Information energy integrated energy storage converter submodule, system and control modulation method

Abstract

The application provides an information and energy integrated energy storage converter submodule, a system and a control modulation method. The submodule is a double half-bridge submodule, comprising a conventional half-bridge unit, a special half-bridge unit and a fault ride-through branch. When a bipolar short-circuit fault is detected on the DC side, the trigger pulse of a fourth fully controllable turn-off device and a second bidirectional thyristor in the submodule is blocked, the third fully controllable turn-off device and a first bidirectional thyristor trigger pulse signal are synchronously turned on or blocked, and the fifth fully controllable turn-off device and a third bidirectional thyristor trigger pulse signal are synchronously turned on or blocked, so as to realize switching control mode, and make the converter using the submodule have a DC side zero voltage ride-through capability. The control modulation method of the information and energy integrated energy storage converter uses the alternate access of the submodule in the non-modulation area to realize the injection and information transmission of special signals in the system, and realizes online precise monitoring of the impedance of the battery cluster.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power transmission and distribution of power systems, in particular to an information-energy integrated energy storage converter sub-module, system and control modulation method. BACKGROUND

[0002] With the increase of renewable energy generation, renewable energy grid connection has become a very important research direction at present. Flexible DC transmission technology provides a solution for renewable energy grid connection, which has strong technical advantages. Among them, the flexible DC transmission technology using modular multilevel converter has better maintainability and scalability than traditional two-level and three-level converters, and there is no problem of switch tube series voltage sharing and parallel current sharing. The structure of each sub-module of the modular multilevel converter is relatively simple and easy to control, and the modularization is easy to expand, which is particularly suitable for high-voltage DC transmission field. The number of levels output by the modular multilevel converter can be adjusted by adjusting the number of sub-modules in the bridge arm, and the voltage on the DC side can also be controlled by adjusting the number of sub-modules in each phase. Therefore, the voltage level and harmonic content of the system composed of the modular multilevel converter can be effectively controlled.

[0003] When renewable energy grid connection adopts flexible DC transmission mode, it may face conditions such as DC side short circuit or power surge, which may cause the energy on the AC side to be unable to be sent out in time. In order to avoid overvoltage of new energy equipment, Crowbar and other methods are needed to dissipate, causing energy loss. If energy storage can be directly configured in the modular multilevel converter, the fluctuation of renewable energy can be smoothed when the working condition changes greatly, thereby improving the output capability of renewable energy grid connection and helping to achieve the double carbon goal.

[0004] Because of the inconsistency of the energy storage battery when it leaves the factory, when the modular multilevel converter is configured with storage, the aging degree of the energy storage battery will differ under long-term operation conditions, which will include changes in impedance information and capacity information. Therefore, how to extract the information of the energy storage battery while ensuring the normal operation and transmission of the system is an extremely important link.

[0005] At present, the modular multilevel converter with storage basically adopts traditional half-bridge modules and two-stage structures to realize power transmission and energy storage configuration of the system. The battery energy storage realized by the current method only has power smoothing function. When a double-pole-to-ground short circuit condition occurs at the DC sending end, not only the renewable energy generation energy on the AC side cannot be effectively sent out or stored, but also overcurrent of the system bridge arm device will be caused, and even burned out. Therefore, in order to ensure the energy sending and system operation stability when the DC side is short-circuited, it is necessary to ensure that the modular multilevel converter has the ability of zero-voltage ride-through on the DC side.

[0006] In addition, since the estimation of battery state information in existing battery energy storage systems basically depends on initial battery model parameters and parameter correction algorithms during operation, it is difficult to accurately obtain the actual battery impedance spectrum information, and the battery impedance spectrum can reflect the battery electrochemical process, and then map the battery state, which is a key parameter for connecting the internal state information of the battery and the external measurable parameters (current, voltage, temperature) of the battery. Therefore, if the battery impedance spectrum can be identified online while the renewable energy is sent out, the accuracy of the state identification of the battery energy storage system and even the safety of the system itself can be effectively improved. SUMMARY

[0007] In view of the defects in the prior art, the purpose of the present application is to provide an information and energy integrated energy storage converter submodule, system and control modulation method.

[0008] According to one aspect of the present application, an information and energy integrated energy storage converter submodule is provided, the submodule being a double half-bridge submodule, comprising a conventional half-bridge unit, a special half-bridge unit and a fault ride-through branch;

[0009] The special half-bridge unit comprises a third fully controlled switching device, a third diode, a fourth fully controlled turn-off device, a fourth diode, a first bidirectional thyristor, a second bidirectional thyristor, a second capacitor, a second inductor and a second battery cluster;

[0010] The special half-bridge unit topology form comprises:

[0011] The high-voltage side terminal of the third fully controlled turn-off device is connected to the positive electrode of the second capacitor, the low-voltage side terminal of the third fully controlled turn-off device is connected to one end of the first bidirectional thyristor, the other end of the first bidirectional thyristor is connected to the high-voltage side terminal of the fourth fully controlled turn-off device, and the connection point simultaneously serves as the positive output terminal of the special half-bridge unit; the low-voltage side terminal of the fourth fully controlled turn-off device is connected to one end of the second bidirectional thyristor, the other end of the second bidirectional thyristor is connected to the negative electrode of the second capacitor, and the connection point simultaneously serves as the negative output terminal of the special half-bridge unit; the third diode and the fourth diode are respectively anti-parallel connected to the third fully controlled turn-off device and the fourth fully controlled turn-off device; one end of the second inductor is connected to the positive output terminal of the second battery cluster, and the other end is connected to the positive electrode of the second capacitor; the negative output terminal of the second battery cluster is connected to the negative electrode of the second capacitor;

