WO2023193729A1 - 一种低频输电***停运方法及装置 - Google Patents

一种低频输电***停运方法及装置 Download PDF

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WO2023193729A1
WO2023193729A1 PCT/CN2023/086385 CN2023086385W WO2023193729A1 WO 2023193729 A1 WO2023193729 A1 WO 2023193729A1 CN 2023086385 W CN2023086385 W CN 2023086385W WO 2023193729 A1 WO2023193729 A1 WO 2023193729A1
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frequency
sub
low
voltage
power
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PCT/CN2023/086385
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English (en)
French (fr)
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许烽
陆翌
陆承宇
裘鹏
黄晓明
倪晓军
陈骞
丁超
郑眉
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国网浙江省电力有限公司电力科学研究院
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Publication of WO2023193729A1 publication Critical patent/WO2023193729A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases

Definitions

  • the invention belongs to the field of power system transmission, and specifically relates to a low-frequency power transmission system outage method and device.
  • Low-frequency power transmission reduces the transmission frequency, reduces line impedance, reduces cable charging reactive power, and improves the transmission and control capabilities of the power grid. It is a useful supplement to power frequency AC power transmission and DC power transmission methods, and is suitable for medium and long-distance offshore wind power transmission and urban power grids. Scenarios such as partition interconnection and island interconnection power supply.
  • the present invention provides a low-frequency power transmission system outage method and device to achieve fast, smooth, and impact-free low-frequency power transmission system outage without adding any primary equipment.
  • a technical solution adopted by the present invention is: a low-frequency power transmission system outage method, which includes:
  • Step 1 Except for the AC frequency switching station with a fixed low-frequency voltage, all other AC frequency switching stations adjust the active power and reactive power on the low-frequency side to zero;
  • Step 2 Control the AC frequency switching station of the low-frequency voltage to gradually reduce the AC voltage amplitude on the low-frequency side to zero;
  • Step 3 In each AC switching station, adjust the tap of the connecting transformer to the maximum transformation ratio position to reduce the AC voltage on the AC switching valve side;
  • Step 4 In each AC frequency switching station, put in redundant sub-modules and increase the voltage modulation ratio to reduce the sub-module capacitor voltage to U smL1 ;
  • N is the total number of sub-modules in each bridge arm, including redundant sub-modules;
  • U v is the AC voltage on the AC valve side;
  • Step 5 Lock all AC frequency switching stations, the low-frequency circuit breaker connected to the low-frequency side AC frequency station and the low-frequency transmission network, disconnect the power frequency circuit breaker connecting the power frequency side transformer to the power frequency system, and disconnect the starting resistor.
  • Step 6 Set the three bridge arms connected to the same phase on the low-frequency side into one group to form multiple groups; after completing the first five steps, all sub-modules of the three bridge arms in each group are switched from the blocking state to the bypass state. , then switch all sub-modules in the first bridge arm from the bypass state to the positive voltage input or negative voltage input state.
  • the capacitance voltage of the sub-module of the bridge arm drops to U smL2
  • all sub-modules of the bridge arm switch back To the bypass state, the operation steps of the second bridge arm and the third bridge arm are the same as those of the first bridge arm.
  • all sub-modules in the group switch from the bypass state to the blocking state;
  • the said U smL2 is greater than the lowest working voltage of the sub-module driver board U smmin ;
  • Step 7 All sub-modules will continue to slowly discharge through the voltage-equalizing resistors connected in parallel with them. After the discharge is completed, use electrical inspection to verify whether the sub-module capacitors have been completely discharged.
  • the low-frequency power transmission system includes alternating frequency switching stations and low-frequency power transmission networks at both ends.
  • the main equipment of the AC frequency switching station from the power frequency side to the low frequency side includes connection transformers, starting resistors, modular multi-level matrix converters, etc.
  • the low-frequency side of the AC switching station with a fixed low-frequency voltage adopts a control method with a fixed low-frequency AC voltage amplitude and frequency, which is the key to maintaining the stability of the frequency and voltage of the low-frequency system; other AC switching stations are divided into There are two types.
  • One type is connected to the active AC power grid.
  • the low-frequency side adopts the control method of constant active power and constant reactive power. By directly setting the active and reactive power instructions to zero, the power can be reduced to zero;
  • the other type is connected to the passive AC power grid. This type of AC frequency switching station achieves the purpose of reducing the power to zero by disconnecting from the power frequency AC.
  • step 3 the tap of the connecting transformer is located on the grid side, the voltage per unit value for each step length adjustment is set to u tap , and the upward adjustment gear of the tap is set to n tap . Then, the connection When the tap of the transformer is adjusted to the maximum transformation ratio position, the AC voltage U v on the AC valve side is:
  • U s is the power frequency network side voltage
  • k is the transformation ratio of the connecting transformer, k>1.
  • the sub-module contains four IGBTs T1-T4 and their anti-parallel diodes.
