WO2018113271A1 - 一种自适应的并联电容器阻抗保护方法 - Google Patents

一种自适应的并联电容器阻抗保护方法 Download PDF

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Publication number
WO2018113271A1
WO2018113271A1 PCT/CN2017/092430 CN2017092430W WO2018113271A1 WO 2018113271 A1 WO2018113271 A1 WO 2018113271A1 CN 2017092430 W CN2017092430 W CN 2017092430W WO 2018113271 A1 WO2018113271 A1 WO 2018113271A1
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impedance
capacitor
real
dyn
time
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English (en)
French (fr)
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宋忠鹏
丁力
余群兵
金震
徐舒
董凯达
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NR Electric Co Ltd
NR Engineering Co Ltd
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NR Electric Co Ltd
NR Engineering Co Ltd
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Priority to CA3047488A priority Critical patent/CA3047488C/en
Priority to US16/470,957 priority patent/US11063424B2/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/16—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for capacitors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/028—Circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2605—Measuring capacitance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/01—Subjecting similar articles in turn to test, e.g. "go/no-go" tests in mass production; Testing objects at points as they pass through a testing station
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/40—Testing power supplies
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/64—Testing of capacitors
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/70—Regulating power factor; Regulating reactive current or power
    • 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
    • Y02E40/30—Reactive power compensation

Definitions

  • Unbalance protection is a protection scheme based on the principle of branch symmetry or three-phase symmetry of capacitor banks. It is closely related to capacitor capacity, wiring method and capacitor component type, and is limited by it. Often unable to choose freely, need to change the secondary wiring method or need to increase the peripheral equipment.
  • the single-star capacitor group adopts the phase difference voltage protection, it is necessary to increase the tap of the discharge PT, and the differential discharge PT secondary side;
  • the bridge capacitor bank is protected by bridge current, it is necessary to add a bridge current CT to the bridge arm.
  • the capacitor capacitance change As a energy storage component, the capacitor has a relatively fixed capacitance, which is not affected by the capacity, wiring method and component type, and does not need to avoid the initial imbalance. There is no dead zone problem.
  • the capacitor capacity is not constant, it is affected by the higher harmonics in the system, affected by external environmental temperature, humidity and other factors, and the capacitor bank is used as a complete set of equipment, and its front end is also connected with other devices such as reactors.
  • the actual impedance is not completely equal to the capacitive reactance of the capacitor bank.
  • the capacitance value When the fault occurs, the capacitance value is not completely changed. There is also a change in the resistance value. Under certain conditions, the capacitance value may change little, and the resistance value changes greatly.
  • the change of the capacitance value is used as a protection action criterion, and the protection sensitivity and reliability are greatly reduced in the actual application process.
  • an update failure alarm is generated; if the relative value of the real-time impedance change exceeds the set protection alarm threshold, and When the delay is reached, a fault alarm is issued; if the relative value of the mode of the real-time impedance change exceeds the set protection trip threshold and the delay is reached, the trip outlet is protected.
  • the terminal voltage and current of the capacitor are monitored; the voltage of the capacitor terminal may be the voltage difference between the voltage of each phase of the bus bar and the neutral point of the capacitor, or the voltage of the discharge PT terminal, and the current may be the current of each phase of the capacitor, or It is the sum of the current vector of each phase of the capacitor, and the real-time impedance of the capacitor is calculated according to the monitored capacitor current and voltage.
  • the calibration is successful, and Z init_(p) is used as the real impedance Z real_(p) when the capacitor is put into operation. Otherwise, the calibration fails, and the calibration is required until the calibration is successful, otherwise the Z ideal is used as the capacitor. The true impedance of the time Z real_(p) .
  • Z dyn_(p) is the real-time impedance of each phase of the capacitor
  • Z real_(p) is the true impedance of each phase of the capacitor.
  • the fundamental vector of the real-time terminal voltage per phase of the capacitor at runtime is the fundamental vector of the real-time current per phase of the capacitor at runtime, ⁇ dyn_(p) is the relative value of the modulus of the real-time impedance variation per phase.
