Impedance adaptation device for multi-voltage-class direct current power supply and distribution system

Abstract

The embodiment of the invention discloses an impedance adaptation device for a multi-voltage-level direct-current power supply and distribution system, and relates to the technical field of direct-current power supply and distribution. The harmonic disturbance generation module in the scheme comprises a full-bridge inverter circuit and a filter circuit, and the matching access module comprises an isolation transformer, a blocking capacitor, a segmented current limiting circuit and a fault protection circuit. The isolation transformer and the segmented current-limiting circuit are used for ensuring smooth starting of the device, and the fault protection circuit is used for reversely driving the segmented current-limiting circuit when a short-circuit fault occurs in the blocking capacitor, limiting short-circuit current and further protecting the impedance adaptation device. The impedance distribution characteristic of the system can be changed after the DC power supply and distribution system is accessed, so that suppression of system resonance is realized; and through introduction of a self-adaptive impedance regulation and control strategy, the impedance adaptation device has a multi-working-condition self-adaptive capability. Impedance distribution of the direct-current power supply and distribution system can be remodeled, broadband oscillation is suppressed, and the stable operation capability of the direct-current power supply and distribution system is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current power supply and distribution, and in particular to an impedance adapter for a multi-voltage level direct current power supply and distribution system. Background Art

[0002] The DC power supply and distribution system is a subsystem used in conjunction with a power supply or similar power supply system. As an important carrier for the integrated consumption of renewable energy, efficient access to electric vehicles, capacity expansion of AC distribution networks, and integrated energy systems, the DC power supply and distribution system has become one of the development directions of future power grids and even energy Internet. However, it has the characteristics of low inertia and weak damping, strong system coupling, etc. Time-varying nonlinear loads, intermittent new energy, equipment parameter migration, etc. are easy to excite the dynamic process of the system, making the source-grid-load random excitation and the wide-band multi-resonance problem caused by it an important factor in testing the safe and high-quality operation of the DC power supply and distribution system. Regarding the resonance suppression problem existing in the DC power supply and distribution system, the current scheme proposes the idea of ​​impedance reshaping: one is to suppress the system resonance by adjusting the port impedance characteristics of the converter through active damping, and the other is to suppress the system resonance by changing the passive devices in the system. Represented by the interface converter with additional active damping control, the basic idea is to inject compensation signals into the control loop to equivalently increase the damping branch to achieve active suppression of internal resonance or active control of input (output) impedance. However, active damping control not only reduces the dynamic characteristics of the converter, but is also constrained by the bandwidth of the controller; and the flexibility of directly replacing passive devices in the system is too poor. Therefore, power electronic devices can be added to the system to simulate different passive devices to suppress system resonance. Compared with the passive damping method, this method does not change the steady-state operating point of the system and is more applicable. However, with the increase of DC system voltage and power level, the stress on the switching devices in the existing devices is large, and the reliability of the devices is difficult to guarantee; in addition, due to the wide resonant frequency band of the DC power supply and distribution system, the control bandwidth and impedance simulation frequency band of the impedance adapter device need to be combined with the resonant frequency band of the system for corresponding design to meet the needs of broadband oscillation suppression, and the existing devices are not designed in a targeted manner.

[0003] Therefore, it is necessary to improve and design an impedance adaptation device that can meet the impedance simulation requirements of multiple voltage levels and multiple operating conditions, so as to achieve the purpose of suppressing the broadband oscillation of the DC power supply and distribution system, so as to ensure the safe and stable operation of the system. Summary of the invention

[0004] An embodiment of the present invention provides an impedance adaptation device for a multi-voltage level DC power supply and distribution system, which can suppress broadband oscillation of the DC power supply and distribution system, thereby ensuring safe and stable operation of the system.

[0005] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: An impedance adapter for a multi-voltage level DC power supply and distribution system, wherein a harmonic disturbance generation module is connected as a system to be adapted through a matching access module; The harmonic disturbance generating module comprises: a full-bridge inverter circuit and a filter circuit, the filter circuit is connected to the full-bridge inverter circuit, and the filter circuit is used to filter out switching harmonics and improve the output quality of harmonic disturbance; The matching access module includes: a segmented current limiting circuit and a fault protection circuit. The matching access module is used as an intermediate link to connect the harmonic disturbance generating module and the DC bus of the system to be adapted. The type of the system to be adapted is a DC power supply and distribution system.

