CN106787876A - A kind of modularization multi-level converter and its high pressure valve group fault to ground guard method - Google Patents

Abstract

A kind of modularization multi-level converter of the present invention and its high pressure valve group fault to ground guard method, simple structure, low cost are easy to control, and protection value is adjusted accurately.It is included in DC side series connection and in AC high pressure valve group and low pressure valve group in parallel；High pressure valve group and each of low pressure valve group are constituted by upper bridge arm and lower bridge arm, and upper bridge arm and lower bridge arm are constituted by multiple blocking-up type submodules and multiple half-bridge sub-module cascades；Or constituted by multiple blocking-up type sub-module cascades；The bypass that break-make is controlled by IGCT is respectively arranged with upper bridge arm and lower bridge arm；During generation high pressure valve group fault to ground, apply trigger signal by IGCT in bypass so that fault current flows through bypass, it is to avoid fault current flows through submodule and charged to submodule electric capacity.By corresponding to the bypass that each bridge arm is formed, when there is high pressure valve group fault to ground, overvoltage protection can be provided for submodule by the on off state of IGCT in rationally control bypass.

Description

A kind of modularization multi-level converter and its high pressure valve group fault to ground guard method

Technical field

The present invention relates to technical field of direct current power transmission, specially a kind of modularization multi-level converter and its high pressure valve group pair Earth fault guard method.

Background technology

Modularization multi-level converter (Modular Multilevel Converter, MMC) technology has construction module The advantages of changing, be easy to extension, since proposition, has been widely used in direct current transportation field.

With the maturation of MMC technologies, MMC will be to higher voltage grade and more high power development.In high pressure, high-power MMC In (such as ± 800kV, the MMC of 5000MW), the valve group of MMC generally uses the scheme of high and low pressure valve group series connection, to reduce to list The demand of individual transverter rated power, and when single valve group hinders out of service for some reason, non-faulting valve group still can maintained just Often operation.

High and low pressure valve group tandem plan exist a serious problems i.e., the direct current negative electrode bus or high pressure of high pressure valve group In valve group during bridge arm low-voltage end fault to ground, the upper bridge arm of high pressure valve group or high pressure valve group will carry rating plate direct current over the ground Pressure, the rating plate voltage-to-ground will charge to failure valve group/failure bridge arm, the submodule electricity of causing trouble valve group or failure bridge arm Hold voltage to steeply rise, so as to damage failure valve group/bridge arm.

The high and low pressure side parallel connection that the existing technology for tackling such failure is usually in each bridge arm or each submodule keeps away Thunder device, so as to be that bridge arm or submodule provide overvoltage protection.Such scheme has a drawback in that the specified electricity to arrester Stream is high with energy requirement, and so as to improve system cost, in such scheme, the level of protection of arrester of how adjusting is also one big Problem.Protection of arrester level adjust it is higher then cannot be for bridge arm/submodule provides effective overvoltage protection, arrester is protected Shield level is adjusted relatively low, and arrester will flow through certain electric current during stable state, increases the loss of system, and high cost, protection are fixed Value is difficult to adjust.

The content of the invention

For problems of the prior art, the present invention provides a kind of modularization multi-level converter and its high pressure valve group Fault to ground guard method, simple structure, low cost is easy to control, and protection value is adjusted accurately.

The present invention is to be achieved through the following technical solutions：

A kind of modularization multi-level converter of the present invention, is included in DC side series connection and in AC high pressure valve group in parallel With low pressure valve group；Described high pressure valve group and low pressure valve group it is each by upper bridge arm and lower bridge arm composition, upper bridge arm and lower bridge Arm is constituted by multiple blocking-up type submodules and multiple half-bridge sub-module cascades；

The bypass that break-make is controlled by IGCT is respectively arranged with described upper bridge arm and lower bridge arm；Generation high pressure valve group pair During earth fault, apply trigger signal by IGCT in bypass so that fault current flows through bypass, it is to avoid fault current flows through Submodule charges to submodule electric capacity.

Preferably, described bypass includes and the one-to-one bypass branch of submodule；Described bypass branch includes every One that the IGCT or output end of the two reverse parallel connections connection in parallel of individual blocking-up type submodule voltage output end are in parallel is two-way IGCT, and each half-bridge submodule voltage output end IGCT in parallel or two IGCTs of reverse parallel connection connection Or a bidirectional thyristor；One IGCT anode connects the high-voltage output end of half-bridge submodule, a negative electrode for IGCT Connect the low-voltage output of half-bridge submodule.

Preferably, described bypass includes including each with the one-to-one bypass branch of valve section, described bypass branch By a bidirectional thyristor in parallel between the high-voltage output end and low-voltage output of blocking-up type submodule valve section in series In parallel one between valve, and each high-voltage output end and low-voltage output by semi-bridge type submodule valve section in series Unidirectional thyristor valve or a bi-directional thyristor valve；The anode of one unidirectional thyristor valve connects correspondence half-bridge submodule valve section High-voltage output end, the negative electrode of a unidirectional thyristor valve connects the low-voltage output of correspondence half-bridge submodule valve section.

Preferably, described bypass includes respectively being grouped one-to-one bypass branch with valve section；By blocking-up type submodule Valve section in series is divided into multigroup；Half-bridge submodule valve section in series is divided into multigroup；

Described bypass branch includes every group of output end of blocking-up type submodule bi-directional thyristor valve in parallel, and The output end of an every group of semi-bridge type submodule unidirectional thyristor valve in parallel or a bi-directional thyristor valve；This unidirectional brilliant The anode of gate tube valve connects every group of high-voltage output end of half-bridge submodule of correspondence, and the negative electrode of a unidirectional thyristor valve connects correspondence often The low-voltage output of group half-bridge submodule valve section.

A kind of modularization multi-level converter of the present invention, connects and in AC high pressure valve group in parallel and low in DC side Pressure valve group；Described high pressure valve group and each of low pressure valve group is constituted by upper bridge arm and lower bridge arm, and upper bridge arm and lower bridge arm are equal It is made up of multiple blocking-up type sub-module cascades；

The bypass controlled by IGCT is respectively arranged with described upper bridge arm and lower bridge arm；The event over the ground of generation high pressure valve group During barrier, apply trigger signal by IGCT in bypass so that fault current flows through bypass, it is to avoid fault current flows through submodule Block charges to submodule electric capacity.

Preferably, described bypass includes and the one-to-one bypass branch of blocking-up type submodule；Described bypass branch IGCT or one including each blocking-up type submodule voltage output end IGCT in parallel or two reverse parallel connection connections Individual bidirectional thyristor；One IGCT anode connects the high-voltage output end of blocking-up type submodule, and the negative electrode of IGCT connects blocking-up type The low-voltage output of module.

Preferably, described bypass includes including each with the one-to-one bypass branch of valve section, described bypass branch By a unidirectional thyristor in parallel between the high-voltage output end and low-voltage output of blocking-up type submodule valve section in series Valve or a bi-directional thyristor valve；The anode of a described unidirectional thyristor valve connects the high pressure of correspondence blocking-up type submodule valve section Output end, the negative electrode of unidirectional thyristor valve connects the low-voltage output of correspondence blocking-up type submodule valve section.

