NL2016237B1 - Method and system for monitoring electric power in a multiple phase power distribution network. - Google Patents

Method and system for monitoring electric power in a multiple phase power distribution network. Download PDF

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Publication number
NL2016237B1
NL2016237B1 NL2016237A NL2016237A NL2016237B1 NL 2016237 B1 NL2016237 B1 NL 2016237B1 NL 2016237 A NL2016237 A NL 2016237A NL 2016237 A NL2016237 A NL 2016237A NL 2016237 B1 NL2016237 B1 NL 2016237B1
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NL
Netherlands
Prior art keywords
sensing unit
voltage
current
phase
current sensing
Prior art date
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NL2016237A
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Dutch (nl)
Inventor
Smit Gerrit
Original Assignee
Liandon B V
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Application filed by Liandon B V filed Critical Liandon B V
Priority to NL2016237A priority Critical patent/NL2016237B1/en
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Publication of NL2016237B1 publication Critical patent/NL2016237B1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/54—Systems for transmission via power distribution lines
    • 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
    • G01R19/175—Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
    • G01R29/18—Indicating phase sequence; Indicating synchronism
    • 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
    • H02J13/00006—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 information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
    • H02J13/00007—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 information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment using the power network as support for the transmission
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2203/00—Indexing scheme relating to line transmission systems
    • H04B2203/54—Aspects of powerline communications not already covered by H04B3/54 and its subgroups
    • H04B2203/5404—Methods of transmitting or receiving signals via power distribution lines
    • H04B2203/5416—Methods of transmitting or receiving signals via power distribution lines by adding signals to the wave form of the power source
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2203/00—Indexing scheme relating to line transmission systems
    • H04B2203/54—Aspects of powerline communications not already covered by H04B3/54 and its subgroups
    • H04B2203/5404—Methods of transmitting or receiving signals via power distribution lines
    • H04B2203/542—Methods of transmitting or receiving signals via power distribution lines using zero crossing information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2203/00—Indexing scheme relating to line transmission systems
    • H04B2203/54—Aspects of powerline communications not already covered by H04B3/54 and its subgroups
    • H04B2203/5462—Systems for power line communications
    • H04B2203/5495—Systems for power line communications having measurements and testing channel
    • 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
    • Y04S40/00—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them
    • Y04S40/12—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment
    • Y04S40/121—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment using the power network as support for the transmission

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

Abstract

Method for monitoring electric power in a multiple phase electric power distribution network, wherein a voltage sensing unit (1) detects a voltage on at least one electric power transmission line (L), and a spaced-apart current sensing unit (2) detects associated current flowing through said at least one electric power transmission line (L), wherein at least one of the voltage sensing unit (1) and the current sensing unit (2) generates phase reference information, wherein the phase reference information is transmitted to a processor, using that information to derive a phase difference between detected voltage and associated detected current.

Description

Title: Method and system for monitoring electric power in a multiple phase power distribution network
The invention relates to a method for monitoring electric power in a multiple phase electric power distribution network, wherein a voltage sensing unit detects a voltage on at least one electric power transmission line, and a spaced-apart current sensing unit detects associated current flowing through said at least one electric power transmission line.
The invention also concerns a system comprising at least one electric power transmission line having a voltage sensing unit and a current sensing unit remote from said voltage sensing unit.
Various methods and systems exist for measuring and monitoring electric current, voltage and power in transmission lines of an electric power distribution network.
These prior art systems reveal several problems. In many cases, technicians have to go on-site, mostly after a problem has been detected. Methods and systems are arranged to be implemented only in case of necessity, for example to find a failure in a circuit or in the network. Connection of measuring devices may imply multiple wired connections to be effected. To measure power on-site, network operation may have to be interrupted in order to guarantee the technicians’ safety. Another major issue in power monitoring is the synchronization of voltage and current measurements at two different locations.
It is an aim of the present invention to solve or alleviate one or more of the above-mentioned problems. Particularly, the invention aims at providing a more efficient method for monitoring electric power in a multiphase electric power distribution network in a pro-active manner, allowing a substantial cost reduction. Furthermore, the invention aims at providing a system which is easy and safe to install and use, reducing or even avoiding extra costs generated by the training of electricians.
To this aim, a first aspect of the invention provides a method characterized by the features of claim 1.
According to an aspect of the invention, at least one of the voltage sensing unit and the current sensing unit generates phase reference information, wherein the phase reference information is used to derive a phase difference between detected voltage and associated detected current.
Thus, a phase difference between voltage and current (also known as “phase angle difference”) can easily be derived, utilizing said reference information, the phase difference being an important value for power monitoring: a direction of power, as well as the amount of real and reactive power, and consequently of power loss, can be derived therefrom.
According to a preferred embodiment, the phase reference information can be transmitted to a signal processor, for example a processor of the current sensing unit in case the phase reference information is generated by the voltage sensing unit or a processor of the voltage sensing unit in case the phase reference information is generated by the current sensing unit, wherein the transmission is carried out for example by superposition or modulating the signal into the respective power transmission line.
Thus, the current sensing unit or alternatively the voltage sensing unit can be configured to carry out the phase difference determination, providing above-mentioned advantages efficiently, with relatively compact means.
