WO2014192021A1 - Capteur de réseau électrique triphasé à quatre fils conçu pour surveiller les déséquilibres de charges et les bruits harmoniques minimes - Google Patents

Capteur de réseau électrique triphasé à quatre fils conçu pour surveiller les déséquilibres de charges et les bruits harmoniques minimes Download PDF

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Publication number
WO2014192021A1
WO2014192021A1 PCT/IN2014/000335 IN2014000335W WO2014192021A1 WO 2014192021 A1 WO2014192021 A1 WO 2014192021A1 IN 2014000335 W IN2014000335 W IN 2014000335W WO 2014192021 A1 WO2014192021 A1 WO 2014192021A1
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Prior art keywords
phase
neutral voltage
distribution network
power distribution
neutral
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PCT/IN2014/000335
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English (en)
Inventor
Deb Narayan NATH
Jaydeb MANDAL
Sagnik NATH
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Indian Association For The Cultivation Of Science
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Publication of WO2014192021A1 publication Critical patent/WO2014192021A1/fr

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Classifications

    • 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
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
    • 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
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • 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
    • G01R31/58—Testing of lines, cables or conductors
    • 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
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00032—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for
    • H02J13/00034—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for the elements or equipment being or involving an electric power substation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
    • G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
    • 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
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase 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
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • 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
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/30—State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge

