Module parameter determination method of flexible chopping type direct current energy consumption device

Abstract

The invention provides a module parameter determination method of a flexible chopping type direct current energy consumption device, and the method specifically comprises the steps: determining the design parameters of all devices in a power electronic device branch and a voltage-sharing circuit in a module according to the determined voltage-sharing reference quantity of the module; wherein the voltage-sharing circuit is connected to two ends of the power electronic device branch. According to the invention, the problem of parameter design of each device in the power module of the flexible chopping type direct-current energy consumption device is effectively solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power transmission and distribution safety control, and particularly relates to a module parameter determination method of a flexible chopper type direct current energy consumption device. BACKGROUND

[0002] Flexible direct current transmission technology is a main technical means for solving offshore wind power grid connection. However, when the receiving end AC power grid fails, the wind farm energy that cannot be consumed in time will cause the direct current voltage to rise rapidly, which threatens the safety of the converter valve and the entire system. Therefore, the direct current energy consumption device is needed to consume the energy that cannot be normally transmitted by the system, so as to achieve the purpose of stabilizing the direct current voltage and assisting the system to complete fault ride-through.

[0003] Controllable high-power semiconductor switching devices are an important part of the research on direct current energy consumption devices. At present, the integrated gate-commutated thyristor (IGCT) and the insulated gate bipolar transistor (IGBT) are mainly used as controllable switching devices in the direct current energy consumption device scheme.

[0004] There are two types of technical routes for the direct current energy consumption device. One type is a centralized energy consumption device with resistors. The other type is a distributed energy consumption device with resistors. The centralized energy consumption device mainly concentrates the energy consumption resistors on both sides of the poles and is arranged outside the valve hall (a room where the power electronic device modules of the energy consumption device are arranged) in actual application, and the energy consumption resistors meet the natural cooling requirements. The distributed energy consumption device distributes the energy consumption resistors in each module between the poles, and the energy consumption resistors need water cooling devices for cooling.

[0005] The existing modular direct current energy consumption device scheme mainly uses power modules similar to the modular multilevel converter (MMC), and the control system determines the switching state of the module by real-time sorting of all module voltages. The scheme is relatively mature, while the flexible chopper type direct current energy consumption device is a new direct current energy consumption device scheme. It is a modular direct current energy consumption device based on full-controlled device direct string. Its basic principle is to realize the consumption of surplus power on the centralized resistor by using current flexible chopping, which is different from the working principle of the existing modular direct current energy consumption device.

[0006] Since the power module of the flexible chopper DC energy consumption device adopts the design of parallel connection of switching devices and RCD (also known as Snubber circuit, wherein R represents resistance, C represents capacitor, and D represents diode) buffer circuit, and the power module is formed based on the straight string of multiple full-controlled devices, the voltage sharing of the straight string of multiple full-controlled devices is particularly important. However, when solving the voltage sharing problem of the straight string of multiple full-controlled devices, the requirements for the devices in the power module for realizing voltage sharing are high, and therefore, the determination of the parameters of the devices in the power module for realizing voltage sharing becomes a technical problem to be solved. SUMMARY

[0007] In view of the above technical problems, the present application provides a module parameter determination method of a flexible chopper DC energy consumption device, wherein the determination method comprises:

[0008] According to the reference amount of module voltage sharing determined, the design parameters of each device in the power electronic device branch and the voltage sharing circuit are determined.

[0009] The voltage sharing circuit is connected at both ends of the power electronic device branch.

[0010] Further, according to the reference amount of module voltage sharing determined, the parameters of each device in the power electronic device branch are determined, comprising:

[0011] According to the first reference amount, the device design parameters of the full-controlled device Tm are determined, wherein the power electronic device branch comprises the full-controlled device Tm, and the reference amount comprises the first reference amount.

[0012] Further, the first reference amount comprises:

[0013] The highest rated voltage Usubmax of the module and the rated current Idc of the flexible DC system.

[0014] Further, the device design parameters of the full-controlled device Tm are:

[0015] The rated voltage of the full-controlled device Tm is greater than 2 times of Usubmax, and the rated current value is greater than Idc or greater than 2 times of Idc.

[0016] Further, the determination of the parameters of each device in the voltage sharing circuit in the module comprises:

[0017] The parameters of each device in the static voltage sharing branch and the dynamic voltage sharing branch are determined.

[0018] Further, the determination of the parameters of each device in the dynamic voltage sharing branch comprises:

[0019] According to the second reference amount, the resistance R S and the capacitance CS a device design parameter of the resistor R

[0020] The reference quantity further comprises the second reference quantity.