Further, described bypass includes respectively being grouped one-to-one bypass branch with valve section；By blocking-up type submodule Valve section in series is divided into multigroup；

Described bypass branch includes every group of output end of blocking-up type submodule unidirectional thyristor valve or in parallel Individual bi-directional thyristor valve；The anode of one unidirectional thyristor valve connects every group of high-voltage output end of blocking-up type submodule of correspondence, should The negative electrode of one unidirectional thyristor valve connects every group of low-voltage output of blocking-up type submodule valve section of correspondence.

Further, the unidirectional thyristor valve is formed by multiple Thyristors in series；The bi-directional thyristor valve is by multiple The unidirectional thyristor that anti-parallel thyristor is in series or is in series by multiple bidirectional thyristors or is coupled by two inverse parallels Valve is formed in parallel.

Further, it is characterised in that be in series with current-limiting resistance in each bypass branch respectively, current-limiting resistance correspondence is connected In the low-voltage output or high-voltage output end of bypass branch.

Further, the resistance of described current-limiting resistance enables to bypass IGCT that overcurrent does not occur, and causes mould The AC circuit breaker of block multilevel converter does not cut-off because of overcurrent, and causes that the pressure drop on current-limiting resistance is in parallel less than it The capacitance voltage sum of all submodules of connection.

Further, the blocking-up type submodule is the modularization multi-level converter for possessing blocking direct fault current ability Power model, can using full-bridge submodule, clamp Shuangzi module, diode clamp bit submodule, from resistance type submodule and crosslinking Any one in submodule.

A kind of high pressure valve group fault to ground guard method of modularization multi-level converter of the present invention, in modular multilevel The bypass that break-make is controlled by IGCT is set up respectively on the upper bridge arm of each phase and lower bridge arm in transverter；Appoint when there is high pressure valve group In one phase during the earth fault of bridge arm arbitrfary point, trigger pulse is applied to the IGCT in the bypass of bridge arm in each phase of high pressure valve group, Make the corresponding by-path turn-on of bridge arm in each phase of high pressure valve group so that fault current flows through bypass.

Preferably, at the IGCT in the bypass also including bridge arm and each bridge arm of low pressure valve group under maintenance each phase of high pressure valve group In blocking.

Preferably, trigger pulse is applied to be continuously applied or only to the IGCT in the bypass of bridge arm in each phase of high pressure valve group Apply once.

Preferably, specifically, after bridge arm arbitrfary point earth fault in any phase of high pressure valve group is monitored, only to high pressure valve The IGCT of forward conduction is controlled to apply a trigger pulse in each phase of group in the bypass of bridge arm；Maintain high pressure valve group and low pressure valve Group every other bypass in IGCT locking, and locking high pressure valve group and low pressure valve group whole all-controlling power electronics devices Trigger pulse.

Further, bypass includes controlling the IGCT of reverse-conducting, when monitoring in any phase of high pressure valve group that bridge arm appoints After meaning point earth fault, only the IGCT for controlling forward conduction in the bypass of bridge arm in each phase of high pressure valve group is applied once to trigger Pulse, when monitoring that the IGCT of control forward conduction in the bypass of bridge arm in failure phase is constantly in conducting state, to each phase The IGCT of reverse-conducting is controlled to be continuously applied trigger pulse in the bypass of upper bridge arm；Maintain the institute of high pressure valve group and low pressure valve group IGCT locking in thering are other to bypass, and whole all-controlling power electronics devices of locking high pressure valve group and low pressure valve group trigger arteries and veins Punching.

A kind of high pressure valve group fault to ground guard method of modularization multi-level converter of the present invention, in modular multilevel The bypass that break-make is controlled by IGCT is set up respectively on the upper bridge arm of each phase and lower bridge arm in transverter；Appoint when there is high pressure valve group Under one phase during the earth fault of bridge arm arbitrfary point, trigger pulse is applied to the IGCT in the bypass of each phase bridge arm of high pressure valve group, made The corresponding by-path turn-on of each phase bridge arm of high pressure valve group so that fault current flows through bypass.

Preferably, also it is in including the IGCT in the bypass for maintaining each phase bridge arm of low pressure valve group and each bridge arm of low pressure valve group Blocking.

Preferably, trigger pulse is applied to be continuously applied or only applying to the IGCT in the bypass of each phase bridge arm of high pressure valve group Plus once.

Preferably, specifically, monitoring under the generation any phase of high pressure valve group after the earth fault of bridge arm arbitrfary point, only to high pressure The IGCT of forward conduction is controlled to apply a trigger pulse in the bypass of each phase bridge arm of valve group；Maintain all sides of low pressure valve group Road IGCT is in blocking, and whole all-controlling power electronics devices of locking high pressure valve group and low pressure valve group trigger arteries and veins Punching.

Further, bypass includes controlling the IGCT of reverse-conducting, monitors bridge arm under any phase of high pressure valve group After the earth fault of arbitrfary point, only the IGCT for controlling forward conduction in the bypass of each phase bridge arm of high pressure valve group is applied once to trigger Pulse, when monitoring to control in the bypass of failure phase bridge arm the IGCT of forward conduction to be constantly in conducting state, give remaining two The IGCT of reverse-conducting is controlled to be continuously applied trigger pulse in the bypass of phase bridge arm；Maintain all bypasses crystalline substance lock of low pressure valve group Pipe be in blocking, and locking high pressure valve group and low pressure valve group whole all-controlling power electronics device trigger pulses.

Preferably, also including all all-controlling power electronics devices in bridge arm in locking each phase of high pressure valve group and lower bridge arm Trigger pulse.

Preferably, also including all all-controlling power electronics devices in bridge arm in locking each phase of low pressure valve group and lower bridge arm Trigger pulse.

Preferably, what is coupled when the DC side of modularization multi-level converter is the phased transverter that is made up of IGCT When, after it there is high pressure valve group fault to ground,

By phased converter blocking,

Or phased transverter is switched into inverter operation state,

Or the current instruction value of phased transverter is adjusted to zero or negative value.

Preferably, also including disconnecting the AC circuit breaker in modularization multi-level converter.

Compared with prior art, the present invention has following beneficial technique effect：

A kind of modularization multi-level converter of the present invention and its high pressure valve group fault to ground guard method, it is only necessary in every height The IGCT or an IGCT of the output end of module two reverse parallel connections connection in parallel form the bypass for corresponding to each bridge arm, hair During raw high pressure valve group fault to ground, overvoltage can be provided for submodule by the on off state of IGCT in rationally control bypass Protection.On average, it is only necessary to additionally increase on each submodule one or two thyristor groups into bypass, it is with low cost, And reliable protection can be provided for high and low pressure valve group, it is convenient to promote the practical of high and low pressure valve group tandem plan；Compared to adopting With the protection scheme of arrester, without Large Copacity arrester so as to substantially reduce cost；While the guarantor of the arrester that need not adjust Shield level, it is to avoid in arrester scheme level of protection adjust it is too high bring for submodule cannot provide effectively protection and protect Shield level adjust it is too low bring steady-state operation loss problem.