In a preferred embodiment, said reference information is a starting time of transmission of a signal, for example a pseudo noise signal, at a predetermined reference time of a phase voltage or of a current, for example a time coinciding with a maximum of a phase voltage or a current, with a minimum of a phase voltage or a current, with a positive zero-crossing of a phase voltage or a current, or with a negative zero-crossing of a phase voltage or a current. The starting time of a signal is an easy-to-implement way to communicate a reference information from a voltage sensing unit to a current sensing unit or vice versa in order to allow deriving said phase difference between voltage and current from said reference information. Alternatively, said reference information may consist of a real time measurement by a clock coinciding with a maximum, minimum or zero crossing of a phase voltage or a current.
Advantageously, the voltage sensing unit and/or the current sensing unit determines and stores times coinciding with a predetermined reference time of a phase voltage or of a current, for example with a maximum of a phase voltage or a current, with a minimum of a phase voltage or a current, with a positive zero-crossing of a phase voltage or a current, or with a negative zero-crossing of a phase voltage or a current. The stored times allow a prediction of a next reference time based on the stored references times. At the same time, the sensing unit receiving the reference information can compare the received reference information with the stored times.
More advantageously, said predetermined reference time of a phase voltage or a current is derived from a sample of a predetermined number of said previous predetermined reference times of said phase voltage or said current. In this way, influence of noise or other signal disturbances on the reference time determination can be reduced of cancelled out, thereby obtaining that time in a more precise manner.
In a preferred embodiment, said signal is transmitted, for example by superposition over said electric power transmission line, for example from said voltage sensing unit to said current sensing unit, or for example from said current sensing unit to said voltage sensing unit. By using power line communication there is no need for supplementary communication devices and lines, which simplifies the installation, thus reducing costs, and avoids additional wiring. Other communication means are possible as well: for example via Bluetooth, DECT or Wifi. Said signal can be emitted by a voltage sensing unit and transmitted to the current sensing unit, or vice versa.
Preferably, the current sensing unit or the voltage sensing unit determines said starting time of transmission of said signal by subtracting a predetermined constant from a signal detection time. As the time difference between the starting time of transmission of a signal and the moment of its detection is constant (equal to all the delays in signal processing in the voltage and the current sensing units), said starting time of transmission can be easily reconstructed. In this way, a reference time is transmitted without the need for synchronization of multiple timing devices.
More preferably, said predetermined reference time of a current and said predetermined reference time of a phase voltage coincide with a same type of event, for example with a positive zero-crossing of a current and of a phase voltage respectively, which simplifies the deduction of the starting time of transmission of said signal from the signal detection time.
In a preferred embodiment, a phase difference between voltage and current is derived from a smallest difference in absolute value between said starting time of transmission of said signal and one of said stored times coinciding with a predetermined reference time of a current or a phase voltage.
In a highly advantageous embodiment, the current sensing unit is integrated within a protective body of an electrical fuse. In a more preferred embodiment, the fuse may be installed in a power distribution transformer end station, particularly an end station configured to convert medium (e.g. lkV or higher) voltage to low voltage (i.e. a voltage lower than 1 kV, for example about 230V or about 115V, e.g. for household appliances).
In one embodiment, said fuse may for example determine a current via a voltage drop measurement across a fusible resistor in the electrical fuse, the resistor being configured to provide overcurrent protection. From the voltage drop and the known resistance of the resistor, the current can then easily be derived, e.g. according to Ohm’s law.
Alternatively, in a preferred embodiment, said fuse may comprise a Rogowski coil. The current can then be derived from the voltage induced by the current’s magnetic field in the Rogowski coil, as this voltage is proportional to the rate of change of the current to be measured.
Such a current sensing unit (integrated in a fuse) can easily and securely be installed, for example in a distribution transformer end station located near a customer’s premise, without having to train technicians, as it merely amounts to an exchange of a standard fuse with the fuse including the integrated current sensing unit. The exchange of fuses is a known procedure for a person skilled in the art, and does not require additional training. For measuring the current, there is no need for connecting additional wiring. As the fuse itself comprises a low resistance resistor, there is no need for a supplementary resistor placed in series with the fusible resistor of the fuse. Measurement of the voltage drop across the fusible resistor of the fuse simplifies the system. Alternatively, the current sensing unit may comprise any other known current measuring device, for example the current sensing unit may comprise a sensor, e.g. a voltmeter, arranged to measure a voltage drop, e.g. across a resistor of the fuse placed in series with the fusible resistor in the electrical fuse. Or for example, the current sensing unit may deduce a current measurement from a sensing of a current induced magnetic field, wherein the current sensing unit comprises for example a Rogowski coil, or for example a Hall effect sensor. A Rogowski coil can provide a highly linear current measurement and usually does not need temperature calibration.