  • T1 and T2 are turned on, T3 and T4 are turned off, or T1 and T2 are turned off, and T3 and T4 are turned on.
  • T1 and T4 are turned on, and T2 and T3 are turned off, the submodule is in the positive voltage input state; when T1 and T4 are turned off, and T2 and T3 are turned on, the submodule is in the negative voltage input state. ;
  • T1-T4 are all turned off, the sub-module is in a locked state.
  • a low-frequency power transmission system shutdown device which includes:
  • AC voltage amplitude zero reduction unit an AC frequency switching station that controls low-frequency voltage and gradually reduces the AC voltage amplitude on the low-frequency side to zero;
  • AC voltage reduction unit In each AC switching station, adjust the tap of the connecting transformer to the maximum transformation ratio position to reduce the AC voltage on the AC switching valve side;
  • Sub-module capacitance voltage reduction unit In each AC frequency switching station, redundant sub-modules are put in and the voltage modulation ratio is increased to reduce the sub-module capacitance voltage to U smL1 ;
  • N is the total number of sub-modules in each bridge arm, including redundant sub-modules;
  • U v is the AC voltage on the AC valve side;
  • Circuit breaker disconnecting unit locks all AC switching stations, disconnects the low-frequency circuit breaker connecting the low-frequency side AC switching station to the low-frequency transmission network, disconnects the power frequency circuit breaker connecting the power frequency side connecting transformer to the power frequency system, and disconnects Open the circuit breaker connected in parallel with the starting resistor;
  • Sub-module control unit Set the three bridge arms connected to the same phase on the low-frequency side into one group to form three groups; after completing the first five steps, all sub-modules of the three bridge arms in each group switch from the blocking state to the bypass state. Then, switch all sub-modules in the first bridge arm from the bypass state to the positive voltage input or negative voltage input state. When the capacitor voltage of the sub-module of the bridge arm drops to U smL2 , all sub-modules of the bridge arm will Switch back to the bypass state.
  • the operation steps for the second bridge arm and the third bridge arm are the same as those for the first bridge arm. After all bridge arms in the group have completed the above operations, all sub-modules in the group will switch from the bypass state to the blocking state. ;
  • the said U smL2 is greater than the lowest working voltage of the sub-module driver board U smmin ;
  • Verification unit All sub-modules will continue to slowly discharge through the voltage-equalizing resistors connected in parallel with them. After the discharge is completed, the electrical inspection method will be used to verify whether the sub-module capacitors have been completely discharged.
  • the present invention has the following beneficial technical effects:
  • the present invention can realize fast, smooth, and impact-free shutdown of the low-frequency power transmission system, ensuring the safety of the power grid and equipment.
  • the present invention can feed back the electric energy stored in the sub-module capacitor to the power grid to the greatest extent, reducing electric energy loss.
  • the present invention realizes the reuse of existing primary equipment through the energy consumption loop composed of the secondary winding of the transformer and the starting resistor. While achieving the purpose of rapid shutdown of the low-frequency power transmission system, it does not increase investment and improves the equipment utilization rate.
  • Figure 1 is a schematic diagram of the low-frequency power transmission system of the present invention
  • Figure 2 is a flow chart of the low-frequency power transmission system outage method of the present invention.
  • FIG. 3 is a schematic diagram of the fast discharge circuit of the present invention.
  • Figure 4 is a schematic structural diagram of the sub-module of the present invention.
  • Figure 5 is a structural block diagram of the low-frequency power transmission system shutdown device of the present invention.
  • FIG. 1 shows a schematic diagram of a three-terminal low-frequency power transmission system. It can be seen from the figure that the three-terminal low-frequency power transmission system includes a three-terminal AC switching station and a low-frequency power transmission network.
  • the main equipment of the AC frequency switching station from the power frequency side to the low frequency side includes connection transformers, starting resistors, modular multi-level matrix converters, etc.
  • the outage method of the low-frequency transmission system is shown in Figure 2. The specific contents are as follows:
  • Step 1 Except for the AC frequency switching station with a fixed low-frequency voltage, all other AC frequency switching stations adjust the active power and reactive power on the low-frequency side to zero.
  • the low-frequency side of the AC switching station with constant low-frequency voltage adopts the control method of constant low-frequency AC voltage amplitude and frequency, which is to maintain the stability of the frequency and voltage of the low-frequency system.
  • Other AC frequency switching stations are divided into two categories. One type is connected to the active AC power grid. The low-frequency side adopts a control method of constant active power and constant reactive power. The active and reactive power instructions are directly set to zero to achieve power. The purpose of reducing the power to zero; the other type is connected to the passive AC power grid. This type of AC frequency switching station needs to disconnect from the power frequency AC in order to achieve the purpose of reducing the power to zero.
  • Step 2 Control the AC frequency switching station of the low-frequency voltage to gradually reduce the AC voltage amplitude on the low-frequency side to zero. This process can be realized by setting the amplitude reference value of the AC voltage of the AC frequency switching station with a fixed low-frequency voltage to zero.
