WO2017000224A1 - Compensateur série synchrone statique sans transformateur et son procédé de protection - Google Patents

Compensateur série synchrone statique sans transformateur et son procédé de protection Download PDF

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Publication number
WO2017000224A1
WO2017000224A1 PCT/CN2015/082836 CN2015082836W WO2017000224A1 WO 2017000224 A1 WO2017000224 A1 WO 2017000224A1 CN 2015082836 W CN2015082836 W CN 2015082836W WO 2017000224 A1 WO2017000224 A1 WO 2017000224A1
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WO
WIPO (PCT)
Prior art keywords
current
transformer
coupled
circuit
voltage source
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Application number
PCT/CN2015/082836
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English (en)
Inventor
Hailian XIE
Tinho LI
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Abb Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abb Technology Ltd filed Critical Abb Technology Ltd
Priority to PCT/CN2015/082836 priority Critical patent/WO2017000224A1/fr
Publication of WO2017000224A1 publication Critical patent/WO2017000224A1/fr

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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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/10—Flexible AC transmission systems [FACTS]

Definitions

  • the invention relates to transformer-less static synchronous series compensator for AC electrical power transmission system, and more particularly to protection device of converter of transformer-less static synchronous series compensator electrically coupled to the transmission line and its protection method.
  • SC series compensation
  • FSC fixed series capacitor
  • CSC controllable series compensation
  • SSSC static synchronous series compensation
  • the compensator includes a transformer connected in series in an AC transmission line of AC electrical power transmission system, and a converter connected with the transformer in parallel. The converter can generate and inject into the AC transmission lines an alternating voltage with desired magnitude and phase angle.
  • An example of SSSC is provided in U.S. Pat. No. 5,814,975 entitled “Inverter Controlled Series Compensator” .
  • the transformer adds significantly to the cost and complexity of the apparatus and renders it less efficient.
  • a bypass circuit is utilized in static synchronous series compensator for bypassing the large transient current through the converter in fault event, when the converter is blocked.
  • An example of such bypass circuit can be done mechanically by means of the bypass breaker, and/or electronically by means of the secondary side fast-acting thyristor bypass switches (TBS) , which is disclosed in “Static Synchronous Series Compensator (SSSC) ” , CIGER B4-40, February 2009, ISBN: 978-2 85873-058-2, in particular considering Section 8.1.2 Protection and figure 8.5 thyristor bypass system (TBS) for protection of series connected VSC based SSSC.
  • TSSSC Static Synchronous Series Compensator
  • TBS can include two thyristors connected in anti-parallel, one of which conducts forward current and the other conducts reverse current.
  • the converter is electrically coupled to a phase of the AC transmission line without a transformer.
  • the power electronics devices of bypass circuit it is required for the power electronics devices of bypass circuit to survive a higher transient current than that used in the conventional bypass circuit, for providing shorting path for the fault current through a phase of the transmission line.
  • the power electronics devices of the bypass circuit is switched on, the energy stored in the capacitive element of the filter can find discharging path along the bypass circuit. Therefore, the current through the bypass circuit is predominately governed by not only the transmission line fault current but also the filter capacitive element discharging current. This brings about the problem of insufficient current handling capacity of the power electronics device of the bypass circuit.
  • a transformer-less static synchronous series compensator for an AC electrical power transmission system having a transmission line carrying an AC current, including: a voltage source converter having a DC input and an AC output and being configured to generate an alternating voltage with controllable magnitude and controllable phase angle across the AC output, the AC output being configured to inject the generated alternating voltage into a phase of the transmission line; a filter circuit being arranged coupled with the voltage source converter in parallel across the AC output of the voltage source converter; a bypass circuit; and an electrical current limiting circuit being coupled with the bypass circuit in series; wherein: the series-coupled current bypass circuit and electrical current limiting circuit is coupled with a first capacitive element of the filter circuit in parallel.
  • the transient nature of the electrical current limiting circuit will limit the increase in the current flowing through the thyristor of the bypass circuit thus limit the current peak when the bypass circuit is switched on. Consequently, the current limiting circuit acts like limiting the current transients generated from the influences of both of the line fault current and the discharging current.
  • the transformer-less static synchronous series compensator for an AC electrical power transmission system having a transmission line carrying an AC current
  • the transformer-less static synchronous series compensator has a voltage source converter and a filter circuit coupled in parallel
  • the method comprising: monitoring the AC current through the transmission line to detect a first fault condition of the AC electrical power transmission system; and providing a closed electrical-current loop coupling the filter circuit and an impedance element in response to the first fault condition when a parameter of said AC current exceeds a first predetermined value, wherein a portion of the electrical-current loop comprising the impedance element bypasses the transmission line current through the voltage source converter.