  • the real impedance put into operation at the initial time is the result of calibration, normal operation, real-time impedance Z dyn_ meet the conditions of a real capacitor impedance Z real_ (p) cycles with (p) the update, the update period up to and updated to meet Under the condition, the impedance change is considered to be a normal change, and the true impedance Z real is updated. Otherwise, the update fails and is not updated.
  • the condition is:
  • ⁇ set_alm_dyn is a relative value limit setting of the modulus of the dynamic update impedance change amount, and according to the nominal temperature coefficient setting of the capacitor, ⁇ set_ub_dyn is a relative value inconsistent limit value of the three-phase dynamic update change amount, according to the capacitor mark Inconsistent setting
  • the new period T can be set according to the actual situation, namely:
  • t dyn_set is the true impedance dynamic update period fixed value
  • t dyn_set range is [0h, 24h]
  • the relative value of the module of the real-time impedance change of the capacitor satisfies the protection alarm condition, and the delay is reached, and the protection alarm is performed, and the protection alarm condition is:
  • ⁇ set_alm is the impedance protection alarm setting value, and is set as the relative value of the mode of the impedance change amount when the capacitor of the sensitivity is considered to be faulty.
  • ⁇ set_trip is the value of the impedance protection trip setting, and is set to a relative value of the mode in which the capacitor fuse of the sensitivity is considered to be blown or the number of breakdowns exceeds the amount of impedance change when the overvoltage multiple is allowed.
  • the invention has the beneficial effects that it is not affected by the capacitor voltage, the wiring mode and the component type, and is not affected by the system voltage level, the operation mode and the power quality, and is not affected by the monitoring system error or the sensing device error, and is not affected by the electromagnetic environment.
  • External environment impacts such as weather and temperature, no additional secondary equipment, no additional secondary wiring complexity, suitable for various operating conditions, suitable for various fault conditions of capacitors and capacitor banks, simple calculation of calculation value Simple and effective, it improves the sensitivity and reliability of capacitor protection.
  • FIG. 1 is a schematic diagram of an application scenario of the present invention
  • FIG. 2 is a schematic diagram of a parallel capacitor impedance protection impedance circle
  • the capacitor bank model is TBB35-12000/200AKW
  • the capacitor unit model is BFM 11-200-1W
  • each phase capacitor bank is 10 and 2 strings.
  • the rated capacity of the unit is 200Kvar
  • the rated voltage is 11kV
  • the capacitor unit is an external fuse capacitor.
  • an adaptive parallel capacitor impedance protection method is implemented as follows:
  • Z ideal theoretical single-phase capacitor rated impedance, U n is the rated line voltage, S n of the rated capacity.
  • the number of fuse-fuse units outside the capacitor unit and the over-voltage multiple of the healthy phase unit and the total impedance per phase are as follows:
  • the overvoltage multiple of the healthy component is 105.34%, which does not exceed 110%. Therefore, the capacitor is allowed to continue to operate, and a fault warning is issued.
  • the overvoltage multiple of the component is 111.11%. Should be tripped, consider 1.5 times sensitivity to set:
  • Serial number Value Settings unit 1 Alarm setting ⁇ set_alm 3.7 % 2 Trip setting ⁇ set_trip 10.26 %
  • Serial number Value Settings unit 1 Inherent deviation limit setting ⁇ set_alm_inh 6 % 2 Dynamic update limit setting ⁇ set_alm_dyn 1 % 3 Three-phase inconsistency limit setting ⁇ set_ub_dyn 1 % 4 Update period t dyn_set 1 h
  • the voltage at the capacitor terminal can be the voltage difference between the voltage of each phase of the busbar and the neutral point of the capacitor, or the voltage of the discharge PT terminal.
  • the current can be the current of each phase of the capacitor, or it can be The capacitor branches the current vector sum per phase, and calculates the real-time impedance of the capacitor based on the monitored capacitor current and voltage.