Preferably, the method comprises the step of transmitting measurement results, or results derived therefrom, for example upon interrogation by an interrogating device, to a central monitoring device, which is communicatively connected via a communication link to an interrogating device or to said voltage sensing unit and/or said current sensing unit; and the step of processing received data from the at least one voltage sensing unit and/or said current sensing unit. The communication link may be a wireless communication link or a wired link, for example a glass fibre or copper-wired link. An important advantage of a wireless communication is the absence of wires to be connected upon installation of the system, which simplifies, and thus speeds up, installation, improves the safety of the place where the system is applied, and reduces installation costs. The system may also comprise a data aggregator or concentrator device, for example connected to an interrogating device and arranged to collect and temporarily store measurement results, an RFID code or other information received for example via the interrogating device from the current sensing unit and/ or from the voltage sensing unit until these results have been transmitted to the central monitoring device, for example once a day or more or less often. The communication link may then also be configured to immediately transmit measurement results, for example in combination with an alarm signal, to the central monitoring device if they exceed predetermined values. The simultaneous knowledge of current, voltage, and power per electric power line, and for example per phase, is useful information allowing to monitor, supervise and control a multiple phase electric power distribution network in a pro-active manner. It allows for example to monitor the power quality, the direction of current in and out the network, power losses, or to show a possible surcharge on a transformer, and decisions can be based on this supervision before possible problems have occurred.
Another aspect of the invention provides a system according to the features of claim 11.
Particularly, according to an aspect, there is provided a system for monitoring electric power in a multiple phase electric power distribution network, for example a system configured to carry out a method according to the invention, the system comprising at least one electric power transmission line having a voltage sensing unit and a current sensing unit remote from said voltage sensing unit, wherein the system is characterized in that at least one of the voltage sensing unit and respective current sensing unit is configured to generate phase reference information concerning a sensed voltage and/or current respectively.
The system can provide one or more of the above-mentioned advantages.
According to a preferred embodiment, the unit that is configured to generate said phase reference information, is also configured to transmit that information to a remote processor, particularly a processor configured to determine a phase difference between a sensed current and associated voltage, the system preferably including a memory for storing said phase difference and/or the system preferably being configured to transmit said phase difference to a remote information receiver.
According to a preferred embodiment, the current sensing unit is integrated within the protective body of an electrical fuse.
According to a preferred embodiment, the current sensing unit comprises a sensor arranged to measure a voltage drop across a resistor, the resistor across which a voltage drop is measured preferably being a fusible element of the fuse, the resistor being configured to provide overcurrent protection.
According to a preferred embodiment, the voltage sensing unit is configured to generate voltage phase reference information concerning a sensed voltage, and to transmit the phase reference information to the current sensing unit, wherein the current sensing unit includes a processor configured to determine a phase of current detected by the current sensing unit, wherein the processor is configured to correlate or compare a determined phase of the current with a phase of a sensed voltage utilizing the voltage phase reference information.
It is also preferred that the system includes three electric power transmission lines corresponding to three different phases, wherein each of the three electric power transmission lines includes a voltage detection unit and associated current detection unit. Thus, all phases can be monitored.
Further, in an embodiment, the voltage sensing unit and/or the current sensing unit comprise a signal generator arranged to superpose a signal on said electric power transmission line, particularly a signal providing said phase reference information.
Said current sensing unit and/or said at least one voltage sensing unit may for example comprise phase reference information detection means arranged to detect said reference information. The skilled person will appreciate that such phase reference information detection means can be configured in various ways, e.g. in hardware and/or software, via a digital signal processor and/or differently.
Also, according to an embodiment, said voltage sensing unit can comprise a data memory arranged to store the voltage sensing unit’s measurements and/or phase voltage predetermined reference times, for example phase voltage zero crossing times.
Similarly, said current sensing unit may comprise a data memory arranged to store the current sensing unit’s measurements and/or current predetermined reference times, for example current zero crossing times.
According to a preferred embodiment, said voltage sensing unit comprises a control unit, for example a microcontroller or a microprocessor, configured to control a functioning of the voltage sensing unit.
Similarly, in a preferred embodiment said current sensing unit comprises a control unit, for example a microcontroller or a microprocessor, configured to control a functioning of the current sensing unit.
According to an embodiment, the voltage sensing unit is configured to transmit, for example upon interrogation by an interrogating device, a signal containing measurement results, or results derived therefrom, from the voltage sensing unit to an interrogating device, the voltage sensing unit preferably including a transmitter to transmit such information. The signal containing the measurement results may be a wireless signal.
Similarly, the current sensing unit can be configured to transmit, for example upon interrogation by an interrogating device, a (preferably wireless) signal containing measurement results, or results derived therefrom, from the current sensing unit to an interrogating device, the current sensing unit preferably including a transmitter to transmit such information.
The system can include a remote central monitoring device communicatively connected via a communication link to the at least one interrogating device, wherein the central monitoring device is arranged to store and process data received from the at least one interrogating device.
Further, the invention provides an electric power distribution network comprising at least one distribution transformer end station located near a customer’s premise and arranged to transform a relatively high transmission voltage, for example medium voltage, to a voltage adapted for household appliances, for example about 230V or about 115V, wherein the distribution transformer end station comprises a system according to the invention.
The network can provide one or more of the above-mentioned advantages.
Further advantageous embodiments are provided by the dependent claims.
The present invention will be further elucidated with reference to figures of exemplary embodiments. Therein, corresponding elements are designated with corresponding reference signs.