[0012] Alternatively,

[0013] The high-voltage side terminal of the fourth controllable turn-off device is connected to the positive electrode of the second capacitor, and the connection point is simultaneously used as a positive output terminal of the special half-bridge unit; one end of the fourth controllable turn-off device is connected to the low-voltage side terminal of the second bidirectional thyristor, and the other end of the second bidirectional thyristor is connected to the high-voltage side terminal of the third controllable turn-off device, and the connection point is simultaneously used as a negative output terminal of the special half-bridge unit; the low-voltage side terminal of the third controllable turn-off device is connected to one end of the first bidirectional thyristor, and the other end of the first bidirectional thyristor is connected to the negative electrode of the second capacitor; the third diode and the fourth diode are respectively connected in antiparallel with the third controllable turn-off device and the fourth controllable turn-off device; one end of the second inductor is connected to the positive output terminal of the second battery cluster, and the other end is connected to the positive electrode of the second capacitor; the negative output terminal of the second battery cluster is connected to the negative electrode of the second capacitor.

[0014] The fault ride-through branch comprises a fifth controllable turn-off device, a fifth diode and a third bidirectional thyristor, wherein the low-voltage side terminal of the fifth controllable turn-off device is connected to one end of the third bidirectional thyristor, the other end of the third bidirectional thyristor is connected to the negative output terminal of the special half-bridge unit, and the high-voltage side terminal of the fifth controllable turn-off device is connected to the positive electrode of the first capacitor in the conventional half-bridge unit, and the fifth diode is connected in parallel with the fifth controllable turn-off device.

[0015] The positive output terminal of the conventional half-bridge unit and the negative output terminal of the special half-bridge unit are respectively used as positive and negative output terminals of the double half-bridge sub-module.

[0016] Preferably, the conventional half-bridge unit comprises a first controllable turn-off device, a first diode, a second controllable turn-off device, a second diode, a first capacitor, a first inductor and a first battery cluster; wherein the high-voltage side terminal of the first controllable turn-off device is connected to the positive electrode of the first capacitor; the low-voltage side terminal of the first controllable turn-off device is connected to the high-voltage side terminal of the second controllable turn-off device, and the connection point is simultaneously used as a positive output terminal of the conventional half-bridge unit; the low-voltage side terminal of the second controllable turn-off device is connected to the negative electrode of the first capacitor, and the connection point is simultaneously used as a negative output terminal of the conventional half-bridge unit; the first diode and the second diode are respectively connected in antiparallel with the first controllable turn-off device and the second controllable turn-off device; one end of the first inductor is connected to the positive output terminal of the first battery cluster, and the other end is connected to the positive electrode of the first capacitor; the negative output terminal of the first battery cluster is connected to the negative electrode of the first capacitor.

[0017] Preferably, the full-controllable turn-off device comprises an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET); for the insulated gate bipolar transistor (IGBT), the high-voltage side terminal is a collector, and the low-voltage side terminal is an emitter; for the metal oxide semiconductor field effect transistor (MOSFET), the high-voltage side terminal is a drain, and the low-voltage side terminal is a source.

[0018] Preferably, when the circuit is working in a normal state, the first and second bidirectional thyristors are in a conducting state.

[0019] The fifth full-controllable turn-off device and the third bidirectional thyristor remain in an off state and are not added to the circuit.

[0020] According to a second aspect of the present application, an information-energy integrated energy storage converter system is provided, comprising three phase units, each phase unit comprising: an upper bridge arm and a lower bridge arm, each bridge arm comprising a plurality of series-connected double half-bridge sub-modules; the double half-bridge sub-module being any of the information-energy integrated energy storage converter sub-modules;

[0021] The number of series-connected double half-bridge sub-modules of the upper bridge arm and the lower bridge arm of each phase unit is the same.

[0022] The upper bridge arm and the lower bridge arm of each phase unit are respectively connected in series with a current-limiting reactor.

[0023] Each phase unit is arranged from top to bottom as follows: all double half-bridge sub-modules of the upper bridge arm, a reactor of the upper bridge arm, a reactor of the lower bridge arm, and all double half-bridge sub-modules of the lower bridge arm.

[0024] A three-phase alternating voltage is connected to the connection between the upper bridge arm and the lower bridge arm of each phase unit.

[0025] The positive output terminal of the uppermost double half-bridge sub-module of the upper bridge arm is connected to the positive pole of a DC bus, and the negative output terminal of the lowermost double half-bridge sub-module of the lower bridge arm is connected to the negative pole of the DC bus.

[0026] Preferably, when a bipolar short-circuit fault is detected on the DC side, the trigger pulses of the fourth full-controllable turn-off device and the second bidirectional thyristor in each double half-bridge sub-module are blocked, the trigger pulse signals of the third full-controllable turn-off device and the first bidirectional thyristor are synchronously turned on or blocked, and the trigger pulse signals of the fifth full-controllable turn-off device and the third bidirectional thyristor are synchronously turned on or blocked.