  • Step 3 In each AC switching station, adjust the tap of the connecting transformer to the maximum transformation ratio position to reduce the AC voltage on the AC switching valve side.
  • the tap of the connecting transformer is located on the grid side.
  • the voltage per unit value for each step length adjustment is u tap
  • the upward adjustment gear of the tap is n tap .
  • U s is the power frequency network side voltage
  • k is the transformation ratio of the connecting transformer (k>1).
  • Step 4 In each AC frequency switching station, put in redundant sub-modules and increase the voltage modulation ratio so that the sub-module capacitor voltage is reduced to U smL1 . Assuming that N is the total number of sub-modules in each bridge arm (including redundant sub-modules), in this way, the sub-module capacitor voltage can be reduced to
  • Step 5 Lock all AC converters, disconnect the low-frequency circuit breaker connecting the low-frequency side AC converter to the low-frequency transmission network, disconnect the power frequency circuit breaker connecting the power frequency side transformer and the power frequency system, disconnect and start Circuit breaker with resistors connected in parallel.
  • the connection and loop method of connecting the secondary winding of the transformer, the starting resistor and the modular multi-level matrix converter are shown in Figure 3.
  • FIG. 4 shows the structural diagram of the submodule.
  • Each submodule contains four IGBTs T1-T4 and their anti-parallel diodes.
  • T1 and T2 are turned on, T3 and T4 are turned off, or T1 and T2 are turned off, and T3 and T4 are turned on.
  • the sub-module is in the bypass state; when T1 and T4 are turned on and T2 and T3 are turned off, the sub-module is in the positive voltage input state; when T1 and T4 are turned off and T2 and T3 are turned on, the sub-module is in the negative voltage input state;
  • T1-T4 are all turned off, the sub-module is in a latched state.
  • Step 6 Set the three bridge arms connected to the same phase on the low-frequency side into one group to form three groups, namely 12 3The bridge arms are group one, the 456 bridge arms are group two, and the 789 bridge arms are group three. After completing the first five steps, all sub-modules in the three bridge arms of group 1 are switched from the blocking state to the bypass state. Then, all sub-modules in the bridge arm 1 are switched from the bypass state to the positive voltage input or negative voltage input state. , when the capacitor voltage of the sub-module of the bridge arm drops to U smL2 , all sub-modules of the bridge arm are switched back to the bypass state. Steps 2 and 3 of the bridge arm are the same as above.
  • all sub-modules in group one switch from bypass state to blocking state. All sub-modules of the three bridge arms in group 2 are switched from the blocking state to the bypass state. Then, all sub-modules in the bridge arm 4 are switched from the bypass state to the positive voltage input or negative voltage input state. Wait for the sub-modules of the bridge arm to When the module capacitor voltage drops to U smL2 , all sub-modules of this bridge arm switch back to the bypass state. Steps 5 and 6 of the bridge arm are the same as above. After all bridge arms in Group 2 have completed the above operations, all sub-modules in Group 2 will switch from the bypass state to the blocking state.
  • Step 7 All sub-modules will continue to slowly discharge through the voltage-equalizing resistors connected in parallel with them. After the discharge is completed, the electrical inspection method can be used to verify whether the sub-module capacitors have been completely discharged.
  • This embodiment provides a low-frequency power transmission system outage device, which consists of a power adjustment unit, an AC voltage amplitude zero reduction unit, an AC voltage reduction unit, a sub-module capacitor voltage reduction unit, a circuit breaker disconnecting unit, a sub-module control unit and The composition of the verification unit is shown in Figure 5.
  • the low-frequency power transmission system includes a three-terminal AC frequency switching station and a low-frequency power transmission network.
  • the main equipment of the AC frequency switching station from the power frequency side to the low frequency side includes connection transformers, starting resistors, modular multi-level matrix converters, etc.
  • AC voltage amplitude zero reduction unit an AC switching station that controls the low-frequency voltage and reduces the AC voltage on the low-frequency side. The voltage amplitude gradually decreases to zero.
  • AC voltage reduction unit In each AC switching station, adjust the tap of the connecting transformer to the maximum transformation ratio position to reduce the AC voltage on the AC switching valve side.
  • Sub-module capacitance voltage reduction unit In each AC frequency switching station, redundant sub-modules are put in and the voltage modulation ratio is increased to reduce the sub-module capacitance voltage to U smL1 ;
  • N is the total number of sub-modules in each bridge arm, including redundant sub-modules;
  • U v is the AC voltage on the AC valve side;
  • Circuit breaker disconnecting unit locks all AC switching stations, disconnects the low-frequency circuit breaker connecting the low-frequency side AC switching station to the low-frequency transmission network, disconnects the power frequency circuit breaker connecting the power frequency side connecting transformer to the power frequency system, and disconnects Open the circuit breaker connected in parallel with the starting resistor.
