type energy storage converter, the method comprising:

[0007] Collect the grid connection point voltage and grid-side current of the energy storage converter;

[0008] According to the grid connection point voltage, grid-side current and active power instruction, active power is adjusted to obtain the output voltage phase;

[0009] Determine the regulation deviation according to the grid-side current, the energy storage filter parameters, the grid-connected voltage target command and the pulse width modulation (PWM) voltage command of the previous control cycle;

[0010] The regulation deviation is adjusted to obtain the virtual internal potential amplitude;

[0011] According to the virtual internal potential amplitude, output voltage phase, grid-connected point voltage and grid-side current, voltage regulation, current regulation, coordinate system transformation and space vector modulation are performed in sequence to generate the driving signal required for controlling the grid-connected energy storage converter.

[0012] In a possible implementation, the regulation deviation is determined according to the grid-side current, the energy storage filter parameters, the grid-connected voltage target command and the PWM voltage command of the previous control cycle, including:

[0013] Calculate the product of the grid-side current and the filter inductance in the energy storage filter parameters to obtain the voltage on the energy storage filter;

[0014] Calculate the sum of the voltage vector on the energy storage filter and the grid-connected voltage target command to obtain an AC voltage command vector;

[0015] Calculate the modulus value of the AC voltage command vector to obtain the AC voltage amplitude command;

[0016] Calculate the modulus value of the PWM voltage command of the previous control cycle;

[0017] The difference between the modulus value of the AC voltage amplitude command and the PWM voltage command of the previous control cycle is calculated to obtain the regulation deviation.

[0018] In a possible implementation, the regulation deviation is determined by the following formula according to the grid-side current, the energy storage filter parameters, the grid-connected voltage target command and the PWM voltage command of the previous control cycle:

[0019] U refi =|U set +i dqi (jX fi +R fi )

[0020] ΔU i =U refi -U Invmi

[0021] Among them, U refi Indicates the AC voltage amplitude command, U setIndicates the grid-connected voltage target instruction, i dqi represents the vector of the grid-side current in the dq axis coordinate system, X fi and R fi They represent the inductive reactance and parasitic resistance of the filter inductor in the energy storage filter parameters, ΔU i Indicates the adjustment deviation,

[0022] U Invmi Indicates the modulus value of the PWM voltage command of the previous control cycle.

[0023] In a possible implementation, the regulation deviation is determined according to the grid-side current, the energy storage filter parameters, the grid-connected voltage target command and the PWM voltage command of the previous control cycle, including:

[0024] Calculate the product of the grid-side current and the energy storage filter parameters to obtain the voltage on the energy storage filter;

[0025] Calculate the difference between the PWM voltage command of the previous control cycle and the voltage on the energy storage filter to obtain the AC feedback voltage;

[0026] Calculate the modulus of the AC feedback voltage;

[0027] The difference between the grid-connected voltage target instruction and the modulus value of the AC feedback voltage is calculated to obtain the regulation deviation.

[0028] In a possible implementation, the regulation deviation is determined by the following formula according to the grid-side current, the energy storage filter parameters, the grid-connected voltage target command and the PWM voltage command of the previous control cycle:

[0029] u fdbdqi =u recdqi -i dqi (jX fi +R fi )

[0030] ΔU i =U seti -|u fdbdqi |

[0031] Among them, u fdbdqi represents the AC feedback voltage, u recdqi The vector representing the PWM voltage command of the previous control cycle in the dq axis coordinate system, i dqi represents the vector of the grid-side current in the dq axis coordinate system, X fi and R fi They represent the inductive reactance and parasitic resistance of the filter inductor in the energy storage filter parameters, ΔU i represents the regulation deviation, U set Indicates the grid-connected voltage target instruction.

[0032] In a possible implementation, active power regulation is performed according to the grid connection point voltage, grid-side current and active power instruction to obtain the output voltage phase, including:

[0033] Calculate the output active power based on the grid connection point voltage and grid-side current;

[0034] Calculate the power deviation between the active power command and the output active power;

[0035] The power deviation is adjusted by a power regulator to obtain the output voltage phase.