  • the closed electrical-current loop is thus formed to limiting the current transients generated fiom the influences of both of the line fault current and the discharging current.
  • the transformer-less static synchronous series compensator has a voltage source converter and a filter circuit coupled in parallel, the method comprising: monitoring electrical current of power semiconductors of the voltage source converter to detect a second fault condition when a parameter of said power semiconductor electrical current exceeds a second predetermined value; and providing a closed-loop coupling the filter circuit and an impedance element in response to the second fault condition, wherein a portion of the electrical-current loop comprising the impedance element bypasses the transmission line current through the voltage source converter.
  • the closed electrical-current loop is thus formed to limiting the current transients generated fiom the influences of both of the line current and the discharging current.
  • Figure 1 illustrates an AC transmission system compensated by a transformer-less series static synchronous series compensator according to an embodiment of present invention
  • Figure 2 depicts a circuit configuration of a transformer-less SSSC 10 electrically coupled with phase A of AC transmission line according to an embodiment of present invention
  • Figure 3 shows a more detailed schematic of an embodiment in accordance of figure 2.
  • Figure 1 illustrates an AC transmission system compensated by a transformer-less series static synchronous series compensator according to an embodiment of present invention.
  • the AC transmission system 1 includes three phases of AC transmission line A, B, C respectively for carrying current I A , I B , I C .
  • Three transformer-less SSSCs 10, 11, 12 are respectively electrically coupled with the respective phase A, B, C in series.
  • the three transforrner-less SSSCs 10, 11, 12 are substantially similar both in circuit configuration and operation and can operate independently fiom each other.
  • a fault current may occur in any of the three phases. For example, a fault current is imposed on phase A of the AC transmission line.
  • the magnitude and phase angle of fault current I Fault is predominantly influenced by the source voltage Vs and series impedance X line of the system.
  • FIG. 2 depicts a circuit configuration of a transformer-less SSSC 10 electrically coupled with phase A of AC transmission line according to an embodiment of present invention.
  • the transformer-less SSSC 10 includes voltage source converter (VSC) 100, a filter circuit101 and a bypass circuit 102.
  • VSC voltage source converter
  • a capacitor 104 is coupled to DC input of VSC 100 in parallel for maintaining relatively constant DC voltage of the VSC 100.
  • the capacitor 104 can store electrical power supplied fiom phase A of the transmission line and act as a DC power source.
  • the skilled person shall understand other types of DC power source, such as batteries can be utilized for supplying the DC electrical power to the VSC 100.
  • the VSC 100 can be controlled to generate an alternating voltage with controllable magnitude and controllable phase angle across the AC output and inject the generated alternating voltage into phase A of the transmission line so as to compensate the impedance of phase A.
  • a filter circuit 101 is coupled with VSC 100 in parallel across the AC output of VSC 100 for suppressing harmonics of the alternating voltage generated by VSC 100.
  • the filter circuit 101 comprises an inductive element 1010 and a capacitive element 1011 electrically coupled in series.
  • the filter 101 can comprise an inductive element, a capacitive element and another inductive element sequentially electrically coupled in series.
  • the bypass circuit 102 and the electrical current limiting circuit 103 are electrically coupled in series.
  • the bypass circuit 102 comprises an electronic bypass switch including two thyristors 1020, 1021 coupled in anti-parallel and a breaker 1022 coupled with the anti-parallel-coupled thyristors 1020, 1021 in parallel.
  • the one conducting forward current is called “forward thyristor” and the other one conducting reverse current is called “reverse thyristor” .
  • the shortest closing time for the breaker 1022 can be achieved with available products is 21 ms and the switching devices of VSC 100 cannot withstand overcurrent for such a long period. Therefore, an electronic bypass switch should be employed to provide fast bypass before the bypass breaker is closed.
  • either of the two thyristors 1020, 1021 can be triggered to provide a shorting path for conducting the fault current I Fault so as to bypass the VSC 100 in the first place because t the time from being triggered to conducting full current is much shorter than the closing time of the mechanical breaker 1022. Substantially at the same time, VSC 100 is controlled to be blocked. Consequently, the mechanical breaker 1022 is closed and the fault current will be shifted from the conducting thyristor 1020, 1021 to the breaker 1022. Alternatively, the bypass circuit 102 can omit the breaker 1022, and the thyristors conduct the fault current all the time.
  • bypass circuit 102 acts as an electrical current path, and energy stored in the capacitive element 1011 of the filter circuit 101 will be transmitted in a form of current I Discharge through the bypass circuit 102.
  • the voltage across the filter circuit capacitor 1011 equals to the voltage injected by the transformer-less SSSC.
  • the voltage across the filter circuit capacitor 1011 will drop to almost zero (actually a value that equals to the forward voltage drop of the triggered thyristor) in a very short period. This sudden change will cause fast discharging of the filter circuit capacitor 1011.
  • the resulting large discharging current together with the already high line current, will flow through the filter circuit capacitor 1011 and the triggered thyristor.