[0021] The dynamic voltage equalization branch comprises the resistor R S and the capacitor C S One end of the resistor R S is connected to one end of the capacitor C S The other end of the resistor R S is connected to the anode of the full-control device Tm, and the other end of the capacitor C S is connected to the cathode of the full-control device Tm.

[0022] Further, the second reference quantity comprises:

[0023] An overvoltage parameter of the module, and a minimum voltage of the module.

[0024] Further, the device design parameter of the resistor R S and the capacitor C S comprises:

[0025] Two side boundaries of the resistor R S and the capacitor C S configuration.

[0026] Further, determining the device parameters in the dynamic voltage equalization branch further comprises:

[0027] According to a third reference quantity, a device design parameter of the forward diode Df is determined, wherein,

[0028] The reference quantity further comprises the third reference quantity; and the dynamic voltage equalization branch further comprises the forward diode Df, wherein the anode of the forward diode Df is connected to the other end of the resistor R S , and the cathode of the forward diode Df is connected to one end of the resistor R S .

[0029] Further, the third reference quantity comprises:

[0030] A rated large current of the full-control device Tm in the module after the full-control device Tm is turned off and commutates.

[0031] Further, the device design parameter of the forward diode Df comprises:

[0032] The transient voltage withstand of the forward diode Df is greater than 4.5kV.

[0033] Further, determining the device parameters in the static voltage equalization branch comprises:

[0034] According to the fourth reference quantity, the static voltage-sharing resistor R D is determined, wherein the reference quantity further comprises the fourth reference quantity, and the static voltage-sharing branch comprises the static voltage-sharing resistor R D .

[0035] Further, the fourth reference quantity comprises:

[0036] In the module, in addition to the static voltage-sharing resistor R D , the static power consumption of other devices is determined.

[0037] Further, the static voltage-sharing resistor R D is determined, and the device design parameters are:

[0038] The static power consumption of the other devices is more than 5 times the static power consumption of the other devices, and is greater than the sum of the static power consumption of the other devices;

[0039] The DC voltage resistance is according to the uneven coefficient of 5% to have a margin, and the resistance error of the static voltage-sharing resistor R D is-1%~+1%.

[0040] On the other hand, the application also provides a module parameter determination system of a flexible chopping type DC energy consumption device, wherein the system comprises:

[0041] A first determination module is configured to determine a reference quantity of module voltage-sharing;

[0042] A second determination module is configured to determine device design parameters in the power electronic device branch and the voltage-sharing circuit in the module according to the determined reference quantity of module voltage-sharing.

[0043] The voltage-sharing circuit is connected between the two ends of the power electronic device branch.

[0044] Further, the device parameters in the power electronic device branch in the module are determined according to the determined reference quantity of module voltage-sharing, and the device parameters in the power electronic device branch in the module are determined according to the determined reference quantity of module voltage-sharing, comprising:

[0045] According to the first reference quantity, the device design parameters of the full-controlled device Tm are determined, wherein the power electronic device branch comprises the full-controlled device Tm, and the reference quantity comprises the first reference quantity.

[0046] Compared with the prior art, the module parameter determination method of the flexible chopping type DC energy consumption device provided by the application can make the power electronic device branch become a branch that can accurately control the opening and closing of the module, thereby controlling the conduction and turn-off of the main loop current, and the device parameters in the static voltage-sharing branch and the dynamic voltage-sharing branch are determined, so that the module with the static voltage-sharing branch and the dynamic voltage-sharing branch can have good voltage-sharing effect.

[0047] Other features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the application. The purposes and other advantages of the present application will be realized and attained by the structure particularly pointed out in the description and appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0049] Figure 1 A flow chart of the determination method according to the embodiment of the present application is shown;

[0050] Figure 2 An equivalent circuit diagram of charge and discharge of the module according to the embodiment of the present application is shown;

[0051] Figure 3 A capacitor C according to the embodiment of the present application is shown; S A voltage waveform schematic diagram is shown;

[0052] Figure 4 A topology diagram of the module according to the embodiment of the present application is shown;

[0053] Figure 5 A topology diagram of the direct current energy consumption device according to the embodiment of the present application is shown;

[0054] Figure 6 A flexible direct current transmission system topology diagram according to the embodiment of the present application is shown;

[0055] Figure 7 A structure diagram of the determination system according to the embodiment of the present application is shown. DETAILED DESCRIPTION