[0036] In a possible implementation, voltage regulation, current regulation, coordinate system transformation and space vector modulation are performed in sequence according to the virtual internal potential amplitude, output voltage phase, grid connection point voltage and grid-side current to generate the driving signal required for controlling the grid-connected energy storage converter, including:

[0037] Determine the AC voltage command according to the virtual internal potential amplitude and the output voltage phase;

[0038] According to the AC voltage command and the grid connection point voltage, a voltage regulator is used to adjust the grid connection point voltage to obtain a grid-side current command;

[0039] According to the grid-side current command, the grid-side current and the grid-connected point voltage, the current regulator is used to adjust the grid-side current to obtain the PWM voltage command of the current control cycle;

[0040] Performing an inverse Park's Transformation (Park's Transformation, Park Transformation) and an inverse Clark Transformation (Clark Transformation, Clark Transformation) on the PWM voltage command of the current control cycle in sequence to obtain a target PWM voltage command;

[0041] The target PWM voltage command is space vector modulated to generate the driving signal required for grid-type converter control.

[0042] In a possible implementation, voltage regulation and current regulation are performed in a two-phase synchronous rotating coordinate system, or in a two-phase stationary coordinate system.

[0043] In a possible implementation, after adjusting the adjustment deviation to obtain the virtual internal potential amplitude, the method further includes:

[0044] Determine the AC voltage command according to the virtual internal potential amplitude and the output voltage phase;

[0045] The AC voltage command is used as the PWM voltage command of the current control cycle, and the PWM voltage command of the current control cycle is subjected to inverse Park transformation, inverse Clark transformation and space vector modulation in sequence to generate the driving signal required for the grid-type converter control.

[0046] According to the second aspect of an embodiment of the present invention, a grid-type energy storage inverter is provided, and the grid-type energy storage inverter includes: a processor and a memory storing computer program instructions; when the processor executes the computer program instructions, the autonomous synchronous networking control method for parallel operation of the grid-type energy storage inverters in the first aspect of the present invention or any possible implementation method of the first aspect is implemented.

[0047] In the autonomous synchronous networking control method for parallel operation of grid-type energy storage inverters provided in the embodiment of the present invention, the grid-type energy storage inverter relies on its own output capacity to adjust the output voltage, does not need to rely on external energy regulation devices, and does not require communication and coordination between energy storage inverters. The implementation is simple, and when multiple energy storage inverters are connected in parallel, it can automatically achieve the coordination and unification of the voltage regulation targets of the grid-connected point of the energy storage inverter and the voltage regulation points of the parallel output points of multiple energy storage inverters, thereby improving the voltage regulation capability of the energy storage inverter while maintaining the stable operation of the energy storage inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0049] Figure 1 A schematic diagram of the structure of an autonomous synchronous networking control system for parallel operation of a networking type energy storage converter provided by an embodiment of the present invention;

[0050] Figure 2 A schematic flow chart of an autonomous synchronous networking control method for parallel operation of a networking type energy storage converter provided by an embodiment of the present invention;

[0051] Figure 3 A schematic diagram of the principle of an autonomous synchronous networking control method for parallel operation of a networking type energy storage converter provided by an embodiment of the present invention;

[0052] Figure 4 A schematic diagram of the principle of another autonomous synchronous networking control method for parallel operation of networking type energy storage converters provided by an embodiment of the present invention;

[0053] Figure 5A schematic diagram showing the characteristics of the voltage amplitude at the grid connection point of a single machine changing with load, using the method provided by an embodiment of the present invention;

[0054] Figure 6 Schematic diagram of the voltage amplitude at the grid connection point of a single machine changing with load in order to adopt a general grid-connected control scheme;

[0055] Figure 7 A schematic diagram showing the characteristics of the voltage amplitude at the grid connection point of a single machine changing with load after the voltage regulation capability is enhanced by adopting a general grid-connected control scheme;

[0056] Figure 8 A schematic diagram of the simulation results of the operating characteristics of the method provided by the embodiment of the present invention when two units are connected in parallel and the impedance of the lines between the two units and the station outlet are different;

[0057] Fig. 9 The schematic diagram of the simulation results of the operation characteristics when two units are connected in parallel and the impedance of the lines between the two units and the station outlet are different, in order to adopt the general network control scheme without the station energy regulator;

[0058] Fig.10 In order to adopt a general network control scheme, under the condition of introducing a station energy regulator, a schematic diagram of the operating characteristics simulation results is shown when two units are connected in parallel and the line impedance between the two units and the station outlet is different. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] Embodiment 1

