CN110289774A

CN110289774A - A kind of high voltage direct current transmission unit and its control method and control device

Info

Publication number: CN110289774A
Application number: CN201910596850.5A
Authority: CN
Inventors: 卢东斌; 李海英; 陈松林; 李九虎
Original assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Current assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Priority date: 2019-07-03
Filing date: 2019-07-03
Publication date: 2019-09-27
Also published as: WO2021000620A1

Abstract

The present invention discloses a kind of high voltage direct current transmission unit, including current source type valve group, the converter power transformer without voltage regulation function, voltage-source type valve group and it is coupled transformer, wherein, current source type valve group connects AC system by not having the converter power transformer of voltage regulation function, voltage-source type valve group connects AC system by being coupled transformer, and current source type valve group is connected in series in DC side and voltage-source type valve group.Such convertor unit adjusts DC voltage by using voltage-source type valve group and converter power transformer adjusting tap is replaced to adjust DC voltage; with it is quick, frequently adjust voltage function; it is easy to protect after voltage-source type valve group failure, will not influence current source type valve group and continue to run.Invention additionally discloses the control methods and control device of a kind of HVDC transmission system major loop, high voltage direct current transmission unit.

Description

A kind of high voltage direct current transmission unit and its control method and control device

Technical field

It is the invention belongs to high-voltage dc transmission electrical domain, in particular to a kind of that DC voltage is adjusted using voltage-source type valve group High voltage direct current transmission unit, and realize the control method controlled and control device and a kind of D.C. high voltage transmission system System major loop structure.

Background technique

Converter power transformer of the HVDC transmission system generally by line commutation inverter and with voltage regulation function, which forms, to be changed Unit is flowed, realizes and alternating current is switched into direct current, to be transmitted at a distance.Rectification side generally maintains line commutation inverter Trigger Angle in reference range, inverter side generally maintains the shutdown angle of line commutation inverter in reference range.It is high Press DC transmission system can a wide range of regulation power, in order to maintain rectification side DC voltage constant, rectification side and inverter side are all The converter power transformer with voltage regulation function is needed to adjust alternating voltage.The voltage regulation function of converter power transformer is to pass through tap switch Different converter power transformer taps are connected to realize.

Tap switch has certain service life using mechanical structures such as motor drive mechanism, selection switch, switching switches； It is difficult to protect after tap switch failure, also easily by fault spread to converter power transformer；It is that classification is adjusted that tap switch, which adjusts voltage, Regulation precision is poor, adjustment speed is slow.With the access of the new energy such as photovoltaic, wind-powered electricity generation, HVDC transmission system needs frequent Regulation power, and AC voltage fluctuations range also becomes larger, and can cause tap switch frequent movement, tap switch is easy to cause to damage It is bad.

The shortcomings that in view of above-mentioned tap switch and the new demand of D.C. high voltage transmission, need one kind can be realized quickly, The high voltage direct current transmission unit for frequently adjusting voltage, and being easy to protect.

Summary of the invention

The purpose of the present invention is to provide a kind of high voltage direct current transmission unit, with the direct current tune of voltage source converter Press function replace converter power transformer AC voltage adjusting function, by DC side series electrical Source Con-verters, it can be achieved that quickly, essence Voltage is really adjusted, and when voltage source converter failure, can be changed by the bypass circuit of investment voltage source converter, trip voltage source The alternating current inlet wire switch of stream device promptly isolates failure, will not damage to line commutation inverter, converter power transformer.

In order to achieve the above objectives, the technical solution adopted by the present invention is that:

A kind of high voltage direct current transmission unit, including current source type valve group, the converter power transformer without voltage regulation function, Voltage-source type valve group and connection transformer, wherein current source type valve group passes through the converter power transformer for not having voltage regulation function and connects AC system, voltage-source type valve group connects AC system by being coupled transformer, and current source type valve group is in DC side and voltage Source type valve group is connected in series.

In above scheme: the converter power transformer without voltage regulation function is the change of current transformation without tap or tap switch Device does not have and adjusts converter power transformer net side and valve side winding no-load voltage ratio function.

It is described be coupled transformer use without tap or tap switch transformer, do not have adjust transformer net side and Valve side winding no-load voltage ratio function；Or be coupled transformer and use the transformer with tap and tap switch, have and adjusts transformer Net side and valve side winding no-load voltage ratio function.

The voltage-source type valve group is also connected with charging resistor with being coupled between transformer, and the charging resistor and switch or Disconnecting link is in parallel.

The current source type valve group uses any one of following three kinds of schemes: the first, using line commutation inverter； Second, using line commutation inverter parallel with one another and bypass cock；The third, including line commutation inverter, bypass Switch, bypass disconnecting link and two connection disconnecting links, wherein line commutation inverter is connected in parallel with bypass cock, after being connected in parallel Both ends be separately connected two connection disconnecting link one end, bypass disconnecting link both ends be separately connected two connection disconnecting link the other ends.

Line commutation inverter be six pulsation bridge circuits, 12 pulsation bridge circuits or by it is multiple six pulsation bridge circuits The circuit being composed in series is made of the half control type power semiconductor that can not be turned off.

The above-mentioned half control type power semiconductor that can not be turned off is thyristor.

The voltage-source type valve group uses any one of following three kinds of schemes: the first, using voltage source converter；The Two kinds, using voltage source converter and bypass cock parallel with one another；The third, including voltage source converter, bypass cock, side Logical disconnecting link and two connection disconnecting links, wherein voltage source converter is connected in parallel with bypass cock, the both ends difference after being connected in parallel The one end for connecting two connection disconnecting links, the both ends for bypassing disconnecting link are separately connected the other end of two connection disconnecting links.

In three kinds of schemes, the voltage source converter is that single voltage source converter or two or more voltage source change It is in parallel to flow device；It further include inductance in the second scheme and the third scheme, inductance is connected with voltage source converter, or Inductance is connected with bypass cock.

Bypass cock is mechanical switch or electronic power switch；The electronic power switch is the valve of Thyristors in series composition The valve group that group or the full-control type power semiconductor that can be turned off are composed in series.

Voltage source converter is following any one or more: two level converters, diode-clamped multilevel converter, Modularization multi-level converter MMC, two level of mixed multi-level inverter HMC, two level cascade current converter CSL or stack Inverter CTL；Wherein, the modularization multi-level converter MMC is the modularization multi-level converter of half-bridge submodule composition, Perhaps the mould of the modularization multi-level converter of full-bridge submodule composition or half-bridge submodule and full-bridge submodule mixing composition Block multilevel converter.

Voltage source converter is made of the full-control type power semiconductor that can be turned off；The full-control type power turned off is partly led Body is following any one or more: insulated gate bipolar transistor IGBT, can turn off brilliant lock at integrated gate commutated thyristor IGCT Pipe GTO, Power MOSFET Power MOSFET, electron injection enhancement grid crystal IEGT, door pole stream-exchanging thyristor GCT or carbonization The enhanced junction field effect transistor SiC-JFET of silicon.

The half-bridge submodule or full-bridge submodule of modularization multi-level converter MMC has by-pass switch or thyristor, institute It states by-pass switch or thyristor is connected in parallel on the half-bridge submodule or full-bridge submodule both ends, for bypassing the half-bridge submodule Or full-bridge submodule.

The half-bridge submodule of modularization multi-level converter MMC also has protection thyristor, and the protection thyristor is in parallel At half-bridge submodule both ends, the backward dioded of the full-control type power semiconductor turned off connected in parallel is protected.

Current source type valve group or the voltage-source type valve group configure bridge arm arrester, DC side arrester, bridge arm reactance Device.

The sun for the current source type valve group is connected in series in DC side and voltage-source type valve group in the current source type valve group Pole is connect with the anode of voltage-source type valve group or the cathode company of the cathode of the current source type valve group and voltage-source type valve group It connects；For inverter side, it is the current source type valve that the current source type valve group is connected in series in DC side and voltage-source type valve group The anode of cathode and the voltage-source type valve group of group connect or the anode of the current source type valve group and voltage-source type valve group are born Pole connection.