  • the initial impedance calibration equation is:
  • Z init_(p) is the initial impedance of each phase of the capacitor at the time of commissioning, The fundamental vector of the initial voltage of each phase for commissioning, The fundamental vector of the initial current per phase for commissioning.
  • the initial impedance of the calibrated capacitor must meet the following requirements:
  • ⁇ inh_ (p) is put into operation inherent deviation initial true impedance relative value mode, ⁇ set_alm_inh limit value as a relative value modulo inherent deviation amount, i.e., in FIG automatic calibration warning second impedance radius of the circle.
  • Z dyn_(p) is the real-time impedance of each phase of the capacitor
  • Z real_(p) is the true impedance of the capacitor.
  • the fundamental vector of the real-time terminal voltage per phase of the capacitor at runtime is the fundamental vector of the real-time current per phase of the capacitor at runtime, ⁇ dyn_(p) is the relative value of the modulus of the real-time impedance variation per phase.
  • ⁇ set_trip is the impedance protection trip setting, ie the radius of the protection trip impedance circle in Figure 2.
  • ⁇ set_alm_dyn is the relative value limit of the modulus of the dynamically updated impedance change amount, that is, the radius of the dynamic update alarm impedance circle in FIG. 2, and ⁇ set_ub_dyn is the relative value inconsistency limit value of the mode of the three-phase dynamic update change amount.
  • the impedance change calculation is considered normal, and the true impedance Z real is updated, otherwise the update is not updated and the update fails.
  • the capacitor dynamics change little in a short time, and the dynamic update period T can be set according to the actual situation, namely:

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Abstract

