CN112366745A - Centralized modular DC Chopper topology and control method - Google Patents

Centralized modular DC Chopper topology and control method Download PDF

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CN112366745A
CN112366745A CN202011075530.4A CN202011075530A CN112366745A CN 112366745 A CN112366745 A CN 112366745A CN 202011075530 A CN202011075530 A CN 202011075530A CN 112366745 A CN112366745 A CN 112366745A
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full
capacitor
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voltage
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CN112366745B (en
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杨林刚
林磊
王霄鹤
严佳男
杨文斌
宋伟宏
高玉青
闵宽
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Huazhong University of Science and Technology
PowerChina Huadong Engineering Corp Ltd
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Huazhong University of Science and Technology
PowerChina Huadong Engineering Corp Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
    • H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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Abstract

The invention provides a centralized modular DC Chopper topology and a control method thereof, wherein the topology is a half-bridge and full-bridge mixed type centralized modular DC Chopper topology, and each bridge arm in the topology consists of N half-bridge submodules containing balance resistors, M full-bridge submodules and energy dissipation resistors. Compared with a centralized modular DC Chopper consisting of only half-bridge or full-bridge, the method has good economy. When this topology can guarantee that the major network side takes place short-circuit fault, flexible direct current transmission system safety and stability operation under the circumstances that the MMC does not lock is favorable to the trouble to be amputated the back, and the system recovers fast, utilizes the half-bridge submodule piece that contains balanced resistance to realize the voltage balance between the submodule piece simultaneously. The topology is particularly suitable for processing serious short-circuit faults of a flexible direct-current power transmission system with high capacity and high voltage level, can be effectively applied to the flexible direct-current power transmission system with wind power integration, and is arranged on the side of a main network.

Description

Centralized modular DC Chopper topology and control method
Technical Field
The invention belongs to the technical field of power electronic systems, and particularly relates to a half-bridge/full-bridge mixed centralized modular DC Chopper topology applied to main network side fault ride-through of a wind power grid-connected flexible direct current transmission system.
Background
The wind power plant is connected into a power grid through the flexible direct current transmission system, and when a voltage drop fault occurs on the main grid side, the flexible direct current transmission system has a certain isolation effect, so that the influence of the fault on the wind power plant side to cause the disconnection of the fan can be avoided. However, the output power of a Modular Multilevel Converter (MMC) on the side of the power grid is blocked, and the MMC on the side of the wind farm continuously injects active power into the direct current line, so that surplus power is generated on the direct current line, the voltage of the direct current transmission line continuously rises, and the overvoltage protection action of the direct current line is triggered. If the direct current line overvoltage protection acts, the flexible direct current power transmission system needs a long time to recover to operate. In order to solve the problems, a DC Chopper needs to be connected in parallel to a direct current line to dissipate surplus power during a fault period, so as to avoid continuous rise of direct current voltage, and thus, the fault ride-through capability of the flexible direct current power transmission system facing a grid-side short-circuit fault is improved. For economic reasons, the DC Chopper is usually installed at the MMC DC outlet on the grid side.
At present, DC choppers are classified into three types, namely, an Insulated Gate Bipolar Transistor (IGBT) direct-string type, a distributed type modular topology and a centralized type modular topology. The IGBT direct series connection type has the problem of dynamic and static voltage sharing among devices, and meanwhile, the larger power fluctuation of a direct current system can be caused, and the fault ride-through performance is influenced; the distributed modular topology adopts a modular structure to reduce the power fluctuation of a direct current system, but the cooling device is distributed, so that the manufacturing cost of equipment is greatly increased; the centralized modular topology integrates the advantages of the two devices, on one hand, the topology adopts a modular structure, the power fluctuation of a direct current system is reduced, and meanwhile, the direct series connection of switching tube IGBTs is avoided, on the other hand, the topology only needs a centralized water cooling device, the cost is low, but the topology has the defects that a large number of IGBT devices need to be adopted, and the cost is increased.