End where the anode of the current source type valve group is end where the anode of line commutation inverter, the current source type End where the cathode of valve group is end where the cathode of line commutation inverter；End where the anode of the voltage-source type valve group is electricity End where the anode of Source Con-verters, end where the cathode of the voltage-source type valve group are the cathode place of voltage source converter End.

The present invention also provides a kind of HVDC transmission system major loops, and HVDC transmission system major loop rectification side is extremely Few to form a direct current pole by above-mentioned high voltage direct current transmission unit, inverter side is by current source type valve group and has voltage regulation function Converter power transformer composition convertor unit, perhaps by voltage-source type valve group and be coupled the convertor unit that forms of transformer or The change of current list being made of current source type valve group, the converter power transformer with voltage regulation function, voltage-source type valve group and connection transformer Member, or corresponding direct current pole is at least formed by above-mentioned high voltage direct current transmission unit；Or the D.C. high voltage transmission system System major loop inverter side at least forms a direct current pole by above-mentioned high voltage direct current transmission unit, and rectification side is by current source type valve The convertor unit of group and the converter power transformer composition with voltage regulation function, or be made of voltage-source type valve group and connection transformer Convertor unit, or by current source type valve group, the converter power transformer with voltage regulation function, voltage-source type valve group and be coupled transformation The convertor unit of device composition, or corresponding direct current pole is at least formed by above-mentioned high voltage direct current transmission unit.

The present invention also provides a kind of control methods suitable for foregoing high voltage direct current transmission unit, according to height The operation conditions for pressing direct-current transmission converter unit, is divided into two kinds of situations:

When the high voltage direct current transmission unit rectification operation, the first control method is the control touching of current source type valve group It is constant to send out angle reference value, voltage-source type valve group adjusts voltage control dc power or DC current is instruction value, second of control Method is current source type valve group control dc power or DC current is instruction value, is examined when the Trigger Angle of current source type valve group exceeds Consider the reference range in Trigger Angle dead zone, voltage-source type valve group, which adjusts voltage, makes the Trigger Angle of current source type valve group return to consideration touching In the reference range for sending out angle dead zone；

When the high voltage direct current transmission unit inverter operation, the first control method is that the control of current source type valve group is closed Angle of rupture reference value is constant, and voltage-source type valve group adjusts voltage to control the DC voltage of rectification side and be instruction value or consider that voltage is dead The instruction value range in area, second of control method are that the DC voltage of current source type valve group control rectification side is instruction value, work as electricity Beyond the reference range for considering shutdown angle dead zone, voltage-source type valve group, which adjusts voltage, makes current source at the shutdown angle of stream source type valve group In the shutdown angular convolution to the reference range for considering shutdown angle dead zone of type valve group.

When above-mentioned high voltage direct current transmission unit rectification operation, in the first described control method, when current source type valve When group detects that DC current instruction value and actual DC current differential are more than current margins, current source type valve group is switched to control Dc power or DC current.

When above-mentioned high voltage direct current transmission unit inverter operation, the first described control method and second of control method In, when current source type valve group detects DC current instruction value and actual DC current differential is more than current margins, current source Type valve group controls DC current.

Above-mentioned current margins are that 0.02 times of rated DC current flows to 0.3 times of rated direct current.

Above-mentioned current source type valve group Trigger Angle is line commutation inverter Trigger Angle, and the voltage-source type valve group adjusts voltage Be by voltage source converter adjust voltage, the current source type valve group shutdown angle be line commutation inverter shutdown angle or Blow-out angle.

Above-mentioned Trigger Angle dead zone is any value between 0 to 15 degree, and the shutdown angle dead zone is any between 0 to 15 degree Value, the voltage dead band are within the 5% of high voltage direct current transmission cells rated voltage；The ginseng for considering Trigger Angle dead zone Examining value range is that reference value subtracts Trigger Angle dead zone and reference value plus between Trigger Angle dead zone, and the consideration turns off angle dead zone Reference range is that reference value subtracts shutdown angle dead zone and reference value adds between shutdown angle dead zone, the consideration voltage dead band Instruction value range is that instruction value subtracts voltage dead band and instruction value plus between voltage dead band.

Above-mentioned voltage-source type valve group adjusts voltage to control the DC voltage of rectification side as instruction value or consider voltage dead band Instruction value range be according to the DC voltage instruction value of rectification side or to consider that the instruction value range of voltage dead band subtracts route pressure Drop calculates the DC voltage instruction value of inverter side or considers the instruction value range of voltage dead band, the DC voltage instruction of inverter side Value considers that the virtual voltage for the current source type valve group that the instruction value range of voltage dead band subtracts inverter side obtains the electricity of inverter side The voltage-source type valve group of the DC voltage instruction value of potential source type valve group or the instruction value range for considering voltage dead band, inverter side is adjusted The DC voltage instruction value of the voltage-source type valve group of inverter side described in voltage to instruction value or the instruction value model for considering voltage dead band It encloses；The DC voltage of the current source type valve group control rectification side, which is instruction value, to be subtracted according to the DC voltage instruction value of rectification side Line drop is gone to calculate the DC voltage instruction value of inverter side, the DC voltage instruction value of inverter side subtracts the voltage of inverter side The virtual voltage of source type valve group obtains the DC voltage instruction value of the current source type valve group of inverter side, the current source type valve of inverter side Organize the DC voltage instruction value for the current source type valve group for adjusting voltage to the inverter side.

When voltage source converter over-voltage or failure in above-mentioned voltage-source type valve group, pass through the side of investment voltage source converter Open up pass isolated fault.

The present invention also provides a kind of high voltage direct current transmission unit control apparatus, for controlling above-mentioned D.C. high voltage transmission Convertor unit, the control device include detection unit and control unit, in which:

Detection unit, for detecting Trigger Angle or the shutdown angle, DC voltage and DC current of current source type valve group；Detection The DC voltage and DC current of voltage-source type valve group；Detect the DC voltage and DC current of direct current pole；

Control unit, when the high voltage direct current transmission unit rectification is run, the first control unit is current source type Valve group control Trigger Angle reference value is constant, and voltage-source type valve group adjusts voltage control dc power or DC current is instruction value, Second of control unit is current source type valve group control dc power or DC current is instruction value, when the current source type valve group Trigger Angle beyond the reference range for considering Trigger Angle dead zone, voltage-source type valve group, which adjusts voltage, makes the touching of current source type valve group It sends out in angular convolution to the reference range for considering Trigger Angle dead zone；When the high voltage direct current transmission unit inverter operation, The first control unit is that current source type valve group control shutdown angle reference value is constant, and it is whole to control that voltage-source type valve group adjusts voltage The DC voltage for flowing side is instruction value or the instruction value range for considering voltage dead band, and second of control unit is current source type valve group The DC voltage for controlling rectification side is instruction value, when the shutdown angle of the current source type valve group is beyond the ginseng for considering shutdown angle dead zone Value range is examined, voltage-source type valve group, which adjusts voltage, makes the shutdown angular convolution of current source type valve group to the ginseng for considering shutdown angle dead zone It examines within the scope of value.

In above scheme: when the rectification operation of high voltage direct current transmission unit, in the first described control method, when described When current source type valve group detects that DC current instruction value and actual DC current differential are more than current margins, the current source type Valve group is switched to control dc power or DC current.

When high voltage direct current transmission unit inverter operation, in the first described control method and second of control method, When the current source type valve group detects DC current instruction value and actual DC current differential is more than current margins, the electricity Stream source type valve group controls DC current.

The current source type valve group Trigger Angle is line commutation inverter Trigger Angle, and the voltage-source type valve group adjusts voltage Be by voltage source converter adjust voltage, the current source type valve group shutdown angle be line commutation inverter shutdown angle or Blow-out angle.