  • Sub-module control unit Set the three bridge arms connected to the same phase on the low-frequency side into one group to form multiple groups; after completing the first five steps, all sub-modules of the three bridge arms in each group switch from the blocking state to the bypass state. Then, switch all sub-modules in the first bridge arm from the bypass state to the positive voltage input or negative voltage input state. When the capacitor voltage of the sub-module of the bridge arm drops to U smL2 , all sub-modules of the bridge arm will Switch back to the bypass state.
  • the operation steps for the second bridge arm and the third bridge arm are the same as those for the first bridge arm. After all bridge arms in the group have completed the above operations, all sub-modules in the group will switch from the bypass state to the blocking state. ;
  • Verification unit All sub-modules will continue to slowly discharge through the voltage-equalizing resistors connected in parallel with them. After the discharge is completed, the electrical inspection method will be used to verify whether the sub-module capacitors have been completely discharged.
  • the low-frequency side of the AC switching station with constant low-frequency voltage adopts the control method of constant low-frequency AC voltage amplitude and frequency.
  • Other AC switching stations are divided into two categories. One category is connected to the active AC power grid, The low-frequency side adopts the control method of constant active power and constant reactive power, and directly sets the active and reactive power instructions to zero; the other type is connected to the passive AC power grid, and this type of AC frequency exchange station communicates with the power frequency by disconnecting The communication between them achieves the purpose of reducing the power to zero.
  • the tap of the connecting transformer is located on the grid side, the voltage per unit value for each step length adjustment is set to u tap , and the upward adjustment gear of the tap is set to n tap . Then, the connection When the tap connected to the transformer is adjusted to the maximum transformation ratio position, the AC voltage U v on the AC valve side is:
  • U s is the power frequency network side voltage
  • k is the transformation ratio of the connecting transformer, k>1.
  • the sub-module contains four IGBTs T1-T4 and their anti-parallel diodes.