Definitions

  • TITLE A 4-WI E 3-PHASE POWER DISTRIBUTION NETWORK SENSOR FOR MONITORING MINUTE LOAD UNBALANCE AND HARMONIC NOISE.
  • the present invention deals with a 3-phase power distribution network sensor. More particularly, the present invention deals with a sensor useful for monitoring load unbalance, harmonic noise and voltage spikes in a 4-wire 3-phase power distribution network. The present invention further deals with a process for manufacturing of the said 3-phase power distribution network sensor. The present invention also discloses a method of protection of a power distribution network against voltage spikes, harmonic noise and fire hazards from neutral failure due to severe load unbalance in 3-phase by involving the said 3-phase power distribution network sensor.
  • Load unbalance in a 4-wire, 3-phase power distribution network is a common nuisance. This causes wasteful energy in the form of large current in the Neutral wire which is normally rated at lower current capacity. Prolonged high current condition in Neutral wire eventually leads to unpredictable neutral failure, causing severe fire hazards and complete disruption of the voltage distribution among different phases. The phase voltage in the lowest loaded phase increases drastically and triggers a chain reaction of damages in the equipments connected to that phase. Moreover, an unbalanced distribution network causes zero- sequence magnetic flux leakage in the sub-station transformer and becomes a source of electro-magnetic-interference (EMI) which impairs the functioning of sensitive electronic instruments.
  • EMI electro-magnetic-interference
  • Present day market available monitoring systems are based on the concept of simultaneous sensing of voltages and currents at the three phases and also in the neutral wire by employing voltage (VT) and current (CT) transformers over a wide Dynamic Range (D.R.) with sample rate ⁇ 16 ksps and all the power grid parameters are computed from the sampled data using a dedicated computer.
  • VT voltage
  • CT current
  • D.R. Dynamic Range
  • the basic object of the present invention is to provide a sensory system which would be adapted to monitor operational parameters of a power distribution network for interpreting operational failure of the power distribution network prior the actual failure and shutting down the power distribution network.
  • Another important object of the present invention is to provide power distribution network sensor which would be adapted to operate in a 4-wire 3-phase power distribution network for monitoring load unbalance, harmonic noise and voltage spikes in the network and generate a prior alarm much before a neutral failure takes place in the network.
  • Yet another object of the present invention is to provide a power distribution network sensor which would be adapted to monitor harmonic noise generated due to non-linear loads (SMPS, switched-mode-power-supply) and voltage spikes in power grid and analyze the noise pattern in the power grid to assert the neutral failure before it actually takes place.
  • SMPS non-linear loads
  • switched-mode-power-supply switched-mode-power-supply
  • a further object of the present invention is to provide a sensing technique which would be adapted to involve phase-sensitive-detection (PSD) technique to detect unbalance in the load and malfunctions in a Distribution Box (DB) within a 3-phase power distribution network.
  • PSD phase-sensitive-detection
  • a still further object of the present invention is to develop fabrication method which would be adapted to construct a reliable and efficient power distribution network sensor for asserting operational failure of the power distribution network prior the actual the actual failure by involving cheap, simple and readily available electronic component.
  • a still further object of the present invention is to develop fabrication method of a load switcher which coupled with the sensor outputs will automatically switch quanta of ballast load from the maximum loaded phase to the least loaded phase when the imbalance crosses a safe limit.
  • a 3-phase power distribution network sensor for monitoring minute load unbalance comprising means for generating stabilized reference signals synchronized to the three phases of said power distribution network or power line and generating inverting neutral voltage with respect to ground; involving said inverting neutral voltage with respect to ground and cooperatively activate means for determining one or more electronic attributes related to the neutral voltage and comparing the said attributes with their predefined set values to monitoring any minute load unbalance in the power distribution network or the power line.
  • said power distribution network sensor for monitoring minute load unbalance comprises means for determining electronic attributes related to the neutral voltage and comparing the said attributes in comparator circuits with their predefined set values to prevent the neutral failure in the power distribution network or the power line.
  • said power distribution network sensor for monitoring minute load unbalance comprises phase sensisitve detection means for detection of phase components of said inverting neutral voltage with respect to ground and its amplification means; means for precision rectification and generating information about neutral voltage w.r.t. Ground. means for yielding the harmonics and noise content in the said Neutral voltage w.r.t. Ground and generation of floating signals; and means for translation of thus obtained electronic attributes with reference to Neutral Point, into Ground-referenced signals to be processed by a central dedicated system; and comparator circuit means to actuate alarms if any of said comparable attribute value exceeds set value .
  • the means for determining electronic attributes related to the neutral voltage comprises one or from precision rectifier and average module for yielding information about root-mean-square (rms) neutral voltage with respect to the ground; notch-filter followed by precision rectification and averaging module for measuring harmonics and noise content in the neutral voltage with respect to ground.
  • phase sensitive detection module for detecting the phase components of neutral voltage along the three supply phasors;
  • the said precision rectifier and average module is operatively connected with said means for generating inverting neutral voltage for yielding the information proportional to r.m.s. value of the neutral voltage phasor with respect to the ground.
  • said notch-filter followed by precision rectification and averaging module is operatively connected with said means for generating inverting neutral voltage and to remove fundamental line frequency from inverting neutral voltage by involving said notch-filter and thereby detect the harmonics and noise content of the neutral voltage by involving the precision rectification and averaging module.
  • the means for determining floating signals comprise three independent phase sensitive detection module for each of the supply phasors for measuring of the phase components of neutral voltage along the three supply phasors and to receive signal from the said notch- filter followed by precision diode rectification and averaging module to measure harmonics content in the neutral current
