Wave-by-wave current limiting protection system and wave-by-wave current limiting protection method

Abstract

The application discloses a kind of energy storage converter three-level ANPC topological system, wave-by-wave current limiting protection method, can solve the technical problem that the implementation form of wave-by-wave current limiting protection is single.Wave-by-wave current limiting protection system can be applied to wave-by-wave current limiting protection under inverter mode, rectification mode, including: energy storage converter digital signal processor, programmable logic controller, three-level ANPC topological power module;Energy storage converter digital signal processor is connected with programmable logic controller, programmable logic controller is connected with three-level ANPC topological power module;Energy storage converter digital signal processor is used to output three-phase wave-by-wave current limiting protection signal to programmable logic controller, and three-phase bridge arm voltage, three-phase bridge arm current direction, programmable logic controller is used to control three-level ANPC topological power module to execute wave-by-wave current limiting protection logic according to three-phase wave-by-wave current limiting protection signal and three-phase bridge arm voltage, three-phase bridge arm current direction.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a three-level ANPC topology system for energy storage converters and a wave-by-wave current limiting protection method. Background Technology

[0002] With the rapid development of the electrochemical energy storage industry, the safety and reliability of energy storage systems are receiving increasing attention. As the core power device in an electrochemical energy storage system, the energy storage converter is prone to various faults. Overcurrent is a frequently occurring fault; if not protected in time, it can lead to overload damage to the power module of the energy storage converter, thus threatening the safe operation of the entire energy storage system. Wave-by-wave current limiting protection is the last line of defense against overcurrent faults. By briefly blocking the power module drive signal, it limits the current, thereby achieving uninterrupted protection against transient overcurrent faults.

[0003] Currently, the main wave-by-wave current limiting protection methods in the technical field, in terms of implementation, are either built using hardware circuitry or implemented through a controller chip. Regarding the wave blocking logic, for a three-level ANPC topology, the wave-by-wave current limiting function limits the current by blocking the switch on the outer side of the faulty phase bridge arm. Current wave-by-wave current limiting protection methods for three-level ANPC topologies are mainly applied to photovoltaic inverter technology, therefore only considering wave-by-wave current limiting protection in inverter mode and unable to achieve wave-by-wave current limiting protection in rectifier mode for energy storage converter applications. Summary of the Invention

[0004] In view of this, the present invention provides a wave-by-wave current limiting protection system and a wave-by-wave current limiting protection method, which can solve the technical problem that the existing wave-by-wave current limiting protection methods can only consider wave-by-wave current limiting protection in inverter mode and cannot realize wave-by-wave current limiting protection in rectifier mode in energy storage converter application scenarios, thus resulting in a single implementation form of wave-by-wave current limiting protection and poor wave-by-wave current limiting protection effect.

[0005] To achieve the above objectives, this application provides a wave-by-wave current limiting protection system, which is applied to wave-by-wave current limiting protection in inverter mode and rectifier mode, and includes: a digital signal processor for energy storage converter, a programmable logic controller, and a three-level ANPC topology power module;

[0006] The energy storage converter digital signal processor is connected to the programmable logic controller, and the programmable logic controller is connected to the three-level ANPC topology power module;

[0007] The energy storage converter digital signal processor is used to output three-phase wave-by-wave current limiting protection signals, as well as three-phase bridge arm voltages and three-phase bridge arm current directions to the programmable logic controller. The programmable logic controller is used to control the three-level ANPC topology power module to execute wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signals, the three-phase bridge arm voltages, and the three-phase bridge arm current directions.

[0008] Optionally, the energy storage converter digital signal processor includes a first wave-by-wave current limiting module, which includes a calculation unit and a comparator configured for each phase of the three-phase power supply. The comparator includes a first input terminal, a second input terminal, and an output terminal.

[0009] The calculation unit is used to transform the instantaneous given value of the current of each phase into a real-time sinusoidal current value through coordinate transformation, calculate the product of the real-time sinusoidal current value and the wave-by-wave current limiting protection ratio K, and determine the product as the dynamic current protection value of each phase.

[0010] The calculation unit is connected to the first input terminal and is used to input the real-time calculated dynamic current protection value of each phase into the comparator module through the first input terminal. The external current sampling circuit is connected to the second input terminal and is used to input the instantaneous value of the external current of each phase into the comparator module through the second input terminal.

[0011] The comparator module is used to determine the three-phase wave-by-wave current limiting protection signal by comparing the dynamic current protection value of each phase with the instantaneous current value of each phase, and outputs the three-phase wave-by-wave current limiting protection signal using the output terminal.

[0012] Optionally, the programmable logic controller includes a communication module, a corresponding second wave-by-wave current limiting module, and a PWM wave generation module;

[0013] The communication module is used to create a communication connection between the programmable logic controller and the digital signal processor of the energy storage converter, so as to receive the three-phase bridge arm voltage and the three-phase bridge arm current direction sent by the digital signal processor of the energy storage converter based on the communication connection.