一种自适应的并联电容器阻抗保护方法，包括对电容器端电压、电流进行监测；电容器投运时对电容器初始阻抗进行自动校准；运行时计算电容器实时阻抗，动态周期更新电容器真实阻抗，若电容器实时阻抗与真实阻抗对比，实时阻抗变化量的模的相对值未超过动态更新限制门槛且达到更新周期则更新真实阻抗，若超过动态更新限制门槛则作更新失败告警；若实时阻抗变化量的模的相对值超过设定的保护告警门槛，并延时达到，则发出故障告警；若实时阻抗变化量的模的相对值超过设定的保护跳闸门槛，并延时达到，则保护跳闸出口。该保护方法适用于电容器及电容器组各种故障情况，整定值计算简单，实现简便，有效提高电容器保护的灵敏度及可靠性。

Description

一种自适应的并联电容器阻抗保护方法 技术领域
本发明涉及一种电力系统继电保护，尤其涉及并联电容器和并联电容器组的监测、保护方法。
背景技术
并联电容器在电力系统中广泛应用，为系统提供无功容量，投切频繁，其安全运行对电力系统安全稳定至关重要。目前我国并联电容器主要保护方法为不平衡保护，不平衡保护是根据电容器组分支对称或者三相对称的原理设计的保护方案，与电容器容量、接线方式、电容器元器件类型密切相关，受其限制，往往不能自如选择，需要改变一二次接线方式或需要增加外围设备，比如单星型电容器组采用相差压保护时，需要增加放电PT的抽头，且要差接放电PT二次侧；再比如H桥型电容器组采用桥差电流保护时，需要在桥臂上增加桥差电流CT。
由于不平衡保护原理的特点，其保护灵敏度及可靠性会受到影响，比如单星型电容器组采用放电PT开口三角电压保护时，其不平衡电压引入了三相放电PT的传递误差，扩大了误差范围，降低了保护精度，在保护定值整定时必须躲过这些起始不平衡值，所以其灵敏度大受影响。然而即使如此也无法避免运行时系统三相电压不对称、谐波等一些因素带来的影响。而且由于不平衡保护原理的特点，必然存在发生对称故障时无法判别故障的死区问题，以双星型电容器组采用中性点不平衡电流保护为例，当两分支上的A相电容器组都发生了一个电容器单元击穿时，双分支各自中性点上产生的不平衡电压是相等的，中性点不平衡电流仍为零，无法感受到故障发生，保护拒动。
当然，有人提出采用电容器容值变化作为电容器监视、保护的方案，电容器作为一个储能元器件，其容值相对固定，不受容量、接线方式、元器件类型影响，无需避免初始不平衡，也不存在死区问题。然而在实际运行中，电容器容值并不是一成不变，其受系统中的高次谐波影响、受外部环境温度、湿度等因素影响，且电容器组作为成套设备，其前端还串联电抗器等其他设备，实际阻抗并不完全等于电容器组容抗，发生故障时不完全是容值变化，也存在阻值变化，某些特定条件下可能容值变化很小，阻值变化很大，所以若采用了容值变化做保护动作判据，实际运用过程中保护灵敏度和可靠性大打折扣。
发明内容
鉴于上述问题，本发明提出了一种自适应的并联电容器阻抗保护方法，实现简便，适应各种工况，针对各种故障情况，有效提高电容器保护精度及可靠性。
为了实现上述方法，本发明采取的技术方案是：
对并联电容器端电压、电流进行监测；电容器投运时对电容器初始阻抗进行自动校准；运行时计算电容器实时阻抗，动态周期更新电容器真实阻抗，若电容器实时阻抗与真实阻抗对比，时阻抗变化量的模的相对值未超过动态更新限制门槛且达到更新周期则更新真实阻抗，若超过动态更新限制门槛则作更新失败告警；若实时阻抗变化量的模的相对值超过设定的保护告警门槛，并延时达到，则发出故障告警；若实时阻抗变化量的模的相对值超过设定的保护跳闸门槛，并延时达到，则保护跳闸出口。
上述方案中，对电容器的端电压、电流进行监测；电容器端电压可以是每相母线电压与电容器中性点电压矢量差，也可以是放电PT端电压，电流可以是电容器每相电流，也可以是电容器每相分支电流矢量和，根据监测的电容器电流、电压计算电容器实时阻抗。
上述方案中，投运时，对电容器初始阻抗进行初始自动校准，其初始阻抗校准方程为：
Figure PCTCN2017092430-appb-000001
其中，(P)指A、B、C三相，Zinit_(p)为投运时电容器每相初始阻抗，
Figure PCTCN2017092430-appb-000002
为投运时每相初始电压的基波矢量，
Figure PCTCN2017092430-appb-000003
为投运时每相初始电流的基波矢量。
进一步地，自动校准的电容器初始阻抗必须满足下列要求：
Figure PCTCN2017092430-appb-000004
εinh_(p)＜εset_alm_inh
其中，εinh_(p)为投运时初始真实阻抗固有偏差量的模的相对值,εset_alm_inh为固有偏差 量的模的相对值限制定值，根据电容器标称的最大的电容偏差设置，
Figure PCTCN2017092430-appb-000005
为电容器单相理论额定阻抗，Un为额定线电压，Sn为额定容量。
进一步地，若满足上述条件则校准成功，将Zinit_(p)作为电容器投运时的真实阻抗Zreal_(p)，否则校准失败，需重新校准直至校准成功，否则以Zideal作为电容器投运时的真实阻抗Zreal_(p)。