[0061] The embodiment of the present invention provides an autonomous synchronous networking control system for parallel operation of networking type energy storage converters, the system structure is as follows: Figure 1 As shown, it includes an equivalent power grid, multiple parallel energy storage converters (including energy storage converter 1, energy storage converter 2...energy storage converter n), and energy storage modules. The energy storage modules are connected to the energy storage converters. The energy storage converters are connected to the power grid through the grid connection points and to the equivalent power grid through the grid connection points. Among them:

[0062] u s : Grid voltage;

[0063] Z g : Line impedance of the power grid;

[0064] u pcc: Voltage at the station exit where multiple energy storage converters are connected in parallel;

[0065] Z l1 : Line impedance between the energy storage converter 1 and the grid connection point;

[0066] u g1 : The grid connection point voltage of the energy storage converter 1;

[0067] i g1 : Grid-side current of energy storage converter 1;

[0068] Z f1 : Filter inductor impedance of energy storage converter 1;

[0069] C f1 : Filter capacitor of energy storage converter 1;

[0070] U set : Grid-connected voltage target instruction;

[0071] P set1 : Work power instruction of energy storage converter 1;

[0072] u dc : DC bus voltage;

[0073] u refG1 : PWM voltage command.

[0074] The above-mentioned multiple parallel energy storage converters all adopt the autonomous synchronous grid-building control method for parallel operation of grid-building type energy storage converters provided in the embodiment of the present invention. Taking energy storage converter 1 as an example, energy storage converter 1 collects its own grid connection point voltage u g1 and grid-side current i g1 , based on the grid voltage target instruction U set , and the grid connection point voltage u of the energy storage converter 1 g1 , grid-side current i g1 and active power command P set1 , execute the autonomous synchronous networking control method provided by the embodiment of the present invention, and obtain the PWM voltage instruction u refG1 , based on the PWM voltage command u refG1 and DC bus voltage u dc , through space vector modulation (SVM), an AC waveform is generated to drive the energy storage inverter 1 to adjust the output voltage of the energy storage inverter 1.

[0075] Among them, SVM is a PWM algorithm used to generate AC waveforms.

[0076] The following takes any one of the energy storage converters as the execution subject to explain the autonomous synchronous networking control method for parallel operation of the networking type energy storage converters provided by the embodiment of the present invention.

[0077] In each control cycle of the energy storage converter, the autonomous synchronous networking control method for parallel operation of the networking type energy storage converter provided by the embodiment of the present invention is executed once. Figure 1 As shown, the method may include the following steps:

[0078] S210, collecting the grid connection point voltage and grid-side current of the energy storage converter.

[0079] S220, performing active power regulation according to the grid connection point voltage, grid-side current and active power instruction to obtain an output voltage phase.

[0080] First, the power is calculated according to the grid-connected point voltage and the grid-side current to obtain the output active power; then, the difference between the active power command and the output active power is calculated, that is, the power deviation between the active power command and the output active power; finally, the power deviation is adjusted by the power regulator to obtain the output voltage phase.

[0081] S230, determining a regulation deviation according to the grid-side current, the energy storage filter parameters, the grid-connected voltage target instruction, and the PWM voltage instruction of the previous control cycle.

[0082] The energy storage filter has a filter inductor. The voltage output by the energy storage converter produces a voltage drop in the energy storage filter. The product of the grid-side current and the filter inductance of the energy storage filter parameters is calculated to obtain the voltage on the energy storage filter. Based on the voltage on the energy storage filter, the grid-connected voltage target instruction and the PWM voltage instruction of the previous control cycle, the regulation deviation is calculated.

[0083] The regulation deviation indicates the current voltage deviation, and the output voltage of the energy storage converter needs to be adjusted based on the regulation deviation to reduce the voltage deviation.

[0084] S240, adjusting the adjustment deviation to obtain a virtual internal potential amplitude.

[0085] An AC voltage amplitude regulator is used to adjust the regulation deviation to obtain the virtual internal potential amplitude.

[0086] S250, according to the virtual internal potential amplitude, output voltage phase, grid-connected point voltage and grid-side current, voltage regulation, current regulation, coordinate system transformation and space vector modulation are performed in sequence to generate the driving signal required for controlling the grid-connected energy storage converter.