[0014] One end of the second wave-by-wave current limiting module is connected to the first wave-by-wave current limiting module and the communication module, and the other end of the second wave-by-wave current limiting module is connected to the PWM wave generator module. It is used to receive the three-phase wave-by-wave current limiting protection signal output by the first wave-by-wave current limiting module and the three-phase bridge arm voltage and the direction of the three-phase bridge arm current sent by the communication module. Based on the three-phase wave-by-wave current limiting protection signal and the three-phase bridge arm voltage and the direction of the three-phase bridge arm current, it determines the wave-by-wave current limiting protection logic, and controls the PWM wave generator module to output a control signal to the three-level ANPC topology power module according to the wave-by-wave current limiting protection logic. The control signal is used to realize wave-by-wave current limiting protection in inverter mode or rectifier mode.

[0015] Optionally, the three-level ANPC topology power module includes a three-level ANPC topology circuit corresponding to each phase arm, used to control the switching transistors in the three-level ANPC topology circuit to turn on or off based on the control signal, thereby achieving wave-by-wave current limiting protection in inverter mode or rectifier mode.

[0016] According to another aspect of this application, a wave-by-wave current limiting protection method is provided, which is applied to the above-mentioned wave-by-wave current limiting protection system, comprising:

[0017] The energy storage converter digital signal processor outputs three-phase wave-by-wave current limiting protection signals, as well as three-phase bridge arm voltage and three-phase bridge arm current direction to the programmable logic controller.

[0018] The second wave-by-wave current limiting module in the programmable logic controller determines the wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signal, the three-phase bridge arm voltage, and the direction of the three-phase bridge arm current.

[0019] The PWM waveform generation module in the programmable logic controller sends a control signal to the three-level ANPC topology power module according to the waveform current limiting protection logic, so as to realize waveform current limiting protection in inverter mode or rectifier mode according to the control signal.

[0020] Optionally, before the energy storage converter digital signal processor outputs the three-phase wave-by-wave current limiting protection signal, as well as the three-phase bridge arm voltage and the three-phase bridge arm current direction to the programmable logic controller, the following method is further included:

[0021] The instantaneous given value of each phase current is transformed into a real-time sinusoidal current value through coordinate transformation. The product of the real-time sinusoidal current value and the wave-by-wave current limiting protection ratio K is calculated, and the product is determined as the dynamic current protection value of each phase.

[0022] The instantaneous value of the current in each phase is obtained based on the external current sampling circuit;

[0023] By comparing the dynamic current protection value of each phase with the instantaneous current value of each phase, the three-phase wave-by-wave current limiting protection signal is determined based on the comparison result.

[0024] Optionally, the step of comparing the dynamic current protection value of each phase with the instantaneous current value of each phase input from the external current sampling circuit, and determining the three-phase wave-by-wave current limiting protection signal based on the comparison result, includes:

[0025] If it is determined that the instantaneous value of the current in each phase is greater than the dynamic current protection value in each phase, then the three-phase wave-by-wave current limiting protection signal is determined to be a high-level protection signal.

[0026] If the instantaneous value of the current in each phase is determined to be less than or equal to the dynamic current protection value in each phase, then the three-phase wave-by-wave current limiting protection signal is determined to be a low-level protection signal.

[0027] Optionally, the wave-by-wave current limiting protection logic includes a first wave-by-wave current limiting protection logic in inverter mode and a second wave-by-wave current limiting protection logic in rectifier mode;

[0028] The second wave-by-wave current limiting module in the programmable logic controller determines the wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signal, the three-phase bridge arm voltage, and the direction of the three-phase bridge arm current, including:

[0029] If the three-phase wave-by-wave current limiting protection signal is detected as a high-level protection signal, then the wave-by-wave current limiting protection logic is determined based on the three-phase bridge arm voltage and the direction of the three-phase bridge arm current.

[0030] The wave-by-wave current limiting protection logic determined based on the three-phase bridge arm voltage and the three-phase bridge arm current direction includes:

[0031] If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current is in the positive direction, or if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current is in the negative direction, then the wave-by-wave current limiting protection logic is determined to be the first wave-by-wave current limiting protection logic under the inverter mode.

[0032] If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current is in the negative direction, or if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current is in the positive direction, then the wave-by-wave current limiting protection logic is determined to be the second wave-by-wave current limiting protection logic under the rectification mode.

[0033] Optionally, if the wave-by-wave current limiting protection logic is the first wave-by-wave current limiting protection logic in inverter mode, the step of implementing wave-by-wave current limiting protection in inverter mode according to the control signal includes:

[0034] If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current direction is positive, then according to the control signal, the first switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, while the second switch remains on, forcing the current to freewheel from the midpoint zero level until the wave-by-wave current limiting protection signal disappears, at which point the normal turn-on and turn-off logic is restored; or,

[0035] If it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current is in the negative direction, then according to the control signal, the fourth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, and the third switch is kept on, forcing the current to continue from the zero level at the midpoint until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored.