Disclosure of Invention
The invention aims to provide a half-bridge and full-bridge mixed centralized modular DC Chopper topology applied to main network side fault ride-through of a wind power grid-connected flexible direct current transmission system and a control strategy thereof. Compared with a centralized modular DC Chopper consisting of a half bridge or a full bridge, the topological structure has good economy, and meanwhile, when a short-circuit fault occurs on the main network side, the flexible direct-current power transmission system can be safely and stably operated under the condition that the MMC is not locked, so that the system can be quickly recovered after the fault is removed. The topology is particularly suitable for processing serious short-circuit faults of a flexible direct-current transmission system with high capacity and high voltage level.
To this end, according to one aspect of the invention, the following technical solutions are adopted:
the utility model provides a centralized modularization DC Chopper topology, installs in flexible direct current transmission system main network side which characterized in that: the half-bridge and full-bridge mixed centralized modular DC Chopper topology is a half-bridge and full-bridge mixed centralized modular DC Chopper topology and has the following circuit structure:
one end of each bridge arm is connected to a direct current circuit, the other end of each bridge arm is grounded, the direct current circuit, the current-limiting reactor, the N half-bridge sub-modules containing balance resistors, the M full-bridge sub-modules, the energy-consuming resistor and the ground are sequentially connected, wherein N and M are natural numbers, N is more than or equal to 1, and M is more than 1; the positive terminals of the capacitors of the full-bridge sub-module and the half-bridge sub-module are in the same direction and are close to the side with high voltage between a direct current circuit and the ground, and the capacitance values of the full-bridge sub-module and the half-bridge sub-module are the same; the two ends of the capacitor of the half-bridge submodule are connected with a switching device T3 and a balancing resistor series branch in parallel;
the switching device on the positive side of the capacitor in the half-bridge submodule is T11, and the switching device on the negative side of the capacitor in the half-bridge submodule is T12; in the full-bridge submodule, the switch device on the positive side of the capacitor at the current input end is T21, the switch device on the negative side is T22, the switch device on the positive side of the capacitor at the current output end is T23, and the switch device on the negative side of the capacitor is T24.
In the full-bridge submodule and the half-bridge submodule, due to the unidirectionality of bridge arm current, a switch tube T21 and a switch tube T24 are omitted from each full-bridge submodule, a switch tube T11 is omitted from each half-bridge submodule, and only anti-parallel diodes of the half-bridge submodule are reserved.
According to the second aspect of the invention, the following technical scheme is adopted:
the control method of the centralized modular DC Chopper topology comprises four processes of starting charging, normal operation, fault ride-through and fault recovery, and is characterized in that the starting charging, the fault ride-through and the fault recovery comprise the following steps:
the starting charging comprises the following steps:
step 1-1: in the starting process of the system, all full-bridge submodules and all half-bridge submodules are locked to charge the capacitors of all the full-bridge submodules and the half-bridge submodules;
step 1-2: when the voltage of the direct current line is charged to a rated value, all the full-bridge submodules are switched to a forward input state from a locking state, and all the half-bridge submodules are switched to an input state from the locking state;
step 1-3: detecting whether the capacitor voltage of each half-bridge submodule exceeds a rated value, if so, switching the half-bridge submodule from an on state to a capacitor balance state until the capacitor voltage of the half-bridge submodule recovers the rated value, and then recovering the half-bridge submodule to the on state;
(II) fault crossing and fault recovery comprises the following steps:
step 2-1: detecting whether the DC voltage exceeds an upper limit value VdcmaxOr isIf not, the relay protection at the AC side sends out a fault signal, if the fault is not detected, the device operates in a normal operation state, and the step 2-1 is executed in a circulating mode; if the fault is detected, turning to the step 2-2;
step 2-2: cutting off all half-bridge sub-modules;
step 2-3: generating a bridge arm PWM wave during fault ride-through to control according to power to be dissipated and total capacitance energy of the bridge arm submodule;
step 2-4: respectively calculating the number of full-bridge submodules needing forward input and reverse input, sequencing the full-bridge submodules according to capacitor voltage, inputting the full-bridge submodules needing the forward input in the order from the capacitor voltage being small to the capacitor voltage being large, and inputting the full-bridge submodules needing the reverse input in the order from the capacitor voltage being large to the capacitor voltage being small;
step 2-5: detecting whether the DC voltage is lower than a lower limit value VdcminOr whether a fault recovery signal sent by the relay protection at the alternating current side is detected or not, and if the fault recovery is not detected, turning to the step 2-3; if the fault recovery is detected, entering the step 2-6;
step 2-6: inputting all half-bridge sub-modules, detecting whether the capacitor voltage in the half-bridge sub-modules exceeds a rated value, and if so, enabling the half-bridge sub-modules with the capacitor voltage exceeding the rated value to enter a capacitor balance mode until the capacitor voltage is reduced to be close to the rated value; when the capacitor voltage is near the nominal value, go to step 2-1.