[0087] like Figure 5As shown, by using the method provided by the embodiment of the present invention, during the change of the active power output by the energy storage converter, the grid voltage of the energy storage converter recovers to a range with a very small deviation near the rated value after a small change. Figure 6 When the general grid-type control scheme is adopted and the voltage regulation capability is enhanced, there is a significant deviation between the grid-connected point voltage and the rated value after the active power output of the energy storage converter increases. Although the voltage regulation capability of the enhanced general grid-type control scheme can reduce the degree of grid-connected point voltage drop caused by the output of active power by the energy storage converter, it will also increase the risk of instability of the energy storage converter operation, such as Figure 7 As shown. Through the above comparison, it can be seen that the method provided by the embodiment of the present invention can adjust the grid connection point voltage to the rated value by relying on the output capacity of the energy storage converter itself, with strong voltage control capability and high voltage regulation accuracy. Compared with the general grid control method, it can take into account the requirements of voltage control and stable operation.

[0088] like Figure 8 The figure shows the simulation results of two units connected in parallel and the impedance of the lines from the parallel units to the grid connection point of the station is different when the method provided by the embodiment of the present invention is used. It can be seen that the voltage of the grid connection point of the station and the grid connection points of the two units are slightly lower than the rated voltage during the load change process; the universal grid control method is used, and under the condition of no station energy regulator, such as Fig. 9 As shown in the figure, when the load increases, the voltage at the grid connection point of the single machine and the grid connection point of the station will be significantly lower than the rated voltage; when the general grid control method is adopted and the station energy regulator is introduced to adjust the grid connection point voltage of the station, as shown in the figure, Fig.10 As shown, although the difference between the grid connection point voltage of the station and the grid connection point voltage of the energy storage converter 1 is significantly reduced compared to the rated voltage, the grid connection voltage of the energy storage converter 2 is higher than the grid connection point voltage, and the grid connection point voltage regulation requirements of the single machine and the grid connection point voltage regulation requirements of the station conflict. Through the above comparison, it can be seen that the method provided by the embodiment of the present invention only relies on the regulation of the energy storage converter itself, and can automatically achieve coordination between units when multiple energy storage converters are connected in parallel.

[0089] In the autonomous synchronous networking control method for parallel operation of grid-type energy storage inverters provided in the embodiment of the present invention, the grid-type energy storage inverter relies on its own output capacity to adjust the output voltage, does not need to rely on an external energy regulation device, and does not require communication and coordination between energy storage inverters. The implementation is simple, and when multiple energy storage inverters are connected in parallel, the voltage regulation targets of a single energy storage inverter grid connection point and parallel output points of multiple energy storage inverters can be automatically coordinated and unified, thereby improving the voltage regulation capability of the energy storage inverter while maintaining the stable operation of the energy storage inverter.

[0090] Embodiment 2

[0091] In some embodiments, Figure 3 or Figure 4 As shown, including a power ring structure, S220, according to the grid point voltage, grid side current and active power instruction, active power regulation is performed to obtain the output voltage phase, which may include the following steps:

[0092] S221, calculate the output active power according to the grid connection point voltage and grid-side current.

[0093] i represents any one of the multiple energy storage converters connected in parallel.

[0094] like Figure 3 The grid voltage u gi Transform the coordinate system to obtain the grid connection point voltage u gi Vector u in the two-phase stationary coordinate system gαβi , grid-side current i gi Transform the coordinate system to obtain the grid-side current i gi The vector i in the two-phase stationary coordinate system αβi , based on u gαβi and i αβi Perform power calculation to obtain the output active power P gi

[0095] Or Figure 4 , for the grid voltage u gi Transform the coordinate system to obtain the grid connection point voltage u gi Vector u in the two-phase rotating coordinate system gdqi , grid-side current i gi Transform the coordinate system to obtain the grid-side current i gi The vector i in the two-phase rotating coordinate system dqi , based on u gdqi and i dqi Perform power calculation to obtain the output active power P gi .

[0096] S222, calculating the power deviation between the active power command and the output active power.

[0097] S223, using a power regulator to adjust the power deviation to obtain an output voltage phase.

[0098] The above steps S222-S223 can be expressed by the following formula:

[0099]

[0100] In the formula, θ i is the output voltage phase, P seti is the output active power command, P gi is the output active power, J and D pare virtual moment of inertia and damping coefficient respectively, ω0 is the rated frequency of the power grid: where the damping coefficient D p Proportional to the rated power of the energy storage converter, that is:

[0101] D p =k Dp P ni

[0102] Where P ni is the rated power of energy storage converter i, k Dp is the proportional coefficient, and the proportional coefficients of different energy storage converters are equal.