Figure 1A is a theoretical voltage-time diagram of a power line signal during operation;
Figure IB is a theoretical current-time diagram of a power line signal during operation;
Figure 2 shows a schematic representation of part of a system according to an aspect of the invention;
Figure 3a shows a schematic representation of a preferred embodiment of a current sensing unit of the system of Figure 2;
Figure 3b shows a schematic representation of an alternative embodiment of a current sensing unit of the system of Figure 2;
Figure 4 shows a preferred embodiment of an electrical fuse in perspective view;
Figure 5 shows a schematic representation of a second embodiment of a system according to the invention; and
Figure 6 shows a schematic representation of part of an electric power distribution network according to an aspect of the invention.
The present invention in particular concerns an AC (alternating current) multiple phase power distribution network, having respective power transmission lines. As is commonly known, the alternating current basically follows a sine wave form (having a predefined frequency, e.g. 50 or 60 Hz). Figure la shows the cyclic wave pattern of a power line voltage as a function of a time t, that can be measured for example by a voltage sensing unit 1 that is electrically connected to a respective power line L (three phase lines LI, L2, L3, usually being mutually out of phase over 120° as is known to the skilled person). Figure lb shows an associated cyclic wave pattern of respective current flowing through one of the power lines L as a function of a time t. This current can be measured for example by a current sensing unit 3 located on the same electric power transmission line L, spaced-apart from said voltage sensing unit 1 (see also e.g. Figure 2).
Referring to the drawings, it is proposed that at least one of a said voltage sensing unit 1 and respective current sensing unit 2 (see below) is configured to generate phase reference information concerning a sensed voltage and/or current respectively. For example, during operation, the voltage sensing unit 1 can detect a voltage on the electric power transmission line L, and the spaced-apart current sensing unit 2 can detect associated current flowing through said at least one electric power transmission line L. Then, it is preferred that at least one of the voltage sensing unit 1 and the current sensing unit 2 generate said phase reference information. Then it is preferred that the phase reference information is used (e.g. by a processor of one of the units 1, 2 or by a remote/other processor) to derive a phase difference between the phase of the voltage and associated current (of the same power line L).
The afore-mentioned phase-reference information can be or be provided by various types of information, as will be described below.
Figure 2 shows a schematic representation of an example of a system according to an aspect of the invention. The system can for example be part of, or installed in, a distribution transformer end station, configured to transform a relatively high transmission voltage, for example medium voltage, into a lower voltage, e.g. adapted for household appliances (for example about 115V or about 230V).
The present system includes an afore-mentioned voltage sensing unit 1 and respective current sensing unit 2.
The voltage sensing unit 1 can be configured in various ways. In the following example, the voltage sensing unit 1 is configured to generate phase reference information, and to transmit that information to the current sensing unit 2.
The voltage sensing unit 1 can comprise a voltage sensor 3, which can have access to a neutral (return) line N (or alternatively a grounded line) and to one of the phase lines/conductors LI, L2 or L3. The sensor 3 is preferably constructed in such a way that it can be installed easily and safely. It is preferred that the system comprises at least one voltage sensing unit 1 to detect a voltage of each of the electric power transmission lines corresponding to the three phases (Ll, L2, L3).
The voltage sensing unit 1 can comprise a data memory 9 arranged to store the voltage sensing unit’s measurements, and/or phase voltage predetermined reference times, for example phase voltage zero crossing times, and/or optionally to store also an identification code. It is preferred that the voltage sensing unit also includes a control unit, for example a microprocessor 11, configured to control a functioning of the voltage sensing unit 3. In that case, the data memory 9 is communicatively linked with a voltage sensor via the microprocessor 11. The control unit, for example the microcontroller or microprocessor, can for example control the voltage sensing unit’s measurements, the storage of measurement data, or for example interrogation by an interrogating device 13 (located e.g. remotely with respect to the sensing unit 1). A microprocessor can also derive other physical current properties from the voltage sensing unit’s measurements, for example mean voltage over a period of time, and/or other quantities. In this way, the entire processing, from the voltage measurement, until transmission of an answer, for example to an interrogation by the interrogating device 13, can be controlled.
In a non-limiting embodiment, a voltage measurement, for example with Vrms in the order of about 230 Volt (or about 115 Volt), can be transmitted, for example via a voltage divider, to the microprocessor 11 via an AD convertor. Optionally, an identification code of the voltage sensing unit 1 can be transmitted to the microprocessor 11. The voltage sensing unit 1 is preferably also configured to transmit, for example upon interrogation by the interrogating device 13, a wireless signal containing measurement results from the voltage sensing unit 1 to the interrogating device 13, the voltage sensing unit preferably including a transmitter or transceiver 14 to transmit such information. The transmitter or transceiver 14, which in this embodiment is operably connected with the microprocessor 9, can be configured to function in a receiving and in a transmitting modus. In a receiving modus, it can receive interrogation commands from the interrogating device 13. In a transmitting modus, the transmitter can transmit data via an antenna to the interrogating device 13, e.g. at an adaptive rate, depending on the transmission technology and the circumstances. Interrogation commands received by the transmitter or transceiver 14 can include types of measurements to be transmitted, for example instantaneous voltage measurements results, or for example mean voltage measurements over a given period of time. Alternatively, in a most basic embodiment, the transmitter 14 can be configured to operate in a “fire and forget” mode to transmit measurement results, optionally together with an identification code, to the interrogating device 13 without being interrogated by the device 13.