The Trigger Angle dead zone is less than 15 degree, and the shutdown angle dead zone is less than 15 degree, and the voltage dead band is high pressure Within the 5% of direct-current transmission converter cells rated voltage；The instruction value range for considering Trigger Angle dead zone subtracts for instruction value Plus between Trigger Angle dead zone, the instruction value range for considering shutdown angle dead zone subtracts for instruction value for Trigger Angle dead zone and instruction value Go shutdown angle dead zone and instruction value plus between shutdown angle dead zone, the instruction value range for considering voltage dead band subtracts for instruction value Go voltage dead band and instruction value plus between voltage dead band.

The voltage-source type valve group adjusts voltage to control the DC voltage of rectification side as instruction value or consider voltage dead band Instruction value range be according to the DC voltage instruction value of rectification side or to consider that the instruction value range of voltage dead band subtracts route pressure Drop calculates the DC voltage instruction value of inverter side or considers the instruction value range of voltage dead band, the DC voltage instruction of inverter side Value considers that the virtual voltage for the current source type valve group that the instruction value range of voltage dead band subtracts inverter side obtains the electricity of inverter side The voltage-source type valve group of the DC voltage instruction value of potential source type valve group or the instruction value range for considering voltage dead band, inverter side is adjusted Voltage to the inverter side voltage-source type valve group DC voltage instruction value or consider voltage dead band instruction value range；It is described It is to subtract route according to the DC voltage instruction value of rectification side that it is instruction value that current source type valve group, which controls the DC voltage of rectification side, Pressure drop calculates the DC voltage instruction value of inverter side, and the DC voltage instruction value of inverter side subtracts the voltage-source type valve of inverter side The virtual voltage of group obtains the DC voltage instruction value of the current source type valve group of inverter side, and the current source type valve group of inverter side is adjusted Voltage to the inverter side current source type valve group DC voltage instruction value.

It, can be by putting into the voltage source converter when the voltage source converter over-voltage or failure in voltage-source type valve group Bypass circuit isolated fault.

After adopting the above scheme, the present invention by DC side series electrical Source Con-verters come replace converter power transformer point Connector voltage regulation function, have quickly, accurately adjust voltage, be easy to protect, do not influence line commutation after voltage source converter failure The convertor unit of inverter and converter power transformer composition operates normally.

Detailed description of the invention

Fig. 1 is the first high voltage direct current transmission unit of the invention；

Fig. 2 is second of high voltage direct current transmission unit of the invention；

Fig. 3 is the third high voltage direct current transmission unit of the invention；

Fig. 4 is the 4th kind of high voltage direct current transmission unit of the invention；

Fig. 5 is a kind of line commutation converter structure of the invention；

Fig. 6 is a kind of voltage source converter structure of the invention；

Fig. 7 is a kind of full-bridge sub-modular structure of the invention；

Fig. 8 is of the invention a kind of half-bridge submodule and full-bridge submodule cascaded structure；

Fig. 9 is a kind of HVDC transmission system major loop of the invention；

Control method when Figure 10 is high voltage direct current transmission unit rectification operation of the invention；

Control method when Figure 11 is high voltage direct current transmission unit inverter operation of the invention；

Figure 12 is the control device of high voltage direct current transmission unit of the invention；

Figure 13 is a kind of extra-high voltage DC transmission system that two stations all use high voltage direct current transmission unit of the invention Major loop；

Figure 14 is a kind of extra-high voltage DC transmission system master of the station one using high voltage direct current transmission unit of the invention Circuit；

Figure 15 is a kind of extra-high voltage DC transmission system master of the station two using high voltage direct current transmission unit of the invention Circuit.

Specific embodiment

The embodiment of the present invention is described by the following drawings, wherein identical component uses identical attached drawing mark Note.

Fig. 1 is the first high voltage direct current transmission unit proposed by the present invention, including at least current source type valve group 1, no Converter power transformer 4, voltage-source type valve group 2 and connection transformer 8 with voltage regulation function, connection type is current source type valve group 1 Anode X2 connect with the positive X3 of voltage-source type valve group 2.Current source type valve group 1 does not have pressure regulation function by the connection of connecting line 3 The net side of the valve side of the converter power transformer 4 of energy, the converter power transformer 4 without voltage regulation function passes through connecting line 5 and AC system Connection.If the line commutation inverter in current source type valve group is six pulsation bridge circuits, do not have changing for voltage regulation function Convertor transformer 4 is three-phase transformer, and connecting line 3 and connecting line 5 are triple line；If the line commutation in current source type valve group changes Flowing device is 12 pulsation bridge circuits, then the converter power transformer 4 without voltage regulation function be star connect-star connects three-phase transformer and star - corner connection three-phase transformer is connect, connecting line 3 and connecting line 5 are two groups of triple lines.Voltage-source type valve group 2 by switch or disconnecting link 6 with The parallel branch of charging resistor 7 and be coupled transformer 8 valve side connect, be coupled transformer 8 net side by connecting line 9 with exchange System connection.Connection transformer 8 is three-phase transformer, and the parallel branch of switch or disconnecting link 6 and charging resistor 7 is parallel three phase branch Road, connecting line 9 are triple line.

Fig. 2 is second of high voltage direct current transmission unit proposed by the present invention, including at least current source type valve group 1, no Converter power transformer 4, voltage-source type valve group 2 and connection transformer 8 with voltage regulation function, connection type is current source type valve group 1 Cathode X1 connect with the cathode X4 of voltage-source type valve group 2.Current source type valve group 1 does not have pressure regulation function by the connection of connecting line 3 The net side of the valve side of the converter power transformer 4 of energy, the converter power transformer 4 without voltage regulation function passes through connecting line 5 and AC system Connection.If the line commutation inverter in current source type valve group is six pulsation bridge circuits, do not have changing for voltage regulation function Convertor transformer 4 is three-phase transformer, and connecting line 3 and connecting line 5 are triple line；If the line commutation in current source type valve group changes Flowing device is 12 pulsation bridge circuits, then the converter power transformer 4 without voltage regulation function be star connect-star connects three-phase transformer and star - corner connection three-phase transformer is connect, connecting line 3 and connecting line 5 are two groups of triple lines.Voltage-source type valve group 2 by switch or disconnecting link 6 with The parallel branch of charging resistor 7 and be coupled transformer 8 valve side connect, be coupled transformer 8 net side by connecting line 9 with exchange System connection.Connection transformer 8 is three-phase transformer, and the parallel branch of switch or disconnecting link 6 and charging resistor 7 is parallel three phase branch Road, connecting line 9 are triple line.

Fig. 3 is the third high voltage direct current transmission unit proposed by the present invention, including at least current source type valve group 1, no Converter power transformer 4, voltage-source type valve group 2 and connection transformer 8 with voltage regulation function, connection type is current source type valve group 1 Cathode X1 connect with the positive X3 of voltage-source type valve group 2.Current source type valve group 1 does not have pressure regulation function by the connection of connecting line 3 The net side of the valve side of the converter power transformer 4 of energy, the converter power transformer 4 without voltage regulation function passes through connecting line 5 and AC system Connection.If the line commutation inverter in current source type valve group is six pulsation bridge circuits, do not have changing for voltage regulation function Convertor transformer 4 is three-phase transformer, and connecting line 3 and connecting line 5 are triple line；If the line commutation in current source type valve group changes Flowing device is 12 pulsation bridge circuits, then the converter power transformer 4 without voltage regulation function be star connect-star connects three-phase transformer and star - corner connection three-phase transformer is connect, connecting line 3 and connecting line 5 are two groups of triple lines.Voltage-source type valve group 2 by switch or disconnecting link 6 with The parallel branch of charging resistor 7 and be coupled transformer 8 valve side connect, be coupled transformer 8 net side by connecting line 9 with exchange System connection.Connection transformer 8 is three-phase transformer, and the parallel branch of switch or disconnecting link 6 and charging resistor 7 is parallel three phase branch Road, connecting line 9 are triple line.