[0036] Optionally, if the wave-by-wave current limiting protection logic is the second wave-by-wave current limiting protection logic in rectification mode, the step of implementing wave-by-wave current limiting protection in rectification mode according to the control signal includes:

[0037] If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current is in the negative direction, then according to the control signal, the third or fifth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, cutting off the zero-level freewheeling path and forcing the current to flow to the positive bus until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored; or,

[0038] If it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current direction is positive, then according to the control signal, the second or sixth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, the zero-level freewheeling path is cut off, and the current is forced to flow to the positive bus until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored.

[0039] This invention provides a wave-by-wave current limiting protection system and a wave-by-wave current limiting protection method. The wave-by-wave current limiting protection system can be applied to wave-by-wave current limiting protection in inverter mode and rectifier mode. It includes an energy storage converter digital signal processor, a programmable logic controller (PLC), and a three-level ANPC topology power module. The energy storage converter digital signal processor is connected to the PLC, and the PLC is connected to the three-level ANPC topology power module. The energy storage converter digital signal processor is used to output three-phase wave-by-wave current limiting protection signals, as well as three-phase bridge arm voltages and three-phase bridge arm current directions, to the PLC. The PLC is used to control the three-level ANPC topology power module to execute wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signals, three-phase bridge arm voltages, and three-phase bridge arm current directions. The technical solution in this application enables the energy storage converter's digital signal processor to calculate in real time the product of the instantaneous setpoint of the three-phase current and the wave-by-wave current limiting protection ratio K, and writes this product into the comparator module of each phase in the energy storage converter's digital signal processor for dynamic wave-by-wave current limiting protection. Even when the real-time value of the three-phase current is small, it can achieve fast and effective wave-by-wave current limiting protection, promptly suppressing overcurrent spikes and preventing current waveform distortion. Furthermore, this application can achieve intelligent decision-making and control of wave-by-wave current limiting protection in inverter or rectifier modes by analyzing the three-phase wave-by-wave current limiting protection signal and judging the consistency of the three-phase bridge arm voltage and current direction. This enriches the implementation forms of wave-by-wave current limiting protection, enabling the wave-by-wave current limiting protection system to support non-stop protection against transient overcurrent faults in energy storage systems under various application scenarios, thereby improving the wave-by-wave current limiting protection effect and ensuring the safety of the energy storage system.

[0040] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0041] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0042] Figure 1 This diagram illustrates a system structure schematic of a wave-by-wave current limiting protection system provided by an embodiment of the present invention.

[0043] Figure 2 This diagram illustrates the structure of a first wave-by-wave current limiting module provided in an embodiment of the present invention.

[0044] Figure 3 A schematic diagram of a comparator provided in an embodiment of the present invention is shown;

[0045] Figure 4 The diagram shows a circuit connection schematic of a three-level ANPC topology circuit provided in an embodiment of the present invention;

[0046] Figure 5 A schematic flowchart of a wave-by-wave current limiting protection method provided by an embodiment of the present invention is shown;

[0047] Figure 6 The diagram illustrates a flow chart of wave-by-wave current limiting protection logic determination provided by an embodiment of the present invention.

[0048] In the picture:

[0049] 1-Digital signal processor for energy storage converter; 11-First wave-by-wave current limiting module; 111-Computing unit; 112-Comparator;

[0050] 2-Programmable Logic Controller, 21-Communication Module, 22-Second Wave-by-Wave Current Limiting Module, 23-PWM Wave Generation Module;

[0051] 3-Three-level ANPC topology power module, 31-Three-level ANPC topology circuit. Detailed Implementation

[0052] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0054] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0056] The following is combined Figures 1 to 4 A wave-by-wave current limiting protection system according to some embodiments of the present invention is described.

[0057] Compared to traditional wave-by-wave current limiting protection methods that only consider inverter mode, the wave-by-wave current limiting protection system in this application can achieve dynamic wave-by-wave current limiting protection in both inverter and rectifier modes. Specifically, as shown... Figure 1 As shown, the wave-by-wave current limiting protection system can be composed of three parts: a digital signal processor 1 for an energy storage converter, a programmable logic controller 2, and a three-level ANPC topology power module 3. The digital signal processor 1 for the energy storage converter is connected to the programmable logic controller 2, and the programmable logic controller 2 is connected to the three-level ANPC topology power module 3. The digital signal processor 1 for the energy storage converter is used to output three-phase wave-by-wave current limiting protection signals, as well as three-phase bridge arm voltages and three-phase bridge arm current directions to the programmable logic controller 2. The programmable logic controller 2 is used to control the three-level ANPC topology power module 3 to execute wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signals, three-phase bridge arm voltages, and three-phase bridge arm current directions.