[0056] In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0057] In order to solve the problem of power module straight string voltage sharing of flexible chopping type direct current energy consumption device, a power module (hereinafter referred to as module) with voltage sharing function needs to be designed, so as to play a dynamic voltage sharing function in the process of frequent opening of the module, stabilize the voltage of each module, and realize the voltage sharing of the module. Therefore, a module needs to be provided, which includes a power electronic device branch and a voltage sharing circuit. The power electronic device branch is a branch that can accurately control the opening and closing of the module, so as to control the conduction and turn-off of the main circuit current. The voltage sharing circuit is used to realize the voltage sharing of the module. The module composed of the power electronic device branch and the voltage sharing circuit can be in the form of straight string in the installation of the entire energy consumption device, that is, a plurality of modules are straightly connected to form an energy consumption valve, and the two ends of the energy consumption valve can be connected through reactors L1 and L2, concentrated energy consumption resistors R1 and R2, so as to form a direct current energy consumption device.

[0058] In the module, the power electronic device branch can be designed as follows: the device of the power electronic device branch includes a full-controlled device Tm; the voltage sharing circuit can be designed to include a static voltage sharing branch and a dynamic voltage sharing branch. Through the static voltage sharing branch, the voltage between the modules can be evenly distributed when the direct current energy consumption device is in operation, so that the overvoltage and under-voltage of the direct current energy consumption device can be avoided. Through the dynamic voltage sharing branch, the dynamic voltage sharing function can be played in the process of frequent opening of the module, and the voltage of each module can be stabilized.

[0059] In the module, the device of the static voltage sharing branch can be designed to include a static voltage sharing resistor R D ; and the dynamic voltage sharing branch can be designed to include a forward diode Df, a resistor R S and a capacitor C S .

[0060] In addition, in the module, a power taking branch can also be used, which mainly supplies the working energy of the high potential board of the module, and the cached energy can support the operation of a single module for more than one second. The power taking branch includes a power taking power supply and a high potential driving board DM.

[0061] Therefore, the above-mentioned devices, i.e. the full-controlled device Tm, the voltage sharing resistor R D , the forward diode Df, the resistor R S and the capacitor C S , have fixed specifications and models when they are produced and leave the factory. Therefore, the electrical parameter design method of all device parts in the module generally adopts the method of directly comparing and selecting alternative models after determining the parameter range. Therefore, in the present application, a module parameter determination method for a flexible chopping type direct current energy consumption device is also provided, which will be described below.

[0062] In the present application, as Figure 1As shown, a module parameter determination method of a flexible chopper DC energy consumption device includes:

[0063] S1. Determine the reference amount of module voltage sharing (the reference amount includes the first reference amount, the second reference amount, the third reference amount, the fourth reference amount, and the fifth reference amount);

[0064] S2. According to the determined reference amount of module voltage sharing, determine the design parameters of each device in the power electronic device branch and the voltage sharing circuit in the module; wherein the voltage sharing circuit is connected across the power electronic device branch.

[0065] The above method will be described in detail below.

[0066] 1. Determine the parameters of each device in the power electronic device branch

[0067] In some embodiments of the present application, according to the determined reference amount of module voltage sharing, the parameters of each device in the power electronic device branch in the module are determined, including:

[0068] According to the first reference amount, determine the device design parameters of the full-controlled device Tm, wherein the power electronic device branch includes the full-controlled device Tm, and the reference amount includes the first reference amount. It should be noted that in the DC energy consumption device, the full-controlled device Tm should have the following characteristics:

[0069] (1) Strong current-carrying capacity and small switching loss;

[0070] (2) Long-term reliable short-circuit failure mode;

[0071] (3) Excellent heat dissipation performance.

[0072] According to the above requirements, the commonly used full-controlled devices are IGBT (Insulated Gate Bipolar Transistor) and IGCT (Integrated Gate-Commutated Thyristor), both of which can be used in the flexible chopper DC energy consumption device described in the present application. In the comparison of the same type of IGBT and IGCT devices, IGCT devices are recommended due to their superior characteristics.