Further, the bridge arm voltage during the fault ride-through period is controlled by Pulse Width Modulation (PWM), wherein the amplitude of the negative half-wave of the PWM is-0.2VdcThe positive half-wave amplitude is larger than zero; the duty ratio of the PWM wave is used for adjusting the charge-discharge balance of the bridge arm in one period, and the amplitude of the positive half wave is used for adjusting the power dissipated by the DC Chopper.
The number relation of the full-bridge sub-modules and the half-bridge sub-modules satisfies the following conditions:
Figure BDA0002716748780000041
in the formula, M is the number of full-bridge submodules, N is the number of half-bridge submodules, Varmp_pumaxIs the per unit value of the maximum PWM positive half-wave amplitude value required.
Compared with the prior art, the invention improves the centralized modular DC Chopper from the cost, provides a topology of the centralized modular DC Chopper with mixed half-bridge and full-bridge on the premise of ensuring the fault ride-through capability of the flexible direct current system, and provides a control strategy of the topology. The half-bridge and full-bridge mixed DC Chopper topology and the control method thereof can be effectively applied to a wind power grid-connected flexible direct current transmission system, are arranged on the side of a main network, and have the following beneficial technical effects:
(1) compared with the centralized modularized DC Chopper consisting of the full-bridge sub-modules and the energy dissipation resistors, the DC Chopper topology disclosed by the invention needs fewer IGBT and diode devices; compared with a centralized modular DC Chopper or a distributed modular DC Chopper which only consists of half-bridge sub-modules and energy dissipation resistors, although more IGBTs and diodes are needed, the cost of the cooling device is lower, and the cost saved on the cooling device exceeds the added cost of the IGBTs and the diodes;
(2) compared with the method for adjusting the dissipated power by using the duty ratio and realizing the charging and discharging energy balance of the bridge arm by using the correction voltage, the method for controlling the bridge arm voltage has the function relation of single values, can adjust the bridge arm voltage in a one-to-one correspondence manner, and is simple in control system;
(3) the invention designs a discharge loop for the half-bridge submodule, which is beneficial to maintaining the balance of capacitance and voltage between the half-bridge submodule and the full-bridge submodule.
Drawings
Fig. 1(a) is a diagram of the operation state of the half-bridge submodule with balanced resistors in the cutting-off state.
Fig. 1(b) is an operation state diagram of a half-bridge submodule including a balance resistor in an on state.
Fig. 1(c) is a diagram of the operation state of the half-bridge submodule with balanced resistance in the capacitance balanced state.
Fig. 2(a) is a half-bridge, full-bridge hybrid centralized modular DC Chopper topology.
Fig. 2(b) is a simplified half-bridge and full-bridge hybrid centralized modular DC Chopper topology.
FIG. 3(a) is a graph of the bridge arm voltage of DC Chopper during normal system operation.
FIG. 3(b) is a graph of bridge arm voltage during a system fault for DC Chopper.
FIG. 4(a) is a control flow diagram of the DC Chopper topology.
FIG. 4(b) is a control block diagram of the DC Chopper topology.
Fig. 5(a) is a PWM waveform diagram of the DC Chopper arm voltage.