  • the electronic attribute related to the neutral voltage includes the harmonics and noise content in the neutral voltage, the phase components of neutral voltage along the three supply phasors.
  • the present power distribution network sensor is adapted to be disposed in electrical communication with logic circuit having OR gate with resettable latch for sensing load imbalance, harmonics and noise in the power distribution network or the power line and automatically tripping the power distribution network or the power line when the sensory parameters exceed a pre-defined safe limit.
  • the present power distribution network sensor comprises signal translator for transforming the said neutral-referenced electrical attributes into ground-referenced signals for converting said signal into its digital equivalent and feeding to a centralized base station to store in memory for further analysis.
  • a three phase load switcher for switching quanta of loads from most loaded phase to least loaded phase and ensuring efficient control of balanced load sharing comprising sensor system for sensing network parameters of 3-phase power distribution network or power line adapted for sensing the phase components of neutral voltage along the supply phase of the 3-phase power distribution network or power line involving a 3-phase power distribution network sensor for monitoring minute load unbalance;
  • Max-Min Logic circuit for placing quanta of ballast loads in the three phases through relay assemblies and automatically switching said ballast loads of the most loaded phase to the least loaded phase when the said sensor system detects the phase components of neutral voltage along the supply phase exceeds a predefined set value; wherein said relay assemblies are operatively connected with said Max-Min Logic circuit via. latch circuit adapted for enabling said relay assemblies only after a delay following the moment of crossing of the phase components of neutral voltage along the supply phase beyond the predefined set value to avoid oscillation in the contacts.
  • a method for sensing and monitoring the network parameter by involving the present power distribution network sensor comprising generating stabilized reference signals synchronized to the three phases of the 3-phase power distribution network or power line; generating inverse of neutral voltage phasor with respect to ground with proper scaling; detecting the components of the neutral voltage phasor along the three phases; detecting the amplitude of neutral voltage; triggering alarms if any of the components of the neutral voltage phasor value along the three phases exceeds pre-defined set value.
  • a method for automatically shutting down the power distribution network in case of malfunction comprising : involving 3-phase power distribution network sensor for monitoring minute load unbalance as claimed in anyone of claims 1 to 10; comparing the electronic attribute related to the neutral voltage with safe limit values in said comparators; feeding the comparator outputs to a multiple input OR gate with resettable Latch to drive a circuit breaker for automatically tripping or shitting the power distribution network.
  • FIG. 1 illustrates a typical 3-phase power supply system.
  • the system comprises a 3-phase power source at the sub-station (the step-down transformer) and one distribution box (DB).
  • Figure 2 illustrates the circuit block diagram indicating the generation of reference signals from the three phases, generation of inverse of neutral voltage with respect to ground ( z ) along with scaled down by 2, 3 and phase-sensitive-detection of the components of z ( ⁇ , ⁇ 3) along these reference signals.
  • the circuit is essentially referenced to the neutral point (not ground-referenced)
  • Figure 3 illustrates the circuit block diagram indicating precision rectification of z followed by averaging to yield ⁇ ⁇ which is proportional to the r.m.s. value of the neutral voltage phasor with respect to ground.
  • Figure 4 illustrates the circuit diagram of the phase-sensitive-detector built around LM565 and LM324 (National Datasheet).
  • Figure 5 illustrates the circuit diagram of the precision rectifier and averager built around
  • Figure 6 illustrates the circuit diagram of the passive 50 Hz notch filter (Art of Electronics, Horowitz and Hill) .
  • Figure 7 illustrates the circuit diagram for transforming the signals (O ⁇ ⁇ and ⁇ ⁇ ) from neutral-referenced to ground-referenced signals by the use of opto-isolator 6N 136 and LM324.
  • Figure 8 illustrates a typical circuit configuration to actuate a circuit breaker (CB) if ⁇ ⁇ , ⁇ ⁇ and ⁇ 's cross safe limit.
  • CB circuit breaker
  • Figure 9 illustrates the actual experimental data of monitoring ⁇ ⁇ over a span of 50 sees. It is evident that no information about loading in the individual phases can be obtained from this data .
  • Figure 10 illustrates the actual experimental data of monitoring ( s over the same span. It is evident that information about loading in the individual phases and the unbalance are clearly depicted (explained in the text later) .
  • Figure 11 illustrates a preferred circuit embodiment of the maximum, minimum control line generator.
  • Figure 12 illustrates a preferred Relay assembly (R.A. ) associated with the present invention.
  • Figure 13 illustrates the detail circuit configuration of an automatic 3 phase load switcher comprising the max-min control line generator and three relay assemblies for three phases , together with a 10 min time lapse delay generator for eliminating oscillation in the relay contacts.
  • the present invention describes a 4-wire 3-phase power distribution network sensor, useful for monitoring load unbalance, harmonic noise and voltage spikes in a network.
  • the present invention also describes a process for manufacturing of the said 3-phase power distribution network sensor and a method of protection in a 3-phase power distribution network against fire hazards and instrument damage (due to neutral failure), using the said sensor.
  • the said sensor works on phase-sensitive-detection (PSD) technique to detect unbalance in the load and malfunctions in a Distribution Box (DB) within a 3-phase power distribution network.
  • PSD phase-sensitive-detection
  • DB Distribution Box
  • This sensor also monitors harmonic noise generated due to non-linear loads (SNIPS, switched-mode-power-supply) and voltage spikes in power grid.
  • SNIPS non-linear loads
  • SNIPS switched-mode-power-supply
  • voltage spikes in power grid As a general rule the power grid becomes noisy before a massive neutral failure and thus the sensor can give a prior alarm much before a neutral failure actually takes place.
  • response time can be programmed in the range of 10 - 100ms, instead of using by cheap analog meters having poor D.R. ( ⁇ 24 dB), where the response time is slow (> 1 s) .
  • a DB can be monitored using the said sensor, by measuring the unbalance information in three phases with large D.R. ( ⁇ 100 dB ) and fast response time (10 to 360 ms).
  • the said sensor is capable of detection of small voltage spikes representing noise or switching transients of reactive loads.
  • the most promising feature of the present invention is however, the nominal cost and ability to manufacture with indigenous components.