Brief description of the drawings

Fig. 1 be possess described in present example isolation high pressure valve group fault to ground by blocking-up type submodule and semi-bridge type The mixed type MMC structure charts that submodule is constituted.

Fig. 2 is that possess the sub by blocking-up type of isolation high pressure valve group fault to ground with current-limiting resistance described in present example The mixed type MMC structure charts that module is constituted with semi-bridge type submodule.

Fig. 3 be bypassed described in present example using thyristor valve possess isolation high pressure valve group fault to ground by hindering The mixed type MMC structure charts that disconnected type submodule is constituted with semi-bridge type submodule.

Fig. 4 is that the bypass with current-limiting resistance described in present example possesses isolation high pressure valve group pair using thyristor valve The mixed type MMC structure charts being made up of blocking-up type submodule and semi-bridge type submodule of earth fault.

Fig. 5 is that IGCT correspondence submodule component is multigroup possess isolation high pressure valve in bypass described in present example The mixed type MMC structure charts being made up of blocking-up type submodule and semi-bridge type submodule of group fault to ground.

Fig. 6 is that IGCT correspondence submodule component is tool multigroup and with current-limiting resistance in bypass described in present example The mixed type MMC structure charts being made up of blocking-up type submodule and semi-bridge type submodule of standby isolation high pressure valve group fault to ground.

Fig. 7 is that possess being made up of blocking-up type submodule for isolation high pressure valve group fault to ground described in present example MMC structure charts.

Fig. 8 is that possess the sub by blocking-up type of isolation high pressure valve group fault to ground with current-limiting resistance described in present example The MMC structure charts of module composition.

Fig. 9 be described in present example bypass in thyristor valve be connected in parallel on bridge arm output end possess isolation high pressure valve group The MMC structure charts being made up of blocking-up type submodule of fault to ground.

Figure 10 is that thyristor valve is connected in parallel on bridge arm output end after being connected with current-limiting resistance in bypass described in present example Possess isolation high pressure valve group fault to ground the MMC structure charts being made up of blocking-up type submodule.

Figure 11 is that IGCT correspondence submodule component is multigroup by blocking-up type submodule in bypass described in present example The MMC structure charts that block is constituted.

Figure 12 is that IGCT correspondence submodule component is multigroup and with current-limiting resistance in bypass described in present example The MMC structure charts being made up of blocking-up type submodule.

Figure 13 is the topology of semi-bridge type submodule described in present example.

(a) to (e) is all kinds of blocking-up type submodule topologys described in present example in Figure 14.

Figure 15 is made up of phased transverter and modularization multi-level converter of the present invention described in present example Direct current transportation topological diagram.

Figure 16 is made up of half-bridge submodule and full-bridge submodule after using the present invention program described in present example Current path of the mixed type transverter in high pressure valve group A phases during bridge arm fault to ground.

Figure 17 be full-bridge submodule described in present example only comprising bypass IGCT by half-bridge submodule and Current path of the mixed type transverter that full-bridge submodule is constituted in high pressure valve group A phases during bridge arm fault to ground.

Figure 18 is the modular multilevel change of current for possessing high pressure valve group fault to ground isolating power described in present example Current path of the device in high pressure valve group A phases during bridge arm fault to ground.

Figure 19 be built on PSCAD/EMTDC described in present example by modularization multi-level converter with it is phased The Hybrid HVDC topology that transverter is constituted, the structure that wherein modularization multi-level converter is connected using high and low pressure valve group.

Figure 20 is the direct fault current waveform that Figure 19 structure simulations are obtained.

Figure 21 is the full-bridge submodule of Figure 19 structure each bridge arms of high pressure valve group and the capacitance voltage average value of half-bridge submodule.

Figure 22 is the full-bridge submodule of Figure 19 structure each bridge arms of low pressure valve group and the capacitance voltage average value of half-bridge submodule.

Figure 23 is Figure 19 structure high pressure valve group valves side alternating current.

Figure 24 is the electric current that each anti-parallel thyristor of bridge arm flows through in Figure 19 structure high pressure valve groups.

In figure：Anti-parallel thyristor bypasses IGCT 2, AC circuit breaker 3, high pressure valve group 4, low pressure valve group 5, high pressure to 1 The upper bridge arm low-pressure side 6 of valve group, the negative dc bus 7 of high pressure valve group, bridge in bridge arm 8, high pressure valve group B phases in high pressure valve group A phases Arm 9, bridge arm 10 in high pressure valve group C phases, phased transverter 11, bi-directional thyristor valve 12, current-limiting resistance 13 bypasses thyristor valve 14。

Specific embodiment

In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to specific embodiment pair The present invention is described in further detail, it will be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and It is not used in the restriction present invention.As long as additionally, technical characteristic involved in invention described below each implementation method Not constituting conflict each other can just be mutually combined.

In flexible direct current power transmission system provided in an embodiment of the present invention, modularization multi-level converter inner high voltage valve group is over the ground Fault protecting method, when can solve the problem that existing high and low valve series operation, the submodule electric capacity that high pressure valve group fault to ground is present Overvoltage problem.

A kind of modularization multi-level converter of the present invention, is the mixed type being made up of blocking-up type submodule and half-bridge submodule Modularization multi-level converter, in the IGCT of the voltage output end of each blocking-up type submodule two reverse parallel connections connection in parallel Bypass branch is formed, bypass branch is formed in the voltage output end of each a half-bridge submodule IGCT in parallel, IGCT Anode connects the high-voltage output end of half-bridge submodule, and the negative electrode of IGCT connects the low-voltage output of half-bridge submodule；In same bridge arm Corresponding bypass branch constitute to should bridge arm bypass, when there is high pressure valve group fault to ground, by the brilliant lock in bypass Pipe applies trigger signal, so that fault current flows through the IGCT in bypass, it is to avoid fault current flows through submodule to son Module capacitance charges.Wherein, the IGCT of the voltage output end of each half-bridge submodule two reverse parallel connections connection in parallel is formed Bypass branch, voltage output end one IGCT of parallel connection of each blocking-up type submodule or two IGCTs of reverse parallel connection connection Form bypass branch.

A kind of modularization multi-level converter of the present invention, is the mixed type being made up of blocking-up type submodule and half-bridge submodule Modularization multi-level converter, in the voltage output end of each the blocking-up type submodule brilliant lock coupled by two reverse parallel connections in parallel The bypass branch that pipe is in series with current-limiting resistance, one in parallel of the voltage output end of each half-bridge submodule by IGCT with The bypass branch that current-limiting resistance is in series, the anode of IGCT connects the high-voltage output end of half-bridge submodule, the negative electrode of IGCT One end of current-limiting resistance is connect, the low-voltage output of another termination half-bridge submodule of current-limiting resistance occurs the event over the ground of high pressure valve group During barrier；In same bridge arm corresponding bypass branch constitute to should bridge arm bypass, by applying to the IGCT in bypass to touch Signal, so that fault current flows through bypass IGCT, it is to avoid fault current flows through submodule and charged to submodule electric capacity.