In an advantageous embodiment, the transmitter or transceiver 14 may include RFID (Radio Frequency Identification Device) transmission means, for example a sensor enabled RFID tag, and the interrogating device 13 may be configured to wirelessly interrogate the RFID transmission means of the voltage sensing unit 1. The sensor enabled RFID tag may be configured to operate in the passive mode, which does not need power supply and only transmits as an answer to an interrogating signal. The sensor enabled RFID tag may also be configured to operate in a semipassive or active mode requiring a power supply, which may for example be supplied by a 230 voltage (or 115 voltage) and an AD convertor or for example by a battery. The RFID tag may include the aforementioned identification code. Standardized RFID transmission technology means offer the possibility of continuous wireless transmission or communication between the voltage sensing unit 1 and the interrogating device 13 while needing less power than other standardized wireless technologies as for example ULE (Ultra Low Power DECT), Zigbee, Bluetooth, or wifi. Another alternative is SAW (Surface Acoustic Wave) technology, wherein the (analogue) transmitter does not need a power supply, but can only be read at very short distances. An additional advantage of RFID transmission technology means is the possibility to identify a unit equipped with an RFID tag.
It is preferred that the voltage sensing unit lgenerates phase reference information during operation, particularly concerning the phase of the voltage signal that is carried by the respective power transmission line L. To that aim, the voltage sensing unit 1 may for example comprise a signal generator 5 arranged to superpose or modulate a sync signal, for example a pseudo noise signal, on said electric power transmission line L.
Transmission of said phase reference information or respective reference signal, for example from the voltage sensing unit 1 to the current sensing unit 2, may start at a predetermined reference time of a phase voltage, for example at a positive zero-crossing of the amplitude of the voltage (time to in Fig la). The phase reference information may be a relatively short triggering or sync signal (e.g. a short burst, a pulse, a short pseudo noise signal), particularly having a signal length that is significantly shorter than the time period of the network operating frequency (i.e. significantly shorter than 20 ms for a 50 Hz network) , or differently.
The current sensing unit 2 includes a detecting means 8, for detecting the particular phase reference information signal transmitted by the voltage sensing unit 1. In Fig. lb, a time t2 indicates the time when the current sensing unit 2 detects a phase reference information/signal (transmitted by the respective voltage sensing unit 1). The current sensing unit 2 (e.g. its controller) can be configured to determine the phase difference between voltage and associated current, based on the received phase reference information, for example based on the time t2 of receiving that information (triggering) as well as a time ti concerning the phase of the current signal. As follows from Figure lb, for example, the latter time ti can be a positive zero-crossing of the amplitude of the current signal, and can be determined by a current sensing unit processor 12 utilizing current measurements made by that unit (and common signal processing).
For example, the current sensing unit 2 can be configured to detect/determine and store every zero-crossing time of the amplitude (or another predetermined phase point) of the (sine waveform) current signal. The current sensing unit 2 can be configured to compare a triggering time t2 of receiving the phase reference information with the array of stored current positive zero-crossing times, and select the time ti that is closest to time to, wherein to = t2 — x, with x being a timing offset (encompassing the time duration of the transmission of the phase reference information and a predetermined -e.g. stored- total processing delay required for detection). The difference between the selected time ti and the triggering time (time of voltage phase information detection) to, and using the timing offset x (which may be stored in a memory of the current sensing unit 2), leads to the true phase difference between voltage phase and current phase. This difference can be determined or computed for example by the processor of the current sensing unit 2, and taking into account the operating frequency of the electric power distribution network (e.g. 50 Hz or 60 Hz).
For example, and referring to Figures la, lb, phase reference information can be chosen to be a time to coinciding with a positive zerocrossing of a phase voltage. It is chosen as starting time of transmission of a sync signal, for example a pseudo noise sequence (PNS) signal. Naturally, another starting time can be selected, for example a time coinciding with a maximum of a phase voltage, with a minimum of a phase voltage, or with a negative zero-crossing of a phase voltage. Preferably, said predetermined reference time of a current and said predetermined reference time of a phase voltage coincide with a same type of event, for example with a positive zero-crossing of a current and of a phase voltage respectively.
During operation, the phase reference signal is transmitted, for example by superposition over said electric power transmission line, for example from the voltage sensing unit 1 to said current sensing unit 2. Reference information may also be chosen as a time coinciding with a positive zero-crossing of a current, with a negative zero-crossing of a current, with a maximum of a current, or with a minimum of a current. In that case, said signal is transmitted, for example by superposition over said electric power transmission line, from said current sensing unit to said voltage sensing unit. The voltage sensing unit 1 may determine and store times coinciding with a predetermined reference time of a phase voltage, for example with a maximum of a phase voltage, with a minimum of a phase voltage, with a positive zero-crossing of a phase voltage, or with a negative zero-crossing of a phase voltage. Said predetermined reference time of a phase voltage can then be derived from a sample of a predetermined number of said previous predetermined reference times of said phase voltage. Also the current sensing unit 2 can determine and store times coinciding with a predetermined reference time of a current, for example with a maximum of a current, with a minimum of a current, with a positive zero-crossing of a current, or with a negative zero-crossing of a current.