[0058] For example, the digital signal processor 1 of the energy storage converter can be a digital signal processor (DSP), and the programmable logic controller 2 can be a field-programmable gate array (FPGA). The digital signal processor 1 and the programmable logic controller 2 together constitute the control module of the energy storage converter, and the wave-by-wave current limiting protection system is implemented based on this control module structure. In specific application scenarios, the digital signal processor 1 can be used to calculate in real time the product of the instantaneous setpoint of the three-phase current and the wave-by-wave current limiting protection ratio K, and write it into the comparator of each phase for dynamic wave-by-wave current limiting protection. Even when the real-time value of the three-phase current is small, it can achieve fast and effective wave-by-wave current limiting protection, promptly suppressing overcurrent spikes and preventing current waveform distortion. The wave-by-wave current limiting protection module of the programmable logic controller 2 can execute the corresponding wave-by-wave current limiting protection logic according to the three-phase wave-by-wave current limiting protection signal sent by the digital signal processor 1 of the energy storage converter, as well as the direction of the corresponding bridge arm voltage and current, to realize the AC current envelope wave-by-wave current limiting protection of the energy storage converter across the entire power factor range.

[0059] In specific application scenarios, such as Figures 1 to 3As shown, the digital signal processor 1 of the energy storage converter may include a first wave-by-wave current limiting module 11. The first wave-by-wave current limiting module 11 includes a calculation unit 111 and a comparator 112 configured for each phase of the three-phase power supply. The comparator 112 includes a first input terminal, a second input terminal, and an output terminal. The calculation unit 111 is used to convert the instantaneous given value of the current of each phase into a real-time sinusoidal current value through coordinate transformation, calculate the product of the real-time sinusoidal current value and the wave-by-wave current limiting protection ratio K, and determine the dynamic current protection value of each phase through the product. The calculation unit 111 is connected to the first input terminal and is used to input the real-time calculated dynamic current protection value of each phase into the comparator module 112 through the first input terminal. The external current sampling circuit is connected to the second input terminal and is used to input the external instantaneous value of the current of each phase into the comparator module 112 through the second input terminal. The comparator module 112 is used to determine the three-phase wave-by-wave current limiting protection signal by comparing the dynamic current protection value of each phase and the instantaneous value of the current of each phase, and output the three-phase wave-by-wave current limiting protection signal through the output terminal. Specifically, the first wave-by-wave current limiting module 11 may include three comparators 112, which are used to generate wave-by-wave current limiting signals for phases A, B, and C, respectively. The dynamic current protection value for each phase input to the first input of the comparator 112 is converted into a real-time sinusoidal current value by the calculation unit 111 based on the given effective value of the AC current through coordinate transformation, and then multiplied by the wave-by-wave current limiting protection ratio K (a typical protection ratio K = 1.3). Each calculation unit 111 calculates and assigns the value once per sampling period, dynamically adjusting in real time. The second input of the comparator 112 is directly connected to an external analog signal of the instantaneous value of the AC current, used to obtain the instantaneous value of the current for each phase. When the instantaneous value of the current for each phase is greater than the dynamic current protection value for each phase, the three-phase wave-by-wave current limiting protection signal output by the comparator 112 is a high-level protection signal; otherwise, a low-level protection signal is continuously output. For example, the comparator 112 may be a CMPSS comparator.

[0060] In specific application scenarios, such as Figure 1As shown, the programmable logic controller 2 includes a communication module 21, a corresponding second wave-by-wave current limiting module 22, and a PWM waveform generation module 23. The communication module 21 is used to establish a communication connection between the programmable logic controller 2 and the energy storage converter digital signal processor 1, so as to receive the three-phase bridge arm voltage and the three-phase bridge arm current direction sent by the energy storage converter digital signal processor 1 based on the communication connection. One end of the second wave-by-wave current limiting module 22 is connected to the first wave-by-wave current limiting module 11 and the communication module 21, and the other end of the second wave-by-wave current limiting module 22 is connected to the first wave-by-wave current limiting module 11 and the communication module 21. Connected to the PWM waveform generation module 23, it receives the three-phase wave-by-wave current limiting protection signal output by the first wave-by-wave current limiting module 11 and the three-phase bridge arm voltage and current direction sent by the communication module 21. Based on the three-phase wave-by-wave current limiting protection signal and the three-phase bridge arm voltage and current direction, it determines the wave-by-wave current limiting protection logic and controls the PWM waveform generation module 23 to output a control signal to the three-level ANPC topology power module 3 according to the wave-by-wave current limiting protection logic. The control signal is used to realize wave-by-wave current limiting protection in inverter mode or rectifier mode. Specifically, the first wave-by-wave current limiting module 11, built in the energy storage converter digital signal processor 1, outputs the three-phase wave-by-wave current limiting protection signal to the second wave-by-wave current limiting module 22 in the programmable logic controller 2 through sampling, detection, calculation, and comparison. The second wave-by-wave current limiting module 22 communicates to obtain the three-phase bridge arm voltage and current direction sent by the energy storage converter digital signal processor 1, thereby controlling the PWM waveform generation module 23 to realize wave-by-wave current limiting protection across the entire power range.