[0027] According to a third aspect of the present application, a control and modulation method of an information-energy integrated energy storage converter is provided, comprising:

[0028] S1.1: determining the DC modulation ratio m of the modular multilevel energy storage converter dc and the AC modulation ratio mac , 0 < m dc , m ac ≤ 1, and the number of sub-modules in the bridge arm N, N > 4, judging the relationship between 1-m ac and 1 / N:

[0029] When 1-m ac ≥ 1 / N, directly jump to step S1.3, at this time the system modulation wave form is:

[0030]

[0031] Otherwise, jump to step S1.2;

[0032] S1.2: When 1-m ac < 1 / N, adopt the third harmonic injection mode, the in-phase third harmonic modulation ratio m 3rd , the modulation wave amplitude is 1 / 6 of the fundamental wave, to reduce the overall modulation wave peak value, leaving at least 1 / N of the modulation ratio space, at this time the system modulation wave form is:

[0033]

[0034] S1.3: adopt the nearest level approximation modulation strategy, according to the real-time modulation ratio, determine the input circuit and the bypassed sub-module; when a module in the converter needs to query the key parameter information, on the basis of the nearest level approximation modulation strategy, limit the module input and bypass timing, and control the remaining modules in the bridge arm to continue to be input and cut off according to the nearest level approximation mode on the basis of the module input / cut-off action.

[0035] Preferably, the nearest level approximation modulation strategy is adopted, according to the real-time modulation ratio, to determine the input circuit and the bypassed sub-module, comprising:

[0036] When the j-phase, j=A, B, C, the modulation wave form is:

[0037]

[0038] The number of sub-modules input in the lower bridge arm of the phase is:

[0039]

[0040] Wherein, round(x) represents the integer closest to x, at this time the number of sub-modules input in the upper bridge arm of the phase is:

[0041]

[0042] When the j-phase, j=A, B, C, the modulation wave form is:

[0043]

[0044] At this time, the number of sub-modules of the lower bridge arm of the phase is:

[0045]

[0046] At this time, the number of sub-modules of the upper bridge arm of the phase is:

[0047]

[0048] Preferably, when a module in the converter needs to query critical parameter information, on the basis of the nearest level approximation modulation strategy, the module on-time and bypass timing are limited, including:

[0049] S2.1: Determine the impedance spectrum frequency points f1 * , f2 * , f3 * , …, f i * , 50Hz, f i+1 * , …, f n * ;

[0050] S2.2: Construct a frequency signal corresponding to a multi-frequency point sinusoidal modulation sequence, specifically:

[0051] f1= 50Hz-f i * ; f2= 50Hz-f i-1 * ; f3= 50Hz-f i-2 * ; …; f i = 50Hz-f1 * ; …; f i+1 = f i+1 -

[0052] 50Hz; …; f n = f n -50Hz;

[0053] S2.3: Construct a multi-frequency point sinusoidal modulation sequence f MFS (t), specifically:

[0054] f MFS (t) = sin(2·π·f1t) + sin(2·π·f2t) + … + sin(2·π·f i t) + … + sin(2·π·f n t)

[0055] S2.4: Based on the multi-frequency point sinusoidal modulation sequence, the corresponding module input and bypass timing f is obtained by taking the sign function BMFS (t) :

[0056] f BMF (t) = sign (sign (f MFS (t) + 1)

[0057] Wherein, the sign function sign (x) represents, when x>0, sign (x) =1, when x<0, sign (x) =-1, when x=0, sign (x) =0; the obtained input and bypass timing f BMFS (t) only contains two values 0 and 1, wherein 0 corresponds to bypass, 1 corresponds to input;

[0058] S2.5: Sampling the required corresponding bridge arm current; using the obtained specific number of bridge arm input submodules, and inputting and bypassing the submodules required to query impedance information according to f BMFS (t), and querying information when energy exchange is carried out.

[0059] According to a fourth aspect of the present application, a control terminal is provided, comprising: at least one processor; and a memory connected in communication with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the control modulation method of the information-energy integrated energy storage converter.

[0060] Compared with the prior art, the embodiments of the present application have at least one of the following beneficial effects:

[0061] (1) The information-energy integrated energy storage converter submodule provided by the embodiments of the present application, when a bipolar short circuit fault is detected at the DC side, the trigger pulses of the fourth fully controllable turn-off device and the second bidirectional thyristor in the submodule are blocked, the third fully controllable turn-off device and the first bidirectional thyristor trigger pulse signal are synchronously turned on or blocked, and the fifth fully controllable turn-off device and the third bidirectional thyristor trigger pulse signal are synchronously turned on or blocked, thereby realizing switching control mode, so that the converter using the module has DC side zero voltage ride-through capability.

[0062] (2) The information-energy integrated energy storage converter system in the embodiments of the present application has DC side short circuit fault ride-through capability, and when a short circuit fault occurs at the DC side, the DC side output voltage can be reduced to 0 under the condition that the AC side voltage of the energy storage converter remains unchanged by switching control mode;

[0063] (3) The control modulation method of the information-energy integrated energy storage converter in the embodiment of the present application can store the energy released by the renewable energy into the energy storage battery in the sub-module through switching the pulse control logic of all controllable devices in the sub-module at the time of failure, which helps to improve the utilization rate of renewable energy and provides a buffer time for the reduced output of renewable energy;

[0064] (4) The control modulation method of the information-energy integrated energy storage converter in the embodiment of the present application can select the number of devices according to the voltage stress and reasonably control the switching sequence of the driving pulse, so that the maximum voltage borne by all devices in the module is the maximum voltage of the capacitor in the sub-module, which facilitates the selection of devices;