  • T1 and T2 When T1 and T2 are turned on, T3 and T4 are turned off, or T1 and T2 are turned off, and T3 and T4 are turned on. , the sub-module is in the bypass state; when T1 and T4 are turned on and T2 and T3 are turned off, the sub-module is in the positive voltage input state; when T1 and T4 are turned off and T2 and T3 are turned on, the sub-module is in the negative voltage input state; When T1-T4 are all turned off, the sub-module is in a latched state.

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Abstract

本发明公开了一种低频输电***停运方法及***。本发明的低频输电***停运方法，包括：将与低频侧同一相相连的三个桥臂设为一组，形成多组；每组内的三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将第一桥臂内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至设定值时，该桥臂所有子模块切回至旁路状态，第二桥臂和第三桥臂的操作步骤同第一桥臂，待组内所有桥臂都完成以上操作后，组内所有子模块从旁路状态切换至闭锁状态；所有子模块将继续通过与其相并联的均压电阻进行缓慢放电。本发明能够实现快速、平稳、无冲击的低频输电***停运，保障了电网和设备安全。

Description

一种低频输电***停运方法及装置 技术领域
本发明属于电力***输电领域，具体涉及一种低频输电***停运方法及装置。
背景技术
低频输电通过降低输电频率，减小线路阻抗、减少电缆充电无功、提升电网的输送能力和调控能力，是工频交流输电与直流输电方式的有益补充，适用于中远距离海上风电送出、城市电网分区互联、海岛互联供电等场景。
对于实际工程而言，低频输电***的停运十分重要，与电网的稳定性密切相关，然而目前关于这方面的研究极少。
发明内容
针对上述现有技术中存在的问题，本发明提供一种低频输电***停运方法及装置，在不增加任何一次设备的情况下，以实现快速、平稳、无冲击的低频输电***停运。
为此，本发明采用的一种技术方案为：一种低频输电***停运方法，其包括：
步骤1：除定低频电压的交交换频站外，其他所有交交换频站将低频侧的有功功率和无功功率均调节至零；
步骤2：控制低频电压的交交换频站，将低频侧的交流电压幅值逐渐降低至零；
步骤3：每个交交换频站内，将联接变压器的分接头调整至最大变比位置，使交交换频阀侧的交流电压降低；
步骤4：每个交交换频站内，投入冗余子模块，并增大电压调制比，使子模块电容电压降低至UsmL1；
式中，N为每个桥臂总子模块个数，包括冗余子模块；Uv为交交换频阀侧的交流电压；
步骤5：闭锁所有交交换频站，低频侧交交换频站与低频输电网络相连的低频断路器，断开工频侧联接变压器与工频***相连的工频断路器，断开与启动电阻相并联的断路器；
步骤6：将与低频侧同一相相连的三个桥臂设为一组，形成多组；完成前五个步骤后，每组内的三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将第一桥臂内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态，第二桥臂和第三桥臂的操作步骤同第一桥臂，待组内所有桥臂都完成以上操作后，组内所有子模块从旁路状态切换至闭锁状态；
所述的UsmL2大于子模块驱动板卡工作最低电压Usmmin；
步骤7：所有子模块将继续通过与其相并联的均压电阻进行缓慢放电，待放电完成后，采用验电方式校验子模块电容是否已完全放完电。
所述的低频输电***包含两端以上的交交换频站及低频输电网络。所述的交交换频站从工频侧至低频侧主要设备依次有联接变压器、启动电阻、模块化多电平矩阵变换器等。
进一步地，所述的步骤1中，定低频电压的交交换频站低频侧采用定低频交流电压幅值和频率的控制方式，是维持低频***频率和电压稳定的关键；其他交交换频站分为两类，一类与有源交流电网相连，低频侧采用定有功功率和定无功功率的控制方式，直接将有功和无功功率指令设置为零，即可实现功率降低为零的目的；另一类与无源交流电网相连，该类交交换频站通过断开与工频交流之间的联络，实现功率降为零的目的。
进一步地，所述的步骤3中，联接变压器的分接头位于网侧，每一步长调节的电压标幺值设为utap，分接头向上调节的档位设为ntap档，那么，将联接变压器的分接头调整至最大变比位置时，交交换频阀侧的交流电压Uv为：
其中，Us为工频网侧电压，k为联接变压器变比，k>1。
进一步地，所述的步骤6中，所述的子模块含有T1-T4四个IGBT及其反并联二极管，当T1和T2开通、T3和T4关断或T1和T2关断、T3和T4开通时，子模块处于旁路状态；当T1和T4开通、T2和T3关断时，子模块处于正电压投入状态；当T1和T4关断、T2和T3开通时，子模块处于负电压投入状态；当T1-T4均关断时，子模块处于闭锁状态。
进一步地，所述的步骤6中，根据子模块电容自身放电特性，取UsmL2＝1.2Usmmin。
本发明采用的另一种技术方案为：一种低频输电***停运装置，其包括：
功率调节单元：除定低频电压的交交换频站外，其他所有交交换频站将低频侧的有功功率和无功功率均调节至零；
交流电压幅值降零单元：控制低频电压的交交换频站，将低频侧的交流电压幅值逐渐降低至零；
交流电压降低单元：每个交交换频站内，将联接变压器的分接头调整至最大变比位置，使交交换频阀侧的交流电压降低；
子模块电容电压降低单元：每个交交换频站内，投入冗余子模块，并增大电压调制比，使子模块电容电压降低至UsmL1；
式中，N为每个桥臂总子模块个数，包括冗余子模块；Uv为交交换频阀侧的交流电压；
断路器断开单元：闭锁所有交交换频站，断开低频侧交交换频站与低频输电网络相连的低频断路器，断开工频侧联接变压器与工频***相连的工频断路器，断开与启动电阻相并联的断路器；