[0061] In specific application scenarios, the three-level ANPC topology power module 3 includes a three-level ANPC topology circuit 31 corresponding to each phase arm, used to control the switching transistors in the three-level ANPC topology circuit to turn on or off based on control signals, thereby achieving wave-by-wave current limiting protection in inverter mode or rectification mode. Specifically, the three-level ANPC topology circuit 31 consists of... Figure 4The first switch G1, the first freewheeling diode D1, the second switch G2, the second freewheeling diode D2, the third switch G3, the third freewheeling diode D3, the fourth switch G4, the fourth freewheeling diode D4, the fifth switch G5, the fifth freewheeling diode D5, the sixth switch G6, the sixth freewheeling diode D6, the first DC bus capacitor C1, and the second DC bus capacitor C2 are connected as shown in the figure. Correspondingly, the three-level ANPC topology circuit includes a DC bus Vdc, two sets of DC bus capacitors (first DC bus capacitor C1 and second DC bus capacitor C2), and six switching transistor circuits (a first switching transistor circuit consisting of a first switching transistor G1 and a first freewheeling diode D1, a second switching transistor circuit consisting of a second switching transistor G2 and a second freewheeling diode D2, a third switching transistor circuit consisting of a third switching transistor G3 and a first freewheeling diode D3, a fourth switching transistor circuit consisting of a fourth switching transistor G4 and a fourth freewheeling diode D4, a fifth switching transistor circuit consisting of a fifth switching transistor G5 and a fifth freewheeling diode D5, and a sixth switching transistor G6 and a sixth freewheeling diode D5). The sixth switching transistor circuit is formed by connecting diode D6. In any of the above switching transistor circuits, the freewheeling diode is connected between the collector and emitter of the switching transistor for commutation with the switching transistor. Two sets of DC bus capacitors are connected in series across the power supply. The fifth and sixth switching transistor circuits in the six switching transistor circuits form a pair of bridge arms, which are connected to the two ends of the DC bus by connecting the first switching transistor circuit in series at one end and the fourth switching transistor circuit in series at the other end. The second and third switching transistor circuits in the six switching transistor circuits form a pair of bridge arms, which are connected to the two ends of the DC bus by connecting the first switching transistor circuit in series at one end and the fourth switching transistor circuit in series at the other end.

[0062] By setting a corresponding three-level ANPC topology circuit 31 for each phase arm, and executing corresponding wave-by-wave current limiting protection logic based on the three-level ANPC topology circuit 31, the AC current envelope-type wave-by-wave current limiting protection of the energy storage converter across the entire power factor range is realized. The wave-by-wave current limiting protection can include both inverter mode and rectifier mode logic. As an optional implementation, when executing the inverter mode wave-by-wave current limiting protection logic based on the aforementioned three-level ANPC topology circuit 31, if the three-phase arm voltage is in the positive half-cycle and current flows out of the arm, when the second wave-by-wave current limiting module of a certain phase detects the wave-by-wave current limiting protection signal of the corresponding phase of the first wave-by-wave current limiting module, regardless of whether the current output is positive or zero level, it immediately turns off the first switch G1 and keeps the second switch G2 on, forcing the current... The current continues from the zero level at the midpoint until the wave-by-wave current limiting protection signal disappears, at which point the normal turn-on and turn-off logic is restored. If the three-phase bridge arm voltage is in the negative half-cycle and current flows into the bridge arm, when the second wave-by-wave current limiting module of a certain phase detects the wave-by-wave current limiting protection signal of the corresponding phase of the first wave-by-wave current limiting module, regardless of whether the current output is negative or zero level, the fourth switch G4 is immediately turned off, and the third switch G3 is kept on, forcing the current to continue from the zero level at the midpoint until the wave-by-wave current limiting protection signal disappears, at which point the normal turn-on and turn-off logic is restored.

[0063] Correspondingly, as another optional implementation, when the rectification mode wave-by-wave current limiting protection logic is executed based on the above-mentioned three-level ANPC topology circuit 31, if the three-phase bridge arm voltage is in the positive half-cycle and current flows into the bridge arm, when the second wave-by-wave current limiting module of a certain phase detects the wave-by-wave current limiting protection signal of the corresponding phase of the first wave-by-wave current limiting module, regardless of whether the current output is positive or zero level, the third switch G3 or the fifth switch G5 is immediately turned off to cut off the zero-level freewheeling path and force the current to continue flowing to the positive bus until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored; if the three-phase bridge arm voltage is in the negative half-cycle, when the second wave-by-wave current limiting module of a certain phase detects the wave-by-wave current limiting protection signal of the corresponding phase of the first wave-by-wave current limiting module, regardless of whether the current output is negative or zero level, the second switch G2 or the sixth switch G6 is immediately turned off to cut off the zero-level freewheeling path and force the current to continue flowing from the negative bus until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored.

[0064] This invention provides a wave-by-wave current limiting protection method, see [link to relevant documentation]. Figure 5 This may include the following steps:

[0065] 101. The digital signal processor of the energy storage converter outputs three-phase wave-by-wave current limiting protection signals, as well as three-phase bridge arm voltage and three-phase bridge arm current direction to the programmable logic controller.