[0073] Since the full-controlled device Tm is the core element of the module, for controlling the conduction and turn-off of the module, the rated voltage and the rated current of the full-controlled device Tm need to be considered. The rated voltage and the rated current of the full-controlled device Tm are related to the highest rated voltage of the module and the rated current of the flexible direct current system, and the highest rated voltage of the module and the rated current of the flexible direct current system are generally related to the rated voltage Udc of the flexible direct current system and the minimum module number Nmin of the energy consumption device, thus, the first reference quantity in the reference quantity needs to be determined according to the rated voltage Udc of the flexible direct current system and the minimum module number Nmin of the energy consumption device. The first reference quantity and the design parameters of the full-controlled device Tm are described as follows:

[0074] The first reference quantity includes the highest rated voltage Usubmax of the module and the rated current Idc of the flexible direct current system. The calculation method of the highest rated voltage Usubmax of the module and the rated current Idc of the flexible direct current system is as follows:

[0075] The highest rated voltage Usubmax of the module and the rated current Idc of the flexible direct current system are calculated according to the rated voltage Udc of the flexible direct current system and the minimum module number Nmin of the energy consumption device.

[0076] Thus, the device design parameters of the full-controlled device Tm are obtained as follows:

[0077] In order to leave a margin, the rated voltage of the full-controlled device Tm is greater than 2 times of Usubmax. Since the rated current definitions of IGBT and IGCT devices are different, after considering the margin, if the full-controlled device Tm is IGBT, the rated current value of the full-controlled device Tm should be greater than Idc, and if the full-controlled device Tm is IGCT, the rated current value of the full-controlled device Tm selected is greater than 2 times of Idc.

[0078] 2. Determining the parameters of each device in the voltage equalization circuit

[0079] In the present application, the parameters of each device in the voltage equalization circuit in the module are determined, including determining the parameters of each device in the static voltage equalization branch and the dynamic voltage equalization branch. The following is described.

[0080] 2.1. Determining the parameters of each device in the dynamic voltage equalization branch

[0081] The dynamic voltage equalization branch can effectively absorb the energy of the commutation when the full-controlled device Tm is turned off, limit the module turn-off transient overvoltage to below the withstand voltage of the full-controlled device Tm, and make the full-controlled device Tm work in the safe working area. When the module is turned on, the energy in the capacitor C S will be released on the resistor R S . At the same time, the capacitor C S provides energy for the whole process of the power supply.

[0082] To design the capacitance C S The parameters of the resistance R S In determining the second reference quantity of the reference quantity, the most serious overvoltage condition of the module under different capacitance C S , resistance R S , and the discharge process of the module opening, the working condition of the power supply, and other factors are combined to determine the reasonable selection of the capacitance C S and the resistance R S Therefore, in the present application, the second reference quantity can be determined as: the overvoltage parameter of the module (the most serious overvoltage parameter), and the minimum voltage of the module (not lower than the lower limit of the input voltage of the lower voltage, that is, not lower than the lower limit of the input voltage of the power supply). Based on this, in some embodiments of the present application, the parameters of each device in the dynamic voltage sharing branch are determined, including: determining the device design parameters of the resistance R S and the capacitance C S According to the second reference quantity.

[0083] In addition, since the dynamic voltage sharing branch also includes a forward diode Df, determining the parameters of each device in the dynamic voltage sharing branch also includes: determining the device design parameters of the forward diode Df according to the third reference quantity. Among them, when selecting the forward diode Df, the third reference quantity in the reference quantity mainly considers the rated large current that needs to pass through the power device after the turn-off, and the wavefront time (that is, the turn-off time of the full-controlled device Tm) is very short, that is, the third reference quantity includes: the rated large current that passes through the full-controlled device Tm after turn-off in the module.

[0084] On the other hand, since the larger the diode current value is, the larger the equivalent junction capacitance is, and it is easy to form oscillation with the stray inductance in the circuit, which is not conducive to the working condition of repeated opening and closing of the energy consumption valve. Therefore, under the condition of meeting the mechanical pressure assembly structure design requirement, the device design parameters of the forward diode Df need to consider selecting a pressure contact type fast recovery diode (for example, using FYB 2000-45-02 type diode) that matches the power electronic switching device (that is, the full-controlled device Tm), the transient voltage withstand is >4.5kV, and the current passing capacity meets the maximum current of the device (direct current energy consumption device) (which can be 1.25 times the rated current of the direct current energy consumption device), and also takes into account economy and reliability.