  • the transformer-less SSSC 10 further includes an electrical current limiting circuit 103 electrically coupled with the bypass circuit 102 in series.
  • the transient nature of the electrical current limiting circuit 103 will limit the increase in the current flowing through the thyristor 1020, 1021 of the bypass circuit 102 thus limit the current peak when the bypass circuit 102 is switched on.
  • the electrical current limiting circuit 103 comprises an inductive element 1030 and a resistant element 1031 coupled in series, acting like an impedance element. Consequently, the current limiting circuit acts like limiting the current transients generated fiom the influences of both of the line fault current I Fault and the discharging current I Discharge .
  • FIG. 3 shows a more detailed schematic of an embodiment in accordance of figure 2.
  • the VSC 100 includes a plurality of power semiconductor pairs 100a, 100b.
  • the power semiconductor can be IGBT, GTO, and IGCT.
  • a first fault condition detection circuit 105 monitors the AC current through phase A of the transmission line using conventional current sensing device 106, controls conduction states of the thyristors 1020, 1021 and the breaker 1022 via control input lines 107 to immediately activate the bypass circuit 102 and controls conduction states of the power semiconductors 100a, 100b via control input lines 108 to immediately inhibit the active portion of VSC 100 whenever a parameter of the AC current exceeds a first predetermined value. For example, the absolute value of the instantaneous line current i L is monitored.
  • the present value together with the four (can be any other number) values at the instants 1 ms, 2 ms, 3 ms, and 4 ms ago are compared with the line current level for converter protection i L-blk . Ifall the values are larger than i L-blk , the thyristors 1020, 1021 and the breaker 1022 will be turned on and the VSC 100 will be blocked. Depending on the current direction, either the forward thyristor or the reverse thyristor will be triggered. As an alternative, the above precondition for turning on the bypass circuit 102 and blocking VSC 100 can be replaced by monitoring magnitude of the line current i L_mag and checking if it exceeds i L-blk .
  • a closed electrical-current loop L c coupling the filter circuit 101 and an impedance element as the electrical current limiting circuit 103 in response to the first fault condition when the parameter of said AC current exceeds a first predetermined value, wherein a portion of the electrical-current loop, including the electrical current limiting circuit 103 and the bypass circuit 102, bypasses the transmission line current through the VSC 100.
  • the transformer-less SSSC 10 further includes a second fault condition detection circuit 109 monitoring electrical current of power semiconductors of VSC 100 by using conventional current sensing device 100c-100j, and controlling conduction states of the thyristors 1020, 1021 and the breaker 1022 via control input lines 111 to immediately activate the bypass circuit 102 and controls conduction states of the power semiconductors 100a, 100b via control input lines 112 to immediately inhibit the active portion of VSC 100 whenever a parameter of the power semiconductor electrical current exceeds a first predetermined value. For example, maximum instantaneous current through all the power semiconductors i IGBT,max and diodes i D, max of pairs 100a, 100b of VSC 100 are monitored.
  • the second fault condition detection circuit 109 based on a second fault condition of the AC electrical power transmission system 1 is monitored by the second fault condition detection circuit 109, it is provided a closed electrical-current loop L C coupling the filter circuit 101 and an impedance element as the electrical current limiting circuit 103 in response to the first fault condition when the parameter of said AC current exceeds a first predetermined value, wherein a portion of the electrical-current loop, including the electrical current limiting circuit 103 and the bypass circuit 102, bypasses the transmission line current through the VSC 100.
  • the VSC 100 is switched from normal control mode to idle control mode.
  • the converter conducts the line current, but output a zero voltage without any switching.
  • An LC or LCL harmonic filter circuit is sufficient for steady state performance.
  • oscillations might be excited by disturbances such as faults in the system.
  • the oscillations may decay due to system damping, but the oscillation period can be long.
  • One of the direct impact of the oscillation is that the voltage across the filter circuit capacitor 1011 will be high. This high voltage will in turn cause high transient current in the thyristor 1020, 1021 during the period when the current is commutating from the VSC 100 to the bypass circuit 102. Therefore, there is a need to add a damping branch.
  • MOV is commonly used in FSC and TCSC to limit overvoltage, it is not recommended to use to limit the high voltage discussed here. The reason can be explained as following.
  • the capacitor in series with the line will take the fault current for a certain period, causing overvoltage across the capacitors.
  • MOVs are used to protect the capacitor from overvoltage.
  • the filter circuit capacitor 1011 that is in series with the line will not take the fault current since its reactance at fundamental frequency is designed at least 10 times larger than the SSSC nominal effective reactance. Therefore, the fault current will not cause overvoltage across the SSSC terminals.
  • the transformer-less SSSC 10 comprises a filter resonance damping circuit 113 coupled with the capacitive element 1011 of the filter circuit 101 in parallel, being configured to suppress a resonance generated by the filter circuit 101 from an influence of fault on the transmission line.
  • the filter resonance damping circuit 113 includes an inductive element 1130 and a resistant element 1131 coupled in parallel and a capacitive element 1132 coupled with the parallel-coupled inductive element 1130 and the resistant element 1131 in series.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