FIG. 5(b) shows the duty ratio D and the positive half-wave bridge arm voltage amplitude Varmp_puA graph of the relationship (c).
FIG. 5(c) shows the average dissipated power P in one cyclediss_puAnd Varmp_puA graph of the relationship (c).
Detailed Description
To describe the present invention more specifically, the following detailed description of the technical solution of the present invention and the related principles thereof are provided with reference to the accompanying drawings and the detailed description.
The full-bridge submodule and the half-bridge submodule are in a topology shown in fig. 2(a), the full-bridge submodule is in a classic full-bridge structure, and the half-bridge submodule is connected with a switching device T3 and a balancing resistor series branch in parallel at two ends of a capacitor on the basis of the classic half-bridge structure; the switching device T3 is connected in series with the balancing resistor.
The switching device on the positive side of the capacitor in the half-bridge submodule is T11, and the switching device on the negative side of the capacitor in the half-bridge submodule is T12; in the full-bridge submodule, the switch device on the positive side of the capacitor at the current input end is T21, the switch device on the negative side is T22, the switch device on the positive side of the capacitor at the current output end is T23, and the switch device on the negative side of the capacitor is T24.
The switching devices T21, T22, T23 and T24 in the full-bridge sub-module and the switching devices T11, T12 and T3 in the half-bridge sub-module all employ IGBTs.
The switching devices T11, T12 and T3 in the half bridge sub-module are connected in anti-parallel with diodes D11, D12 and D3, respectively. The switching devices T21, T22, T23 and T24 in the full bridge sub-module are connected in anti-parallel with diodes D21, D22, D23 and D24, respectively.
The half-bridge submodule with balanced resistors has three working states, namely, cut-off state, input state and capacitance balanced state, as shown in table 1. The three operating states are shown in fig. 1(a), 1(b) and 1(c), wherein the dashed lines indicate the operating circuits. When the half-bridge submodule is in a cut-off state, the voltage of a port is 0, which is equivalent to the short circuit of the submodule; when the half-bridge submodule is in the on state, the port voltage is equal to the capacitor voltage Uc(ii) a When the half-bridge sub-modules are in a capacitance balance state, the switch tube T3 is conducted, redundant energy in the capacitor is dissipated through the balance resistor, direct current voltage is shared by all the sub-modules in the bridge arm, capacitor voltage of the half-bridge sub-modules is lower and lower, capacitor voltage of the full-bridge sub-modules is higher and higher until the voltage of the half-bridge sub-modules is reduced to be close to a rated value, at the moment, the voltage of the full-bridge sub-modules is also increased to be close to the rated value, and therefore sub-module capacitance voltage balance is.
Table 1: working principle of half-bridge submodule containing balance resistor
Figure BDA0002716748780000061
Figure BDA0002716748780000071
As shown in fig. 2(a), the topology of the half-bridge and full-bridge hybrid centralized modular DC Chopper of the present invention is characterized in that:
one end of each bridge arm is connected to a direct current circuit, the other end of each bridge arm is grounded, the direct current circuit, a current-limiting reactor, N half-bridge submodules (HBSMn, N is more than or equal to 1 and less than or equal to N) containing balance resistors, M full-bridge submodules (FBSMm, M is more than or equal to 1 and less than or equal to M), an energy-consuming resistor and the ground are sequentially connected, wherein N and M are natural numbers, N is more than or equal to 1, and M is; the positive terminals of the capacitors of the full-bridge sub-module and the half-bridge sub-module are in the same direction and are close to the side with high voltage between a direct current circuit and the ground, and the capacitance values of the full-bridge sub-module and the half-bridge sub-module are the same; the two ends of the capacitor of the half-bridge submodule are connected with a switching device T3 and a balancing resistor series branch in parallel; the aforementioned HBSM is an abbreviation for Half-Bridge SM, and FBSM is an abbreviation for Full-Bridge SM.
Due to the unidirectionality of the bridge arm currents, T21 and T24 may be omitted for each full-bridge submodule, and T11 may be omitted for each half-bridge submodule, with only its antiparallel diodes remaining, as shown in fig. 2 (b).