A kind of modularization multi-level converter of the present invention, is the mixed type being made up of blocking-up type submodule and half-bridge submodule Modularization multi-level converter, in parallel one between each high and low pressure output end by blocking-up type submodule valve section in series Individual bi-directional thyristor valve constitutes bypass branch, and the bi-directional thyristor valve is in series or by two by multiple anti-parallel thyristors Inverse parallel connection unidirectional thyristor valve be formed in parallel, each by semi-bridge type submodule it is in series valve section high and low pressure A unidirectional thyristor valve in parallel constitutes bypass branch between output end, and the unidirectional thyristor valve is by multiple Thyristors in series Into the anode of unidirectional thyristor valve connects the high-voltage output end of half-bridge submodule valve section, and the negative electrode of unidirectional thyristor valve connects half-bridge The low-voltage output of modular valve section；In same bridge arm corresponding bypass branch constitute to should bridge arm bypass, there is high pressure valve During group fault to ground, trigger signal is applied by the IGCT in bypass, so that fault current flows through bypass IGCT, Avoid fault current from flowing through submodule to be charged to submodule electric capacity.

Wherein, after bi-directional thyristor valve can be connected with current-limiting resistance again parallel connection to blocking-up type submodule connect structure Into valve section on, the unidirectional thyristor valve connected with current-limiting resistance after again parallel connection to half-bridge submodule valve in series Duan Shang.

The valve section that blocking-up type submodule can also be constituted is divided into multigroup, every group of output end parallel connection bidirectional thyristor valve group Or the tandem compound that bidirectional thyristor valve group is constituted with current-limiting resistance.By half-bridge submodule constitute valve section be divided into it is multigroup, every group Output end parallel connection unidirectional thyristor valve group or the tandem compound that constitutes of unidirectional thyristor valve group and current-limiting resistance.

To the modularization multi-level converter of above-described mixed type, there is bridge arm arbitrfary point in any phase of high pressure valve group During earth fault, including the steps,

Apply trigger pulse to IGCT in the bypass of bridge arm in each phase of high pressure valve group.

The bypass IGCT of bridge arm and each bridge arm of low valve maintains blocking under maintenance each phase of high pressure valve group.

The trigger pulse of all all-controlling power electronics devices of each mutually upper and lower bridge arm of locking high pressure valve group.

In any phase of generation high pressure valve group during the earth fault of bridge arm arbitrfary point, the low valve of locking each mutually upper and lower bridge arm owns The trigger pulse of all-controlling power electronics device.

Wherein, the trigger pulse constantly applies or only applies once on IGCT.

Specifically, after monitoring to break down, only to controlling forward conduction in the bypass of bridge arm in each phase of high pressure valve group IGCT applies a trigger pulse, monitors to control the IGCT of forward conduction to be constantly in failure phase in the bypass of bridge arm During conducting state, trigger pulse is continuously applied to the IGCT of reverse-conducting is controlled in the bypass of bridge arm in each phase；Maintain high pressure Whole full-control types of IGCT locking and locking high pressure valve group and low pressure valve group in the every other bypass of valve group and low pressure valve group Power electronic devices trigger pulse.

To above-described modularization multi-level converter, there is bridge arm arbitrfary point earth fault under any phase of high pressure valve group When, including the steps,

Bypass IGCT to each phase bridge arm of high pressure valve group applies trigger pulse.

The bypass IGCT of each bridge arm of low valve is maintained to be in blocking.

The trigger pulse of all all-controlling power electronics devices of each mutually upper and lower bridge arm of locking high pressure valve group.

The trigger pulse of all all-controlling power electronics devices of each mutually upper and lower bridge arm of the low valve of locking.

Wherein, the trigger pulse constantly applies or only applies once on IGCT.

Specifically, after monitoring to break down, only to the crystalline substance of control forward conduction in the bypass of each phase bridge arm of high pressure valve group Brake tube applies a trigger pulse, monitors to control the IGCT of forward conduction to be constantly in conducting in the bypass of failure phase bridge arm During state, to controlling the IGCT of reverse-conducting to be continuously applied trigger pulse in the bypass of remaining two-phase bridge arm, low pressure valve is maintained Group all bypass IGCTs be in blocking, and locking high pressure valve group and low pressure valve group whole full-control type power electronic devices Part trigger pulse.

A kind of modularization multi-level converter of the present invention, is the modular multilevel change of current being made up of blocking-up type submodule Device, bypass branch is constituted in the voltage output end of each a blocking-up type submodule IGCT in parallel, and the anode of IGCT connects resistance The high-voltage output end of disconnected type submodule, the negative electrode of IGCT connects the low-voltage output of blocking-up type submodule；Correspondence in same bridge arm Bypass branch constitute to should bridge arm bypass, occur high pressure valve group fault to ground when, by bypass IGCT apply touch Signal, so that fault current flows through bypass IGCT, it is to avoid fault current flows through submodule and charged to submodule electric capacity.

Wherein, voltage of the parallel connection in blocking-up type submodule after the bypass branch is connected by IGCT with current-limiting resistance Constituted on output port.

Preferably, thyristor valve is constituted after multiple Thyristors in series, the high pressure of thyristor valve terminates the high pressure of each bridge arm Output end, the low pressure of IGCT terminates the low-voltage output of each bridge arm, forms the bypass of correspondence bridge arm.

After can also thyristor valve be connected with current-limiting resistance, the voltage output end of parallel connection to each bridge arm forms side Road branch road.

To the modularization multi-level converter of above-described pure blocking-up type, bridge arm any point connects in high pressure valve group During earth fault, including the steps, to a bypass IGCT trigger pulse of applying of bridge arm in all high pressure valve groups, maintain The bypass IGCT of bridge arm and all low valves is blocking state, and lock modules multilevel converter under high pressure valve group.

When under high pressure valve group there is earth fault in bridge arm any point, including the steps, to all high pressure valve groups Bypass IGCT applies a trigger pulse, and it is blocking state to maintain all of bypass IGCT of low valve, and lock modules are more Level converter.

In this example, blocking-up type submodule is the modularization multi-level converter work(for possessing blocking direct fault current ability Rate module, can using full-bridge submodule, clamp Shuangzi module, diode clamp bit submodule, from resistance type submodule and crosslinking Various known topologys such as module.

When modularization multi-level converter DC side couple be the phased transverter being made up of IGCT when, occur By phased converter blocking or by phased transverter inverter operation state is switched to after high pressure valve group fault to ground or changed phased The current instruction value for flowing device is adjusted to zero or negative value, so as to quickly absorb the rudimental energy on DC power transmission line, reduces to side The resistance to stream demand of road IGCT.

After generation high pressure valve group fault to ground is detected, the AC circuit breaker of modularization multi-level converter is cut-off.

Wherein, the selection principle of current-limiting resistance resistance is to cause that bypass IGCT does not occur overcurrent, and causes that exchange is disconnected Road device does not cut-off because of overcurrent, and causes that the pressure drop on current-limiting resistance is less than the submodule of its parallel connection, valve section or bridge arm Submodule capacitor voltage sum.