[0066] In specific application scenarios, since the digital signal processor of the energy storage converter determines the three-phase wave-by-wave current limiting protection signal by comparing the dynamic current protection value of each phase with the instantaneous current value of each phase using comparators, before the energy storage converter's digital signal processor outputs the three-phase wave-by-wave current limiting protection signal to the programmable logic controller, it is necessary to first obtain the dynamic current protection value of each phase at the corresponding negative input terminal (first input terminal) of the input comparator for each phase, and the instantaneous current value of each phase at the corresponding positive input terminal (second input terminal) of the input comparator for each phase, and determine the three-phase wave-by-wave current limiting protection signal by comparing the two input values. Accordingly, the specific steps of the embodiment may also include: converting the instantaneous current setpoint of each phase into a real-time sinusoidal current value through coordinate transformation; calculating the product of the real-time sinusoidal current value and the wave-by-wave current limiting protection ratio K; determining the dynamic current protection value of each phase based on the product; obtaining the instantaneous current value of each phase based on the external current sampling circuit; comparing the dynamic current protection value of each phase with the instantaneous current value of each phase; and determining the three-phase wave-by-wave current limiting protection signal based on the comparison result.

[0067] The three-phase wave-by-wave current limiting protection signal includes a high-level protection signal and a low-level protection signal. Correspondingly, when comparing the dynamic current protection value and the instantaneous current value of each phase to determine the three-phase wave-by-wave current limiting protection signal based on the comparison result, the specific steps of the embodiment may include: if it is determined that the instantaneous current value of each phase is greater than the dynamic current protection value of each phase, then the three-phase wave-by-wave current limiting protection signal is determined to be a high-level protection signal; if it is determined that the instantaneous current value of each phase is less than or equal to the dynamic current protection value of each phase, then the three-phase wave-by-wave current limiting protection signal is determined to be a low-level protection signal.

[0068] 102. The second wave-by-wave current limiting module in the programmable logic controller determines the wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signal, the three-phase bridge arm voltage, and the direction of the three-phase bridge arm current.

[0069] The wave-by-wave current limiting protection logic includes a first wave-by-wave current limiting protection logic in inverter mode and a second wave-by-wave current limiting protection logic in rectifier mode. In specific application scenarios, when determining the wave-by-wave current limiting protection logic, such as... Figure 6 As shown, it can first be determined whether there is a three-phase wave-by-wave current limiting protection signal, that is, whether the three-phase wave-by-wave current limiting protection signal is a high-level protection signal; if it is determined that the three-phase wave-by-wave current limiting protection signal is a high-level protection signal, then it is determined whether the three-phase bridge arm voltage and the three-phase bridge arm current are in the same direction; if it is determined that the three-phase bridge arm voltage and the three-phase bridge arm current are in the same direction, then the first wave-by-wave current limiting protection logic in inverter mode is executed; or, if it is determined that the three-phase bridge arm voltage and the three-phase bridge arm current are not in the same direction, then the second wave-by-wave current limiting protection logic in rectifier mode is executed.

[0070] Accordingly, step 102 of the embodiment may specifically include: if the detected three-phase wave-by-wave current limiting protection signal is a high-level protection signal, then determine the wave-by-wave current limiting protection logic based on the three-phase bridge arm voltage and the direction of the three-phase bridge arm current. Specifically, when determining the wave-by-wave current limiting protection logic based on the three-phase bridge arm voltage and the direction of the three-phase bridge arm current, it may include: if it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current direction is positive, or if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current direction is negative, then determine the wave-by-wave current limiting protection logic as the first wave-by-wave current limiting protection logic in the inverter mode; if it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current direction is negative, or if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current direction is positive, then determine the wave-by-wave current limiting protection logic as the second wave-by-wave current limiting protection logic in the rectifier mode.

[0071] 103. The PWM waveform generation module in the programmable logic controller sends a control signal to the three-level ANPC topology power module according to the waveform current limiting protection logic, so as to realize the waveform current limiting protection in inverter mode or rectifier mode according to the control signal.

[0072] In this embodiment, if the wave-by-wave current limiting protection logic is the first wave-by-wave current limiting protection logic in the inverter mode, as an optional approach, in this embodiment, when implementing wave-by-wave current limiting protection in the inverter mode according to the control signal, the specific steps may include: if it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current direction is positive, then according to the control signal, control the first switch of the three-level ANPC topology circuit in the three-level ANPC topology power module to turn off, and maintain the second switch to conduct, forcing the current to continue from the midpoint zero level until the wave-by-wave current limiting protection signal disappears, and then restore the normal turn-on and turn-off logic; or, if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current direction is negative, then according to the control signal, control the fourth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module to turn off, and maintain the third switch to conduct, forcing the current to continue from the midpoint zero level until the wave-by-wave current limiting protection signal disappears, and then restore the normal turn-on and turn-off logic.