The control method of the half-bridge and full-bridge mixed centralized modular DC Chopper topology comprises four processes of starting charging, normal operation, fault ride-through and fault recovery, wherein a control block diagram is shown in FIG. 4(a), and the specific working process is as follows:
the starting charging comprises the following steps:
step 1-1: in the starting process of the system, all full-bridge submodules and all half-bridge submodules are locked to charge the capacitors of all the submodules;
step 1-2: when the voltage of the direct current line is charged to a rated value, all the full-bridge submodules are switched to a forward input state from a locking state, and all the half-bridge submodules are switched to an input state from the locking state;
step 1-3: detecting whether the capacitor voltage of each half-bridge submodule exceeds a rated value, if so, switching the half-bridge submodule from an on state to a capacitor balance state until the capacitor voltage of the half-bridge submodule recovers the rated value, and then recovering the half-bridge submodule to the on state;
and (ii) in a normal operation state, as shown in fig. 3(a), all half-bridge sub-modules in the bridge arm are in an on state, all full-bridge sub-modules are in a forward on state, all sub-modules share the whole direct-current voltage, and at this time, the voltage across the energy dissipation resistor is 0, and power is not dissipated.
(III) the fault crossing and fault recovery comprises the following steps:
step 2-1: detecting whether the DC voltage exceeds an upper limit value VdcmaxOr whether the relay protection at the AC side is detected to send out a fault signal or not, and if the fault is not detectedIf so, the device operates in a normal operation state and executes the step 2-1 in a circulating manner; if the fault is detected, turning to the step 2-2;
step 2-2: cutting off all half-bridge sub-modules, and only keeping full-bridge sub-modules, as shown in fig. 3 (b);
step 2-3: generating a bridge arm PWM wave during fault ride-through to control according to power to be dissipated and total energy of full-bridge sub-module capacitors in a bridge arm;
step 2-4: respectively calculating the number of full-bridge submodules needing forward input and reverse input, sequencing the full-bridge submodules according to capacitor voltage, inputting the full-bridge submodules needing the forward input in the order from the capacitor voltage being small to the capacitor voltage being large, and inputting the full-bridge submodules needing the reverse input in the order from the capacitor voltage being large to the capacitor voltage being small;
step 2-5: detecting whether the DC voltage is lower than a lower limit value VdcminOr whether the relay protection at the alternating current side is detected to send a fault recovery signal or not is detected, and if the fault recovery is not detected, the step 2-3 is carried out; if the fault recovery is detected, entering the step 2-6;
step 2-6: inputting all half-bridge sub-modules, detecting whether the capacitor voltage in the half-bridge sub-modules exceeds a rated value, and if so, enabling the half-bridge sub-modules with the capacitor voltage exceeding the rated value to enter a capacitor balance mode until the capacitor voltage is reduced to be close to the rated value; when the capacitor voltage is near the nominal value, go to step 2-1.
During the fault period, after the half-bridge sub-module is cut off, the bridge arm voltage only containing the full-bridge sub-module is controlled by PWM waves, wherein the amplitude of the negative half-wave of the PWM waves is-0.2VdcThe positive half-wave amplitude is greater than zero. The duty ratio of the PWM wave is used to adjust the charging and discharging balance of the bridge arm in one period, the amplitude of the PWM positive half wave is used to adjust the power dissipated by the DC Chopper, and the control block diagram is shown in fig. 4 (b). Let the cycle of the bridge arm PWM wave be T and the duty ratio be D, so the time of the negative half-wave of the bridge arm is T.D, the time of the positive half-wave is T (1-D), and the bridge arm PWM wave is shown in FIG. 5 (a).
The relationship among the direct current voltage, the bridge arm voltage and the energy consumption resistance voltage is
Varm+VRdiss＝Vdc (1)
In the formula, VarmIs bridge arm voltage, VdcIs a direct-current line voltage, VRdissIs the voltage of the energy dissipation resistor (the same below).