It is specific as described below.

Fig. 1 is illustrated using the modularization multi-level converter topology of protection scheme of the present invention, and the modular multilevel is changed Stream device is in series by high pressure valve group 4 and low pressure valve group 5, and the scheme of such high and low pressure valve series connection is compared to using the single change of current The scheme of valve can reduce the capacity and insulation requirements of each AC transformer so as to reduces cost.High and low pressure valve group in Fig. 1 Each bridge arm be in series by one or more blocking-up type submodules and half-bridge submodule, be simplify draw, each bridge in Fig. 1 Arm only illustrates a blocking-up type submodule and a half-bridge submodule.

But there are safety risks in such high and low pressure valve tandem plan.When the upper bridge arm low-pressure side 6 or high pressure of high pressure valve group When the negative dc bus 7 of valve group occurs earth fault, the polar curve voltage-to-ground of DC power transmission line will be applied in high pressure valve group On bridge arm or high pressure valve group, because all submodule capacitor voltage sums of the upper bridge arm of high pressure valve group are only 1/2 specified polar curve pair Ground voltage, high pressure valve group is equal with rating plate line-to-earth voltage per mutually all submodule capacitor voltage sums, it is considered to direct current transportation After the energy storage remained on circuit and DC inductance, in the upper bridge arm low-pressure side 6 or the negative direct current of high pressure valve group of above-mentioned high pressure valve group When bus 7 breaks down, even if whole all-controlling power electronics devices of locking high pressure valve group, the upper bridge arm or height of high pressure valve group The submodule electric capacity of upper and lower bridge arm of the pressure valve group per phase will be charged to high voltage so as to damage submodule.

To solve the above problems, it is made up of blocking-up type submodule and half-bridge submodule as shown in figure 1, giving in this example Mixed type MMC high pressure valve group fault to ground protection structure.The number ratio of blocking-up type submodule and half-bridge submodule in Fig. 1 Example about 1：1.The feature of the protection structure designed by the present invention is：The voltage output end of each blocking-up type submodule it is in parallel by Two anti-parallel thyristors of IGCT reverse parallel connection composition are to a 1 or in parallel bidirectional thyristor；In each half-bridge submodule Voltage output end bypass IGCT 2 in parallel, the anode of the IGCT in parallel with half-bridge submodule connects half-bridge submodule High-voltage output end, negative electrode connects the low-voltage output of half-bridge submodule.With bridge arm low-voltage output, i.e. A phases in high pressure valve group A phases As a example by the upper fault to ground of bridge arm low-pressure side 6 of high pressure valve group, there is the upper fault to ground of bridge arm low-pressure side 6 of the high pressure valve group of A phases When, will apply to the bypass IGCT of each submodule of bridge arm 10 in bridge arm 9 in bridge arm 8, B phases in high pressure valve group A phases and C phases Trigger pulse so that fault current is through bypassing IGCT circulation so as to avoid fault current from being charged to submodule electric capacity.Correspondence is high When the trouble point 6d or 7d of the negative dc bus 7 of the upper bridge arm low-pressure side 6 or high pressure valve group of pressure valve group occur earth fault, recommend The trigger pulse of whole all-controlling power electronics devices of locking high pressure valve group and low pressure valve group is so as to prevent submodule electric capacity Discharged through trouble point 6d or trouble point 7d.When there is earth fault in trouble point 6d, preferably maintain under each phase of high pressure valve group bridge arm with And the bypass IGCT of the submodule of all bridge arms of low pressure valve group be in blocking so as to reduce AC and trouble point 6d it Between short-circuit reactance value, reduce ac-side current.Similarly, when trouble point 7d occurs earth fault, low pressure valve group institute is preferably maintained The bypass IGCT for having the submodule of bridge arm is in blocking.

In order to further reduce fault current, Fig. 2 gives the improvement project of Fig. 1, and its improvement is brilliant each inverse parallel After brake tube is connected to 1 or each bypass IGCT 2 with current-limiting resistance 13, then parallel connection to submodule output end so that simultaneously Reduce direct fault current and AC fault electric current, reduce the resistance to stream demand of bypass IGCT and reduce and AC network is disturbed It is dynamic.The suitable Rational choice of resistance of current-limiting resistance 13, too small then its current limitation effect of its resistance is not obvious, the too big then current limliting electricity of its resistance Pressure drop in resistance is too high, and each submodule can be caused to bear overvoltage.Recommend the selection principle of current-limiting resistance 13 to cause that bypass is brilliant There is no overcurrent in brake tube, and cause that AC circuit breaker does not cut-off because of overcurrent, and cause that the pressure drop on current-limiting resistance is less than The submodule of its parallel connection.

Fig. 3-Fig. 4 is the homotype scheme of Fig. 1-Fig. 2.Fig. 3 is that anti-parallel thyristor is to 1 or bypass compared to Fig. 1 differences The not direct parallel connection of IGCT 2 is on each submodule, but multiple anti-parallel thyristors are to obtaining two-way side after series connection In on the tandem compound that blocking-up type submodule is constituted, multiple bypass Thyristors in series obtains side for parallel connection after road thyristor valve 12 After road thyristor valve 14, parallel connection is on the tandem compound that half-bridge submodule is constituted.It is brilliant that Fig. 3 lower left corners give two-way bypass Two kinds of implementation methods of gate tube valve 12.One kind is obtained unidirectionally to bypass the reverse parallel connections of thyristor valve 14 by two, as shown in 12a. Another kind is obtained to be connected to 1 or multiple bidirectional thyristor by multiple anti-parallel thyristors, as shown in 12b.

Similarly, after Fig. 4 schemes are connected for two-way bypass thyristor valve 12 with current-limiting resistance 13, parallel connection is in blocking-up type On the tandem compound of module composition, and after unidirectional bypass thyristor valve 14 and current-limiting resistance string 13, parallel connection is in half-bridge On the tandem compound of module composition.The selection principle of each current-limiting resistance 13 is to cause that bypass IGCT does not occur overcurrent in Fig. 4, And cause that AC circuit breaker does not cut-off because of overcurrent, and cause the pressure drop on current-limiting resistance less than the submodule of its parallel connection Rated capacity voltage sum.

Fig. 3-Fig. 4 schemes are convenient centralized management bypass IGCT and current-limiting resistance compared to the advantage of Fig. 1-Fig. 2, from And the topological structure of existing submodule and layout need not be changed, the two-way bypass thyristor valve 12 of shortcoming and unidirectionally bypass thyristor valve 14 form by multiple Thyristors in series, when the IGCT number of series connection is more, there is Thyristors in series and press asking for difficulty Topic.