上述方案中，正常运行时，计算电容器每相实时阻抗及每相实时阻抗变化量的模的相对值，其计算方程为：
Figure PCTCN2017092430-appb-000006
Figure PCTCN2017092430-appb-000007
其中，Zdyn_(p)为电容器每相实时阻抗，Zreal_(p)为电容器每相真实阻抗，
Figure PCTCN2017092430-appb-000008
为运行时电容器每相实时端电压的基波矢量，
Figure PCTCN2017092430-appb-000009
为运行时电容器每相实时电流的基波矢量，εdyn_(p)为每相实时阻抗变化量的模的相对值。
进一步地，投运初始时刻的真实阻抗即为校准后的结果，正常运行时，电容器真实阻抗Zreal_(p)周期的用满足条件的实时阻抗Zdyn_(p)更新，更新周期达到且满足更新条件，则认为阻抗变化为正常变化，更新真实阻抗Zreal，否则报更新失败，不更新，其条件为：
εdyn_(p)＜εset_alm_dyn
max(|εdyn_A-εdyn_B|,|εdyn_B-εdyn_C|,|εdyn_C-εdyn_A|)＜εset_ub_dyn
其中，εset_alm_dyn为动态更新阻抗变化量的模的相对值限制定值，根据电容器标称的温度系数设置，εset_ub_dyn为三相动态更新变化量的模的相对值不一致限制定值，根据电容器标称的不一致性设置；
进一步地，考虑非故障情况正常运行时，在短时间内电容器动态变化甚微，动态更 新周期T可根据实际情况设置，即：
T＝tdyn_set
其中，tdyn_set为真实阻抗动态更新周期定值，tdyn_set范围为[0h,24h]，当tdyn_set＝0代表实时更新。
上述方案中，故障时，电容器实时阻抗变化量的模的相对值满足保护告警条件，并延时达到，则作保护告警，其保护告警条件为：
εdyn_(p)＞εset_alm
其中，εset_alm为阻抗保护告警定值，设置为考虑灵敏度的电容器发生故障时的阻抗变化量的模的相对值。
上述方案中，故障时，电容器实时阻抗变化量的模的相对值满足保护跳闸条件，并延时达到，则作保护跳闸，其保护跳闸条件为：
εdyn_(p)＞εset_trip
其中，εset_trip为阻抗保护跳闸定值，设置为考虑灵敏度的电容器熔丝熔断或击穿个数超过允许承受过电压倍数时阻抗变化量的模的相对值。
本发明的有益效果在于：不受电容器容量、接线方式、元器件类型影响，不受系统电压等级、运行方式、电能质量影响，不受监测系统误差、传感设备误差影响，不受电磁环境、天气、温度等外部环境影响，不额外增加一二次设备，不增加一二次接线复杂度，适用于各种运行工况，适用于电容器及电容器组各种故障情况，整定值计算简单，实现简便，有效提高电容器保护的灵敏度及可靠性。
附图说明
图1是本发明应用场景实例示意图；
图2是并联电容器阻抗保护阻抗圆原理图；
图3是本发明实施例的保护流程图；
具体实施方式
下面结合附图对本发明作进一步说明。
以某个35kV电压等级的并联电容器组为例，电容器组型号为TBB35-12000/200AKW，电容器单元型号BFM 11-200-1W，每相电容器组10并2串，电容 器单元额定容量为200Kvar，额定电压为11kV，电容器单元为外熔丝电容器。
如图3所示，一种自适应的并联电容器阻抗保护方法其实施步骤如下：
(1)根据设定的电容器额定容量，额定电压等参数，先预计算电容器理论的定阻抗：
Figure PCTCN2017092430-appb-000010
其中，Zideal为电容器单相理论额定阻抗，Un为额定线电压，Sn为额定容量。
(2)设定相关设备参数，保护定值；
根据电容器串并联个数算得电容器单元外熔丝熔断单元个数与健全相单元过电压倍数及每相总阻抗关系如下所示：
Figure PCTCN2017092430-appb-000011
当电容器熔丝熔断1根时，健全元件过电压倍数为105.34％，未超过110％所以允许电容器继续运行，发出故障告警提示，当电容器熔丝熔断2根时，健元件过电压倍数为111.11％，应该跳闸，考虑1.5倍灵敏度则设置：
εset_alm＝5.55/1.5＝3.7
εset_trip＝(12.62-5.55)/1.5+5.55＝10.26
所以设置保护告警定值及跳闸定值如下：
序号 定值 设置值 单位
1 告警定值εset_alm 3.7 ％
2 跳闸定值εset_trip 10.26 ％
根据《GB/T 11024.1-2010标称电压1000V以上交流电力系统用并联电容器第1部分：总则》的相关规定设置定值如下：
序号 定值 设置值 单位
1 固有偏差限制定值εset_alm_inh 6 ％