[0085] In some embodiments of the present application, the device design parameters of the resistance R S and the capacitance C S include the two side boundaries (the upper limit and the lower limit of the capacitance / resistance value that meets the design requirement) of the resistance R S and the capacitance C S Specifically:

[0086] When the fully controlled device Tm is turned off, the commutation energy mainly comes from reactors L1 and L2, and this energy is released in the centralized energy-consuming resistor and the voltage equalization circuit of each module. Since the current flowing through the flexible chopper-type DC energy-consuming device is the rated current when it is stably conducting, the only difference between the module turn-off actions under different operating conditions, except for a few cases where the current on the DC energy-consuming device is still rising (i.e., when the turn-off action is performed), is the capacitor C. S The initial voltage, and the capacitor C is charged. S The energy difference is not significant. Therefore, capacitor C can be considered. S The discharge time is short, that is, the duty cycle is low, so that the capacitor C S The initial voltage is higher. In this case, the module's charging and discharging equivalent circuit is related to the capacitor C. S The voltage waveform diagrams are as follows: Figure 2 and Figure 3 As shown, combined Figure 2 and Figure 3 From this, we can derive the two side boundaries of the resistor RS and capacitor CS configuration:

[0087] Since the forward diode Df will turn off in reverse after transitioning from state (a) to state (b), the resistor R in the equivalent circuit of state (b) is a series equivalent of the concentrated energy dissipation resistor and the absorption resistor of each module (i.e., resistor Rs), which is not the same as state (a).

[0088] First, state (c) is equivalent to a simple first-order RC discharge circuit, which is easy to derive:

[0089]

[0090] In the formula, u C (t) represents the capacitor voltage in the equivalent circuit, u C (0) represents the initial voltage across the capacitor in the equivalent circuit, t represents the duration of state (c), and R S and C S The resistors R in the original module are respectively S and capacitor C S .

[0091] The analytical solution for the capacitor voltage expression in states (a) and (b) can be obtained from the KVL equations of the equivalent circuit:

[0092]

[0093] In the formula, n represents the number of modules, Uc represents the capacitor voltage in the equivalent circuit, L represents the reactance of the equivalent circuit, and U DC This indicates the voltage between the two ends of a DC power-consuming device.

[0094] Since the module returns to state (a) from state (c) at the end of a cycle, the end capacitor voltage is equal to the initial capacitor voltage, which can be solved simultaneously. The final solution is that, under the condition of a specified capacitor voltage initial value, different resistances Rs and capacitances C S The maximum overvoltage corresponding to the configuration is determined. According to the insulation requirements of the flexible system, after ensuring a certain margin, the resistance Rs and the capacitance C S The one-side boundary of the configuration is determined.

[0095] In addition, during the entire operation of the module, the output voltage of the power supply should be stable to support the normal operation of the full-control device Tm. Although the power supply internally designs a short-time energy storage system, which can ensure that the output voltage can still support the full-control device to work for a period of time after the capacitor voltage is lower than the power-off voltage of the power supply, in order to ensure the overall reliability of the DC energy-consuming device, the minimum value of the module voltage should not be lower than the power-off voltage. At this time, the discharge time of Cs is long, that is, the working duty cycle is high, and the equivalent circuit is analyzed according to the above, and the resistance Rs and the capacitance C S The other side boundary of the configuration is determined. Finally, combined with the economic requirement, the parameter design of the resistance Rs and the capacitance C S is completed.

[0096] 2.2. Determine the parameters of each device in the static voltage-sharing branch

[0097] In the fourth reference quantity of the reference quantity, the following conditions need to be determined: the static voltage-sharing resistance R D needs to be ensured that, in the steady state of the DC energy-consuming device, the power consumption is much larger than the sum of the static power consumptions of other devices, so that the module voltage in the steady state is mainly determined by the resistance error of the static voltage-sharing resistance R D , which has a good static voltage-sharing effect.

[0098] Therefore, when designing the device design parameters of the static voltage-sharing resistance R D , the static power consumption is designed to be more than 5 times the static power consumption of other groups of devices, the DC voltage resistance is taken with a margin of 5% non-uniformity coefficient, and the resistance error of the voltage-sharing resistance is-1% to +1%, so as to ensure the uniformity of the static voltage resistance.

[0099] 3. Determine the device parameters of other devices

[0100] In the module, in order to prevent reverse voltage, a reverse-parallel diode Dr can also be used, which can be connected in parallel with the static voltage-sharing resistance R DThe fifth reference quantity of the reference quantity at both ends of the reference quantity can be determined according to the characteristic of the anti-parallel diode Dr, that is, the anti-parallel diode Dr does not need to conduct a large current and is mainly used to prevent reverse voltage); on the other hand, since the greater the diode current value, the greater the equivalent junction capacitance, it is easy to form oscillation with the stray inductance in the circuit (the circuit where the anti-parallel diode Dr is located), which is not conducive to the working condition of repeated opening and closing of the energy consumption valve. Therefore, under the condition of meeting the mechanical pressure assembly structure design requirement, the device design parameter of the anti-parallel diode Dr is a pressure connection type ordinary rectifier diode which is matched with the full control device Tm, has a transient voltage not less than the rated voltage of the full control device Tm, and has a small current capacity, and also takes into account economy and reliability.