Fig. 5-Fig. 6 is the homotype scheme of Fig. 3-Fig. 4, and to reduce map format, Fig. 5 and Fig. 6 depict only high pressure valve group 4 Topology.Fig. 5-Fig. 6 principles are consistent with Fig. 3-Fig. 4, and difference is that blocking-up type submodule is divided into multigroup, every group of blocking-up type submodule Output end one two-way bypass thyristor valve 12 of parallel connection or two-way bypass thyristor valve 12 and current-limiting resistance 13 tandem compound, Half-bridge submodule is also classified into multigroup, one in parallel unidirectional bypass thyristor valve 14 or unidirectional of every group of output end of half-bridge submodule The tandem compound that bypass thyristor valve 14 is constituted with current-limiting resistance 13.Fig. 5-Fig. 6 schemes exist compared to the advantage of Fig. 3-Fig. 4 schemes In IGCT number that two-way bypass thyristor valve 12 and unidirectional bypass thyristor valve 14 connected can be reduced so as to reduce side The pressure difficulty of road IGCT.

The selection principle of each current-limiting resistance 13 is to cause that the brilliant gate valve of bypass does not occur overcurrent in Fig. 6, and causes that exchange is disconnected Road device does not cut-off because of overcurrent, and causes the pressure drop on current-limiting resistance less than the submodule rated capacity voltage of its parallel connection Sum.

Another scheme be given in this example, is the height of the MMC being made up of blocking-up type submodule as shown in Figs. 7-8 The structure of pressure valve group fault to ground protection.One bypass of the voltage output end reverse parallel connection of each blocking-up type submodule in Fig. 7 IGCT 2, the anode for bypassing IGCT 2 connects the high-voltage output end of submodule, and the negative electrode for bypassing IGCT 2 connects the low pressure of submodule Output end.When monitoring bridge arm low-voltage output fault to ground in high pressure valve group, by the bypass to all submodules of failure bridge arm IGCT 2 applies a trigger pulse so that fault current circulates through bypassing IGCT 2, and maintains the brilliant lock of every other bypass Pipe 2 is in the trigger signal of blocking and the locking all all-controlling power electronics devices of high pressure valve group.Direct fault current mistake After zero, bypass IGCT 2 will automatically shut down.

Fig. 8 is similar with Fig. 7, and difference is that each bypass IGCT 2 is also connected with current-limiting resistance 13 so as to reduce direct current event Fault current during barrier.

Fig. 9 is similar with Fig. 7, and difference is that each bypass IGCT is not connected on each submodule, but multiple other Road IGCT 2 constituted after connecting unidirectional bypass thyristor valve 14 again parallel connection in the high and low pressure output end of bridge arm.Fig. 9 is opened up Flutter and be compared to the advantage of Fig. 7 topologys, it is not necessary to change the structure and design of each submodule, be easy to centralized management bypass brilliant Brake tube valve group.Its inferior position brought is there is certain pressure difficulty after multiple Thyristors in series.

Figure 10 is similar with Fig. 9, and difference is that each bypass thyristor valve 14 has also connected current-limiting resistance 13 such that it is able to add Fault current is reduced to zero speed and fault current limiting size soon.

Figure 11 is that the blocking-up type submodule of each bridge arm is divided into multiple packets, upper one or more crystalline substances in parallel of each packet The bypass thyristor valve 14 that brake tube is in series.The performance of Figure 11 was avoided between Fig. 7 and Fig. 9, both changes each submodule The topology of block it also avoid excessively bypassing the pressure difficulty brought after Thyristors in series.

Figure 12 is similar with Figure 11, and difference is that each bypass thyristor valve 14 has also connected current-limiting resistance 13 so as to reduce event Hinder the size of electric current.；

Figure 13 illustrates the topology of half-bridge submodule.(a)-(e) illustrates the topology of blocking-up type submodule, Figure 14 in Figure 14 (a)-(e) be respectively full-bridge submodule topology, clamp Shuangzi module topology, diode clamp bit submodule, from resistance type submodule and Crosslinking submodule.Figure 13-Figure 14 systems known technology, its details is repeated no more.

In this example, as shown in figure 15, give by the phased transverter 11 of monopole positive polarity and monopole positive polarity mixed type The two-terminal direct current transmission system topological structure that modularization multi-level converter is constituted.Wherein, modularization multi-level converter is by height Pressure valve group 4 and low pressure valve group 5 are constituted.When the upper bridge arm low-pressure end 6 of high pressure valve group 4 occurs earth fault, by high pressure valve group 4 The bypass IGCT 1 of each submodule of bridge arm applies trigger pulse on A, B, C three-phase, maintains bridge arm and low under each phase of high pressure valve group The bypass IGCT of each submodule of all bridge arms of pressure valve group is in the institute of blocking, locking high pressure valve group and low pressure valve group There is the trigger pulse of all-controlling power electronics device, simultaneously, when phased transverter side monitors failure, by its triggering of locking Pulse causes that phased transverter works to inverter mode so as to phased transverter to be fed into the direct current of bypass IGCT Stream is down to zero, prevents bypass IGCT from flowing continuously through electric current and damaging bypass IGCT.

In this example, Figure 16 illustrates high pressure by taking the mixed type MMC being made up of half-bridge submodule and full-bridge submodule as an example In valve group A phases during bridge arm low-voltage output fault to ground, each phase current path.Wherein each bridge arm half-bridge submodule is sub with full-bridge The ratio of module is 1：1 or so.In Figure 16, flow through the element of electric current with black lines illustrate, the element in blocking with Grey lines are illustrated.Under the failure, high pressure valve group A, B, the upper bridge arm bypass IGCT of C three-phases will be triggered, remaining each bridge arm Bypass IGCT maintain the modularization multi-level converter of blocking, failure pole (Figure 16 depict only positive pole) to be closed Lock, the modularization multi-level converter of non-faulting pole (negative pole, Figure 16 does not draw) still maintains normal operating condition.Figure 16 shows event Barrier electric current will via on A, B, C three-phase bridge arm bypass IGCT circulate, fault current will not to submodule electric capacity charge from Without bringing submodule capacitance overvoltage problem.

When the bypass IGCT that Figure 17 illustrates full-bridge submodule is single IGCT, the electric current of high pressure valve group fault to ground Path.The ratio of full-bridge submodule and half-bridge submodule is about 1 in Figure 17：1.In high pressure valve group A phases there is earth fault in bridge arm When, DC current fault current path is consistent with Figure 16.Except direct fault current, AC is also by circulating current, such as Figure 17 B, A two-phase solid arrow shown in.Understand, AC will charge to the full-bridge submodule of bridge arm in B phases, therefore the full-bridge of Figure 17 is sub Scheme of the module only comprising single bypass IGCT is the infeasible scheme of technology.

The submodule that Figure 18 illustrates each bridge arm is the modularization multi-level converter high pressure valve group A of full-bridge submodule AC incipient fault current path in phase during bridge arm earth fault.By taking B, A two-phase of high pressure valve group as an example, high pressure valve group The capacitance voltage of all submodules of bridge arm will be reversed and access to current path in B phases.Due to each bridge arm or so submodule Capacitance voltage sum is higher than the peak value of the phases line voltage of B, A two, so the incipient fault current path of Figure 18 examples can not circulate Electric current.When all submodules of bridge arm are blocking-up type submodule, it is only necessary in the output end reverse parallel connection one of each submodule Bypass IGCT, the anode and negative electrode that bypass IGCT connect the high-voltage output end and low-voltage output of submodule respectively.Generation is high Bridge arm fault to ground or during high pressure valve group low-voltage direct busbar grounding failure in pressure valve group, to bridge arm, B in the A phases of high pressure valve group It is that may be such that direct fault current that the bypass IGCT of all submodules of bridge arm applies a trigger pulse in bridge arm and C phases in phase Circulated via bypass IGCT, it is to avoid direct fault current charges to submodule electric capacity.