[0065] (5) The control modulation method of the information-energy integrated energy storage converter in the embodiment of the present application uses the alternate access of the sub-modules in the non-modulation area to realize the injection of special signals and information transmission in the system, which can extract the battery impedance information while the system is transmitting energy, and helps to improve the accuracy of battery state identification. BRIEF DESCRIPTION OF DRAWINGS

[0066] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the following drawings:

[0067] Figure 1 Fig. 1 is a schematic diagram of the information-energy integrated energy storage converter sub-module in an embodiment of the present application, (a) is a first topological form, and (b) is a second topological form;

[0068] Figure 2 Fig. 2 is a schematic diagram of the information-energy integrated energy storage converter system of a preferred embodiment of the present application;

[0069] Figure 3 Fig. 3 is the switching logic of the double half-bridge sub-module of the converter in the preferred embodiment of the present application when a bipolar short circuit fault occurs at the DC side of the DC transmission system and the switching logic in the normal state;

[0070] Figure 4 Fig. 4 is a flowchart of the control modulation method of the information-energy integrated energy storage converter in an embodiment of the present application;

[0071] Figure 5 Fig. 5 is each display diagram of the impedance identification method in an embodiment of the present application, (a) is a multi-frequency point voltage spectrum diagram, (b) is a multi-frequency point voltage spectrum diagram, (c) is the obtained impedance identification result, and (d) is an impedance error comparison effect diagram. DETAILED DESCRIPTION

[0072] The application will be described in detail below with specific embodiments. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the application. These are within the scope of the present application.

[0073] As shown in the figure, in one embodiment of the application, an information and energy integrated energy storage converter sub-module is provided, which is a double half-bridge sub-module, including a conventional half-bridge unit, a special half-bridge unit and a fault ride-through branch. According to the specific connection relationship of the internal devices of the special half-bridge unit, two topological forms can be formed: Figure 1 The special half-bridge unit of the two topological forms is composed of a third fully controlled switching device T3, a third diode D2, a fourth fully controlled turn-off device T4, a fourth diode D4, a first bidirectional triode thyristor TRIAC1, a second bidirectional triode thyristor TRIAC2, a second capacitor C2, a second inductor L2 and a second battery cluster Bat2, wherein,

[0074] In the first topological form, the high-voltage side terminal of the third fully controlled turn-off device T3 is connected to the positive electrode of the second capacitor C2, the low-voltage side terminal of the third fully controlled turn-off device T3 is connected to one end of the first bidirectional triode thyristor TRIAC1, the other end of the first bidirectional triode thyristor TRIAC1 is connected to the high-voltage side terminal of the fourth fully controlled turn-off device T4, and the connection point simultaneously serves as the positive output terminal of the special half-bridge unit; the low-voltage side terminal of the fourth fully controlled turn-off device T4 is connected to one end of the second bidirectional triode thyristor TRIAC2, the other end of the second bidirectional triode thyristor TRIAC2 is connected to the negative electrode of the second capacitor C2, and the connection point simultaneously serves as the negative output terminal of the special half-bridge unit; the third diode D3 and the fourth diode D4 are respectively anti-parallel connected with the third fully controlled turn-off device T3 and the fourth fully controlled turn-off device T4; one end of the second inductor L2 is connected to the positive output terminal of the second battery cluster Bat2, and the other end is connected to the positive electrode of the second capacitor C2; the negative output terminal of the second battery cluster Bat2 is connected to the negative electrode of the second capacitor C2;

[0075]

[0076] ​In the second topological form, the high-voltage side terminal of the fourth full-control turn-off device T4 is connected to the positive electrode of the second capacitor C2, and the connecting point simultaneously serves as the positive output terminal of the special half-bridge unit; one end of the fourth full-control turn-off device T4 is connected to the low-voltage side terminal of the second bidirectional thyristor TRIAC2, the other end of the second bidirectional thyristor TRIAC2 is connected to the high-voltage side terminal of the third full-control turn-off device T3, and the connecting point simultaneously serves as the negative output terminal of the special half-bridge unit; one end of the third full-control turn-off device T3 is connected to the low-voltage side terminal of the first bidirectional thyristor TRIAC1, and the other end of the first bidirectional thyristor TRIAC1 is connected to the negative electrode of the second capacitor C2; the third diode D3 and the fourth diode D4 are respectively connected in antiparallel with the third full-control turn-off device T3 and the fourth full-control turn-off device T4; one end of the second inductor L2 is connected to the positive output terminal of the second battery cluster Bat2, and the other end is connected to the positive electrode of the second capacitor C2; the negative output terminal of the second battery cluster Bat2 is connected to the negative electrode of the second capacitor C2.

[0077] The fault ride-through branch of the two topological forms is composed of the fifth full-control turn-off device T5, the fifth diode D5 and the third bidirectional thyristor TRIAC3, wherein the low-voltage side terminal of the fifth full-control turn-off device T5 is connected to one end of the third bidirectional thyristor TRIAC3, the other end of the third bidirectional thyristor TRIAC3 is connected to the negative output terminal of the special half-bridge unit, and the high-voltage side terminal of the fifth full-control turn-off device T5 is connected to the positive electrode of the first capacitor C1 in the conventional half-bridge unit; the fifth diode D5 is connected in parallel with the fifth full-control turn-off device T5.