Bridge arm charging power P in positive half wavecIs composed of
Figure BDA0002716748780000091
In the formula, VarmpIs the positive half-wave amplitude, R, of the bridge arm voltagedissIs the resistance value of the energy consumption resistor. Charging power P of bridge armcWith bridge arm voltage VarmpThe change being with respect to VdcA/2 symmetrical parabola.
Bridge arm discharge power P in negative half-wavedIs composed of
Figure BDA0002716748780000092
In order to ensure that the charge and discharge energy of the bridge arm is balanced in one period, the formula (4) needs to be satisfied.
Figure BDA0002716748780000093
Calculating to obtain duty ratio D and positive half-wave V of bridge arm voltagearmpIn a relationship of
Figure BDA0002716748780000094
In the formula, Varmp_puPer unit value, i.e. V, of the positive half-wave of the bridge arm voltagearmp_pu＝Varmp/Vdc(the same applies below). As shown in fig. 5(b), when the amplitude of the PWM positive half-wave varies from 0 to 1pu, the charge-discharge energy balance of the bridge arm in one period can be achieved by adjusting the duty ratio.
Average dissipation power P of energy dissipation resistor in one perioddissIs calculated by the formula
Figure BDA0002716748780000095
Under the condition of maintaining the energy balance of the bridge arm, namely substituting the formula (5) into the formula (6), obtaining the average dissipated power P in one perioddissAnd PWM positive half wave amplitude Varmp_puIn a relationship of
Figure BDA0002716748780000101
Defining a nominal dissipation power Ps＝Vdc 2/RdissSo the per unit value P of the average dissipated power in one cyclediss_puAnd Varmp_puIn a relationship of
Figure BDA0002716748780000102
Per unit value P of average dissipated power in one cyclediss_puAnd Varmp_puFIG. 5(c) shows the relationship (2). Therefore, the required maximum bridge arm voltage V can be calculated by combining the fault ride-through capability of the MMC and the fault ride-through requirementarmp_pumaxThen, the ratio of the full-bridge sub-module to the half-bridge sub-module is obtained, and the relation is
Figure BDA0002716748780000103
In the formula, M is the number of full-bridge submodules, and N is the number of half-bridge submodules.
The embodiments described above are intended to facilitate the understanding and appreciation of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to the above-described embodiments may be made, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications to the present invention based on the disclosure of the present invention within the protection scope of the present invention.

Claims (5)

1. The utility model provides a centralized modularization DC Chopper topology, installs in flexible direct current transmission system main network side which characterized in that: the half-bridge and full-bridge mixed centralized modular DC Chopper topology is a half-bridge and full-bridge mixed centralized modular DC Chopper topology and has the following circuit structure:
one end of each bridge arm is connected to a direct current circuit, the other end of each bridge arm is grounded, the direct current circuit, the current-limiting reactor, the N half-bridge sub-modules containing balance resistors, the M full-bridge sub-modules, the energy-consuming resistor and the ground are sequentially connected, wherein N and M are natural numbers, N is more than or equal to 1, and M is more than 1; the positive terminals of the capacitors of the full-bridge sub-module and the half-bridge sub-module are in the same direction and are close to the side with high voltage between a direct current circuit and the ground, and the capacitance values of the full-bridge sub-module and the half-bridge sub-module are the same; the two ends of the capacitor of the half-bridge submodule are connected with a switching device T3 and a balancing resistor series branch in parallel;
the switching device on the positive side of the capacitor in the half-bridge submodule is T11, and the switching device on the negative side of the capacitor in the half-bridge submodule is T12; in the full-bridge submodule, the switch device on the positive side of the capacitor at the current input end is T21, the switch device on the negative side is T22, the switch device on the positive side of the capacitor at the current output end is T23, and the switch device on the negative side of the capacitor is T24.
2. The centralized modular DC Chopper topology of claim 1, wherein in the full-bridge and half-bridge sub-modules, each full-bridge sub-module omits switching devices T21 and T24 and each half-bridge sub-module omits switching device T11 but retains its anti-parallel diodes due to the unidirectionality of the bridge arm currents.