[0101] 4. Power module

[0102] Based on the above: the process of determining the parameters of each device in the power electronic device branch, determining the parameters of each device in the voltage sharing circuit, and determining the parameters of other devices, a module topology as shown in Figure 4 can be set, which is described below.

[0103] As shown in Figure 4 , the application provides a module, which comprises a power electronic device branch, a voltage sharing circuit and an anti-parallel diode Dr, the voltage sharing circuit is connected between the poles of the power electronic device branch, specifically: the anti-parallel diode Dr, the static voltage sharing resistor R D and the full control device Tm are connected in parallel with each other, and the dynamic voltage sharing circuit is connected between the poles of the full control device Tm.

[0104] Among them, the anti-parallel diode Dr, the static voltage sharing resistor R D and the full control device Tm are connected in parallel in the following way: the anode of the anti-parallel diode Dr is connected to one end of the static voltage sharing resistor R D , and the cathode of the anti-parallel diode Dr is connected to the other end of the static voltage sharing resistor R D ; one end of the static voltage sharing resistor R D is connected to the anode of the full control device Tm, and the other end of the static voltage sharing resistor R D is connected to the cathode of the full control device Tm.

[0105] In some embodiments of the application, the dynamic voltage sharing circuit comprises a forward diode Df, a resistor R S and a capacitor C S . Among them, the dynamic voltage sharing circuit is connected between the poles of the full control device Tm in the following way: one end of the resistor R S is connected to one end of the capacitor C S , the other end of the resistor R S is connected to the anode of the full control device Tm, and the other end of the capacitor C SThe other end is connected to the cathode of the fully controlled device Tm; the anode of the forward diode Df is connected to the resistor R. S At the other end, the cathode of the forward diode Df is connected to resistor R. S One end.

[0106] In some embodiments of the present invention, the module further includes an energy harvesting branch, which includes a power supply and a high-potential driver board DM, wherein one end of the power supply is connected to the cathode of the forward diode Df, and the other end of the power supply is connected to the cathode of the fully controlled device Tm; one end of the power supply is also connected to the capacitor C. S One end of the power supply is connected, and the other end of the power source is also connected to capacitor C. S The other end is connected; one end of the high-potential drive board DM is connected to the power supply, and the other end of the high-potential drive board DM is connected to the gate of the fully controlled device Tm.

[0107] Furthermore, in some embodiments of the present invention, the functions of the various components in the module are as follows:

[0108] Anti-parallel diode Dr: A diode with a junction capacitance that is the same as or similar to that of the fully controlled device Tm. Before the fully controlled device Tm is subjected to reverse voltage, the anti-parallel diode Dr conducts, thereby protecting the fully controlled device Tm.

[0109] Static equalizing resistor R D Its main function is to even out the voltage between modules when the DC power consumption device is running, so that the DC power consumption device does not experience overvoltage or undervoltage, and ensures the normal operation of the device.

[0110] The main function of the fully controlled device Tm is to control the magnitude of the current flowing through the module. That is, the fully controlled device Tm operates at a certain frequency and effectively adjusts the effective value of the current by controlling the on-time of the current.

[0111] C S R S Df forms the damping branch of the power module, and its main function is to dynamically equalize the voltage during the frequent switching of the module, thereby stabilizing the voltage of each module.

[0112] Power supply branch: Its main function is to supply the high-potential board (i.e. DM) of the module with working energy. The energy cached once can support the operation of a single module for more than a few seconds.

[0113] Power source (i.e.) Figure 4 The power supply in the middle: mainly from the buffer capacitor (i.e., capacitor C) S Energy is obtained from the drive unit (i.e., DM), and the obtained energy provides the energy used by the drive unit.

[0114] High potential drive board DM: realize the opening and closing control of full control device Tm, realize the opening and closing of full control device Tm through the energy change control of gate-cathode of full control device Tm.

[0115] 5. DC energy consumption device

[0116] Based on the above-mentioned module, the application further provides a flexible chopper type DC energy consumption device, as shown in the drawings. Figure 5 The DC energy consumption device comprises a main circuit, wherein the main circuit comprises an electric reactor L1, a concentrated DC energy consumption resistor R1, an energy consumption valve, a concentrated DC energy consumption resistor R2 and an electric reactor L2 connected in series, wherein the energy consumption valve comprises N modules (SM-1, SM-2…SM-N) described above, and the N modules are connected in series.