[0078] The positive output terminal of the conventional half-bridge unit and the negative output terminal of the special half-bridge unit respectively serve as the positive and negative output terminals of the double half-bridge sub-module.

[0079] In another embodiment of the present application, the conventional half-bridge unit of the two topological forms is composed of the first full-control turn-off device T1, the first diode D1, the second full-control turn-off device T2, the second diode D2, the first capacitor C1, the first inductor L1 and the first battery cluster Bat1; wherein the high-voltage side terminal of the first full-control turn-off device T1 is connected to the positive electrode of the first capacitor C1; the low-voltage side terminal of the first full-control turn-off device T1 is connected to the high-voltage side terminal of the second full-control turn-off device T2, and the connecting point simultaneously serves as the positive output terminal of the conventional half-bridge unit; the low-voltage side terminal of the second full-control turn-off device T2 is connected to the negative electrode of the first capacitor C1, and the connecting point simultaneously serves as the negative output terminal of the conventional half-bridge unit; the first diode D1 and the second diode D2 are respectively connected in antiparallel with the first full-control turn-off device T1 and the second full-control turn-off device T2; one end of the first inductor L1 is connected to the positive output terminal of the first battery cluster Bat1, and the other end is connected to the positive electrode of the first capacitor C1; the negative output terminal of the first battery cluster Bat1 is connected to the negative electrode of the first capacitor C1.

[0080] When a bipolar short-circuit fault is detected at the DC side, the trigger pulses of the fourth controllable turn-off device and the second triac in the sub-module in the above embodiment are blocked, the third controllable turn-off device and the first triac trigger pulse signal are synchronously turned on or blocked, and the fifth controllable turn-off device and the third triac trigger pulse signal are synchronously turned on or blocked, so as to realize switching control mode, so that the converter using the module has a DC side zero voltage ride-through capability.

[0081] In some embodiments, the controllable turn-off devices T1, T2, T3, T4 and T5 can be selected from insulated gate bipolar transistors (IGBT), metal oxide semiconductor field effect transistors (MOSFET) and the like; for the insulated gate bipolar transistor, the high-voltage side terminal is the collector, and the low-voltage side terminal is the emitter; for the metal oxide semiconductor field effect transistor, the high-voltage side terminal is the drain, and the low-voltage side terminal is the source.

[0082] Since the triac of the same voltage level has a lower conduction voltage drop than the insulated gate bipolar transistor and the diode. According to the analysis of the data manual of the existing devices, the double half-bridge sub-module proposed in the above embodiment has a lower conduction loss than all existing sub-modules with fault ride-through capability composed of conventional insulated gate bipolar transistors and diodes.

[0083] In some embodiments, when the circuit works in a normal state, the first and second triacs TRIAC1 and TRIAC2 are both in a conduction state, and the entire module is equivalent to two half-bridge modules in series, so it can output 0, V C , 2V C three levels. The fifth controllable turn-off device T5 and the third triac TRIAC3 remain in an off state and are not added to the circuit. In a normal working condition, the fault ride-through branch drive pulse signal is blocked and in an off state, so no current flows and no loss is generated.

[0084] Based on the same inventive concept, in another embodiment of the present application, an information and energy integrated energy storage converter system is provided, as shown in Figure 2 The converter in this embodiment includes three phase units, each phase unit including: an upper bridge arm and a lower bridge arm, each bridge arm including a plurality of double half-bridge sub-modules in series;

[0085] The number of double half-bridge sub-modules in series in the upper bridge arm and the lower bridge arm of each phase unit is the same;

[0086] The upper bridge arm and the lower bridge arm of each phase unit are respectively in series with a current limiting reactor;

[0087] Each phase unit has, from top to bottom: all double half-bridge sub-modules of the upper bridge arm, a reactor of the upper bridge arm, a reactor of the lower bridge arm, and all double half-bridge sub-modules of the lower bridge arm.

[0088] Three-phase AC voltage is externally connected at the connection point between the upper and lower bridge arms of each phase unit;

[0089] The positive output terminal of the uppermost dual half-bridge submodule of the upper bridge arm is connected to the positive terminal of the DC bus, and the negative output terminal of the lowermost dual half-bridge submodule of the lower bridge arm is connected to the negative terminal of the DC bus. The DC bus voltage is v. dc .

[0090] like Figure 3 The diagram shows the switching logic of the dual half-bridge submodule of the converter when a bipolar short-circuit fault occurs on the DC side of the DC transmission system, as well as the switching logic under normal conditions.

[0091] When a bipolar short-circuit fault is detected on the DC side, taking the first type of topology as an example, the control scheme for this situation involves blocking the trigger pulses of the fourth fully controllable turn-off device T4 and the second bidirectional thyristor TRIAC2 in each of the dual half-bridge submodules. The trigger pulse signals of the third fully controllable turn-off device T3 and the first bidirectional thyristor TRIAC1 are simultaneously turned on or off. The trigger pulse signals of the fifth fully controllable turn-off device T5 and the third bidirectional thyristor TRIAC3 are simultaneously turned on or off. At this time, the output voltage of the dual half-bridge submodule can be adjusted according to... Figure 3 (a) Figure 3 (b) The method shown outputs -V C +V C ;

[0092] Under normal operating conditions, the submodule can be configured as follows: Figure 3 Output +V as shown in (c), (d), (e), and (f) C +V C There are three voltage levels: 0, 0, and 1. The difference between the highest and lowest voltage levels is 2V. C Therefore, after switching the switching logic, the voltage amplitude on the AC side of the system can be kept unchanged.