[0006] In the harmonic disturbance generating module, the full-bridge inverter circuit includes: a first MOS tube Q 1 to the fourth MOS tube Q 4. DC side capacitor C d connected in parallel to the input side of the full-bridge inverter circuit; the filter circuit is connected to the output side of the full-bridge inverter circuit, and the front-stage filter inductor L f and filter capacitors C f The filter circuit is constituted.

[0007] In the matching access module, it includes: an isolation transformer T r , Post-stage filter inductor L s , DC blocking capacitor C s and circuit breaker 2 S h ; Isolation transformer T r The primary side passes through the circuit breaker S c Connected to the filter branch, isolation transformer T r The secondary side is connected in series with the post-stage filter inductor of the matching access module L s and DC blocking capacitors C s A circuit breaker is provided between the segmented current limiting circuit and the DC bus of the system to be adapted. S h ; Specifically, the components constituting the segmented current limiting circuit include: first to second current limiting resistors R s1 and R s2 , the first to third trigger resistors Rg1 to R g3 , the first to second trigger capacitor C g1 and C g2 , the first to the second Zener diode D g1 and D g2 , and the first to second trigger MOS tubes Q g1 and Q g2 ; R s1 and R s2 In passing C s During the charging process, the MOS tubes are triggered in turn. Q g1 and Q g2 Cut off, so as to suppress the current impact during the charging process in segments. R g1 to R g3 To trigger Q g1 and Q g2 The conduction provides a stable gate voltage; the trigger resistor R g1 ~ R g3 Through the basic principle of series voltage division, the MOS tube is triggered Q g1 and Q g2 The conduction provides a stable gate voltage; the trigger capacitor C g1 and C g2 With trigger resistor R g1 and R g2 Jointly determine the current limiting resistor R s1 and R s2 Cut-off time; Zener diode D g1 and D g2 Used to ensure triggering of MOS tube Q g1 and Q g2 Stabilization of gate voltage.

[0008] The fault protection circuit comprises: an optical coupler, an operational amplifier and a voltage stabilizing diode; when C s When a short circuit occurs, the secondary side of the optocoupler outputs a low level to the operational amplifier, which then outputs a low level and triggers Q g2 Shut down, at this time R s2 The matching circuit is put into use to suppress the short-circuit impact current, thereby protecting the impedance matching device. T r The segmented current limiting circuit is used to ensure smooth startup of the device. The fault protection circuit is used to reversely drive the segmented current limiting circuit when a short-circuit fault occurs in the DC isolation capacitor, thereby limiting the short-circuit current and protecting the impedance adapter.

[0009] Furthermore, the adaptation process of the impedance adaptation device for the multi-voltage level DC power supply and distribution system includes: The output port of the matching access module is connected in parallel to the DC bus of the system to be adapted. S c With circuit breaker 2 S h All are in disconnected state; Close circuit breaker 2 S h , and wait for the DC blocking capacitor C s Charge to bus voltage; Start the harmonic disturbance generation module and select the adaptation mode, then close the circuit breaker. S c , the impedance adaptation device starts to run, and the adaptation modes include: fixed impedance simulation and adaptive impedance simulation.

[0010] In the impedance simulation control loop, the bandpass filter BPF1 is used to obtain the bus voltage v bus Extract the oscillating harmonic component as the signal reference of the inner loop current command value; directly multiply the oscillating harmonic component by the conductance reference value G ref Get the current command value of the resistance simulation i z_ref ; or, multiply the oscillation harmonic component by the capacitance reference value after the differential link C ref get i z_ref ; i z_ref Input inner loop quasi-PR regulator. i z_refThrough the inner loop quasi-PR regulator G i ( s ) so that the impedance adapter simulates resistance or capacitance at the system resonant frequency, thereby suppressing system resonance.

[0011] In the capacitor voltage self-maintaining control loop, the DC side capacitor C d The command value v Cd_ref and actual value v Cd The difference passes through the PI regulator of the voltage outer loop G v ( s ) to obtain the inner loop current command value i v_ref The signal reference is multiplied by the harmonic component outside the impedance simulation frequency to obtain the inner loop current command value of the capacitor voltage self-maintaining control i v_ref Inner loop current command value i v_ref Through the inner loop quasi-PR regulator G r ( s ) tracking, so that the impedance adapter simulates negative resistance outside the system resonant frequency, sends energy to the system to maintain the DC side capacitance C d The voltage is stable.