3. A control method of a centralized modular DC Chopper topology according to claim 1 or 2, comprising four procedures of start-up charging, normal operation, fault ride-through and fault recovery, characterized in that the start-up charging, fault ride-through and fault recovery respectively comprise the following steps:
the starting charging comprises the following steps:
step 1-1: in the starting process of the system, the full-bridge sub-modules and the half-bridge sub-modules are locked, and capacitors of all the full-bridge sub-modules and the half-bridge sub-modules are charged;
step 1-2: when the voltage of the direct current line is charged to a rated value, the full-bridge submodule is switched to a forward input state from a locking state, and the half-bridge submodule is switched to an input state from the locking state;
step 1-3: detecting whether the capacitor voltage of each half-bridge submodule exceeds a rated value, if so, switching the half-bridge submodule from an on state to a capacitor balance state until the capacitor voltage of the half-bridge submodule recovers the rated value, and then recovering the half-bridge submodule to the on state;
(II) fault crossing and fault recovery comprises the following steps:
step 2-1: detecting whether the DC voltage exceeds an upper limit value VdcmaxOr whether the relay protection at the alternating current side is detected to send out a fault signal or not, if the fault is not detected, the device operates in a normal operation state, and the step 2-1 is executed in a circulating mode; if the fault is detected, turning to the step 2-2;
step 2-2: cutting off all half-bridge sub-modules;
step 2-3: generating a bridge arm PWM wave during fault ride-through to control according to power to be dissipated and total capacitance energy of the bridge arm submodule;
step 2-4: respectively calculating the number of full-bridge submodules needing forward input and reverse input, sequencing the full-bridge submodules according to capacitor voltage, inputting the full-bridge submodules needing the forward input in the order from the capacitor voltage being small to the capacitor voltage being large, and inputting the full-bridge submodules needing the reverse input in the order from the capacitor voltage being large to the capacitor voltage being small;
step 2-5: detecting whether the DC voltage is lower than a lower limit value VdcminOr whether a fault recovery signal sent by the relay protection at the alternating current side is detected or not, and if the fault recovery is not detected, turning to the step 2-3; if the fault recovery is detected, entering the step 2-6;
step 2-6: inputting all half-bridge sub-modules, detecting whether the capacitor voltage in each half-bridge sub-module exceeds a rated value, and if so, entering a capacitor balance mode until the capacitor voltage is reduced to be close to the rated value; when the capacitor voltage is near the nominal value, go to step 2-1.
4. The control method of claim 3, wherein the bridge arm voltage during fault ride-through is controlled using PWM having a negative half-wave amplitude of-0.2VdcThe positive half-wave amplitude is larger than zero; the duty ratio of the PWM wave is used for adjusting the charge-discharge balance of the bridge arm in one period, and the amplitude of the positive half wave is used for adjusting the power dissipated by the DC Chopper.
5. The control method of claim 4, wherein the number relationship between the full-bridge sub-modules and the half-bridge sub-modules is as follows:
Figure FDA0002716748770000031
in the formula, M is the number of full-bridge submodules, N is the number of half-bridge submodules, Varmp_pumaxIs the per unit value of the maximum PWM positive half-wave amplitude value required.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113675875A (en) * 2021-09-06 2021-11-19 国网江苏省电力有限公司电力科学研究院 Direct current engineering complete set energy consumption device and control system thereof
CN113671367A (en) * 2021-08-30 2021-11-19 华北电力大学 Converter valve fault self-ride-through equivalent test method and application thereof
CN113708654A (en) * 2021-07-27 2021-11-26 华北电力大学 Flexible direct-current converter valve integrating surplus power dissipation function and control method