[0103] The method provided in the embodiment of the present invention obtains the output voltage phase of the energy storage converter, which is used to adjust the output voltage of the energy storage converter.

[0104] Embodiment 3

[0105] In some embodiments, the principle of the autonomous synchronous networking control method for parallel operation of the networking type energy storage converter provided in the embodiment of the present invention is as follows: Figure 3 As shown, including a power loop structure, S230: determining the regulation deviation according to the grid-side current, the energy storage filter parameters, the grid-connected voltage target instruction and the PWM voltage instruction of the previous control cycle, may include the following steps:

[0106] S231, calculating the product of the grid-side current and the filter inductance of the energy storage filter to obtain the voltage on the energy storage filter.

[0107] S232, calculating the sum of the voltage vector on the energy storage filter and the grid-connected voltage target command to obtain an AC voltage command vector.

[0108] S233, calculating the modulus of the AC voltage command vector to obtain an AC power amplitude command;

[0109] Combination Figure 3 The power ring structure of the above steps S231-S233 can be expressed by the following formula:

[0110] U refi =|U set +i dqi (jX fi +R fi )

[0111] Among them, U refi Indicates the AC voltage amplitude command, U set represents the grid-connected voltage target instruction, i dqi represents the vector of the grid-side current in the dq axis coordinate system, X fi and R fiThey respectively represent the inductive reactance and parasitic resistance of the filter inductor in the energy storage filter parameters.

[0112] S234, calculating the modulus value of the PWM voltage command of the previous control cycle.

[0113] U Invmi =u recdqi |

[0114] U Invmi Indicates the modulus value of the PWM voltage command of the previous control cycle; u recdqi The vector representing the PWM voltage command of the previous control cycle in the dq-axis coordinate system.

[0115] S235, calculating the difference between the modulus value of the AC voltage amplitude command and the PWM voltage command of the previous control cycle to obtain a regulation deviation.

[0116] Combination Figure 3 , the above steps S234-S235 can be expressed by the following formula:

[0117] ΔU i =U refi -U Invmi

[0118] Among them, ΔU i Indicates the adjustment deviation.

[0119] The method provided in the embodiment of the present invention takes the voltage on the energy storage filter into consideration when determining the regulation deviation, so that the obtained regulation deviation is more accurate.

[0120] Embodiment 4

[0121] In some embodiments, when the first voltage instruction is the PWM voltage instruction of the previous control cycle, and the second voltage instruction is the grid-connected voltage target instruction, the principle of the autonomous synchronous grid-connected control method for parallel operation of grid-connected energy storage converters provided in the embodiment of the present invention is as follows: Figure 4 As shown, S230: determining the adjustment deviation according to the grid-side current, the filter inductance of the energy storage filter, the first voltage instruction and the second voltage instruction may include the following steps:

[0122] S236, calculating the product of the grid-side current and the energy storage filter parameter to obtain the voltage on the energy storage filter.

[0123] S237, calculating the difference between the PWM voltage command of the previous control cycle and the voltage on the energy storage filter to obtain an AC feedback voltage;

[0124] S238, calculating the modulus of the AC feedback voltage.

[0125] S239, calculating the difference between the grid-connected voltage target instruction and the modulus value of the AC feedback voltage to obtain a regulation deviation.

[0126] Combination Figure 4 The power ring structure of the above steps can be expressed as follows:

[0127] u fdbdqi =u recdqi -i dqi (jX fi +R fi )

[0128] ΔU i =U seti -u fdbdqi |

[0129] Among them, u fdbdqi represents the AC feedback voltage, u recdqi The vector representing the PWM voltage command of the previous control cycle in the dq axis coordinate system, i dqi represents the vector of the grid-side current in the dq axis coordinate system, X fi and R fi They represent the inductive reactance and parasitic resistance of the filter inductor in the energy storage filter parameters, ΔU i represents the regulation deviation, U set Indicates the grid-connected voltage target instruction.

[0130] The method provided in the embodiment of the present invention takes the voltage on the energy storage filter into consideration when determining the regulation deviation, so that the obtained regulation deviation is more accurate.