[0093] Based on the same inventive concept, other embodiments of the present invention provide a control and modulation method for an integrated information and energy storage converter, such as... Figure 4 As shown, the control modulation method of the integrated energy storage converter consists of three parts: the first part is to determine the number of modules to be put into each bridge arm; the second part is to determine the integrated energy information modulation switching logic; and the third part is to determine the specific method for obtaining impedance information.

[0094] S101, Determine the modulation ratio m of the modular multilevel energy storage converter. ac (0 <m ac ≤1) and the number of submodules N (N>4) within the bridge arm, determine 1-m ac The relationship with 1 / N, when 1-m acWhen ≥1 / N, directly jump to step S103, at this time directly pass through modulation coefficient m dc , m ac forms system modulation wave, specifically:

[0095]

[0096] Wherein m dc is direct current modulation ratio, used for supporting direct current bus voltage v dc , generally v dc / N.

[0097] Otherwise, jump to S102;

[0098] S102, when 1-m ac <1 / N, adopt third harmonic injection mode, injected in-phase third harmonic modulation ratio m 3rd , modulation wave amplitude is 1 / 6 of fundamental wave, to reduce overall modulation wave peak value, leave at least 1 / N modulation ratio space, at this time system modulation wave form is:

[0099]

[0100] S103, since 1 / N modulation ratio space is reserved, at least 1 submodule in bridge arm can exist and be bypassed, therefore when adopting nearest level approximation modulation strategy, can determine input circuit and bypassed submodule according to real-time modulation ratio. Specifically, under normal working condition, nearest level approximation modulation strategy implementation method is as follows:

[0101] When j phase (j=A, B, C) modulation wave form is:

[0102]

[0103] The number of bridge arm submodules of this phase is:

[0104]

[0105] Wherein, round (x) represents taking the integer closest to x, at this time the number of bridge arm submodules of this phase is:

[0106]

[0107] When j phase (j=A, B, C) modulation wave form is:

[0108]

[0109] The number of bridge arm submodules of this phase is:

[0110]

[0111] where round(x) represents taking the integer closest to x, and the number of phase upper bridge arm sub-modules put into operation is:

[0112]

[0113] Further, the second part is implemented to determine the energy information integrated modulation switch logic, and the specific process is as follows:

[0114] S201: Determine the impedance spectrum corresponding frequency points f1 * , f2 * , f3 * , …, f i * , 50Hz, f i+1 * , …, f n * ; (the frequency increases from left to right, wherein the 50Hz frequency corresponds to the frequency of the Chinese power grid)

[0115] S202: Construct a multi-frequency point sinusoidal modulation sequence corresponding frequency signal, which is in the form of:

[0116] f1= 50Hz-f i * ; f2= 50Hz-f i-1 * ; f3= 50Hz-f i-2 * ; …; f i = 50Hz-f1 * ; …; f i+1 = f i+1 -

[0117] 50Hz; …; f n = f n -50Hz;

[0118] S203: Construct a multi-frequency point sinusoidal modulation sequence f MFS (t), which is in the form of:

[0119] f MFS (t) = sin(2·π·f1t) + sin(2·π·f2t) + … + sin(2·π·f i t) + … + sin(2·π·f n t)

[0120] S204: Based on the multi-frequency point sinusoidal sequence, the corresponding module put-in and bypass timing f BMFS (t) is obtained by taking the sign function:

[0121] fBMFS (t) = sign(sign(f MFS (t)) + 1)

[0122] Wherein, the sign function sign(x) represents, when x>0, sign(x)=1, when x<0, sign(x)=-1, when x=0, sign(x)=0, the input and bypass timing f BMFS (t) obtained by this way only contains two values of 0 and 1, wherein 0 corresponds to bypass, and 1 corresponds to input.

[0123] Through the above steps S201-S204, the switching timing of the impedance information acquisition submodule can be determined.

[0124] Further, in a preferred embodiment, the corresponding bridge arm current required for sampling is obtained according to the method of step S103, the number of bridge arm specific input submodules is obtained, and the submodules required for querying impedance information are input and bypassed according to the input and bypass timing in step S204, and the information is queried when energy exchange is performed.

[0125] In the technical solutions involved in the foregoing embodiments, impedance detection can be performed while electric energy is released and stored, without completely stopping the operation of the entire energy storage system, and without waiting until the energy storage system has no charging and discharging task to perform impedance detection. The impedance information of the module can be queried at any time, so that the impedance information of the module can be queried in real time.

[0126] As Figure 5 Fig. 6 shows the battery input and bypass timing effect and the corresponding impedance identification accuracy achieved by the control modulation method of the information and energy integrated energy storage converter. As can be seen from its (a)-(d) graphs, the battery impedance identified by the method has high accuracy at the measured frequency point, which can meet the accuracy requirement of battery impedance spectrum identification.

[0127] Based on the same inventive concept, in other embodiments of the present application, a control terminal is provided, comprising: at least one processor; and a memory communicatively connected with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute any one of the control modulation methods of the information and energy integrated energy storage converter.

[0128] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application. The above preferred features can be combined for use in the case of not conflicting with each other.