The determining of phase difference can be carried out by the current sensing unit 2, as described above, wherein that unit 2 can be configured to transmit a result of the phase difference determination to a remote receiver, for example an interrogation device 13 or remote server (via a suitable communication network, computer network, Internet or the-like). Alternatively, determining of phase difference can be carried out remotely from the current sensing unit 2, for example by a remote data processing unit that is configured to receive transmitted phase reference information as well as current sensing unit data (such as times coinciding with a predetermined reference time of a current), and t, and optionally a respective sensor timing offset x) to process received data to obtain the phase difference.
Also, alternatively, the voltage sensing unit can comprise a signal detection means (not shown), arranged to detect transmission of a phase reference information transmitted by the current sensing unit, whereas the current sensing unit can be configured to generate and transmit such information to the voltage sensing unit. In that case, the current sensing unit can trigger the remote voltage sensing unit to process respective phase point detection times and determine the difference between current and voltage phase (again, utilizing a predetermined timing offset concerning signal processing delays).
According to a highly preferred embodiment, the current sensing unit 2 may be integrated within the protective body of an electrical fuse (see Figures 3a, 3b, 4). The electrical fuse can for example be a blade type fuse, for example a standardized NH-type fuse, having a square or oblong body with blade-style terminals according to the IEC 60269 standard for low-voltage power fuses. NH-type fuses are commonly present in distribution transformer end stations, where a voltage is transformed from a transmission voltage, for example medium voltage, to a voltage adapted for household appliances, for example about 115 V or 230 V, or may also be present in main switch rooms of large buildings or industrial plants. Other fuse types, for example diazed or neozed types or other types, are also possible. NH-fuses have a larger current range than screw type fuses, up to for example 1.25 kA. For example, a standardized NH DIN 2 fuse has a current range of 125-400 A. Alternatively, the electric fuse can also be a standardized fuse according to the North-American UL 248 standard. The current sensing unit 2 can comprise a sensor 4 arranged to measure a voltage drop across a resistor R. The resistor R across which a voltage drop is measured, may be a fusible resistor of the fuse, which is the replaceable fuse link of the electric fuse, an element which is irreversibly blown if a current exceeds a given threshold current value, for example of, or more than, 250 A or another value. The fuse’s resistor R can for example have a resistance of the order of 0.3 ηιΩ. With a current in a range of for example 1-250 A, a voltage drop in the range of 0.3-75 mV can be measured. A voltage drop could also be measured across a second resistor put in series with a fuse’s resistor or differently.
Alternatively, the current sensing unit 2 may comprise an integrated Rogowski coil 20, e.g. arranged to detect current flowing through the respective electrical fuse. The current can then be derived from the voltage induced by the current’s magnetic field in the Rogowski coil, as this voltage is proportional to the rate of change of the current to be measured.
In another alternative, the current sensing unit 2 can be arranged to deduce a current measurement from a sensing of a current induced magnetic field, wherein the current sensing unit 2 may comprise for example a Hall effect sensor.
The current sensing unit 2 can also comprise a data memory 10 arranged to store the current sensing unit’s measurements, and/or current predetermined reference times, for example current positive or negative zero crossing times, or optionally to store also an identification code. It allows an interrogating device 13 to interrogate the current sensing unit 2 to receive the stored data, e.g. periodically, while it can still collect a complete set of measurements taken between two moments of interrogation.
It is preferred that the current sensing unit 2 also includes a control unit, for example a microprocessor 12, configured to control a functioning of the current sensing unit 2, such as determining said phase difference, as is described above.
The control unit, for example the microcontroller or microprocessor 12, can for example control the current sensing unit’s measurements, the storage of measurement data, and/or interrogation by the interrogating device 13. A microprocessor 12 can also derive other physical current properties from the current sensing unit’s measurements, for example mean current over a period of time, and/or other quantities, as for example a phase difference between voltage and current (see above). In this way, the entire processing, from the current measurement, for example via a voltage drop measurement, until transmission of an answer, for example to an interrogation by the interrogating device, can be controlled from within the protective body of the fuse. As shown in Figure 2, the data memory 10 can be communicatively linked with a current sensor 4 via the microprocessor 12. A current measurement, for example via a voltage measurement by the sensor 4, can be transmitted to the microprocessor 12 via an AD convertor. Also an identification code of the current sensing unit 2 can be transmitted to the microprocessor 12.
The current sensing unit 2 is preferably also configured to transmit, for example upon interrogation by the interrogating device 13, a (preferably wireless) signal containing measurement results from the current sensing unit 2 to the interrogating device 13. It is preferred that the current sensing unit 2 is configured to transmit a determined phase difference between detected voltage and associated detected current, to the interrogating device 13.