[0117] The N modules are connected in series in the following manner:

[0118] The anode of the full control device Tm in the previous module is connected with the cathode of the full control device Tm in the next module, wherein the anode of the full control device Tm in the first module is connected with the concentrated DC energy consumption resistor R1, and the cathode of the full control device Tm in the Nth module is connected with the concentrated DC energy consumption resistor R2.

[0119] In some embodiments of the application, the functions of the components in the DC energy consumption device are as follows:

[0120] The full control device Tm can accurately control the opening and closing of the module, thereby controlling the conduction and closing of the main circuit current, and the opening and closing time of the module can be controlled by adjusting the duty cycle, so as to achieve the purpose of flexible control.

[0121] R1 and R2 are called concentrated DC energy consumption resistors, and their main function is to convert energy from electric energy to heat energy, thereby achieving the purpose of suppressing the voltage rise of the DC transmission line.

[0122] The electric reactors L1 and L2 have a large inductance value, and their main function is to suppress the current change rate (di / dt) during the opening and closing of the full control device Tm.

[0123] Rs and Cs can form an absorption circuit to absorb the energy during the closing of the full control device Tm, thereby achieving the purpose of limiting the voltage across the full control device Tm.

[0124] In some embodiments of the application, the DC energy consumption device is installed in a flexible DC transmission system, which can refer to the drawings. Figure 6 The flexible DC transmission system comprises a wind farm, an MMC rectifier station, a DC transmission line and an MMC inverter station connected in series.

[0125] The wind farm includes a cluster of wind turbine units. The MMC rectifier station includes a first connecting transformer and a first MMC converter valve. The DC transmission line includes overhead lines and cables. The MMC inverter station includes a current-limiting reactor, a second MMC converter valve, and a second connecting transformer.

[0126] The input of the first connecting transformer is connected to the wind turbine cluster, and the output is connected to the input of the first MMC converter valve. One end of each of the two overhead lines is connected to the output of the first MMC converter valve. One end of each of the two cables is connected to the other end of the two overhead lines. The other ends of the two cables are connected to one end of a current-limiting reactor. The other ends of the current-limiting reactors are connected to the input of the second MMC converter valve. The input of the second connecting transformer is connected to the output of the second MMC converter valve. The input of the second connecting transformer is connected to the AC power grid.

[0127] The general operation mode of a flexible DC transmission system is as follows: offshore wind turbine clusters convert wind energy into alternating current (AC), which is then input to the first connecting transformer for step-up. The stepped-up AC is then converted into DC via the first MMC converter valve and transmitted to an onshore smoothing reactor (i.e.,...) through overhead lines or cables. Figure 3 The medium-current limiting reactor filters the current (not mandatory, that is, it can be set or not set as needed), and then transmits it to the second MMC converter valve to be converted into AC power, and then through the second connecting transformer to be stepped up and transmitted to the AC power grid.

[0128] in, Figure 5 The DC power dissipation device shown is installed between the other ends of the two current-limiting reactors, i.e. Figure 5 In the circuit, the end of reactor L1 that is furthest from DC energy-consuming resistor R1 is connected to the other end of one of the current-limiting reactors, and the end of reactor L2 that is furthest from DC energy-consuming resistor R2 is connected to the other end of another current-limiting reactor.

[0129] like Figure 7 As shown, in another aspect, the present invention also provides a module parameter determination system for a flexible chopper-type DC power consumption device, wherein the system includes:

[0130] The first determining module is used to determine the reference value for the voltage equalization of the module;

[0131] The second determining module is used to determine the design parameters of each device in the power electronic device branch and the voltage equalization circuit in the module based on the determined reference value of the voltage equalization of the module.

[0132] The voltage equalization circuit is connected to both ends of the power electronic device branch.

[0133] Other functions and implementation manners of each module of the module parameter determination system of the flexible chopper DC energy consumption device of the present application are consistent with other functions and implementation manners of each step of the module parameter determination method of the flexible chopper DC energy consumption device of the present application, and thus, will not be repeated here.

[0134] In summary, the present application provides a DC energy consumption device power module parameter design method based on full-controlled devices, solves the problem of parameter design of each device in the power module of the flexible chopper DC energy consumption device, and can be applied to the flexible DC power transmission system, and can effectively guarantee the safe operation of the ultra / extra-high voltage flexible power transmission system.