Claims

1. An information-energy integrated energy storage converter sub-module, characterized in that, The submodule is a double half-bridge submodule, comprising a normal half-bridge unit, a special half-bridge unit and a fault ride-through branch; The special half-bridge unit comprises a third fully-controlled turn-off device, a third diode, a fourth fully-controlled turn-off device, a fourth diode, a first bidirectional thyristor, a second bidirectional thyristor, a second capacitor, a second inductor and a second battery cluster; The special half-bridge unit has a topology form comprising: The third fully-controlled turn-off device is connected to the positive pole of the second capacitor at a high-voltage side terminal, and is connected to one end of the first bidirectional thyristor at a low-voltage side terminal; the other end of the first bidirectional thyristor is connected to the high-voltage side terminal of the fourth fully-controlled turn-off device, and the connecting point is simultaneously used as a positive output terminal of the special half-bridge unit; the low-voltage side terminal of the fourth fully-controlled turn-off device is connected to one end of the second bidirectional thyristor, and the other end of the second bidirectional thyristor is connected to the negative pole of the second capacitor, and the connecting point is simultaneously used as a negative output terminal of the special half-bridge unit; the third diode and the fourth diode are respectively connected in antiparallel with the third fully-controlled turn-off device and the fourth fully-controlled turn-off device; one end of the second inductor is connected to the positive output terminal of the second battery cluster, and the other end is connected to the positive pole of the second capacitor; and the negative output terminal of the second battery cluster is connected to the negative pole of the second capacitor; Alternatively, The fourth fully-controlled turn-off device is connected to the positive pole of the second capacitor at a high-voltage side terminal, and the connecting point is simultaneously used as a positive output terminal of the special half-bridge unit; the low-voltage side terminal of the fourth fully-controlled turn-off device is connected to one end of the second bidirectional thyristor, and the other end of the second bidirectional thyristor is connected to the high-voltage side terminal of the third fully-controlled turn-off device, and the connecting point is simultaneously used as a negative output terminal of the special half-bridge unit; the low-voltage side terminal of the third fully-controlled turn-off device is connected to one end of the first bidirectional thyristor, and the other end of the first bidirectional thyristor is connected to the negative pole of the second capacitor; the third diode and the fourth diode are respectively connected in antiparallel with the third fully-controlled turn-off device and the fourth fully-controlled turn-off device; one end of the second inductor is connected to the positive output terminal of the second battery cluster, and the other end is connected to the positive pole of the second capacitor; and the negative output terminal of the second battery cluster is connected to the negative pole of the second capacitor; The fault ride-through branch comprises a fifth fully-controlled turn-off device, a fifth diode and a third bidirectional thyristor, wherein the low-voltage side terminal of the fifth fully-controlled turn-off device is connected to one end of the third bidirectional thyristor, the other end of the third bidirectional thyristor is connected to the negative output terminal of the special half-bridge unit, the high-voltage side terminal of the fifth fully-controlled turn-off device is connected to the positive pole of the first capacitor in the normal half-bridge unit, and the fifth diode is connected in parallel with the fifth fully-controlled turn-off device; The positive output terminal of the normal half-bridge unit and the negative output terminal of the special half-bridge unit are respectively used as the positive and negative output terminals of the double half-bridge submodule.

2. The information-energy integrated energy accumulator inverter sub-module according to claim 1, characterized in that, The conventional half-bridge unit comprises a first fully controllable turn-off device, a first diode, a second fully controllable turn-off device, a second diode, a first capacitor, a first inductor and a first battery cluster; wherein the high-voltage side terminal of the first fully controllable turn-off device is connected to the positive electrode of the first capacitor; the low-voltage side terminal of the first fully controllable turn-off device is connected to the high-voltage side terminal of the second fully controllable turn-off device, and the connecting point is simultaneously the positive output terminal of the conventional half-bridge unit; the low-voltage side terminal of the second fully controllable turn-off device is connected to the negative electrode of the first capacitor, and the connecting point is simultaneously the negative output terminal of the conventional half-bridge unit; the first diode and the second diode are respectively anti-parallel connected to the first fully controllable turn-off device and the second fully controllable turn-off device; one end of the first inductor is connected to the positive output terminal of the first battery cluster, and the other end is connected to the positive electrode of the first capacitor; the negative output terminal of the first battery cluster is connected to the negative electrode of the first capacitor.

3. The IEES sub-module of any of claims 1-2, wherein, The fully controllable turn-off device comprises an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET); for the insulated gate bipolar transistor (IGBT), the high-voltage side terminal is the collector, and the low-voltage side terminal is the emitter; for the metal oxide semiconductor field effect transistor (MOSFET), the high-voltage side terminal is the drain, and the low-voltage side terminal is the source.

4. The information-energy integrated energy accumulator inverter sub-module according to claim 2, characterized in that, When the circuit works in a normal state, the first and second bidirectional thyristors are in a conducting state; The fifth fully controllable turn-off device and the third bidirectional thyristor remain in an off state and are not connected to the circuit.