[0131] Embodiment 5

[0132] In some embodiments, Figure 3 or Figure 4 The power ring structure shown, S240: adjusting the adjustment deviation to obtain the virtual internal potential amplitude, may include the following steps:

[0133] The AC voltage amplitude regulator is used to adjust the regulation deviation to obtain the virtual internal potential amplitude, which can be expressed by the following formula:

[0134] E refi =G Ext ΔU i

[0135] Among them, E refi represents the virtual internal potential amplitude, G Ext The AC voltage amplitude regulator adopts PI regulator or quasi-PI regulator, ΔU i To adjust the deviation.

[0136] The method provided in the embodiment of the present invention determines the adjusted virtual internal potential amplitude, and uses the adjusted virtual internal potential amplitude to control the voltage output by the energy storage converter, so that the voltage at the grid-connected point of the energy storage converter is closer to the grid-connected point voltage regulation target, thereby improving the control accuracy.

[0137] Embodiment 6

[0138] In some embodiments, Figure 3 or Figure 4 The voltage loop and current loop structure shown in S250: according to the virtual internal potential amplitude, output voltage phase, grid-connected point voltage and grid-side current, voltage regulation, current regulation, coordinate system transformation and space vector modulation are performed in sequence to generate the driving signal required for controlling the grid-type energy storage converter, including:

[0139] S251, determining an AC voltage command according to the virtual internal potential amplitude and the output voltage phase.

[0140] According to the virtual internal potential amplitude E refi and output voltage phase θ i , determine the AC voltage command E dq_refi , which can be expressed as follows:

[0141] E dq_refi =E refi +j0

[0142] Where j is the imaginary unit of the complex number.

[0143] S252, according to the AC voltage instruction and the grid connection point voltage, use a voltage regulator to adjust the grid connection point voltage to obtain a grid-side current instruction.

[0144] The AC voltage command E dq_refi Subtract the grid connection point voltage u gdqi , get the voltage deviation, use the voltage regulator to adjust the voltage deviation, and get the grid-side current instruction i dq_refi , which can be expressed as follows:

[0145] i dq_refi =G VAC (E dq_refi -u gdqi )

[0146] In the formula, G VAC is the transfer function of the voltage regulator. The voltage regulator adopts PI regulator or virtual admittance regulator. The transfer function in the frequency domain can be expressed as:

[0147]

[0148]

[0149] S253, according to the grid-side current instruction, the grid-side current and the grid-connection point voltage, use a current regulator to regulate the grid-side current to obtain a PWM voltage instruction of a current control cycle.

[0150] The grid-side current command i dq_refi Subtract the grid-side current i dqi , get the current deviation, use the current regulator to adjust the current deviation, and then add it to the grid voltage u gdqi Add together to get the PWM voltage command u of the current control cycle recdqi , which can be expressed as follows:

[0151] u recdqi =G CR (i dq_refi -i dqi )+u gdqi

[0152] Among them, G CR is the transfer function of the current regulator, which is generally a PI regulator.

[0153] The voltage regulation of S252 and the current regulation of S253 may be performed in a two-phase synchronous rotating coordinate system or in a two-phase stationary coordinate system.

[0154] S254, performing inverse Park transformation and inverse Clark transformation on the PWM voltage command of the current control cycle in sequence to obtain a target PWM voltage command.

[0155] The PWM voltage command u for the current control cycle recdqi Perform inverse Park transform to get u recαβi , for u recαβi Perform inverse Clark transform to obtain the target PWM voltage command u refGi , which can be expressed as follows:

[0156]

[0157] u refGi =C 2s / 3s u recαβi

[0158] S255, performing space vector modulation on the target PWM voltage command to generate a driving signal required for controlling the energy storage converter.

[0159] The method provided by the embodiment of the present invention uses the adjusted virtual internal potential amplitude to control the voltage output by the energy storage converter, so that the voltage at the grid-connected point of the energy storage converter is closer to the grid-connected point voltage regulation target, thereby improving the control accuracy.

[0160] Embodiment 7

[0161] In some embodiments, Figure 2 As shown, the method may further include the following steps:

[0162] S260, determining an AC voltage command according to the virtual internal potential amplitude and the output voltage phase.