[0012] The impedance adapter device for a multi-voltage level DC power supply and distribution system provided in an embodiment of the present invention includes a harmonic disturbance generating module, including a full-bridge inverter circuit and a filter circuit. The filter circuit is connected to the full-bridge inverter circuit to filter out switching harmonics and improve the quality of harmonic disturbance output; a matching access module includes an isolation transformer, a DC blocking capacitor, a segmented current limiting circuit and a fault protection circuit, which serves as an intermediate link to connect the harmonic disturbance generating module and the busbar of the system to be adapted. Among them, the isolation transformer and the segmented current limiting circuit are used to ensure the smooth start-up of the device, and the fault protection circuit is used to reversely drive the segmented current limiting circuit when a short-circuit fault occurs in the DC blocking capacitor, so as to limit the short-circuit current and thus protect the impedance adapter device. The impedance adapter device of the present invention has a wide-band port impedance simulation capability, and can change the impedance distribution characteristics of the system after being connected to the DC power supply and distribution system to achieve the suppression of system resonance; and through the introduction of an adaptive impedance control strategy, the impedance adapter device of the present invention has the ability to adapt to multiple working conditions. The impedance adapter can adapt to DC power supply and distribution systems with different voltage levels and operating conditions. It has the ability to simulate the port's wide-band impedance, can reshape the impedance distribution of the DC power supply and distribution system, and suppress wide-band oscillations, thereby greatly improving the DC power supply and distribution system's ability to operate stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 The circuit structure diagram of the impedance matching device provided by the present invention is shown in FIG. Figure 1 middle, v Cd Indicates the DC side capacitor voltage, v inv Represents the bridge arm output voltage, i Lf Represents the pre-stage filter inductor current, i o Indicates the device output port current, V cc Represents the optocoupler supply voltage of the fault protection circuit, V ref Represents the input reference voltage of the operational amplifier in the fault protection circuit.

[0015] Figure 2 This is a block diagram of the basic control strategy for impedance adaptation provided by the present invention; Figure 2 middle, v bus Represents the DC bus voltage of the system to be adapted, BPF1 represents a bandpass filter, which is used to extract the oscillation harmonic components, BPF2 represents a bandpass filter, which is used to extract the available harmonic components outside the impedance simulation frequency, HPF represents a high-pass filter, which is used to simulate the differential link, G ref represents the conductivity reference value, C ref Indicates the capacitance reference value, i v_ref Indicates the current command value used to maintain the stability of the DC side capacitor voltage. i z_ref Indicates the current command value for impedance simulation, v Cd_ref Indicates the DC side capacitor reference voltage, cos(ω v t ) represents the time domain expression of the available harmonic components outside the impedance simulation frequency, ω v represents the angular frequency of the available harmonic components, t Indicates time, G i ( s ) represents a quasi-PR regulator, Gv ( s ) represents the PI regulator, G r ( s ) represents a quasi-PR regulator, K pwm represents the modulation gain, s represents a complex frequency domain variable, T s Indicates control delay, v Cf Indicates filter capacitor C f The voltage across the terminals, L f Indicates the inductance value of the pre-stage filter. i p Represents the primary current of the isolation transformer, i Cf Indicates filter capacitor C f On current, Z p (s) represents the primary equivalent parallel impedance of the isolation transformer, n Indicates the primary-to-secondary turns ratio of the isolation transformer, Z s (s) represents the equivalent series impedance of the secondary side of the isolation transformer.

[0016] Figure 3 This is a block diagram of the adaptive impedance control considering DC bus voltage distortion provided by the present invention. Figure 3 In the above example, RMS represents the root mean square value extraction step. V rms Indicates the RMS value of the busbar harmonic voltage, V lim Indicates the upper limit of busbar harmonic voltage distortion value. G R ( s ) represents the PI regulator, G C ( s ) represents the PI regulator, G x represents the adaptive conductance value, C x Represents the adaptive adaptation capacitance value, i R_ref Indicates the current command value of the resistor simulation, i C_ref Indicates the current command value of capacitor simulation, Δ V rms Indicates the rate of change of the RMS value of the busbar harmonic voltage, Δ V limIndicates the reference value of the busbar harmonic voltage root mean square value change rate, I max Indicates the upper limit of the RMS value of the output current of the adapter device. I rms Indicates the RMS value of the impedance simulation current command value. ≥1 indicates an OR operation, and & indicates an AND operation. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention. It can be understood by those skilled in the art that, unless specifically stated, the singular forms "one", "one", "said" and "the" used herein may also include plural forms. It should be further understood that the term "including" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups. It should be understood that when we say that an element is "connected" or "coupled" to another element, it can be directly connected or coupled to other elements, or there may also be intermediate elements. In addition, the "connection" or "coupling" used here may include wireless connection or coupling. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items. It can be understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0018] In this embodiment, a main circuit of an impedance adapter device applicable to a multi-voltage level DC power supply and distribution system and having an adaptive impedance simulation capability is provided, such as Figure 1 As shown, the device includes: a harmonic disturbance generating module, including a DC side capacitor C d , MOS tube Q 1~ Q 4. Pre-filter inductor L f 、Filter capacitor C f And circuit breakerS c .