It is the technical feasibility of the designed scheme of the checking present invention, simulation example has been built under PSCAD/EMTDC, such as schemes Shown in 19.In Figure 19, LCC represents phased transverter, and MMC_High is the high pressure valve group of modularization multi-level converter, MMC_ Low is the low pressure valve group of modularization multi-level converter.High and low pressure valve group is using the topology shown in Figure 16.

Figure 20~Figure 24 gives corresponding simulation result.When the failure for being applied is 0.8s, the modular multilevel change of current There is earth fault in the high pressure valve group A phases low-pressure end of device.After monitoring the failure, bridge arm in the A phase, B phase, C phase of high pressure valve group All bypass IGCTs be continuously applied trigger signal, all bypasses of bridge arm and low pressure valve group are brilliant under A phase, B phase, C phase Brake tube maintains blocking, meanwhile, after monitoring failure, whole all-controlling power electronics devices of high and low pressure valve group will be by Locking.Phased transverter, also can locking its trigger pulse after the failure is detected.

Figure 20 is dc current waveform, it is known that after breaking down, and DC current can be reduced to zero in 15ms.Figure 21 and Figure 22 It is the full-bridge submodule and the average capacitor voltage of half-bridge submodule of each phase bridge arm of high pressure valve group, it is known that, in present invention design Under scheme, during high pressure valve group fault to ground, each submodule electric capacity will not occur overvoltage.Figure 23 valves side alternating current, it is known that In scheme designed by the present invention, during high pressure valve group fault to ground, without substantially exchange overcurrent.Figure 24 is each to flow through high pressure valve group Bridge arm bypass IGCT in phase, it is known that each bypass IGCT is also without flow through obvious overcurrent.

Claims (26)

1. a kind of modularization multi-level converter, it is characterised in that be included in DC side series connection and in AC high pressure in parallel Valve group and low pressure valve group；Described high pressure valve group and each of low pressure valve group constitute by upper bridge arm and lower bridge arm, upper bridge arm with Lower bridge arm is constituted by multiple blocking-up type submodules and multiple half-bridge sub-module cascades；

The bypass that break-make is controlled by IGCT is respectively arranged with described upper bridge arm and lower bridge arm；The event over the ground of generation high pressure valve group During barrier, apply trigger signal by IGCT in bypass so that fault current flows through bypass, it is to avoid fault current flows through submodule Block charges to submodule electric capacity.

2. a kind of modularization multi-level converter according to claim 1, it is characterised in that described bypass includes and son The one-to-one bypass branch of module；Described bypass branch includes in parallel two of each blocking-up type submodule voltage output end The IGCT or an output end bidirectional thyristor in parallel of reverse parallel connection connection, and each half-bridge submodule voltage output end An IGCT or two IGCTs or a bidirectional thyristor of reverse parallel connection connection in parallel；One IGCT anode connects The high-voltage output end of half-bridge submodule, the negative electrode of an IGCT connects the low-voltage output of half-bridge submodule.

3. a kind of modularization multi-level converter according to claim 1, it is characterised in that described bypass includes and valve The one-to-one bypass branch of section, described bypass branch includes each high pressure by blocking-up type submodule valve section in series A bi-directional thyristor valve in parallel between output end and low-voltage output, and each is in series by semi-bridge type submodule A unidirectional thyristor valve in parallel or a bi-directional thyristor valve between the high-voltage output end and low-voltage output of valve section；This one The anode of individual unidirectional thyristor valve connects the high-voltage output end of correspondence half-bridge submodule valve section, a negative electrode for unidirectional thyristor valve Connect the low-voltage output of correspondence half-bridge submodule valve section.

4. a kind of modularization multi-level converter according to claim 1, it is characterised in that described bypass includes and valve One-to-one bypass branch is respectively grouped in section；Blocking-up type submodule valve section in series is divided into multigroup；By half-bridge submodule Block valve section in series is divided into multigroup；

Described bypass branch includes every group of output end of blocking-up type submodule bi-directional thyristor valve in parallel, and every group The output end of a semi-bridge type submodule unidirectional thyristor valve in parallel or a bi-directional thyristor valve；One unidirectional thyristor The anode of valve connects every group of high-voltage output end of half-bridge submodule of correspondence, and the negative electrode of a unidirectional thyristor valve connects every group of correspondence half The low-voltage output of bridge submodule valve section.

5. a kind of modularization multi-level converter, it is characterised in that connected in DC side and in AC high pressure valve group in parallel With low pressure valve group；Described high pressure valve group and low pressure valve group it is each by upper bridge arm and lower bridge arm composition, upper bridge arm and lower bridge Arm is constituted by multiple blocking-up type sub-module cascades；

The bypass controlled by IGCT is respectively arranged with described upper bridge arm and lower bridge arm；Generation high pressure valve group fault to ground When, apply trigger signal by IGCT in bypass so that fault current flows through bypass, it is to avoid fault current flows through submodule Charged to submodule electric capacity.

6. a kind of modularization multi-level converter according to claim 5, it is characterised in that described bypass includes and resistance The disconnected type one-to-one bypass branch of submodule；Described bypass branch includes that each blocking-up type submodule voltage output end is in parallel An IGCT or the connection of two reverse parallel connections IGCTs or a bidirectional thyristor；One IGCT anode connects blocking-up type The high-voltage output end of submodule, the negative electrode of IGCT connects the low-voltage output of blocking-up type submodule.

7. a kind of modularization multi-level converter according to claim 5, it is characterised in that described bypass includes and valve The one-to-one bypass branch of section, described bypass branch includes each high pressure by blocking-up type submodule valve section in series A unidirectional thyristor valve in parallel or a bi-directional thyristor valve between output end and low-voltage output；Described one is unidirectional The anode of thyristor valve connects the high-voltage output end of correspondence blocking-up type submodule valve section, and the negative electrode of unidirectional thyristor valve connects correspondence blocking The low-voltage output of type submodule valve section.

8. a kind of modularization multi-level converter according to claim 7, it is characterised in that described bypass includes and valve One-to-one bypass branch is respectively grouped in section；Blocking-up type submodule valve section in series is divided into multigroup；

Described bypass branch include the output end of an every group of blocking-up type submodule unidirectional thyristor valve in parallel or one it is double To thyristor valve；The anode of one unidirectional thyristor valve connects every group of high-voltage output end of blocking-up type submodule of correspondence, this The negative electrode of unidirectional thyristor valve connects every group of low-voltage output of blocking-up type submodule valve section of correspondence.