[0163] According to the virtual internal potential amplitude E ref and the output voltage phase θ to determine the AC voltage command E dq_ref ,

[0164] It can be expressed as follows:

[0165] E dq_refi =E refi +j0

[0166] S270, taking the AC voltage command as the PWM voltage command of the current control cycle, performing inverse Park transformation, inverse Clark transformation and space vector modulation on the PWM voltage command of the current control cycle in sequence, and generating a driving signal required for controlling the grid-type converter.

[0167] The AC voltage command is used as the PWM voltage command u of the current control cycle recdqi , the PWM voltage command u for the current control cycle recdqi Perform inverse Park transform to get u recαβi , for u recαβi Perform inverse Clark transform to obtain the target PWM voltage command u refGi , which can be expressed as follows:

[0168]

[0169] u refGi =C 2s / 3s u recαβi

[0170] The target PWM voltage command is space vector modulated to generate the drive signal required for energy storage converter control.

[0171] The method provided in the embodiment of the present invention uses the adjusted virtual internal potential amplitude to control the voltage output by the energy storage inverter, so that the voltage at the grid-connected point of the energy storage inverter is closer to the grid-connected point voltage regulation target, thereby improving the control accuracy and eliminating the need for voltage regulation and current regulation processes, thereby achieving better dynamic response performance.

[0172] Embodiment 8

[0173] Another embodiment of the present invention further proposes a grid-type energy storage inverter, including a processor and a memory storing computer program instructions. The processor executes the program stored in the memory and calls other devices, which can be used to implement the various steps of the autonomous synchronous networking control method for parallel operation of any grid-type energy storage inverter provided in the above embodiments of the present invention.

[0174] For the above-mentioned method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0175] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0176] The steps in the methods of the embodiments of the present invention may be adjusted in order, combined, or deleted according to actual needs, and the technical features recorded in the embodiments may be replaced or combined.

[0177] In the several embodiments provided by the present invention, it should be understood that the disclosed terminal and method can be implemented in other ways. For example, the terminal embodiments described above are only schematic, for example, the division of modules or submodules is only a logical function division, and there may be other division methods in actual implementation, for example, multiple submodules or modules can be combined or integrated into another module, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or modules, which can be electrical, mechanical or other forms.

[0178] The modules or submodules described as separate components may or may not be physically separated, and the components of the modules or submodules may or may not be physical modules or submodules, that is, they may be located in one place, or they may be distributed on multiple network modules or submodules. Some or all of the modules or submodules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0179] In addition, each functional module or submodule in each embodiment of the present invention may be integrated into one processing module, or each module or submodule may exist physically separately, or two or more modules or submodules may be integrated into one module. The above-mentioned integrated modules or submodules may be implemented in the form of hardware or in the form of software functional modules or submodules.

[0180] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0181] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly by hardware, software units executed by a processor, or a combination of the two. The software units may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0182] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0183] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An autonomous synchronous networking control method for parallel operation of networking type energy storage converters, characterized in that: The method comprises: Collect the grid connection point voltage and grid-side current of the energy storage converter; According to the grid connection point voltage, the grid-side current and the active power instruction, active power regulation is performed to obtain an output voltage phase; Determining a regulation deviation according to the grid-side current, energy storage filter parameters, grid-connected voltage target instruction and a pulse width modulation (PWM) voltage instruction of a previous control cycle; Adjusting the adjustment deviation to obtain a virtual internal potential amplitude; According to the virtual internal potential amplitude, the output voltage phase, the grid-connected point voltage and the grid-side current, voltage regulation, current regulation, coordinate system transformation and space vector modulation are performed in sequence to generate the driving signal required for controlling the grid-connected energy storage converter.

2. The method according to claim 1, characterized in that Determining the regulation deviation according to the grid-side current, the energy storage filter parameter, the grid-connected voltage target instruction and the PWM voltage instruction of the previous control cycle includes: Calculating the product of the grid-side current and the filter inductance in the energy storage filter parameters to obtain a voltage vector on the energy storage filter; Calculating the sum of the voltage vector on the energy storage filter and the grid-connected voltage target command to obtain an AC voltage command vector; Calculate the modulus value of the AC voltage command vector to obtain the AC voltage amplitude command; Calculating the modulus value of the PWM voltage instruction of the previous control cycle; The difference between the modulus value of the AC voltage amplitude command and the PWM voltage command of the previous control cycle is calculated to obtain the adjustment deviation.