[0019] Matching access modules, including isolation transformers T r , Post-stage filter inductor L s , DC blocking capacitor C s , Current limiting resistor R s1 and R s2 , trigger resistor R g1 ~ R g3 , trigger capacitor C g1 and C g2 , Zener diode D g1 and D g2 , trigger MOS tube Q g1 and Q g2 And circuit breaker 2 S h .

[0020] In the impedance matching device provided in this embodiment, the MOS tube Q 1~ Q 4 form a full-bridge inverter circuit, the DC side capacitor C d Connected in parallel to the input side of the full-bridge inverter circuit. L f 、Filter capacitor C f It forms a pre-stage filter circuit and is connected to the output side of the full-bridge inverter circuit; isolation transformer T r The primary side passes through the circuit breaker S c Connected to the filter branch, the secondary side is directly connected in series with the post-stage filter inductor L s With DC blocking capacitor C s .

[0021] In the impedance matching device provided in this embodiment, the front-stage filter inductor L f 、Filter capacitor C f , isolation transformer and post-stage filter inductor L sThe LCL filter circuit is composed to ensure the waveform quality of the device output current. When the device is connected to the system, the post-stage filter inductor L s With current limiting resistor R s1 , R s2 And DC blocking capacitors C s The RLC second-order segmented buffer circuit can fully suppress the current impact and take into account the charging efficiency of the DC blocking capacitor.

[0022] In the impedance matching device provided in this embodiment, the current limiting resistor R s1 and R s2 , trigger resistor R g1 ~ R g3 , trigger capacitor C g1 and C g2 , Zener diode D g1 and D g2 , and trigger MOS tube Q g1 and Q g2 Composed of segmented current limiting circuit, current limiting resistor R s1 and R s2 In the DC blocking capacitor C s During the charging process, the MOS tubes are triggered in sequence. Q g1 and Q g2 Cut off, segmented suppression of current shock during charging; trigger resistor R g1 ~ R g3 Through the basic principle of series voltage division, the MOS tube is triggered Q g1 and Q g2 The conduction provides a stable gate voltage; the trigger capacitor C g1 and C g2 With trigger resistor R g1 and R g2 Jointly determine the current limiting resistor R s1and R s2 The time when the voltage regulator diode is cut off D g1 and D g2 Used to ensure triggering of MOS tube Q g1 and Q g2 Stabilization of gate voltage.

[0023] In the impedance matching device provided in this embodiment, the fault protection circuit is composed of an optical coupler, an operational amplifier and a voltage regulator diode. C s When a short circuit occurs, the secondary side of the optocoupler outputs a low level to the operational amplifier, which then outputs a low level to trigger the MOS tube. Q g2 Shutdown, current limiting resistor R s2 A matching circuit is added to suppress short-circuit impact current and protect the device.

[0024] In this embodiment, a basic control strategy principle block diagram of the impedance matching device is provided, such as Figure 2 As shown in the figure, the basic control loop of impedance adaptation includes: impedance simulation control loop, which is responsible for impedance simulation of the device port; and capacitor voltage self-maintaining control loop, which is responsible for maintaining the DC side capacitor C d The voltage is stable.

[0025] In the impedance simulation control loop provided in this embodiment, the bandpass filter BPF1 is derived from the system bus voltage v bus Extract the oscillation harmonic component as the inner loop current command value i z_ref The signal reference is then multiplied by the conductivity reference value G ref Get the current command value of the resistance simulation i z_ref , or multiplied by the capacitance reference value after the differential link C ref Get the current command value of capacitor simulation i z_ref . Current command value i z_ref Through the inner loop quasi-PR regulator G i ( s ) so that the impedance adapter simulates resistance or capacitance at the system resonant frequency, thereby suppressing system resonance.