Fig. 4 is the 4th kind of high voltage direct current transmission unit proposed by the present invention, including at least current source type valve group 1, no Converter power transformer 4, voltage-source type valve group 2 and connection transformer 8 with voltage regulation function, connection type is current source type valve group 1 Anode X2 connect with the cathode X4 of voltage-source type valve group 2.Current source type valve group 1 does not have pressure regulation function by the connection of connecting line 3 The net side of the valve side of the converter power transformer 4 of energy, the converter power transformer 4 without voltage regulation function passes through connecting line 5 and AC system Connection.If the line commutation inverter in current source type valve group is six pulsation bridge circuits, do not have changing for voltage regulation function Convertor transformer 4 is three-phase transformer, and connecting line 3 and connecting line 5 are triple line；If the line commutation in current source type valve group changes Flowing device is 12 pulsation bridge circuits, then the converter power transformer 4 without voltage regulation function be star connect-star connects three-phase transformer and star - corner connection three-phase transformer is connect, connecting line 3 and connecting line 5 are two groups of triple lines.Voltage-source type valve group 2 by switch or disconnecting link 6 with The parallel branch of charging resistor 7 and be coupled transformer 8 valve side connect, be coupled transformer 8 net side by connecting line 9 with exchange System connection.Connection transformer 8 is three-phase transformer, and the parallel branch of switch or disconnecting link 6 and charging resistor 7 is parallel three phase branch Road, connecting line 9 are triple line.

Fig. 5 is a kind of typical line commutation inverter, using 12 pulsation bridge circuits, shares 12 bridge arms 10, Each 10 lightning arrester connected in parallel 11 of bridge arm, arrester is respectively configured in anode, cathode and the midpoint of line commutation inverter.

Fig. 6 is a kind of typical voltage source converter, and using modularization multi-level converter, there are six bridge arms altogether, each Bridge arm is composed in series by N number of submodule 12 and a reactor 13, each 13 lightning arrester connected in parallel 14 of reactor, modular multilevel Arrester is respectively configured in the anode and cathode of inverter.Fig. 7 is the submodule using full bridge structure, by four 15 Hes of IGBT device The full bridge structure of one capacitor 16 composition.Fig. 8 is the submodule mixed using half-bridge and full bridge structure, by the submodule of half-bridge structure The submodule of block and full bridge structure is composed in series, wherein the submodule of half-bridge structure is by two IGBT devices 17 and a capacitor 18 compositions.

Fig. 9 is the HVDC transmission system major loop proposed by the present invention being made of Fig. 1, Fig. 2, Fig. 3 and Fig. 4.Stand one 19 pole I is made of Fig. 1, and the one 19 pole II of standing is made of Fig. 2, and the 2 20 pole I of standing is made of Fig. 3, stand 2 20 pole II by Fig. 4 It constitutes.It stands and one 19 is connect with DC line 22 by smoothing reactor 21, standing 2 20 passes through smoothing reactor 21 and DC line 22 connections.It stands and one 19 is connect with earthing pole by ground electrode circuit 23, standing 2 20 passes through ground electrode circuit 24 and connect with earthing pole. When power is just sent, AC conversion is by one 19 AC system 25 of standing by its current source type valve group 1 and voltage-source type valve group 2 Direct current arrives at a station 2 20 by the conveying of DC line 22, stand 2 20 by its current source type valve group 1 and the general of voltage-source type valve group 2 DC conversion is that alternating current is sent to AC system 26, to realize that dc power is just sent；When anti-power delivery, stand 2 20 exchange AC conversion is direct current by its current source type valve group 1 and voltage-source type valve group 2 by system 26, defeated by DC line 22 It is sent to station 1, stand one 19 is sent to friendship for DC conversion by its current source type valve group 1 and voltage-source type valve group 2 for alternating current Streaming system 25 is sent to realize that dc power is counter.HVDC transmission system major loop configuring direct current electric current measuring point Id, direct current are female Line voltage measuring point Udl, voltage-source type valve group busbar voltage measuring point Udm and DC neutral busbar voltage measuring point Udn, DC voltage Ud =| Udl-Udn |, voltage-source type valve group voltage Udv=| Udm-Udn |.

Control method when Figure 10 is a kind of high voltage direct current transmission unit rectification operation proposed by the present invention, control figure 1, the high voltage direct current transmission unit of Fig. 2, Fig. 3 or Fig. 4.First determine whether to include current source type valve group, have voltage regulation function Converter power transformer, voltage-source type valve group and be coupled transformer convertor unit be in rectification operation or inverter operation；When above-mentioned When convertor unit is in rectification operation, (the first control of rectification operation of trigger angle control strategy is determined in the selection of current source type valve group Method) or constant current control strategy (second of control method of rectification operation), if current source type valve group is to determine Trigger Angle The Trigger Angle α of control strategy, current source type valve group is equal to Trigger Angle reference value alpha_ord, the adjustment process of current source type valve group terminates； Voltage-source type valve group judges whether its DC current instruction value Io is equal with actual DC electric current Id simultaneously, if Io=Id, electricity The uncomfortable section voltage of potential source type valve group, the adjustment process of voltage-source type valve group terminate；If Io > Id, voltage-source type valve group increases it DC voltage Udv, if Io < Id, voltage-source type valve group reduces its DC voltage Udv, until Io=Id.If current source type valve Group is constant current control strategy, current source type valve group judge its DC current instruction value Io whether with actual DC electric current Id phase Deng if Io=Id, current source type valve group does not adjust Trigger Angle α, and the adjustment process of current source type valve group terminates；If Io > Id, Current source type valve group reduces its Trigger Angle α, if Io < Id, current source type valve group increases its Trigger Angle α, until Io=Id；Simultaneously When the Trigger Angle of current source type valve group is greater than or equal to the lower limit value α of consideration Trigger Angle dead zone Δ α_ordΔ α and it is less than or equal to Consider the upper limit value α of Trigger Angle dead zone Δ α_ordWhen+Δ α, the adjustment process of voltage-source type valve group terminates；When current source type valve group Trigger Angle be greater than consider Trigger Angle dead zone Δ α upper limit value α_ordWhen+Δ α, voltage-source type valve group reduces its DC voltage Udv, When the Trigger Angle of current source type valve group is less than the lower limit value α of consideration Trigger Angle dead zone Δ α_ordWhen Δ α, voltage-source type valve group increases Its DC voltage Udv, until α >=α_ordΔ α and α≤α_ord+Δα。

Control method when Figure 11 is a kind of high voltage direct current transmission unit inverter operation proposed by the present invention, control figure 1, the high voltage direct current transmission unit of Fig. 2, Fig. 3 or Fig. 4.First determine whether to include current source type valve group, have voltage regulation function Converter power transformer, voltage-source type valve group and be coupled transformer convertor unit be in rectification operation or inverter operation；When above-mentioned When convertor unit is in inverter operation, (the first control of inverter operation of hold-off angle control strategy is determined in the selection of current source type valve group Method) or determine rectification side DC voltage control strategy (second of control method of inverter operation), if current source type valve group It is to determine hold-off angle control strategy, the shutdown angle γ of current source type valve group is equal to shutdown angle reference value γ_ord, current source type valve group Adjustment process terminates；Simultaneously voltage-source type valve group judge rectification side DC voltage instruction value Uo whether with actual DC voltage Ud Equal, if Uo=Ud, the uncomfortable section voltage of voltage-source type valve group, the adjustment process of voltage-source type valve group terminates；If Uo > Ud, Voltage-source type valve group increases its DC voltage Udv, if Uo < Ud, voltage-source type valve group reduces its DC voltage Udv, until Uo =Ud.If current source type valve group is constant voltage control strategy, current source type valve group judges the DC voltage instruction value of rectification side Whether Uo is equal with actual DC voltage Ud, if Uo=Ud, current source type valve group does not adjust shutdown angle γ, current source type valve group Adjustment process terminate；If Uo>Ud, current source type valve group reduces it and turns off angle γ, if Uo<Ud, current source type valve group increases Big its turns off angle γ, until Uo=Ud；Trigger Angle dead zone Δ is considered when the shutdown angle of current source type valve group is greater than or equal to simultaneously The lower limit value γ of γ_ordΔ γ and the upper limit value γ for being less than or equal to consideration Trigger Angle dead zone Δ γ_ordWhen+Δ γ, voltage-source type The adjustment process of valve group terminates；When the shutdown angle of current source type valve group is greater than the upper limit value γ of consideration Trigger Angle dead zone Δ γ_ord+ When Δ γ, voltage-source type valve group reduces its DC voltage Udv, considers Trigger Angle dead zone when the shutdown angle of current source type valve group is less than The lower limit value γ of Δ γ_ordWhen Δ γ, voltage-source type valve group increases its DC voltage Udv, until γ >=γ_ordΔ γ and γ≤ γ_ord+Δγ.In D.C. high voltage transmission operational process, above-mentioned adjustment process is repeated, and adjusts Trigger Angle, shutdown angle to ginseng Value is examined, adjusts DC voltage to instruction value.