子模块控制单元：将与低频侧同一相相连的三个桥臂设为一组，形成三组；完成前五个步骤后，每组内的三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将第一桥臂内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态，第二桥臂和第三桥臂的操作步骤同第一桥臂，待组内所有桥臂都完成以上操作后，组内所有子模块从旁路状态切换至闭锁状态；
所述的UsmL2大于子模块驱动板卡工作最低电压Usmmin；
校验单元：所有子模块将继续通过与其相并联的均压电阻进行缓慢放电，待放电完成后，采用验电方式校验子模块电容是否已完全放完电。
与现有技术相比，本发明具有的有益技术效果如下：
(1)本发明能够实现快速、平稳、无冲击的低频输电***停运，保障了电网和设备安全。
(2)本发明能够最大程度地将储存于子模块电容内的电能回馈至电网，减少了电能损失。
(3)本发明通过变压器副边绕组和启动电阻组成的耗能回路实现了现有一次设备的复用，在达到低频输电***快速停运目的的同时，不增加投资，提升了设备利用率。
附图说明
图1为本发明低频输电***示意图；
图2为本发明低频输电***停运方法流程图；
图3为本发明快速放电回路示意图；
图4为本发明子模块结构示意图；
图5为本发明低频输电***停运装置的结构框图。
具体实施方式
为了更为具体地描述本发明，下面结合说明书附图及具体实施方式对本发明的技术方案及其相关原理进行详细说明。
实施例1
本实施例提供一种低频输电***停运方法，图1所示为三端低频输电***示意图，从图中可要看出，三端低频输电***包含三端交交换频站及低频输电网络。交交换频站从工频侧至低频侧主要设备依次有联接变压器、启动电阻、模块化多电平矩阵变换器等。低频输电***停运方法如图2所示，具体内容如下：
步骤1：除定低频电压的交交换频站外，其他所有交交换频站将低频侧的有功功率和无功功率均调节至零。其中，定低频电压的交交换频站低频侧采用定低频交流电压幅值和频率的控制方式，是维持低频***频率和电压稳定 的关键。其他交交换频站分为两类，一类与有源交流电网相连，低频侧采用定有功功率和定无功功率的控制方式，直接将有功和无功功率指令设置为零，即可实现功率降低至零的目的；另一类与无源交流电网相连，该类交交换频站需要通过断开与工频交流之间的联络，才能实现功率降低为零的目的。
步骤2：控制低频电压的交交换频站，将低频侧的交流电压幅值逐渐降低至零。该过程通过将定低频电压的交交换频站的交流电压的幅值参考值设置为零即可实现。
步骤3：每个交交换频站内，将联接变压器的分接头调整至最大变比位置，使得交交换频阀侧的交流电压降低。其中，联接变压器的分接头位于网侧，每一步长调节的电压标幺值为utap，分接头向上调节的档位为ntap档，那么，将联接变压器的分接头调整至最大变比位置时，阀侧的交流电压为
其中，Us为工频网侧电压，k为联接变压器变比(k>1)。
步骤4：每个交交换频站内，投入冗余子模块，并增大电压调制比，使得子模块电容电压降低至UsmL1。假设N为每个桥臂总子模块个数(包括冗余子模块)，如此，可使得子模块电容电压降低至
步骤5：闭锁所有交交换频器，断开低频侧交交换频器与低频输电网络相连的低频断路器，断开工频侧联接变压器和工频***相连的工频断路器，断开与启动电阻相并联的断路器。该步骤完成后，联接变压器副边绕组、启动电阻和模块化多电平矩阵变换器的连接和回路方式如图3所示。
图4所示为子模块的结构示意图，每个子模块含有T1-T4四个IGBT及其反并联二极管，当T1和T2开通、T3和T4关断或T1和T2关断、T3和T4开通时，子模块处于旁路状态；当T1和T4开通、T2和T3关断时，子模块处于正电压投入状态；当T1和T4关断、T2和T3开通时，子模块处于负电压投入状态；当T1-T4均关断时，子模块处于闭锁状态。
步骤6：将与低频侧同一相相连的三个桥臂设为一组，形成三组，即①② ③桥臂为组一、④⑤⑥桥臂为组二、⑦⑧⑨桥臂为组三。完成前五个步骤后，组一内三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将桥臂①内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态。桥臂②和③步骤同上。待组一内所有桥臂都完成以上操作后，组一内所有子模块从旁路状态切换至闭锁状态。组二内三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将桥臂④内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态。桥臂⑤和⑥步骤同上。待组二内所有桥臂都完成以上操作后，组二内所有子模块从旁路状态切换至闭锁状态。组三内三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将桥臂⑦内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态。桥臂⑧和⑨步骤同上。待组三内所有桥臂都完成以上操作后，组三内所有子模块从旁路状态切换至闭锁状态。其中，UsmL2大于子模块驱动板卡工作最低电压Usmmin，根据子模块电容自身放电特性，一般可取UsmL2＝1.2Usmmin。
步骤7：所有子模块将继续通过与其相并联的均压电阻进行缓慢放电，待放电完成后，可采用验电方式校验子模块电容是否已完全放完电。
实施例2
本实施例提供一种低频输电***停运装置，其由功率调节单元、交流电压幅值降零单元、交流电压降低单元、子模块电容电压降低单元、断路器断开单元、子模块控制单元和校验单元组成，如图5所示。
所述的低频输电***包含三端交交换频站及低频输电网络。所述的交交换频站从工频侧至低频侧主要设备依次有联接变压器、启动电阻、模块化多电平矩阵变换器等。
功率调节单元：除定低频电压的交交换频站外，其他所有交交换频站将低频侧的有功功率和无功功率均调节至零。
交流电压幅值降零单元：控制低频电压的交交换频站，将低频侧的交流 电压幅值逐渐降低至零。
交流电压降低单元：每个交交换频站内，将联接变压器的分接头调整至最大变比位置，使交交换频阀侧的交流电压降低。