2 动态更新限制定值εset_alm_dyn 1 ％
3 三相不一致限制定值εset_ub_dyn 1 ％
4 更新周期tdyn_set 1 h
(3)对电容器的端电压、电流进行监测；电容器端电压可以是每相母线电压与电容器中性点电压矢量差，也可以是放电PT端电压，电流可以是电容器每相电流，也可以是电容器每相分支电流矢量和，根据监测的电容器电流、电压计算电容器实时阻抗。
(4)投运时，对电容器初始阻抗进行自动校准，初始阻抗校准方程为：
Figure PCTCN2017092430-appb-000012
其中，p指A、B、C三相，Zinit_(p)为投运时电容器每相初始阻抗，
Figure PCTCN2017092430-appb-000013
为投运时每相初始电压的基波矢量，
Figure PCTCN2017092430-appb-000014
为投运时每相初始电流的基波矢量。
校准的电容器初始阻抗必须满足下列要求：
Figure PCTCN2017092430-appb-000015
εinh_(p)＜εset_alm_inh
其中，εinh_(p)为投运时初始真实阻抗固有偏差量的模的相对值,εset_alm_inh为固有偏差量的模的相对值限制定值，即图2中自动校准告警阻抗圆的半径。
若电容器接线正常，传感器精度满足要求，电容器自动校准成功。
(6)然后投入运行，正常运行时，计算电容器每相实时阻抗及实时阻抗相对变化量的模，其计算方程为：
Figure PCTCN2017092430-appb-000016
Figure PCTCN2017092430-appb-000017
其中，Zdyn_(p)为电容器每相实时阻抗，Zreal_(p)为电容器的真实阻抗，
Figure PCTCN2017092430-appb-000018
为运行时电容器每相实时端电压的基波矢量，
Figure PCTCN2017092430-appb-000019
为运行时电容器每相实时电流的基波矢量，εdyn_(p)为每相实时阻抗变化量的模的相对值。
(7)判断电容器是否发生故障，当发电容器实时阻抗满足故障条件，若此时电容器并延时达到，则认为电容器发生故障，保护跳闸，其保护跳闸条件为：
εdyn_(p)＞εset_trip
其中，εset_trip为阻抗保护跳闸定值，即图2中保护跳闸阻抗圆的半径。
(6)若电容器未发生故障，正常运行时，统计电容器真实阻抗的更新周期，当更新周期达到时，判断实时阻抗满足更新条件：
εdyn_(p)＜εset_alm_dyn
max(|εdyn_A-εdyn_B|,|εdyn_B-εdyn_C|,|εdyn_C-εdyn_A|)＜εset_ub_dyn
其中，εset_alm_dyn为动态更新阻抗变化量的模的相对值限制定值，即图2中动态更新告警阻抗圆的半径，εset_ub_dyn为三相动态更新变化量的模的相对值不一致限制定值。
若满足更新条件则认为阻抗变化计算正常，更新真实阻抗Zreal，否则不更新并报更新失败。
考虑非故障情况正常运行时，在短时间内电容器动态变化甚微，动态更新周期T可根据实际情况设置，即：
T＝tdyn_set
以上实例仅为说明本发明的技术思想，不能以此限定本发明的保护范围，凡是按照本发明提出的技术思想，在技术方案基础上所做的任何改动，均落入本发明保护范围内。

Claims (13)

  1. 一种自适应的并联电容器阻抗保护方法，其特征在于，所述方法包括：
    对电容器的端电压、电流进行监测；
    电容器投运时对电容器初始阻抗进行自动校准；
    运行时计算电容器实时阻抗，动态周期更新电容器真实阻抗；
    若电容器实时阻抗与真实阻抗相比，实时阻抗变化量的模的相对值未超过动态更新限制门槛，并且动态更新达到更新周期则更新真实阻抗；若实时阻抗变化量的模的相对值超过动态更新限制门槛则作更新失败告警；
    若实时阻抗变化量的模的相对值满足保护告警条件，并延时达到，则作保护告警；
    若实时阻抗变化量的模的相对值满足保护跳闸条件，并延时达到，则保护跳闸出口。
  2. 根据权利要求1所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的对电容器的端电压、电流进行监测；电容器端电压为每相母线电压与电容器中性点电压矢量差，或者为放电PT端电压；电流为电容器每相电流，或者为电容器每相分支电流矢量和。
  3. 根据权利要求1所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述电容器阻抗保护跳闸条件为，
    εdyn_(p)＞εset_trip；
    其中，(p)指A、B、C三相，εdyn_(p)为电容器故障时刻每相实时阻抗变化量的模的相对值，εset_trip为阻抗保护跳闸定值。