L'invention concerne un compensateur série synchrone statique sans transformateur (SSSC) pour un réseau de transport d'énergie en courant alternatif ayant une ligne de transport transportant un courant alternatif et un procédé de protection contre les dommages électriques. Le SSSC sans transformateur comprend : un convertisseur de source de tension (100) ayant une entrée en courant continu et une sortie en courant alternatif et étant conçu pour générer une tension alternative avec une amplitude réglable et un angle de phase réglable à travers la sortie en courant alternatif, la sortie en courant alternatif étant conçue pour injecter la tension alternative générée dans une phase de la ligne de transport; un circuit filtrant (101) étant agencé de manière à être couplé avec le convertisseur de source de tension (100) en parallèle à travers la sortie en courant alternatif du convertisseur de source de tension (100); un circuit de dérivation (102); et un circuit de limitation de courant électrique (103) étant couplé avec le circuit de dérivation (102) en série; lequel circuit de dérivation (102) de courant couplé en série et lequel circuit de limitation de courant électrique (103) sont couplés avec un premier élément capacitif (1011) du circuit filtrant (101) en parallèle. La nature transitoire du circuit de limitation de courant électrique (103) limite l'augmentation du courant passant par le thyristor du circuit de dérivation (102) et limite donc le pic de courant lorsque le circuit de dérivation (102) est mis en marche. En conséquence, le circuit de limitation de courant (103) agit pour limiter les phénomènes transitoires de courant générés à partir de l'influence à la fois du courant de défaut de la ligne et du courant de décharge.
PCT/CN2015/082836 2015-06-30 2015-06-30 Compensateur série synchrone statique sans transformateur et son procédé de protection WO2017000224A1 (fr)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106786562A (zh) * 2017-02-23 2017-05-31 全球能源互联网研究院 一种静止同步串联补偿器的自励启动系统及方法
CN107623328A (zh) * 2017-09-21 2018-01-23 广东电网有限责任公司惠州供电局 一种降低配电网合环电流的方法
CN108011372A (zh) * 2017-02-22 2018-05-08 全球能源互联网研究院 一种静止同步串联补偿器的机电暂态建模方法及装置
CN108075455A (zh) * 2017-11-15 2018-05-25 中国科学院电工研究所 一种直流配电网的限流阻断装置及方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101346868A (zh) * 2005-12-30 2009-01-14 Abb技术有限公司 平衡设备
WO2010097122A1 (fr) * 2009-02-27 2010-09-02 Abb Technology Ltd Convertisseur de source de tension modulaire
CN102064555A (zh) * 2010-12-31 2011-05-18 中电普瑞科技有限公司 采用机械开关的链式statcom链节单元旁路结构
CN102931667A (zh) * 2012-11-09 2013-02-13 无锡市锡容电力电器有限公司 一种静止同步补偿器的补偿电路
CN103606951A (zh) * 2013-11-14 2014-02-26 广东电网公司电力科学研究院 基于风能发电的电能质量补偿控制装置与方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101346868A (zh) * 2005-12-30 2009-01-14 Abb技术有限公司 平衡设备
WO2010097122A1 (fr) * 2009-02-27 2010-09-02 Abb Technology Ltd Convertisseur de source de tension modulaire
CN102064555A (zh) * 2010-12-31 2011-05-18 中电普瑞科技有限公司 采用机械开关的链式statcom链节单元旁路结构
CN102931667A (zh) * 2012-11-09 2013-02-13 无锡市锡容电力电器有限公司 一种静止同步补偿器的补偿电路
CN103606951A (zh) * 2013-11-14 2014-02-26 广东电网公司电力科学研究院 基于风能发电的电能质量补偿控制装置与方法

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108011372A (zh) * 2017-02-22 2018-05-08 全球能源互联网研究院 一种静止同步串联补偿器的机电暂态建模方法及装置
CN108011372B (zh) * 2017-02-22 2021-04-16 全球能源互联网研究院 一种静止同步串联补偿器的机电暂态建模方法及装置
CN106786562A (zh) * 2017-02-23 2017-05-31 全球能源互联网研究院 一种静止同步串联补偿器的自励启动系统及方法
CN107623328A (zh) * 2017-09-21 2018-01-23 广东电网有限责任公司惠州供电局 一种降低配电网合环电流的方法
CN108075455A (zh) * 2017-11-15 2018-05-25 中国科学院电工研究所 一种直流配电网的限流阻断装置及方法

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