Figure 12 be a kind of high voltage direct current transmission unit control apparatus proposed by the present invention, control figure 1, Fig. 2, Fig. 3 or The high voltage direct current transmission unit of Fig. 4, above-mentioned control device include detection unit and control unit, in which:

Detection unit detects Trigger Angle or the shutdown angle, DC voltage and DC current of current source type valve group；Detect voltage The DC voltage and DC current of source type valve group；Detect the DC voltage and DC current of direct current pole；

Control unit, when the rectification of high voltage direct current transmission unit is run, the first control unit is current source type valve group Control Trigger Angle reference value it is constant, voltage-source type valve group adjust voltage control dc power or DC current be instruction value, second Kind control unit is current source type valve group control dc power or DC current is instruction value, when the touching of the current source type valve group Angle is sent out beyond the reference range for considering Trigger Angle dead zone, voltage-source type valve group, which adjusts voltage, makes the Trigger Angle of current source type valve group It returns in the reference range for considering Trigger Angle dead zone；When high voltage direct current transmission unit inverter operation, the first control Unit processed is that current source type valve group control shutdown angle reference value is constant, and voltage-source type valve group adjusts voltage to control the straight of rectification side Galvanic electricity pressure is instruction value or the instruction value range for considering voltage dead band, and second of control unit is the control rectification of current source type valve group The DC voltage of side is instruction value, when the shutdown angle of the current source type valve group is beyond the reference value model for considering shutdown angle dead zone It encloses, voltage-source type valve group, which adjusts voltage, makes the shutdown angular convolution of current source type valve group to the reference value model for considering shutdown angle dead zone In enclosing.

Embodiment 1:

Figure 13 shows the extra-high voltage DC transmission system major loop embodiment that two stations all use above-mentioned convertor unit.High pressure DC transmission system major loop is made of station 1,2 20, DC circuit 22 of standing, ground electrode circuit 23 and ground electrode circuit 24. Stand 1 include high voltage direct current transmission unit, the converter power transformer 28 without voltage regulation function, be coupled transformer 35, direct current Filter 32, alternating current filter 33, smoothing reactor 21, AC system 25 and ground electrode circuit 24, wherein do not have pressure regulation function The converter power transformer 28 of energy is not adjustable tap；Stand 2 20 include high voltage direct current transmission unit, do not have voltage regulation function Converter power transformer 28, be coupled transformer 35, DC filter 32, alternating current filter 33, smoothing reactor 21, AC system 26 With ground electrode circuit 25, wherein the converter power transformer 28 without voltage regulation function is not adjustable tap.D.C. high voltage transmission changes Stream unit is made of current source type valve group 39, voltage-source type valve group 40.Current source type valve group 39 includes two using 12 pulsation Line commutation inverter 27, bypass cock 29, connection disconnecting link 30 and the bypass disconnecting link 31 of bridge circuit, the packet of voltage-source type valve group 40 It includes using the voltage source converter 34 of modularization multi-level converter, bypass cock or bypass electronic power switch 36, connection knife Lock 30 and bypass disconnecting link 31, wherein voltage source converter 34 includes submodule 38 and bridge arm reactor 37, and submodule 38 is full-bridge Submodule or half-bridge submodule.

It stands and one 19 connect with earthing pole by ground electrode circuit 23, stand 2 20 passes through ground electrode circuit 24 and earthing pole company It connects.When power is just sent, stand 1 AC system 25 by its current source type valve group 39 and voltage-source type valve group 40 by alternating current It is converted into direct current, arrives at a station 2 20 by the conveying of DC line 22, stand 2 20 passes through its current source type valve group 39 and voltage-source type DC conversion is that alternating current is sent to AC system 26 by valve group 40, to realize that dc power is just sent；When anti-power delivery, two are stood AC conversion is direct current by its current source type valve group 39 and voltage-source type valve group 40 by 20 AC system 26, by straight The conveying of Flow Line 22 arrives at a station 1, and stand one 19 is by DC conversion by its current source type valve group 39 and voltage-source type valve group 40 Alternating current is sent to AC system 25, send to realize that dc power is counter.

When power is just sent, stand 1 in rectification operation, current source type valve group 39 selection determine trigger angle control strategy or Constant current control strategy, if current source type valve group 39 is to determine trigger angle control strategy, the Trigger Angle α of current source type valve group 39 etc. In Trigger Angle reference value alpha_ord, the adjustment process of current source type valve group 39 terminates；Voltage-source type valve group 40 judges its direct current simultaneously Whether equal with actual DC electric current Id flow instruction value Io, if Io=Id, the uncomfortable section voltage of voltage-source type valve group 40, voltage source The adjustment process of type valve group 40 terminates；If Io>Id, voltage-source type valve group 40 increases its DC voltage Udv, if Io<Id, electricity Potential source type valve group 40 reduces its DC voltage Udv, until Io=Id.If current source type valve group 39 is constant current control strategy, Current source type valve group 39 judges whether its DC current instruction value Io is equal with actual DC electric current Id, if Io=Id, electric current Source type valve group 39 does not adjust Trigger Angle α, and the adjustment process of current source type valve group 39 terminates；If Io > Id, current source type valve group 39 Reduce its Trigger Angle α, if Io < Id, current source type valve group 39 increases its Trigger Angle α, until Io=Id；Work as current source type simultaneously The Trigger Angle of valve group 39 is greater than or equal to the lower limit value α for considering Trigger Angle dead zone Δ α_ordΔ α and be less than or equal to consider triggering The upper limit value α of angle dead zone Δ α_ordWhen+Δ α, the adjustment process of voltage-source type valve group 40 terminates；When the touching of current source type valve group 39 It sends out angle and is greater than the upper limit value α for considering Trigger Angle dead zone Δ α_ordWhen+Δ α, voltage-source type valve group 40 reduces its DC voltage Udv, when The Trigger Angle of current source type valve group 39 is less than the lower limit value α for considering Trigger Angle dead zone Δ α_ordWhen Δ α, voltage-source type valve group 40 increases Big its DC voltage Udv, until α >=α_ordΔ α and α≤α_ord+Δα.Whole process, converter power transformer 28 do not adjust tap To change net side and valve side winding no-load voltage ratio.