The current sensing unit preferably including a transmitter or transceiver 15 to transmit such information. The transmitter or transceiver 15, which in this embodiment is operably connected with the microprocessor 12, can be configured to function in a receiving and in a transmitting modus. In a receiving modus, it can receive interrogation commands from the interrogating device 13. In a transmitting modus, the transmitter can transmit data via an antenna to the interrogating device 13, e.g. at an adaptive rate, depending on the transmission technology and the circumstances. Interrogation commands received by the transmitter or transceiver 15 can include types of measurements to be transmitted, for example instantaneous current measurements results, or for example mean current measurements over a given period of time. Alternatively, in a most basic embodiment, the transmitter 15 can be configured to operate in a “fire and forget” mode to transmit measurement results, optionally together with an identification code, to the interrogating device 13 without being interrogated by the device 13.
In an advantageous embodiment, the transmitter or transceiver 15 may include RFID transmission means, for example a sensor enabled RFID tag, and the interrogating device 13 may be configured to wirelessly interrogate the RFID transmission means of the current sensing unit 2. The sensor enabled RFID tag may be configured to operate in the passive mode, which does not need power supply and only transmits as an answer to an interrogating signal. The sensor enabled RFID tag may also be configured to operate in a semi-passive or active mode requiring a power supply, for example a battery. The RFID tag may include the aforementioned identification code. Standardized RFID transmission technology means offer the possibility of continuous wireless transmission or communication between the current sensing unit and the interrogating device while needing less power than other standardized wireless technologies as for example ULE (Ultra Low Power DECT), Zigbee, Bluetooth, or wifi. Another alternative is SAW (Surface Acoustic Wave) technology, wherein the (analogue) transmitter does not need a power supply, but can only be read at very short distances. An additional advantage of RFID transmission technology means is the possibility to identify a unit equipped with an RFID tag.
In a preferred embodiment, the current sensing unit 2 may comprise an energy harvesting means, for example a coil, replacing a battery or a supercapacitor, arranged to provide the current sensing unit 2 with energy to operate. This is a more long-lasting solution than the integration of a battery as a power supply needing regular replacement, thus reducing the total cost of ownership of the system. At the same time, an energy harvesting means, for example a coil, takes little space. An energy harvesting coil can advantageously be installed near an inner side of the protective body of the fuse. The coil can make use of an induced magnetic field generated by, for example, a current in the fuse.
Alternatively, the voltage drop over the fuse’s resistor could, for example in combination with a transformer, be used to provide voltage to the current sensing unit.
Further, the current sensing unit 2 of the depicted embodiment comprises a signal detection means 8, arranged to detect said phase reference information (transmitted from the voltage sensing unit 1 via the transmission line L). For example, the information can be a starting time of transmission of a signal by the voltage sensing unit 1, for example of a pseudo noise signal.
During use, electric power distribution in a network -comprising the system as schematically illustrated in the Figures-, can be efficiently monitored so that possible problems in or near an end-user part of the network can be timely detected or prevented before they might occur. A current, voltage and power concerning each (low voltage) power transmission line L can be determined, for example at regular intervals. In one embodiment, current determinations from the current sensing unit 2, and voltage determinations from the respective voltage sensing unit 1, together with reference information to derive a phase difference between voltage and current, can be transmitted, for example together with an RFID code, to an interrogating device 13, where received data from the at least one voltage sensing unit and current sensing unit can be processed. Alternatively, the current sensing unit 2 can determine the phase difference, and transmit that phase difference to the interrogating device 13. Also, in another alternative embodiment, the voltage sensing unit 1 can determine the phase difference, and transmit that phase difference to the interrogating device 13.
Figure 3a shows a schematic representation of a preferred embodiment of the current sensing unit 2 of the system of Figure 2. In this case, the current sensing unit 2 is integrated within the protective body 19 of an electrical fuse 18. The at least one fuse is integrated in an electricity network via two connections B1 and B2, for example blade-type connections. A blade BI, B2 can e.g. be a rigid electrically conducting flange, extending outwardly on top of the housing (see Fig. 2). Other connection styles, like screw type connections are also possible. The at least one fuse can for example be found in a distribution transformer end station 16, where a transmission voltage, for example medium voltage, is transformed into a lower voltage, e.g. adapted for household appliances. A set of standard voltages for use in low and high voltage AC electricity supply means is determined by the International Standard IEC 60038. According to this standard, a voltage of 50-1000 Vrms is considered to be low voltage, 1-35 kVrms is a medium voltage, and above 35 kV, a voltage can be a high, extra high or ultra high voltage. The electrical fuse can for example be a blade type fuse (see Figure 4). The electric fuse comprises a fuse link, an element which is irreversibly blown if a current exceeds a given threshold current value, for example of, or more than, 250 A or another value. In the preferred embodiment of Figure 3a, the current sensing unit 2 comprises a Rogowski coil 20 wrapped around a fuse’s current conductor B. The current in the conductor B can then be obtained by integrating, for example by an electronic integrator 21, the voltage measured in the Rogowski coil which is induced by the encircled current’s magnetic field, as this voltage is proportional to the rate of change of the current to be measured. The electronic integrator 21 may also be comprised in a microprocessor 12 (Fig. 2). In the alternative embodiment of Figure 3b, the current sensing unit 2 comprises a sensor 5 arranged to measure a voltage drop across a resistor R. The resistor R across which a voltage drop is measured, may be a fusible resistor of the fuse, which is the replaceable fuse link of the electric fuse.