[0026] In the capacitor voltage self-maintaining control loop provided in this embodiment, the DC side capacitor C d The command value v Cd_ref and actual value v Cd The difference passes through the PI regulator of the voltage outer loop G v ( s ) to obtain the inner loop current command value i v_ref The signal reference is then multiplied by the harmonic component outside the impedance simulation frequency to obtain the inner loop current command value of the capacitor voltage self-maintaining control i v_ref Inner loop current command value i v_ref Through the inner loop quasi-PR regulator G r ( s ) tracking, so that the impedance adapter simulates negative resistance outside the system resonant frequency, sends energy to the system to maintain the DC side capacitance C d The voltage is stable.

[0027] In this embodiment, an adaptive impedance control block diagram considering DC bus voltage distortion is provided, such as Figure 3 System bus voltage v bus The AC harmonic component obtained by the bandpass filter BPF1 is used as the reference signal of the resistance-capacitance simulation and sent to the RMS value extraction link to obtain the system harmonic RMS value. V rms ;Will V rms The upper limit of busbar harmonic voltage distortion is V lim After the difference is made, it is sent to the PI regulator G R ( s )and G C ( s ), thus obtaining the conductivity reference value G x With the capacitor reference value C x The above reference value is multiplied to obtain the current command value i R_ref and i C_ref , the final current command value of the impedance simulation i z_ref Determined by the adaptive switching judgment link. Considering the power demand of the device, capacitor simulation is given priority, that is, the command value iz_ref Pick i C_ref Then, the two comparators detect the rate of change of the RMS value of the busbar harmonic voltage and the impedance simulation current command value. When any of the values ​​does not meet the requirements, the capacitor simulation is switched to the resistor simulation, that is, the command value i z_ref Switch to i R_ref , while the PI regulator G R ( s ) output for initialization processing; Similarly, if the resistance simulation still cannot meet the adaptation requirements, the command value i z_ref will be set to zero. i z_ref The output is sent to the impedance simulation control loop to achieve adaptive impedance control of the impedance adapter.

[0028] The following is a description of the impedance matching process of the present embodiment: 1. Connect the output port of the matching access module to the DC bus of the system to be adapted. S c With circuit breaker 2 S h All are in disconnected state.

[0029] 2. Close circuit breaker 2 S h , waiting for the DC blocking capacitor C s Charge to bus voltage.

[0030] 3. Start the harmonic disturbance generation module and select the adaptation mode according to actual needs, then close the circuit breaker. S c , the device starts running.

[0031] The impedance adapter device for a multi-voltage DC power supply and distribution system provided by the embodiment of the present invention solves the problem of large device stress in the existing impedance adapter device through reasonable design of the topology; through reasonable design of the control strategy, the device can fully suppress the broadband oscillation of the DC power supply and distribution system while meeting the adaptation requirements of various complex working conditions. Among them, the harmonic disturbance generation module, which is composed of a DC side capacitor, a full-bridge inverter circuit and a filter circuit, is responsible for generating high-quality harmonic currents to ensure the accuracy of the device port impedance simulation; the matching access module, which is composed of an isolation transformer, a DC blocking capacitor, a segmented current limiting circuit and a fault protection circuit, is responsible for balancing the voltage and current stress of the switching devices in the device, realizing electrical isolation between the device and the system to be adapted, and solving the overcurrent problem when the device is connected to the system and the DC blocking capacitor fails, and finally suppressing the broadband oscillation of the DC power supply and distribution system, thereby ensuring the safe and stable operation of the system.

[0032] In practical applications, the impedance adapter adopts a basic control strategy of dual-loop superposition, including an impedance simulation control loop and a DC capacitor voltage self-maintaining control loop. On the basis of the basic control strategy, an adaptive impedance control strategy that takes into account the DC bus voltage distortion is adopted. By detecting the distortion value of the system bus voltage, the impedance simulation value is continuously adjusted, thereby achieving the effect of automatically suppressing the system's broadband oscillation.

[0033] Specifically, the solution of this embodiment has the following advantages: 1. Through the modular main circuit topology design, the voltage and current stress of the device switch components during operation is greatly reduced, and the device is applicable to multiple voltage levels. 2. The introduction of the segmented current limiting circuit solves the overcurrent problem when the device is connected to the system; the introduction of the fault protection circuit ensures the safe and stable operation of the device. 3. Through the effective design of the control strategy, the device has the ability of wide-band adaptive impedance simulation to meet the needs of multi-condition operation.