When power is just sent, stand 2 20 in inverter operation, the selection of current source type valve group 39 determine hold-off angle control strategy or Determine rectification side DC voltage control strategy, if current source type valve group 39 is to determine hold-off angle control strategy, current source type valve group It turns off angle γ and is equal to shutdown angle reference value γ_ord, the adjustment process of current source type valve group 39 terminates；Voltage-source type valve group 40 simultaneously Judge whether the DC voltage instruction value Uo of rectification side is equal with actual DC voltage Ud, if Uo=Ud, voltage-source type valve group 40 uncomfortable section voltages, the adjustment process of voltage-source type valve group 40 terminate；If Uo > Ud, voltage-source type valve group 40 increases its direct current Voltage Udv, if Uo < Ud, voltage-source type valve group 40 reduces its DC voltage Udv, until Uo=Ud.If current source type valve group 39 be constant voltage control strategy, and current source type valve group 39 judges whether the DC voltage instruction value Uo of rectification side is electric with actual DC Press Ud equal, if Uo=Ud, current source type valve group 39 does not adjust shutdown angle γ, the adjustment process knot of current source type valve group 39 Beam；If Uo>Ud, current source type valve group 39 reduces it and turns off angle γ, if Uo<Ud, current source type valve group 39 increases its shutdown Angle γ, until Uo=Ud；Consider under the Δ γ of Trigger Angle dead zone when the shutdown angle of current source type valve group 39 is greater than or equal to simultaneously Limit value γ_ordΔ γ and the upper limit value γ for being less than or equal to consideration Trigger Angle dead zone Δ γ_ordWhen+Δ γ, voltage-source type valve group 40 Adjustment process terminate；When the shutdown angle of current source type valve group 39 is greater than the upper limit value γ of consideration Trigger Angle dead zone Δ γ_ord+Δ When γ, voltage-source type valve group 40 reduces its DC voltage Udv, considers that Trigger Angle is dead when the shutdown angle of current source type valve group 39 is less than The lower limit value γ of area Δ γ_ordWhen Δ γ, voltage-source type valve group 40 increases its DC voltage Udv, until γ >=γ_ordΔ γ and γ≤γ_ord+Δγ.Whole process, converter power transformer 28 do not adjust tap to change net side and valve side winding no-load voltage ratio.

Embodiment 2:

Figure 14 shows station one using the extra-high voltage DC transmission system major loop embodiment of above-mentioned convertor unit.High straightening Stream transmission system major loop is made of station 1,2 20, DC circuit 22 of standing, ground electrode circuit 23 and ground electrode circuit 24.It stands One 19 include high voltage direct current transmission unit, the converter power transformer 28 without voltage regulation function, connection transformer 35, direct current filter Wave device 32, alternating current filter 33, smoothing reactor 21, AC system 25 and ground electrode circuit 24, wherein do not have voltage regulation function Converter power transformer 28 be not adjustable tap；Stand 2 20 include current source type valve group 39, the change of current transformation with voltage regulation function Device 41 is coupled transformer 35, DC filter 32, alternating current filter 33, smoothing reactor 21, AC system 26 and ground connection polar curve Road 25, wherein the converter power transformer 41 with voltage regulation function is adjustable tap.High voltage direct current transmission unit is by current source Type valve group 39, voltage-source type valve group 40 form.Current source type valve group 39 includes two power grids using 12 pulsation bridge circuits Commutation inverter 27, bypass cock 29, connection disconnecting link 30 and bypass disconnecting link 31, voltage-source type valve group 40 include more using modularization Voltage source converter 34, bypass cock or the bypass electronic power switch 36 of level converter connect disconnecting link 30 and bypass disconnecting link 31, wherein voltage source converter 34 includes submodule 38 and bridge arm reactor 37, and submodule 38 is full-bridge submodule or half-bridge Module.

It stands and one 19 connect with earthing pole by ground electrode circuit 23, stand 2 20 passes through ground electrode circuit 24 and earthing pole company It connects.When power is just sent, stand 1 AC system 25 by its current source type valve group 39 and voltage-source type valve group 40 by alternating current Be converted into direct current, arrive at a station 2 20 by the conveying of DC line 22, stand 2 20 by its current source type valve group 39 by direct current turn It turns to alternating current and is sent to AC system 26, to realize that dc power is just sent；When anti-power delivery, stand 2 20 AC system 26 it is logical It is direct current that its current source type valve group 39, which is crossed, by AC conversion, arrives at a station 1 by the conveying of DC line 22, and standing one 19 passes through DC conversion is that alternating current is sent to AC system 25 by its current source type valve group 39 and voltage-source type valve group 40, to realize straight Flow anti-power delivery.

When power is just sent, stand 2 20 in inverter operation, the selection of current source type valve group 39 determine hold-off angle control strategy or Determine rectification side DC voltage control strategy, if current source type valve group 39 is to determine hold-off angle control strategy, current source type valve group It turns off angle γ and is equal to shutdown angle reference value γ_ord, the adjustment process of current source type valve group 39 terminates；Current source type valve group 39 simultaneously Judge rectification side DC voltage instruction value Uo whether with actual DC voltage Ud consider voltage dead band Δ Ud instruction value model It encloses, if | Uo-Ud |≤Δ Ud, converter power transformer 41 do not adjust tap；If Uo-Ud > Δ Ud, converter power transformer 41 is adjusted The unloaded DC voltage of tap increase current source type valve group 39；If Ud-Uo > Δ Ud, converter power transformer 41 adjusts tap Reduce the unloaded DC voltage instruction value of current source type valve group 39, until | Uo-Ud |≤Δ Ud.If current source type valve group 39 is Constant voltage control strategy, current source type valve group 39 judge rectification side DC voltage instruction value Uo whether with actual DC voltage Ud Equal, if Uo=Ud, current source type valve group 39 does not adjust shutdown angle γ, and the adjustment process of current source type valve group 39 terminates；Such as Fruit Uo>Ud, current source type valve group 39 reduces it and turns off angle γ, if Uo<Ud, current source type valve group 39 increases it and turns off angle γ, Until Uo=Ud；Simultaneously when the shutdown angle of current source type valve group 39 is greater than or equal to the lower limit value of consideration shutdown angle dead zone Δ γ γ_ordΔ γ and the upper limit value γ for being less than or equal to consideration shutdown angle dead zone Δ γ_ordWhen+Δ γ, converter power transformer 41 is not adjusted Tap；When the shutdown angle of current source type valve group 39 is greater than the upper limit value γ for considering to turn off angle dead zone Δ γ_ordWhen+Δ γ, the change of current Transformer 41 adjusts the unloaded DC voltage that tap reduces current source type valve group 39, when the shutdown angle of current source type valve group 39 is small In the lower limit value γ for considering shutdown angle dead zone Δ γ_ordWhen Δ γ, converter power transformer 41 adjusts tap and increases current source type valve The unloaded DC voltage of group 39, until γ >=γ_ordΔ γ and γ≤γ_ord+Δγ.Whole process, converter power transformer 41 are adjusted Tap changes net side and valve side winding no-load voltage ratio.

Embodiment 3:

Figure 15 shows station two using the extra-high voltage DC transmission system major loop embodiment of above-mentioned convertor unit.High straightening Stream transmission system major loop is made of station 1,2 20, DC circuit 22 of standing, ground electrode circuit 23 and ground electrode circuit 24.It stands 1 include current source type valve group 39, the converter power transformer 41 with voltage regulation function, be coupled transformer 35, DC filter 32, Alternating current filter 33, smoothing reactor 21, AC system 25 and ground electrode circuit 24, wherein the change of current with voltage regulation function becomes Depressor 28 is adjustable tap；Stand 2 20 include high voltage direct current transmission unit, the converter power transformer without voltage regulation function 28, it is coupled transformer 35, DC filter 32, alternating current filter 33, smoothing reactor 21, AC system 26 and ground electrode circuit 25, wherein the converter power transformer 28 without voltage regulation function is not adjustable tap.High voltage direct current transmission unit is by electric current Source type valve group 39, voltage-source type valve group 40 form.Current source type valve group 39 includes two electricity using 12 pulsation bridge circuits Net commutation inverter 27, bypass cock 29, connection disconnecting link 30 and bypass disconnecting link 31, voltage-source type valve group 40 include using modularization Voltage source converter 34, bypass cock or the bypass electronic power switch 36 of multilevel converter connect disconnecting link 30 and bypass knife Lock 31, wherein voltage source converter 34 includes submodule 38 and bridge arm reactor 37, and submodule 38 is full-bridge submodule or half-bridge Submodule.