CN114167167A (en) * 2021-11-15 2022-03-11 许继集团有限公司 Modular multilevel converter short-circuit current test device and test method
CN115441739A (en) * 2022-09-02 2022-12-06 东北林业大学 Direct current energy consumption device based on offshore wind power generation and control method thereof

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105450070A (en) * 2016-01-25 2016-03-30 华北电力大学 Non-auxiliary-capacitance type half-bridge/full-bridge parallel-serial MMC self-voltage-sharing topology based on inequality constraints
CN107994613A (en) * 2017-12-22 2018-05-04 华中科技大学 A kind of the alternating current-direct current fault traversing and energy dissipation method of the soft direct join net of wind-powered electricity generation
CN108336752A (en) * 2018-04-04 2018-07-27 国网江苏省电力有限公司泗洪县供电分公司 The capacitor voltage balance method of the uncontrollable pre-charging stage of modularization multi-level converter
JP6440923B1 (en) * 2017-09-26 2018-12-19 三菱電機株式会社 Power converter
CN109256964A (en) * 2018-10-15 2019-01-22 中国矿业大学 A kind of MMC model predictive control method of half-bridge and the mixing of full-bridge submodule
US20200076321A1 (en) * 2017-01-16 2020-03-05 Nr Electric Co., Ltd Charging method for sub-module based hybrid converter
CN110867884A (en) * 2019-11-18 2020-03-06 西安西电电力系统有限公司 Energy consumption module, offshore wind power flexible direct current delivery system and fault ride-through strategy
CN111404191A (en) * 2020-04-19 2020-07-10 中国电建集团华东勘测设计研究院有限公司 MMC converter station low-voltage ride through method and control system based on resonance controller

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105450070A (en) * 2016-01-25 2016-03-30 华北电力大学 Non-auxiliary-capacitance type half-bridge/full-bridge parallel-serial MMC self-voltage-sharing topology based on inequality constraints
US20200076321A1 (en) * 2017-01-16 2020-03-05 Nr Electric Co., Ltd Charging method for sub-module based hybrid converter
JP6440923B1 (en) * 2017-09-26 2018-12-19 三菱電機株式会社 Power converter
CN107994613A (en) * 2017-12-22 2018-05-04 华中科技大学 A kind of the alternating current-direct current fault traversing and energy dissipation method of the soft direct join net of wind-powered electricity generation
CN108336752A (en) * 2018-04-04 2018-07-27 国网江苏省电力有限公司泗洪县供电分公司 The capacitor voltage balance method of the uncontrollable pre-charging stage of modularization multi-level converter
CN109256964A (en) * 2018-10-15 2019-01-22 中国矿业大学 A kind of MMC model predictive control method of half-bridge and the mixing of full-bridge submodule
CN110867884A (en) * 2019-11-18 2020-03-06 西安西电电力系统有限公司 Energy consumption module, offshore wind power flexible direct current delivery system and fault ride-through strategy
CN111404191A (en) * 2020-04-19 2020-07-10 中国电建集团华东勘测设计研究院有限公司 MMC converter station low-voltage ride through method and control system based on resonance controller

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113708654A (en) * 2021-07-27 2021-11-26 华北电力大学 Flexible direct-current converter valve integrating surplus power dissipation function and control method
CN113671367A (en) * 2021-08-30 2021-11-19 华北电力大学 Converter valve fault self-ride-through equivalent test method and application thereof
CN113671367B (en) * 2021-08-30 2023-03-14 华北电力大学 Converter valve fault self-ride-through equivalent test method and application thereof
CN113675875A (en) * 2021-09-06 2021-11-19 国网江苏省电力有限公司电力科学研究院 Direct current engineering complete set energy consumption device and control system thereof
CN113675875B (en) * 2021-09-06 2024-02-20 国网江苏省电力有限公司电力科学研究院 Complete energy consumption device for direct current engineering and control system thereof
CN114167167A (en) * 2021-11-15 2022-03-11 许继集团有限公司 Modular multilevel converter short-circuit current test device and test method
CN114167167B (en) * 2021-11-15 2024-02-09 许继集团有限公司 Short-circuit current test device and test method for modularized multi-level converter
CN115441739A (en) * 2022-09-02 2022-12-06 东北林业大学 Direct current energy consumption device based on offshore wind power generation and control method thereof
CN115441739B (en) * 2022-09-02 2024-04-26 东北林业大学 DC energy consumption device based on offshore wind power generation and control method thereof

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