[0034] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The above is only a specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An impedance adapter for a multi-voltage DC power supply and distribution system, characterized in that: The harmonic disturbance generation module is connected to the system to be adapted through the matching access module; The harmonic disturbance generating module comprises: a full-bridge inverter circuit and a filter circuit, the filter circuit is connected to the full-bridge inverter circuit, and the filter circuit is used to filter out switching harmonics; The matching access module includes: a segmented current limiting circuit and a fault protection circuit. The matching access module is used as an intermediate link to connect the harmonic disturbance generating module and the DC bus of the system to be adapted. The type of the system to be adapted is a DC power supply and distribution system.

2. The impedance adapter for a multi-voltage DC power supply and distribution system according to claim 1, characterized in that: In the harmonic disturbance generating module, the full-bridge inverter circuit includes: a first MOS tube Q 1 to the fourth MOS tube Q 4. DC side capacitor C d Connected in parallel to the input side of the full-bridge inverter circuit; The filter circuit is connected to the output side of the full-bridge inverter circuit, and the front-stage filter inductor L f and filter capacitors C f The filter circuit is constituted.

3. The impedance adapter for a multi-voltage DC power supply and distribution system according to claim 1, characterized in that: In the matching access module, it includes: an isolation transformer T r , Post-stage filter inductor L s , DC blocking capacitor C s and circuit breaker 2 S h ; Isolation transformer T r The primary side passes through the circuit breaker S c Connected to the filter branch, isolation transformer T r The secondary side is connected in series with the post-stage filter inductor of the matching access module L s and DC blocking capacitors C s ; A circuit breaker is provided between the segmented current limiting circuit and the DC bus of the system to be adapted. S h .

4. The impedance adapter for a multi-voltage DC power supply and distribution system according to claim 3, characterized in that: The components constituting the segmented current limiting circuit include: first to second current limiting resistors R s1 and R s2 , the first to third trigger resistors R g1 to R g3 , the first to second trigger capacitor C g1 and C g2 , the first to the second Zener diode D g1 and D g2 , and the first to second trigger MOS tubes Q g1 and Q g2 ; R s1 and R s2 In passing C s During the charging process, the MOS tubes are triggered in turn. Q g1 and Q g2 Cut off, thereby suppressing the current impact during the charging process in segments.

5. The impedance adapter for a multi-voltage DC power supply and distribution system according to claim 4, characterized in that: The fault protection circuit comprises: an optical coupler, an operational amplifier and a voltage stabilizing diode; when C s When a short circuit occurs, the secondary side of the optocoupler outputs a low level to the operational amplifier, which then outputs a low level and triggers Q g2 Shut down, at this time R s2 A matching circuit is put into use to suppress short-circuit impact current.

6. The impedance adapter for a multi-voltage DC power supply and distribution system according to any one of claims 1 to 5, characterized in that: The adaptation process of the impedance adaptation device includes: The output port of the matching access module is connected in parallel to the DC bus of the system to be adapted. S c With circuit breaker 2 S h All are in disconnected state; Close circuit breaker 2 S h , and wait for the DC blocking capacitor C s Charge to bus voltage; Start the harmonic disturbance generation module and select the adaptation mode, then close the circuit breaker. S c , the impedance adaptation device starts to run, and the adaptation modes include: fixed impedance simulation and adaptive impedance simulation.

7. The impedance adapter for a multi-voltage DC power supply and distribution system according to claim 6, characterized in that: In the impedance simulation control loop, the bandpass filter BPF1 is used to obtain the bus voltage v bus Extracting the oscillation harmonic component as the signal reference of the inner loop current command value; Directly multiply the oscillating harmonic component by the conductance reference value G ref Get the current command value of the resistance simulation i z_ref Or, the oscillation harmonic component is multiplied by C ref get i z_ref ; i z_ref Input inner loop quasi-PR regulator.

8. The impedance adapter for a multi-voltage DC power supply and distribution system according to claim 7, characterized in that: In the capacitor voltage self-maintaining control loop, the DC side capacitor C d The command value v Cd_ref and actual value v Cd The difference passes through the PI regulator of the voltage outer loop G v ( s ) to obtain the inner loop current command value i v_ref The signal reference; The signal reference is multiplied by the harmonic component outside the impedance simulation frequency to obtain the inner loop current command value of the capacitor voltage self-maintaining control i v_ref。

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