It stands and one 19 connect with earthing pole by ground electrode circuit 23, stand 2 20 passes through ground electrode circuit 24 and earthing pole company It connects.When power is just sent, stand 1 AC system 25 by its current source type valve group 39 by AC conversion be direct current, pass through The conveying of DC line 22 arrives at a station 2 20, and stand 2 20 passes through its current source type valve group 39 and voltage-source type valve group 40 for DC conversion It is sent to AC system 26 for alternating current, to realize that dc power is just sent；When anti-power delivery, 2 20 AC system 26 of standing passes through AC conversion is direct current by its current source type valve group 39 and voltage-source type valve group 40, arrives at a station one by the conveying of DC line 22 19, stand 1 by its current source type valve group 39 by DC conversion be alternating current be sent to AC system 25, to realize direct current Anti-power delivery.

When power is just sent, 1 are stood in rectification operation, current source type valve group 39 uses constant current control strategy, current source Type valve group 39 judges whether its DC current instruction value Io is equal with actual DC electric current Id, if Io=Id, current source type valve Group 39 does not adjust Trigger Angle α, and the adjustment process of current source type valve group 39 terminates；If Io > Id, current source type valve group 39 reduces it Trigger Angle α, if Io < Id, current source type valve group 39 increases its Trigger Angle α, until Io=Id；Work as current source type valve group 39 simultaneously Trigger Angle be greater than or equal to consider Trigger Angle dead zone Δ α lower limit value α_ordΔ α and be less than or equal to consider Trigger Angle dead zone The upper limit value α of Δ α_ordWhen+Δ α, converter power transformer 41 does not adjust tap；It is examined when the Trigger Angle of current source type valve group 39 is greater than Consider the upper limit value α of Trigger Angle dead zone Δ α_ordWhen+Δ α, converter power transformer 41 adjusts the sky that tap reduces current source type valve group 39 DC voltage is carried, when the Trigger Angle of current source type valve group 39 is less than the lower limit value α of consideration Trigger Angle dead zone Δ α_ordWhen Δ α, change Convertor transformer 41 adjusts the unloaded DC voltage that tap increases current source type valve group 39, until α >=α_ordΔ α and α≤α_ord+ Δα.Whole process, converter power transformer 41 adjust tap to change net side and valve side winding no-load voltage ratio.

The above examples only illustrate the technical idea of the present invention, and this does not limit the scope of protection of the present invention, all According to the technical idea provided by the invention, any changes made on the basis of the technical scheme each falls within the scope of the present invention Within.

Claims

1. a kind of high voltage direct current transmission unit, it is characterised in that: including current source type valve group, changing without voltage regulation function Convertor transformer, voltage-source type valve group and connection transformer, wherein current source type valve group passes through the change of current for not having voltage regulation function and becomes Depressor connects AC system, and voltage-source type valve group connects AC system by being coupled transformer, and current source type valve group is in direct current Side and voltage-source type valve group are connected in series.

2. a kind of high voltage direct current transmission unit as described in claim 1, it is characterised in that: described not have voltage regulation function Converter power transformer be converter power transformer without tap or tap switch, do not have and adjust converter power transformer net side and valve side Winding no-load voltage ratio function.

3. a kind of high voltage direct current transmission unit as described in claim 1, it is characterised in that: the connection transformer uses Without tap or the transformer of tap switch, does not have and adjust transformer net side and valve side winding no-load voltage ratio function；Or it is coupled Transformer uses the transformer with tap and tap switch, has the function of to adjust transformer net side and valve side winding no-load voltage ratio.

4. a kind of high voltage direct current transmission unit as described in claim 1, it is characterised in that: the voltage-source type valve group with It is coupled between transformer and is also connected with charging resistor, and the charging resistor is in parallel with switch or disconnecting link.

5. a kind of high voltage direct current transmission unit as described in claim 1, it is characterised in that: the current source type valve group is adopted With following three kinds of schemes any one: the first, using line commutation inverter；Second, using power grid parallel with one another Commutation inverter and bypass cock；The third, including line commutation inverter, bypass cock, bypass disconnecting link and two connection knives Lock, wherein line commutation inverter is connected in parallel with bypass cock, and the both ends after being connected in parallel are separately connected two connection disconnecting links One end, bypass disconnecting link both ends be separately connected two connection disconnecting link the other ends.

6. a kind of high voltage direct current transmission unit as claimed in claim 5, it is characterised in that: the line commutation inverter Using six pulsation bridge circuits, 12 pulsation bridge circuits or by multiple circuits for being composed in series of six pulsation bridge circuits, by The half control type power semiconductor that can not be turned off is constituted.

7. a kind of high voltage direct current transmission unit as claimed in claim 6, it is characterised in that: the half control that can not be turned off Type power semiconductor is thyristor.

8. a kind of high voltage direct current transmission unit as described in claim 1, it is characterised in that: the voltage-source type valve group is adopted With following three kinds of schemes any one: the first, using voltage source converter；Second, using voltage source parallel with one another Inverter and bypass cock；The third, including voltage source converter, bypass cock, bypass disconnecting link and two connection disconnecting links, In, voltage source converter is connected in parallel with bypass cock, and the both ends after being connected in parallel are separately connected one end of two connection disconnecting links, The both ends of bypass disconnecting link are separately connected the other end of two connection disconnecting links.

9. a kind of high voltage direct current transmission unit as claimed in claim 8, it is characterised in that: in three kinds of schemes, institute Stating voltage source converter is that single voltage source converter or two or more voltage source converter are in parallel；The second scheme and It further include inductance, inductance is connected with voltage source converter or inductance is connected with bypass cock in the third scheme.

10. a kind of high voltage direct current transmission unit as claimed in claim 8, it is characterised in that: the bypass cock uses Mechanical switch or electronic power switch, the electronic power switch are the valve groups being made of Thyristors in series or complete by what can be turned off Control type power semiconductor valve group in series.

11. a kind of high voltage direct current transmission unit as claimed in claim 8, it is characterised in that: the voltage source converter It is changed using two level converters, diode-clamped multilevel converter, modularization multi-level converter MMC, mixed multi-level Flow device HMC, two level converter CTL of two level cascade current converter CSL or stack；Wherein, the modular multilevel changes Flow the modular multilevel of modularization multi-level converter or full-bridge submodule composition that device MMC is half-bridge submodule composition The modularization multi-level converter of inverter or half-bridge submodule and full-bridge submodule mixing composition.

12. a kind of high voltage direct current transmission unit as claimed in claim 11, it is characterised in that: the modular multilevel The half-bridge submodule or full-bridge submodule of inverter MMC has by-pass switch or thyristor, and the by-pass switch or thyristor are simultaneously Half-bridge submodule or full-bridge submodule both ends are associated in, for bypassing half-bridge submodule or full-bridge submodule.

13. a kind of high voltage direct current transmission unit as claimed in claim 11, it is characterised in that: the modular multilevel The half-bridge submodule of inverter MMC also has protection thyristor, and the protection thyristor is connected in parallel on half-bridge submodule both ends, protection The backward dioded of the full-control type power semiconductor turned off connected in parallel.

14. a kind of high voltage direct current transmission unit as claimed in claim 8, it is characterised in that: the voltage source converter It is made of the full-control type power semiconductor that can be turned off, the full-control type power semiconductor turned off is brilliant using insulated gate bipolar Body pipe IGBT, integrated gate commutated thyristor IGCT, turn-off thyristor GTO, Power MOSFET Power MOSFET, electronics Injection enhancing grid crystal IEGT, door pole stream-exchanging thyristor GCT or SiC reinforcement type junction field effect transistor SiC-JFET.