[0135] The above only describes preferred embodiments of the present application and does not limit the present application in any form. Although the present application has been described above with reference to the preferred embodiments, the present application is not limited thereto. Any person skilled in the art can make some changes or modifications to the above disclosed technical contents without departing from the scope of the technical solution of the present application, and any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application still belong to the scope of the technical solution of the present application.

Claims

1. A method for determining module parameters of a flexible chopper DC energy dissipating device, wherein, The determination method comprises: According to the determined reference amount of the module voltage sharing, the design parameters of each device in the power electronic device branch and the voltage sharing circuit in the module are determined; The voltage sharing circuit is connected at both ends of the power electronic device branch.

2. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 1, wherein, According to the determined reference amount of the module voltage sharing, the design parameters of each device in the power electronic device branch in the module are determined, which comprises: According to the first reference amount, the design parameters of the fully controlled device Tm are determined, wherein the power electronic device branch comprises the fully controlled device Tm, and the reference amount comprises the first reference amount.

3. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 2, wherein, The first reference amount comprises: The highest rated voltage Usubmax of the module and the rated current Idc of the flexible direct current system.

4. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 3, wherein, The design parameters of the fully controlled device Tm are: The rated voltage of the fully controlled device Tm is greater than 2 times of Usubmax, and the rated current value is greater than Idc or greater than 2 times of Idc.

5. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 4, wherein, The design parameters of each device in the voltage sharing circuit in the module are determined, which comprises: The design parameters of each device in the static voltage sharing branch and the dynamic voltage sharing branch are determined.

6. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 5, wherein, The design parameters of each device in the dynamic voltage sharing branch are determined, which comprises: According to a second reference quantity, the device design parameters of the resistance R S and the capacitance C S are determined, wherein, The reference amount further comprises the second reference amount; The dynamic equalizing branch comprises the resistor R S and the capacitor C S , one end of the resistor R S is connected to one end of the capacitor C S , the other end of the resistor R S is connected to the anode of the full-control device Tm, and the other end of the capacitor C S is connected to the cathode of the full-control device Tm.

7. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 6 wherein, The second reference amount comprises: The overvoltage parameter of the module and the minimum voltage of the module.

8. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 7, wherein, a resistor R S and a capacitor C S device design parameters, including: Resistor R S And capacitor C S Configured two side boundaries.

9. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to any one of claims 5 to 8, wherein, The design parameters of each device in the dynamic voltage sharing branch are determined, which further comprises: According to the third reference amount, the design parameters of the forward diode Df are determined, wherein, The reference quantity further comprises the third reference quantity; the dynamic voltage-sharing branch further comprises the forward diode Df, wherein an anode of the forward diode Df is connected to the other end of the resistor R S , and a cathode of the forward diode Df is connected to the one end of the resistor R S .

10. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 9, wherein, The third reference amount comprises: The rated large current of the fully controlled device Tm after commutation in the module.

11. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 10, wherein, The design parameters of the forward diode Df comprise: The transient voltage withstand of the forward diode Df is greater than 4.5kV.

12. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 11, wherein, The design parameters of each device in the static voltage sharing branch are determined, which comprises: According to a fourth reference quantity, a static equalization resistor R is determined D of the device design parameters, wherein the reference quantities further include the fourth reference quantity, and the static equalization branch includes the static equalization resistor R D .

13. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 12, wherein, The fourth reference amount comprises: In the module, in addition to the static voltage equalization resistor R D the static power consumption of other devices.

14. A method of determining the parameters of a module of a flexible chopper DC energy dissipating device according to claim 13, wherein, Static equalization resistor R D The device design parameters are: More than 5 times of the static power consumption of the other devices, and greater than the sum of the static power consumption of the other devices; The DC voltage resistance is according to the uneven coefficient of 5% to take the margin, and the static voltage resistance R D The resistance error is -1%~+1%.

15. A flexible chopper DC energy consuming device module parameter determination system wherein, The system comprises: A first determination module is configured to determine the reference amount of the module voltage sharing; A second determination module is configured to determine the design parameters of each device in the power electronic device branch and the voltage sharing circuit in the module according to the determined reference amount of the module voltage sharing; The voltage sharing circuit is connected at both ends of the power electronic device branch.

16. A flexible chopper DC energy dissipating device module parameter determination system according to claim 15 wherein, The design parameters of each device in the power electronic device branch in the module are determined according to the determined reference amount of the module voltage sharing, which comprises: According to the first reference amount, the design parameters of the fully controlled device Tm are determined, wherein the power electronic device branch comprises the fully controlled device Tm, and the reference amount comprises the first reference amount.

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