[0073] Correspondingly, if the wave-by-wave current limiting protection logic is the second wave-by-wave current limiting protection logic in the rectification mode, as another optional method, for this embodiment, when implementing wave-by-wave current limiting protection in the rectification mode according to the control signal, the specific steps of the embodiment may include: if it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current direction is negative, then according to the control signal, control the shutdown of the third or fifth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module, cut off the zero-level freewheeling path, and force the current to continue flowing to the positive bus until the wave-by-wave current limiting protection signal disappears, and then restore the normal turn-on and turn-off logic; or, if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current direction is positive, then according to the control signal, control the shutdown of the second or sixth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module, cut off the zero-level freewheeling path, and force the current to continue flowing to the positive bus until the wave-by-wave current limiting protection signal disappears, and then restore the normal turn-on and turn-off logic.

[0074] The wave-by-wave current limiting protection system and method described in this application firstly utilize the first wave-by-wave current limiting module in the digital signal processor of the energy storage converter to sample, detect, calculate, and compare, and output a three-phase wave-by-wave current limiting protection signal to the second wave-by-wave current limiting module in the programmable logic controller. The second wave-by-wave current limiting module in the programmable logic controller then determines the wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signal, the three-phase bridge arm voltage, and the direction of the three-phase bridge arm current. Furthermore, the PWM wave generation module in the programmable logic controller is controlled to send a control signal to the three-level ANPC topology power module according to the wave-by-wave current limiting protection logic, thereby achieving wave-by-wave current limiting protection in inverter mode or rectifier mode based on the control signal. The technical solution in this application enables intelligent decision-making and control of wave-by-wave current limiting protection in inverter or rectifier modes by analyzing the three-phase wave-by-wave current limiting protection signal and judging the consistency of the three-phase bridge arm voltage and current direction. This enriches the implementation forms of wave-by-wave current limiting protection, enabling the wave-by-wave current limiting protection system to support non-stop protection against transient overcurrent faults in energy storage systems under various application scenarios. This, in turn, improves the wave-by-wave current limiting protection effect and ensures the safety of energy storage systems.

[0075] All articles and references disclosed above, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute included by “may” is optional.

[0076] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0077] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be considered as a failure of the applicant to consider that subject matter as part of the disclosed inventive subject matter. It is evident that various modifications and variations can be made to the invention by those skilled in the art without departing from the spirit and scope of the invention. Thus, the invention is also intended to include such modifications and variations if they fall within the scope of the claims and their equivalents.

Claims

1. A wave-by-wave current limiting protection system, characterized in that, Wave-by-wave current limiting protection applied in inverter mode and rectifier mode includes: energy storage converter digital signal processor, programmable logic controller, and three-level ANPC topology power module; The energy storage converter digital signal processor is connected to the programmable logic controller, and the programmable logic controller is connected to the three-level ANPC topology power module; The energy storage converter digital signal processor is used to output a three-phase wave-by-wave current limiting protection signal, as well as the three-phase bridge arm voltage and the three-phase bridge arm current direction to the programmable logic controller. The programmable logic controller is used to control the three-level ANPC topology power module to execute the wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signal, the three-phase bridge arm voltage, and the three-phase bridge arm current direction. The energy storage converter digital signal processor includes a first wave-by-wave current limiting module. The first wave-by-wave current limiting module includes a calculation unit and a comparator configured for each phase of the three-phase power supply. The comparator includes a first input terminal, a second input terminal, and an output terminal. The calculation unit is used to transform the instantaneous given value of the current of each phase into a real-time sinusoidal current value through coordinate transformation, calculate the product of the real-time sinusoidal current value and the wave-by-wave current limiting protection ratio K, and determine the product as the dynamic current protection value of each phase. The calculation unit is connected to the first input terminal and is used to input the dynamically calculated protection value of each phase in real time into the comparator through the first input terminal. The external current sampling circuit is connected to the second input terminal and is used to input the instantaneous value of the external current of each phase into the comparator through the second input terminal. The comparator is used to determine the three-phase wave-by-wave current limiting protection signal by comparing the dynamic current protection value of each phase with the instantaneous current value of each phase, and outputs the three-phase wave-by-wave current limiting protection signal using the output terminal.

2. The wave-by-wave current limiting protection system according to claim 1, characterized in that, The programmable logic controller includes a communication module, a corresponding second wave-by-wave current limiting module, and a PWM wave generation module; The communication module is used to create a communication connection between the programmable logic controller and the digital signal processor of the energy storage converter, so as to receive the three-phase bridge arm voltage and the three-phase bridge arm current direction sent by the digital signal processor of the energy storage converter based on the communication connection. One end of the second wave-by-wave current limiting module is connected to the first wave-by-wave current limiting module and the communication module, and the other end of the second wave-by-wave current limiting module is connected to the PWM wave generator module. It is used to receive the three-phase wave-by-wave current limiting protection signal output by the first wave-by-wave current limiting module and the three-phase bridge arm voltage and the direction of the three-phase bridge arm current sent by the communication module. Based on the three-phase wave-by-wave current limiting protection signal and the three-phase bridge arm voltage and the direction of the three-phase bridge arm current, it determines the wave-by-wave current limiting protection logic, and controls the PWM wave generator module to output a control signal to the three-level ANPC topology power module according to the wave-by-wave current limiting protection logic. The control signal is used to realize wave-by-wave current limiting protection in inverter mode or rectifier mode.