3. The method according to claim 2, characterized in that According to the grid-side current, energy storage filter parameters, grid-connected voltage target command and the PWM voltage command of the previous control cycle, the regulation deviation is determined by the following formula: U refi =|U set +i dqi (jX fi +R fi ) ΔU i =U refi -U Invmi Among them, U refi Indicates the AC voltage amplitude command, U set represents the grid-connected voltage target instruction, i dqi represents the vector of the grid-side current in the dq axis coordinate system, X f i and R f i They represent the inductive reactance and parasitic resistance of the filter inductor in the energy storage filter parameters, ΔU i represents the regulation deviation, U Invmi Indicates the modulus value of the PWM voltage command of the previous control cycle.

4. The method according to claim 1, characterized in that Determining the regulation deviation according to the grid-side current, the energy storage filter parameter, the grid-connected voltage target instruction and the PWM voltage instruction of the previous control cycle includes: Calculating the product of the grid-side current and the filter inductance in the energy storage filter parameters to obtain the voltage on the energy storage filter; Calculating the difference between the PWM voltage command of the previous control cycle and the voltage on the energy storage filter to obtain an AC feedback voltage; Calculating the modulus of the AC feedback voltage; The difference between the grid-connected voltage target instruction and the modulus of the AC feedback voltage is calculated to obtain the regulation deviation.

5. The method according to claim 4, characterized in that According to the grid-side current, energy storage filter parameters, grid-connected voltage target command and the PWM voltage command of the previous control cycle, the regulation deviation is determined by the following formula: u fdbdqi =u recdqi -i dqi (jX fi +R fi ) ΔU i =U seti -u fdbdqi | Among them, u fdbdqi represents the AC feedback voltage, u recdqi The vector representing the PWM voltage command of the previous control cycle in the dq axis coordinate system, i dqi represents the vector of the grid-side current in the dq axis coordinate system, X fi and R fi They represent the inductive reactance and parasitic resistance of the filter inductor in the energy storage filter parameters, ΔU i represents the regulation deviation, U set Indicates the grid-connected voltage target instruction.

6. The method according to claim 1, characterized in that Active power regulation is performed according to the grid connection point voltage, the grid-side current and the active power instruction to obtain an output voltage phase, including: Calculating the output active power according to the grid connection point voltage and grid-side current; Calculating a power deviation between an active power command and the output active power; The power deviation is adjusted by a power regulator to obtain an output voltage phase.

7. The method according to any one of claims 1 to 6, characterized in that: According to the virtual internal potential amplitude, the output voltage phase, the grid connection point voltage and the grid-side current, voltage regulation, current regulation, coordinate system transformation and space vector modulation are performed in sequence to generate a driving signal required for controlling the grid-connected energy storage converter, including: Determining an AC voltage command according to the virtual internal potential amplitude and the output voltage phase; According to the AC voltage command and the grid connection point voltage, a voltage regulator is used to adjust the grid connection point voltage to obtain a grid-side current command; According to the grid-side current instruction, the grid-side current and the grid-connection point voltage, a current regulator is used to adjust the grid-side current to obtain a PWM voltage instruction of a current control cycle; Performing inverse Park transformation and inverse Clark transformation on the PWM voltage command of the current control cycle in sequence to obtain a target PWM voltage command; The target PWM voltage command is subjected to space vector modulation to generate a driving signal required for controlling the grid-type converter.

8. The method according to claim 7, characterized in that The voltage regulation and the current regulation are performed in a two-phase synchronous rotating coordinate system, or in a two-phase stationary coordinate system.

9. The method according to any one of claims 1 to 6, characterized in that: After adjusting the adjustment deviation to obtain the virtual internal potential amplitude, the method further includes: Determining an AC voltage command according to the virtual internal potential amplitude and the output voltage phase; The AC voltage command is used as the PWM voltage command of the current control cycle, and the PWM voltage command of the current control cycle is subjected to inverse Park transformation, inverse Clark transformation and space vector modulation in sequence to generate the driving signal required for controlling the grid-type converter.

10. A grid-type energy storage converter, characterized in that: The grid-type energy storage inverter comprises: a processor and a memory storing computer program instructions; when the processor executes the computer program instructions, it implements the autonomous synchronous grid-forming control method for parallel operation of grid-type energy storage inverters as described in any one of claims 1-9.

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