子模块电容电压降低单元：每个交交换频站内，投入冗余子模块，并增大电压调制比，使子模块电容电压降低至UsmL1；
式中，N为每个桥臂总子模块个数，包括冗余子模块；Uv为交交换频阀侧的交流电压；
断路器断开单元：闭锁所有交交换频站，断开低频侧交交换频站与低频输电网络相连的低频断路器，断开工频侧联接变压器与工频***相连的工频断路器，断开与启动电阻相并联的断路器。
子模块控制单元：将与低频侧同一相相连的三个桥臂设为一组，形成多组；完成前五个步骤后，每组内的三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将第一桥臂内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态，第二桥臂和第三桥臂的操作步骤同第一桥臂，待组内所有桥臂都完成以上操作后，组内所有子模块从旁路状态切换至闭锁状态；
所述的UsmL2大于子模块驱动板卡工作最低电压Usmmin，根据子模块电容自身放电特性，一般可取UsmL2＝1.2Usmmin。
校验单元：所有子模块将继续通过与其相并联的均压电阻进行缓慢放电，待放电完成后，采用验电方式校验子模块电容是否已完全放完电。
所述的功率调节单元中，定低频电压的交交换频站低频侧采用定低频交流电压幅值和频率的控制方式，其他交交换频站分为两类，一类与有源交流电网相连，低频侧采用定有功功率和定无功功率的控制方式，直接将有功和无功功率指令设置为零；另一类与无源交流电网相连，该类交交换频站通过断开与工频交流之间的联络，实现功率降为零的目的。
所述的交流电压降低单元中，联接变压器的分接头位于网侧，每一步长调节的电压标幺值设为utap，分接头向上调节的档位设为ntap档，那么，将联 接变压器的分接头调整至最大变比位置时，交交换频阀侧的交流电压Uv为：
其中，Us为工频网侧电压，k为联接变压器变比，k>1。
所述的子模块控制单元中，所述的子模块含有T1-T4四个IGBT及其反并联二极管，当T1和T2开通、T3和T4关断或T1和T2关断、T3和T4开通时，子模块处于旁路状态；当T1和T4开通、T2和T3关断时，子模块处于正电压投入状态；当T1和T4关断、T2和T3开通时，子模块处于负电压投入状态；当T1-T4均关断时，子模块处于闭锁状态。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种低频输电***停运方法，其特征在于，包括：
    步骤1：除定低频电压的交交换频站外，其他所有交交换频站将低频侧的有功功率和无功功率均调节至零；
    步骤2：控制低频电压的交交换频站，将低频侧的交流电压幅值逐渐降低至零；
    步骤3：每个交交换频站内，将联接变压器的分接头调整至最大变比位置，使交交换频阀侧的交流电压降低；
    步骤4：每个交交换频站内，投入冗余子模块，并增大电压调制比，使子模块电容电压降低至UsmL1；
    式中，N为每个桥臂总子模块个数，包括冗余子模块；Uv为交交换频阀侧的交流电压；
    步骤5：闭锁所有交交换频站，断开低频侧交交换频站与低频输电网络相连的低频断路器，断开工频侧联接变压器与工频***相连的工频断路器，断开与启动电阻相并联的断路器；
    步骤6：将与低频侧同一相相连的三个桥臂设为一组，形成多组；完成前五个步骤后，每组内的三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将第一桥臂内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态，第二桥臂和第三桥臂的操作步骤同第一桥臂，待组内所有桥臂都完成以上操作后，组内所有子模块从旁路状态切换至闭锁状态；
    所述的UsmL2大于子模块驱动板卡工作最低电压Usmmin；
    步骤7：所有子模块将继续通过与其相并联的均压电阻进行缓慢放电，待放电完成后，采用验电方式校验子模块电容是否已完全放完电。
  2. 根据权利要求1所述的低频输电***停运方法，其特征在于，所述的步骤1中，定低频电压的交交换频站低频侧采用定低频交流电压幅值和频率 的控制方式，其他交交换频站分为两类，一类与有源交流电网相连，低频侧采用定有功功率和定无功功率的控制方式，直接将有功和无功功率指令设置为零；另一类与无源交流电网相连，该类交交换频站通过断开与工频交流之间的联络，实现功率降为零的目的。
  3. 根据权利要求1所述的低频输电***停运方法，其特征在于，所述的步骤3中，联接变压器的分接头位于网侧，每一步长调节的电压标幺值设为utap，分接头向上调节的档位设为ntap档，那么，将联接变压器的分接头调整至最大变比位置时，交交换频阀侧的交流电压Uv为：
    其中，Us为工频网侧电压，k为联接变压器变比，k>1。
  4. 根据权利要求1所述的低频输电***停运方法，其特征在于，所述的步骤6中，所述的子模块含有T1-T4四个IGBT及其反并联二极管，当T1和T2开通、T3和T4关断或T1和T2关断、T3和T4开通时，子模块处于旁路状态；当T1和T4开通、T2和T3关断时，子模块处于正电压投入状态；当T1和T4关断、T2和T3开通时，子模块处于负电压投入状态；当T1-T4均关断时，子模块处于闭锁状态。
  5. 根据权利要求1所述的低频输电***停运方法，其特征在于，所述的步骤6中，UsmL2＝1.2Usmmin。
  6. 一种低频输电***停运装置，其特征在于，包括：
    功率调节单元：除定低频电压的交交换频站外，其他所有交交换频站将低频侧的有功功率和无功功率均调节至零；
    交流电压幅值降零单元：控制低频电压的交交换频站，将低频侧的交流电压幅值逐渐降低至零；
    交流电压降低单元：每个交交换频站内，将联接变压器的分接头调整至最大变比位置，使交交换频阀侧的交流电压降低；
    子模块电容电压降低单元：每个交交换频站内，投入冗余子模块，并增大电压调制比，使子模块电容电压降低至UsmL1；
    式中，N为每个桥臂总子模块个数，包括冗余子模块；Uv为交交换频阀侧的交流电压；