  • phase-sensitive-detection method which is also known as lock-in technique has been employed with inherent high dynamic range ( > 80 dB ) and noise immunity.
  • Basic principle of detection :
  • FIG. 1 A typical 3-phase power supply system is represented by Figure-1.
  • Z N impedance of neutral path ⁇ ⁇ Z l r Z 2 , Z 3 (load in three phases)
  • e N Neutral voltage w.r.t. Ground ⁇ e N i + e N2 + e N3 (components along the three phases)
  • ⁇ / r 2 , r 3 are three reference square waves synchronous to the three voltage phasors of the power grid supply
  • phase-sensitive detection between ri and e N yields a dc output ⁇
  • ⁇ 2 const . R . (- 1 e Ni
  • ⁇ 3 const . R . (- 1 e N 1 1. 0.5 -
  • e N2 1
  • e N3 1 and ⁇ ! 0
  • ⁇ values are a measure of unbalance endowed with inherent high dynamic range ( > 80 dB ) and noise immunity (characteristics of Lock-in detection) .
  • R1-Z1-D1 generates mono-polar, stabilized reference signals (XI, X2, X3) in phase with the three supply voltage phasors e lr e 2 and e 3 . All the signals and the whole circuit including the DC power supplies are floating with respect to Ground and is essentially referenced to NEUTARL point.
  • Figure 3 which illustrates the circuit block diagram for indicating precision rectification of z followed by averaging to yield ⁇ ⁇ which is proportional to the r.m.s. value of the neutral voltage phasor with respect to ground.
  • z is the scaled e GN and is used to measure the neutral voltage after precision rectification and averaging . This is also used to measure the harmonics content in the neutral voltage after filtering in a 50 Hz notch filter followed by precision filtering and averaging (Fig-3) .
  • V n is the same signal through a diode limiter and is fed to the input of the three PSDs built around three PLL565 ICs.
  • ⁇ , ⁇ 2 , ⁇ 3 thus are measures of the phase components of neutral voltage along the three supply phasors.
  • Figure 4 depicts the basic phase-sensitive-detector (PSD) for each phase.
  • PSD phase-sensitive-detector
  • a first-order filter has been employed with CI and the internal 3K6 ⁇ resistor of LM565 and the time constant is on the order of 360 ms.
  • a gain of x2.7 is employed with LM324 (1/4) and PI is set to bring the PSD output at zero (i .e. at NEUTRL point) with v n shorted to NEUTRAL point (i.e. zero) but x signals being connected.
  • Figure 5 shows a preferred circuit embodiment of the precision rectifier and average used for measuring neutral voltage ⁇ ⁇ ( in Fig-3) and also the harmonics content ⁇ ⁇ ⁇
  • Dl 1N4148
  • R5 10K ⁇ , 250 mW, 1%
  • R9 IK ⁇ , 250 mW, 1%
  • R10 10K ⁇ , 250 mW, 1%
  • C2 470MF, 25 V, electrolytic.
  • Figure 6 depicts a preferred embodiment of Passive Twin-T (bridged differentiator tunable notch filter); three capacitors are selected to be as identical as possible; resistance on the top must be exactly six times the bottom resistance [15] .
  • the bottom pre-set is adjusted for frequency tuning at 50 Hz.
  • the attenuation of the filter when implemented in the circuit (Fig-3) at 50 Hz is much higher than 60 dB and the transmission at 150 Hz is on the order of 50% .
  • Fig-9 depicts the change of e NG (neutral voltage w.r.t ground) with time but there is no information of load unbalance in specific phases. However, from Fig-10 we get all the unbalance information.
  • e NG neutral voltage w.r.t ground
  • ⁇ value of the most loaded phase is most negative and that for the least loaded phase is most positive.
  • the 3 rd phase will have intermediate ⁇ value depending on its loading .
  • phase-1 is most loaded and phase-3 is least loaded .
  • phase-2 becomes the least loaded phase.
  • Phase- 1 remains the most loaded phase all the time.
  • ⁇ ⁇ value has uncertainty of only a few mV (the input offset voltage of LM324 is on the order of 1 mV and the gain in the circuit is 2.7, Fig-4 ) and considering a power supply of +/- 9 V the dynamic range of unbalance detection is on the order of 80 dB. Further if we consider the fact that this unbalance is in a power distribution network of nominal 240 V AC then the effective dynamic range of the unbalance measurement is 100 dB.
  • the spike in ⁇ 3 approximately corresponds to 0.5 V r.m.s. voltage hike at neutral point due to switching on load in phase-3.
  • Z N 160 m ohm (typically 200 m of 95 Sq mm cable, 150 A per phase)
  • Harmonic detection In present prototype (the gain in amplifier A is one i.e A is absent, Fig-3) at 3 rd harmonic ( 150 Hz) 1.6 V r. m.s. signal in eN triggers the LED. Actually it doesn't mean anything but considering the fact that the dc sig out in the rectifier is in mV scale and sufficient amplification can be given ( say ⁇ 100) so that 16 mV r. m .s. can be easily detected corresponding to 100 mA of 3 rd harmonic current in the neutral wire.
  • Voltage spikes are generated in the power supply network either from the source (at the sub-station transformer) or from switching reactive loads. These are manifested in the three phases and neutral points as spikes with respect to ground . As spike generation rarely occurs synchronously in all three phases, neutral point always reflects the spikes in the system. In our prototype the noise LED (Fig-3) gets triggered with 8 V, 1 ms pulse in the neutral . Implementation of the gain A ( ⁇ 100, Fig-3) will increase the sensitivity substantially. Normally a spike in the power line has bipolar characteristic and these are easily detected by the half-wave precision rectifier (Fig-5). For better performance regarding harmonics and spike detection a full wave precision rectifier can be used .
  • the embodiment of the present invention can be used as a stand-alone unit to monitor the unbalance in load, harmonics and noise in the power line. Coupled with a set of comparators and logic circuits (Fig-8) and actuator, it can safe guard and switch off a DB, if parameters cross safe limit, preventing fire and instrument damage.
  • the detail circuit of the automatic load switcher is depicted in Figure 13.
  • the 6 bit control line data from the Max-Min Logic Circuit is fed to the three relay assemblies via a latch.
  • the three ⁇ s are fed to three comparators and a OR gate activates when any of the ⁇ value exceed allowable safe unbalance (analogous to Figure 8).
  • the capacitor C starts charging through R and after a set lapse time (say 10 min) set by another comparator circuit triggers a monostable (M.S. 2, positive edge triggered) to fire a strobe pulse (pulse width 100 ns) to the latch.
  • M.S. 2 monostable
  • strobe pulse pulse width 100 ns
  • a set of sensors connected to various DBs in a power distribution network can be easily fed to a base station equipped with a single channel 12 bit ADC and a computer.
  • the input information (5 channels per DB) is de-multiplexed and after A/D conversion can be stored in the computer memory over a long period of time.
  • system troubleshooting will become much simpler. It is evident that the cost of such base station will be substantially cheaper than the present day technology.
  • a typical circuit to convert the neutral referenced signals to ground referenced signals to be fed to the computer is shown in Fig-7. It uses opto- coupler chip and is self explanatory.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Monitoring And Control Of Power-Distribution Networks (AREA)