3. The wave-by-wave current limiting protection system according to claim 2, characterized in that, The three-level ANPC topology power module includes a three-level ANPC topology circuit corresponding to each phase arm, which is used to control the switching transistors in the three-level ANPC topology circuit to turn on or off based on the control signal, thereby realizing wave-by-wave current limiting protection in inverter mode or rectifier mode.

4. A wave-by-wave current limiting protection method, characterized in that, The wave-by-wave current limiting protection system according to any one of claims 1 to 3 comprises: The energy storage converter digital signal processor outputs three-phase wave-by-wave current limiting protection signals, as well as three-phase bridge arm voltage and three-phase bridge arm current direction to the programmable logic controller. The second wave-by-wave current limiting module in the programmable logic controller determines the wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signal, the three-phase bridge arm voltage, and the direction of the three-phase bridge arm current. The PWM waveform generation module in the programmable logic controller sends a control signal to the three-level ANPC topology power module according to the waveform current limiting protection logic, so as to realize waveform current limiting protection in inverter mode or rectifier mode according to the control signal. Before the energy storage converter digital signal processor outputs the three-phase wave-by-wave current limiting protection signal, as well as the three-phase bridge arm voltage and the three-phase bridge arm current direction to the programmable logic controller, the following steps are also included: The instantaneous given value of each phase current is transformed into a real-time sinusoidal current value through coordinate transformation. The product of the real-time sinusoidal current value and the wave-by-wave current limiting protection ratio K is calculated, and the product is determined as the dynamic current protection value of each phase. The instantaneous value of the current in each phase is obtained by an external current sampling circuit; By comparing the dynamic current protection value of each phase with the instantaneous current value of each phase, the three-phase wave-by-wave current limiting protection signal is determined based on the comparison result; The wave-by-wave current limiting protection logic includes a first wave-by-wave current limiting protection logic in inverter mode and a second wave-by-wave current limiting protection logic in rectifier mode. The second wave-by-wave current limiting module in the programmable logic controller determines the wave-by-wave current limiting protection logic based on the three-phase wave-by-wave current limiting protection signal, the three-phase bridge arm voltage, and the direction of the three-phase bridge arm current, including: If the three-phase wave-by-wave current limiting protection signal is detected as a high-level protection signal, then the wave-by-wave current limiting protection logic is determined based on the three-phase bridge arm voltage and the direction of the three-phase bridge arm current. The wave-by-wave current limiting protection logic determined based on the three-phase bridge arm voltage and the three-phase bridge arm current direction includes: If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current is in the positive direction, or if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current is in the negative direction, then the wave-by-wave current limiting protection logic is determined to be the first wave-by-wave current limiting protection logic under the inverter mode. If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current is in the negative direction, or if it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current is in the positive direction, then the wave-by-wave current limiting protection logic is determined to be the second wave-by-wave current limiting protection logic under the rectification mode.

5. The method according to claim 4, characterized in that, The process of comparing the dynamic current protection value of each phase with the instantaneous current value of each phase input from the external current sampling circuit, and determining the three-phase wave-by-wave current limiting protection signal based on the comparison result, includes: If it is determined that the instantaneous value of the current in each phase is greater than the dynamic current protection value in each phase, then the three-phase wave-by-wave current limiting protection signal is determined to be a high-level protection signal. If the instantaneous value of the current in each phase is determined to be less than or equal to the dynamic current protection value in each phase, then the three-phase wave-by-wave current limiting protection signal is determined to be a low-level protection signal.

6. The method according to claim 4, characterized in that, If the wave-by-wave current limiting protection logic is the first wave-by-wave current limiting protection logic in inverter mode, the step of implementing wave-by-wave current limiting protection in inverter mode according to the control signal includes: If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current direction is positive, then according to the control signal, the first switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, while the second switch remains on, forcing the current to freewheel from the midpoint zero level until the wave-by-wave current limiting protection signal disappears, at which point the normal turn-on and turn-off logic is restored; or, If it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current is in the negative direction, then according to the control signal, the fourth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, and the third switch is kept on, forcing the current to continue from the zero level at the midpoint until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored.

7. The method according to claim 4, characterized in that, If the wave-by-wave current limiting protection logic is the second wave-by-wave current limiting protection logic in rectification mode, the step of implementing wave-by-wave current limiting protection in rectification mode according to the control signal includes: If it is determined that the three-phase bridge arm voltage is in the positive half-cycle and the three-phase bridge arm current is in the negative direction, then according to the control signal, the third or fifth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, cutting off the zero-level freewheeling path and forcing the current to flow to the positive bus until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored; or, If it is determined that the three-phase bridge arm voltage is in the negative half-cycle and the three-phase bridge arm current direction is positive, then according to the control signal, the second or sixth switch of the three-level ANPC topology circuit in the three-level ANPC topology power module is turned off, the zero-level freewheeling path is cut off, and the current is forced to flow to the positive bus until the wave-by-wave current limiting protection signal disappears, and then the normal turn-on and turn-off logic is restored.

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