15. a kind of high voltage direct current transmission unit as described in claim 1, it is characterised in that: the current source type valve group Or the equal lightning arrester connected in parallel of each bridge arm of voltage-source type valve group；The DC side of the current source type valve group or voltage-source type valve group is equal Lightning arrester connected in parallel.

16. a kind of high voltage direct current transmission unit as described in claim 1, it is characterised in that: for rectification side, the electricity The anode and voltage-source type valve for the current source type valve group is connected in series in DC side and voltage-source type valve group in stream source type valve group The anode connection of group or the cathode of the current source type valve group are connect with the cathode of voltage-source type valve group；For inverter side, institute It states current source type valve group and the cathode and voltage source for the current source type valve group is connected in series in DC side and voltage-source type valve group The anode connection of type valve group or the anode of the current source type valve group are connect with the cathode of voltage-source type valve group.

17. a kind of high voltage direct current transmission unit as claimed in claim 16, it is characterised in that: the current source type valve group Comprising line commutation inverter, end where the anode of current source type valve group is end where the anode of line commutation inverter, described End where the cathode of current source type valve group is end where the cathode of line commutation inverter；The voltage-source type valve group includes voltage Source inverter, end where the anode of voltage-source type valve group are end where the anode of voltage source converter, the voltage-source type valve group Cathode where end be voltage source converter cathode where end.

18. a kind of HVDC transmission system major loop, it is characterised in that: the HVDC transmission system major loop rectification side At least the high voltage direct current transmission unit described in any one of claim 1-17 forms a direct current pole；Or the high pressure The DC transmission system major loop inverter side at least high voltage direct current transmission unit group as described in any one of claim 1-17 At a direct current pole.

19. a kind of control method suitable for the described in any item high voltage direct current transmission units of claim 1 to 17, special Sign is: according to the operation conditions of high voltage direct current transmission unit, it is divided into two kinds of situations:

When the high voltage direct current transmission unit rectification operation, the first control method is that current source type valve group controls Trigger Angle Reference value is constant, and voltage-source type valve group adjusts voltage control dc power or DC current is instruction value, second of control method Dc power is controlled for current source type valve group or DC current is instruction value, when the Trigger Angle of current source type valve group is beyond consideration touching The reference range in angle dead zone is sent out, voltage-source type valve group, which adjusts voltage, makes the Trigger Angle of current source type valve group return to consideration Trigger Angle In the reference range in dead zone；

When the high voltage direct current transmission unit inverter operation, the first control method is current source type valve group control shutdown angle Reference value is constant, and voltage-source type valve group adjusts voltage to control the DC voltage of rectification side as instruction value or consider voltage dead band Instruction value range, second of control method are that the DC voltage of current source type valve group control rectification side is instruction value, work as current source Beyond the reference range for considering shutdown angle dead zone, voltage-source type valve group, which adjusts voltage, makes current source type valve at the shutdown angle of type valve group In the shutdown angular convolution to the reference range for considering shutdown angle dead zone of group.

20. a kind of high voltage direct current transmission unit control method as claimed in claim 19, it is characterised in that: the high pressure When the rectification operation of direct-current transmission converter unit, in the first described control method, when current source type valve group detects DC current When instruction value and actual DC current differential are more than current margins, current source type valve group is switched to control dc power or direct current Stream.

21. a kind of high voltage direct current transmission unit control method as claimed in claim 19, it is characterised in that: the high pressure When direct-current transmission converter unit inverter operation, in the first described control method and second of control method, when current source type valve When group detects that DC current instruction value and actual DC current differential are more than current margins, current source type valve group controls direct current Stream.

22. a kind of high voltage direct current transmission unit control method as described in claim 20 or 21, it is characterised in that: described Current margins are that 0.02 times of rated DC current flows to 0.3 times of rated direct current.

23. a kind of high voltage direct current transmission unit control method as claimed in claim 19, it is characterised in that: the electric current Source type valve group Trigger Angle is line commutation inverter Trigger Angle, and it is to pass through voltage source converter that the voltage-source type valve group, which adjusts voltage, Device adjusts voltage, and the shutdown angle of the current source type valve group is the shutdown angle or blow-out angle of line commutation inverter.

24. a kind of high voltage direct current transmission unit control method as claimed in claim 19, it is characterised in that: the triggering Angle dead zone is any value between 0 to 15 degree, and the shutdown angle dead zone is any value of 0 to 15 degree, and the voltage dead band is height Within press direct-current transmission converter cells rated voltage 5%；The reference range for considering Trigger Angle dead zone subtracts for reference value Go Trigger Angle dead zone and reference value plus between Trigger Angle dead zone, the reference range for considering shutdown angle dead zone is reference value Shutdown angle dead zone and reference value are subtracted plus between shutdown angle dead zone, the instruction value range for considering voltage dead band is instruction value Voltage dead band and instruction value are subtracted plus between voltage dead band.

25. a kind of high voltage direct current transmission unit control method as claimed in claim 19, it is characterised in that: the voltage Source type valve group adjusts voltage to control the DC voltage of rectification side and be instruction value or consider that the instruction value range of voltage dead band is root It subtracts line drop according to the DC voltage instruction value of rectification side or the instruction value range of consideration voltage dead band and calculates inverter side DC voltage instruction value or the instruction value range for considering voltage dead band, the DC voltage instruction value of inverter side or consideration voltage dead band The instruction value range current source type valve group that subtracts inverter side virtual voltage obtain inverter side voltage-source type valve group direct current The voltage-source type valve group of voltage instruction value or the instruction value range for considering voltage dead band, inverter side is adjusted described in voltage to instruction value The DC voltage instruction value of the voltage-source type valve group of inverter side or the instruction value range for considering voltage dead band；The current source type valve It is to subtract line drop according to the DC voltage instruction value of rectification side to calculate that the DC voltage of group control rectification side, which is instruction value, The DC voltage instruction value of inverter side, the DC voltage instruction value of inverter side subtract the practical electricity of the voltage-source type valve group of inverter side Pressure obtains the DC voltage instruction value of the current source type valve group of inverter side, and the current source type valve group of inverter side adjusts voltage described in The DC voltage instruction value of the current source type valve group of inverter side.

26. a kind of high voltage direct current transmission unit control method as claimed in claim 19, it is characterised in that: the voltage When voltage source converter over-voltage or failure in the type valve group of source, pass through the bypass cock isolated fault of investment voltage source converter.

27. a kind of control device suitable for the described in any item high voltage direct current transmission units of claim 1 to 17, special Sign is: including detection unit and control unit, in which:

Detection unit, for detecting Trigger Angle or the shutdown angle, DC voltage and DC current of current source type valve group；Detect voltage The DC voltage and DC current of source type valve group；Detect the DC voltage and DC current of direct current pole；

Control unit, when the high voltage direct current transmission unit rectification is run, the first control unit is current source type valve group Control Trigger Angle reference value it is constant, voltage-source type valve group adjust voltage control dc power or DC current be instruction value, second Kind control unit is current source type valve group control dc power or DC current is instruction value, when the touching of the current source type valve group Angle is sent out beyond the reference range for considering Trigger Angle dead zone, voltage-source type valve group, which adjusts voltage, makes the Trigger Angle of current source type valve group It returns in the reference range for considering Trigger Angle dead zone；When the high voltage direct current transmission unit inverter operation, first Kind control unit is that current source type valve group control shutdown angle reference value is constant, and voltage-source type valve group adjusts voltage to control rectification side DC voltage be instruction value or consider voltage dead band instruction value range, second of control unit be current source type valve group control The DC voltage of rectification side is instruction value, when the shutdown angle of the current source type valve group is beyond the reference value for considering shutdown angle dead zone Range, voltage-source type valve group, which adjusts voltage, makes the shutdown angular convolution of current source type valve group to the reference value for considering shutdown angle dead zone In range.