  4. 根据权利要求1所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述电容器阻抗保护告警条件为，
    εdyn_(p)＞εset_alm；
    其中，(p)指A、B、C三相，εdyn_(p)为电容器故障时刻每相实时阻抗变化量的模的相对值，εset_alm为阻抗保护告警定值。
  5. 根据权利要求3所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的电容器每相实时阻抗变化量的模的相对值计算方程为，
    Figure PCTCN2017092430-appb-100001
    其中，Zdyn_(p)为电容器每相实时阻抗，Zreal_(p)为电容器每相真实阻抗。
  6. 根据权利要求5所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的电容器每相实时阻抗计算方程为，
    Figure PCTCN2017092430-appb-100002
    其中，
    Figure PCTCN2017092430-appb-100003
    为运行时电容器每相实时端电压的基波矢量，
    Figure PCTCN2017092430-appb-100004
    为运行时电容器每相实时电流的基波矢量。
  7. 根据权利要求5所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的电容器真实阻抗Zreal_(p)用满足要求的实时阻抗周期更新。
  8. 根据权利要求7所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的电容器真实阻抗的更新周期通过真实阻抗动态更新周期定值设置。。
  9. 根据权利要求7所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的电容器真实阻抗Zreal_(p)动态周期更新，必须满足的条件为，
    εdyn_(p)＜εset_alm_dyn；
    max(|εdyn_A-εdyn_B|,|εdyn_B-εdyn_C|,|εdyn_C-εdyn_A|)＜εset_ub_dyn；
    其中，εset_alm_dyn为动态更新阻抗变化量的模的相对值限制定值，εset_ub_dyn为三相动态更新变化量的模的相对值不一致限制定值；
    若满足条件则以Zdyn_(p)更新真实阻抗，否则不更新，并作更新失败告警。
  10. 根据权利要求5所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的电容器真实阻抗Zreal_(p)动态周期更新，其更新初始值为投运时自动校准后的真实 阻抗；
    若自动校准成功，真实阻抗Zreal_(p)为投运时电容器每相校准后的初始阻抗Zinit_(p)，否则真实阻抗Zreal_(p)为电容器单相理论额定阻抗
    Figure PCTCN2017092430-appb-100005
    Un为额定线电压，Sn为额定容量。
  11. 根据权利要求10所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的投运时对电容器初始阻抗进行自动校准，其初始阻抗校准方程为，
    Figure PCTCN2017092430-appb-100006
    其中，
    Figure PCTCN2017092430-appb-100007
    为投运时每相初始电压的基波矢量，
    Figure PCTCN2017092430-appb-100008
    为投运时每相初始电流的基波矢量。
  12. 根据权利要求10所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的投运时对电容器初始阻抗进行自动校准，其校准成功条件为，
    εinh_(p)＜εset_alm_inh；
    其中，εinh_(p)为投运时初始真实阻抗固有偏差量的模的相对值,εset_alm_inh为固有偏差量的模的相对值限制定值。
  13. 根据权利要求12所述的一种自适应的并联电容器阻抗保护方法，其特征在于：所述的投运时初始阻抗固有偏差量的模的相对值计算方程为，
    Figure PCTCN2017092430-appb-100009
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