5. An information-energy integrated energy storage inverter system, characterized in that, Each phase unit comprises an upper bridge arm and a lower bridge arm, each bridge arm comprising a plurality of double half-bridge sub-modules connected in series; the double half-bridge sub-module is the information energy integrated energy storage converter sub-module of any one of claims 1 to 4; The number of double half-bridge sub-modules connected in series in the upper bridge arm and the lower bridge arm of each phase unit is the same; The upper bridge arm and the lower bridge arm of each phase unit are respectively connected in series with current-limiting reactors; From top to bottom in each phase unit: all double half-bridge sub-modules of the upper bridge arm, the reactor of the upper bridge arm, the reactor of the lower bridge arm, all double half-bridge sub-modules of the lower bridge arm; A three-phase alternating voltage is connected to the connection between the upper bridge arm and the lower bridge arm of each phase unit; The positive output terminal of the uppermost double half-bridge sub-module of the upper bridge arm is connected to the positive electrode of a DC bus, and the negative output terminal of the lowermost double half-bridge sub-module of the lower bridge arm is connected to the negative electrode of the DC bus.

6. The information-energy integrated energy accumulator converter system according to claim 5, characterized in that, In a DC power transmission system, when a bipolar short-circuit fault is detected on the DC side, the trigger pulses of the fourth fully controllable turn-off device and the second bidirectional thyristor in each double half-bridge sub-module are blocked, the third fully controllable turn-off device and the first bidirectional thyristor trigger pulse signal are synchronously turned on or blocked, and the fifth fully controllable turn-off device and the third bidirectional thyristor trigger pulse signal are synchronously turned on or blocked.

7. A control modulation method of an information-energy integrated energy storage converter, using the information-energy integrated energy storage converter system of claim 5, characterized in that, Comprise: S1.1: Determine the DC modulation ratio m of the modular multilevel energy storage converter dc and the AC modulation ratio m ac , 0 < m dc , m ac ≤ 1, and the number of submodules within a bridge arm N, N > 4, determine the relationship between 1-m ac and 1 / N: When 1 - m ac ≥ 1 / N, directly jump to step S1.3, at this time the system modulation wave form is: Otherwise, jump to step S1.2; S1.2: When 1–m ac <1 / N, the third harmonic injection method is adopted, and the injected in-phase third harmonic modulation ratio m 3rd , the modulation wave amplitude value is 1 / 6 of the fundamental wave, to reduce the overall modulation wave peak value, leaving at least 1 / N of the modulation ratio space, at this time the system modulation wave form is: S1.3: using a nearest level modulation strategy, determining the sub-modules to be put into the circuit and bypassed according to the real-time modulation ratio; When a module in the converter needs to query key parameter information, on the basis of the nearest level approximation modulation strategy, the module is limited in the input and bypass timing, and the remaining modules in the bridge arm where the module is located continue to be input and cut off according to the nearest level approximation mode on the basis of the action of the module input or cut-off.

8. The control modulation method of the information-energy integrated energy accumulator converter according to claim 7, characterized in that, The nearest level approximation modulation strategy is adopted, the input circuit and the bypassed sub-module are determined according to the real-time modulation ratio, and the input circuit and the bypassed sub-module are determined according to the real-time modulation ratio. When the j-phase, j=A, B, C, the modulation wave form is: The number of sub-modules input in the lower bridge arm of the phase is: Wherein, round(x) represents taking the integer closest to x, at this time, the number of sub-modules input in the upper bridge arm of the phase is: When the j-phase, j=A, B, C, the modulation wave form is: The number of sub-modules input in the lower bridge arm of the phase is: Wherein, round(x) represents taking the integer closest to x, at this time, the number of sub-modules input in the upper bridge arm of the phase is:

9. The control modulation method of the information-energy integrated energy accumulator converter according to claim 7, characterized in that, When the module in the converter needs to query key parameter information, on the basis of the nearest level approximation modulation strategy, the module is limited in the input and bypass timing, and the remaining modules in the bridge arm where the module is located continue to be input and cut off according to the nearest level approximation mode on the basis of the action of the module input or cut-off. S2.1: determining the frequency points f1 * , f2 * , f3 * ,..., f i * , 50 Hz, f i+1 * ,..., f n * ; S2.2: Construct a multi-frequency point sine modulation sequence corresponding to the frequency signal, specifically: f1= 50Hz - f i * ; f2= 50Hz - f i-1 * ; f3= 50Hz - f i-2 * ;... ; f i = 50Hz - f1 * ;... ; f i+1 = f i+1 - 50Hz;... ; f n = f n - 50Hz; S2.3: Constructing the multi-frequency point sinusoidal modulation sequence f MFS (t), in particular: f MFS (t) = sin(2 - π - f1t) + sin(2 - π - f2t) +... + sin(2 - π - fnt) i t) = sin(2 - π - f1t) + sin(2 - π - f2t) +... + sin(2 - π - fnt) n t) = sin(2 - π - f1t) + sin(2 - π - f2t) +... + sin(2 - π - fnt) S2.4: Based on the multi-frequency point sinusoidal modulation sequence, the corresponding module input and bypass timing f is obtained by taking the sign function BMFS (t): f BMFS (t) = sign(sign(f MFS (t))+1) where the sign function sign(x) is defined as sign(x) = 1 for x > 0, sign(x) = -1 for x < 0, and sign(x) = 0 for x = 0; the obtained input and bypass timing f BMFS (t) contains only the two values 0 and 1, where 0 corresponds to bypass and 1 corresponds to input; S2.5: Sampling the required corresponding bridge arm current; using the obtained bridge arm specific number of input submodules, and querying the impedance information of the required submodule according to f BMFS (t) Proceeding with input and bypass, and querying information when energy exchange is performed.

10. A control terminal, characterized by, Including: At least one processor; And the memory connected with the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the control modulation method of the information energy integrated energy storage converter in any one of claims 7-9.

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