    断路器断开单元：闭锁所有交交换频站，断开低频侧交交换频站与低频输电网络相连的低频断路器，断开工频侧联接变压器与工频***相连的工频断路器，断开与启动电阻相并联的断路器；
    子模块控制单元：将与低频侧同一相相连的三个桥臂设为一组，形成多组；完成前五个步骤后，每组内的三个桥臂所有子模块从闭锁状态切换为旁路状态，然后，将第一桥臂内所有子模块从旁路状态切换为正电压投入或负电压投入状态，待该桥臂的子模块电容电压降低至UsmL2时，该桥臂所有子模块切回至旁路状态，第二桥臂和第三桥臂的操作步骤同第一桥臂，待组内所有桥臂都完成以上操作后，组内所有子模块从旁路状态切换至闭锁状态；
    所述的UsmL2大于子模块驱动板卡工作最低电压Usmmin；
    校验单元：所有子模块将继续通过与其相并联的均压电阻进行缓慢放电，待放电完成后，采用验电方式校验子模块电容是否已完全放完电。
  7. 根据权利要求6所述的低频输电***停运装置，其特征在于，所述的功率调节单元中，定低频电压的交交换频站低频侧采用定低频交流电压幅值和频率的控制方式，其他交交换频站分为两类，一类与有源交流电网相连，低频侧采用定有功功率和定无功功率的控制方式，直接将有功和无功功率指令设置为零；另一类与无源交流电网相连，该类交交换频站通过断开与工频交流之间的联络，实现功率降为零的目的。
  8. 根据权利要求6所述的低频输电***停运装置，其特征在于，所述的交流电压降低单元中，联接变压器的分接头位于网侧，每一步长调节的电压标幺值设为utap，分接头向上调节的档位设为ntap档，那么，将联接变压器的分接头调整至最大变比位置时，交交换频阀侧的交流电压Uv为：
    其中，Us为工频网侧电压，k为联接变压器变比，k>1。
  9. 根据权利要求6所述的低频输电***停运装置，其特征在于，所述的子模块控制单元中，所述的子模块含有T1-T4四个IGBT及其反并联二极管，当T1和T2开通、T3和T4关断或T1和T2关断、T3和T4开通时，子模块处于旁路状态；当T1和T4开通、T2和T3关断时，子模块处于正电压投入状态；当T1和T4关断、T2和T3开通时，子模块处于负电压投入状态；当T1-T4均关断时，子模块处于闭锁状态。
  10. 根据权利要求6所述的低频输电***停运装置，其特征在于，所述的子模块控制单元中，UsmL2＝1.2Usmmin。
PCT/CN2023/086385 2022-04-08 2023-04-06 一种低频输电***停运方法及装置 WO2023193729A1 (zh)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104201709A (zh) * 2014-08-15 2014-12-10 浙江大学 一种混合型直流输电***的停运控制方法
CN110932538A (zh) * 2019-12-06 2020-03-27 国网江苏省电力有限公司经济技术研究院 适用于lcc-mmc混合级联直流输电***的停运控制方法
CN114142463A (zh) * 2021-11-26 2022-03-04 国网浙江省电力有限公司 基于m3c的两端柔性低频输电***两相运行控制方法
CN114696360A (zh) * 2022-04-08 2022-07-01 国网浙江省电力有限公司电力科学研究院 一种低频输电***停运方法及装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104201709A (zh) * 2014-08-15 2014-12-10 浙江大学 一种混合型直流输电***的停运控制方法
CN110932538A (zh) * 2019-12-06 2020-03-27 国网江苏省电力有限公司经济技术研究院 适用于lcc-mmc混合级联直流输电***的停运控制方法
CN114142463A (zh) * 2021-11-26 2022-03-04 国网浙江省电力有限公司 基于m3c的两端柔性低频输电***两相运行控制方法
CN114696360A (zh) * 2022-04-08 2022-07-01 国网浙江省电力有限公司电力科学研究院 一种低频输电***停运方法及装置

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
LU LIWEN; WU XIAODAN; QIU DEFENG; DONG YUNLONG; QIU PENG: "Flexible Startup and Shutdown Strategy of Low Frequency Transmission System Based on Modular Multilevel Matrix Converter", GAODIANYA-JISHU : JIKAN - HIGH VOLTAGE ENGINEERING, WUHAN : SHUILI DIANLI BU WUHAN GAOYA YANJIUSUO, CN, vol. 49, no. 1, 20 November 2021 (2021-11-20), CN , pages 248 - 257, XP009549291, ISSN: 1003-6520, DOI: 10.13336/j.1003-6520.hve.20211609 *
ZHANG ZHEREN; XU ZHENG; XU FENG; XUE YINGLIN: "Shut-down Control Scheme for Modular Multilevel Converter Based HVDC", PROCEEDINGS OF THE CSEE, ZHONGGUO DIANJI GONGCHENG XUEHUI, CN, vol. 35, no. 11, 5 June 2015 (2015-06-05), CN , pages 2670 - 2680, XP009550190, ISSN: 0258-8013, DOI: 10.13334/j.0258-8013.pcsee.2015.11.005 *

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