Abstract

Cette invention concerne un système de capteur conçu pour détecter les paramètres de réseau d'un réseau de distribution ou d'une ligne de transport d'électricité triphasé(e) pour interpréter les défaillances du neutre dans ledit réseau de distribution ou dans la ligne de transport d'électricité, comprenant des moyens conçus pour générer des signaux de référence stabilisés synchronisés sur les trois phases dudit réseau de distribution ou de ladite ligne de transport d'électricité, et générer ainsi une tension de phase neutre inversée par rapport à la masse, ainsi que des moyens conçus pour déterminer un attribut électronique corrélé à la tension du neutre. Les attributs électroniques déterminés sont comparés dans des circuits comparateurs à leurs valeurs de consigne prédéterminées afin d'interpréter la défaillance du neutre dans le réseau de distribution ou la ligne de transport d'électricité. Un commutateur de charge automatique est commandé par lesdits attributs pour rétablir l'équilibre dans le réseau de distribution.
PCT/IN2014/000335 2013-05-29 2014-05-19 Capteur de réseau électrique triphasé à quatre fils conçu pour surveiller les déséquilibres de charges et les bruits harmoniques minimes WO2014192021A1 (fr)

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JP6299934B1 (ja) * 2017-01-24 2018-03-28 中国電力株式会社 配電経路相管理支援方法、及び配電経路相管理支援システム
CN109301848A (zh) * 2018-11-13 2019-02-01 上海光维电力科技有限公司 一种有源三相不平衡自动调节装置
US10223906B2 (en) 2017-01-23 2019-03-05 Florida Power & Light Company Open neutral detection

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