9. a kind of modularization multi-level converter according to claim 3,4,7 or 8, it is characterised in that the unidirectional crystalline substance Gate tube valve is formed by multiple Thyristors in series；The bi-directional thyristor valve is in series or by multiple by multiple anti-parallel thyristors Bidirectional thyristor is in series or is formed in parallel by the unidirectional thyristor valve that two inverse parallels couple.

10. a kind of modularization multi-level converter according to claim 2,3,4,6,7 or 8, it is characterised in that by each Current-limiting resistance is in series with the branch road of road respectively, current-limiting resistance correspondence is connected on the low-voltage output or High voltage output of bypass branch End.

11. a kind of modularization multi-level converters according to claim 10, it is characterised in that described current-limiting resistance Resistance enables to bypass IGCT that overcurrent does not occur, and causes the AC circuit breaker of modularization multi-level converter not because of mistake Electric current and cut-off, and cause current-limiting resistance on pressure drop less than its parallel connection all submodules capacitance voltage sum.

A kind of 12. modularization multi-level converters according to claim 1 or 5, it is characterised in that the blocking-up type submodule Block be possess blocking direct fault current ability modularization multi-level converter power model, can using full-bridge submodule, Clamp Shuangzi module, diode clamp bit submodule, any one from resistance type submodule and crosslinking submodule.

The high pressure valve group fault to ground guard method of 13. a kind of modularization multi-level converters, it is characterised in that many in modularization The bypass that break-make is controlled by IGCT is set up respectively on the upper bridge arm of each phase and lower bridge arm in level converter；When generation high pressure valve In any phase of group during the earth fault of bridge arm arbitrfary point, triggering arteries and veins is applied to the IGCT in the bypass of bridge arm in each phase of high pressure valve group Punching, makes the corresponding by-path turn-on of bridge arm in each phase of high pressure valve group so that fault current flows through bypass.

A kind of high pressure valve group fault to ground guard method of 14. modularization multi-level converters according to claim 13, Characterized in that, also include maintain each phase of high pressure valve group under bridge arm and each bridge arm of low pressure valve group bypass in IGCT be in close Lock status.

A kind of high pressure valve group fault to ground guard method of 15. modularization multi-level converters according to claim 13, Characterized in that, applying trigger pulse to be continuously applied or only applying to the IGCT in the bypass of bridge arm in each phase of high pressure valve group Once.

A kind of high pressure valve group fault to ground guard method of 16. modularization multi-level converters according to claim 13, Characterized in that, specifically, after bridge arm arbitrfary point earth fault in any phase of high pressure valve group is monitored, it is only each to high pressure valve group The IGCT of forward conduction is controlled to apply a trigger pulse in phase in the bypass of bridge arm；Maintain high pressure valve group and low pressure valve group IGCT locking in every other bypass, and locking high pressure valve group and low pressure valve group whole all-controlling power electronics devices triggering Pulse.

A kind of high pressure valve group fault to ground guard method of 17. modularization multi-level converters according to claim 16, Characterized in that, bypass includes the IGCT of control reverse-conducting, when monitoring bridge arm arbitrfary point in any phase of high pressure valve group After earth fault, only the IGCT for controlling forward conduction in the bypass of bridge arm in each phase of high pressure valve group is applied once to trigger arteries and veins Punching, when monitoring that the IGCT of control forward conduction in the bypass of bridge arm in failure phase is constantly in conducting state, in each phase The IGCT of reverse-conducting is controlled to be continuously applied trigger pulse in the bypass of bridge arm；Maintain all of high pressure valve group and low pressure valve group IGCT locking in other bypasses, and whole all-controlling power electronics devices of locking high pressure valve group and low pressure valve group trigger arteries and veins Punching.

The high pressure valve group fault to ground guard method of 18. a kind of modularization multi-level converters, it is characterised in that many in modularization The bypass that break-make is controlled by IGCT is set up respectively on the upper bridge arm of each phase and lower bridge arm in level converter；When generation high pressure valve Under any phase of group during the earth fault of bridge arm arbitrfary point, triggering arteries and veins is applied to the IGCT in the bypass of each phase bridge arm of high pressure valve group Punching, makes the corresponding by-path turn-on of each phase bridge arm of high pressure valve group so that fault current flows through bypass.

A kind of high pressure valve group fault to ground guard method of 19. modularization multi-level converters according to claim 18, Characterized in that, also including maintaining the IGCT in the bypass of each phase bridge arm of low pressure valve group and each bridge arm of low pressure valve group to be in locking State.

A kind of high pressure valve group fault to ground guard method of 20. modularization multi-level converters according to claim 18, Characterized in that, applying trigger pulse to be continuously applied or only applying one to the IGCT in the bypass of each phase bridge arm of high pressure valve group It is secondary.

A kind of high pressure valve group fault to ground guard method of 21. modularization multi-level converters according to claim 18, Characterized in that, specifically, monitoring under the generation any phase of high pressure valve group after the earth fault of bridge arm arbitrfary point, only to high pressure valve group The IGCT of forward conduction is controlled to apply a trigger pulse in the bypass of each phase bridge arm；Maintain all bypasses of low pressure valve group brilliant Brake tube be in blocking, and locking high pressure valve group and low pressure valve group whole all-controlling power electronics device trigger pulses.

A kind of high pressure valve group fault to ground guard method of 22. modularization multi-level converters according to claim 21, Characterized in that, bypass includes controlling the IGCT of reverse-conducting, bridge arm is any under monitoring any phase of high pressure valve group After point earth fault, only the IGCT for controlling forward conduction in the bypass of each phase bridge arm of high pressure valve group is applied once to trigger arteries and veins Punching, when monitoring that the IGCT of control forward conduction in the bypass of failure phase bridge arm is constantly in conducting state, gives remaining two-phase The IGCT of reverse-conducting is controlled to be continuously applied trigger pulse in the bypass of bridge arm；Maintain all bypass IGCTs of low pressure valve group In blocking, and locking high pressure valve group and low pressure valve group whole all-controlling power electronics device trigger pulses.

A kind of high pressure valve group fault to ground protection side of 23. modularization multi-level converter according to claim 13 or 18 Method, it is characterised in that also including all all-controlling power electronics devices in bridge arm in locking each phase of high pressure valve group and lower bridge arm Trigger pulse.

A kind of high pressure valve group fault to ground protection side of 24. modularization multi-level converter according to claim 13 or 18 Method, it is characterised in that also including all all-controlling power electronics devices in bridge arm in locking each phase of low pressure valve group and lower bridge arm Trigger pulse.

A kind of high pressure valve group fault to ground protection side of 25. modularization multi-level converter according to claim 13 or 18 Method, it is characterised in that when modularization multi-level converter DC side couple be the phased transverter being made up of IGCT when, After it there is high pressure valve group fault to ground,

By phased converter blocking,

Or phased transverter is switched into inverter operation state,

Or the current instruction value of phased transverter is adjusted to zero or negative value.

A kind of high pressure valve group fault to ground protection side of 26. modularization multi-level converter according to claim 13 or 18 Method, it is characterised in that also including disconnecting the AC circuit breaker in modularization multi-level converter.