The fuse’s resistor R can for example have a resistance of the order of 0.3 ιηΩ. With a current in a range of for example 1-250 A, a voltage drop in the range of 0.3-75 mV can be measured. A voltage drop could also be measured across a second resistor put in series with a fuse’s resistor or differently.
Figure 4 shows a preferred embodiment of an electrical fuse 18 in perspective view. The electric fuse 18 in Figure 4 is a standardized NH-type fuse, having a square or oblong body with blade-style terminals BI, B2, according to the IEC 60269 standard for low-voltage power fuses. NH-fuses have a larger current range than screw type fuses, up to for example 1.25 kA. For example, a standardized NH DIN 2 fuse has a current range of 125-400 A. Alternatively, the electric fuse can also be a standardized fuse according to the North-American UL 248 standard. The fuse 18 includes a protective body 19, in this case a square or oblong body enclosing the fusible resistor R. The fuse can be integrated in an electricity network via two connections B1 and B2, which can be blade-style terminals varying in length according to the fuse size between for example 70-200 mm, or approximately 150 mm for the standardized NH DIN2 type fuse. Preferably, the protective body 19 can be made entirely of for example ceramics and/or another type of protective material, the ceramics or other protective material completely enclosing the current sensing unit 2. Alternatively, parts of the current sensing unit, for example an antenna or a chip, or, in the most extreme case, the whole current sensing unit, may be integrated in the protective housing itself, thus forming part of the protective body. A ceramic part of the protective body (if any) and an electronics part (sensor 4, data memory 10, control unit or microprocessor 12, transmitter 15) of a current sensing unit 2 in the protective body 19 together can then either be thicker than a standardized size of, for example, a NH DIN 2 type fuse, or, for example, a thickness of a protective body of the fuse may be adapted, i.e. made thinner, such that a ceramic part of the protective body (if any) and an electronics part of a current sensing unit in the protective body together can still comply with a standardized size of, for example, a NH DIN 2 type fuse.
Figure 5 shows a schematic representation of a second embodiment of a system according to the invention. The system further comprises a remote central monitoring device 14, e.g. a server, computer, computer system or the like, communicatively connected via a communication link 15 to at least one interrogating device 13, in this case to a plurality of interrogating devices 13. The communication link 15 may be a wireless communication link 15 or a wired link, for example a glass fibre or copper-wired link. Each of the plurality of interrogating devices 13 may be located in one of a plurality of distribution transforming end stations 16 of an electric power distribution network, in each of which can be installed a plurality of voltage sensing units 1 and current sensing units 2 and at least one interrogating device 13 per distribution transforming end station 16. In each distribution transforming end station 16 the communication between a voltage sensing unit 1 and/or a current sensing unit 2 on the one hand and the interrogating device 13 on the other can be effected via RFID communication as described above. Each interrogating device 13 can also be equipped with a modem 17 configured to communicate with the central monitoring device 14, which is arranged to store and process data received from the at least one interrogating device 13. This communication can for example be effected wirelessly, for example via Code Division Multiple Access (CDMA) communication, or otherwise. In each distribution transforming end station 16 the system may also comprise a data aggregator or concentrator device connected to the interrogating device 13 and arranged to collect and temporarily store measurement results received via the interrogating device 13 from the voltage sensing unit 1 or the current sensing unit 2 until these results have been transmitted to the central monitoring device 14, for example once a day or more or less often. The communication link 15 may then also be configured to immediately transmit measurement results, for example in combination with an alarm signal, to the central monitoring device 14 if they exceed predetermined values. In this way, pro-active network supervision and control, for example of the electric voltage, current, and/or power (e.g. a determined phase difference between voltage and respective current concerning one of the power lines L), and the status of a low voltage network at any moment, can be effected, thus providing useful information for the optimization of the network, for example a detection of a possible bottleneck in the network. Decisions based on this supervision can be taken before possible problems occur. This information can then be used to optimize the network in a proactive way, preventing problems rather than solving them when they occur.
Figure 6 shows a schematic representation of part of an electric power distribution network according to an aspect of the invention. The network, for example extending in a city or a country, may comprise a main electric power station P, from which electric power can be transported via high or medium voltage power transmission cables H to a plurality of distribution transforming end stations 16. These end stations 16 are preferably located near customers’ premises E and arranged to transform a voltage from a transmission voltage, for example high or medium voltage, to a voltage adapted for household appliances, for example a low voltage of circa 110, 220 or 230 V. The end stations 16 are connected to end users E via low voltage power transmission cables L, adapted for one- or three-phase LI, L2, L3 electric power transmission. Each of the plurality of distribution transforming end stations 16 can then equipped with a system according to the invention and/or as schematically shown in Figure 3. In case of three-phase electric power transmission, it can for example be very advantageous to install three voltage sensing units and three current sensing units per three-phase power distribution cable, one for each phase, so that voltage, current and power can be sensed per cable.
For a still more complete monitoring system, other sensing units or non-sensing assets, in a distribution transforming end station, for example an air temperature or humidity sensing unit, or an transformer’s oil temperature sensing unit, or a transformer, could also be equipped with an RFID tag, so as to complete the electric current monitoring system with relevant additional network information, for example the positioning and identification of every individual element within a network. The RFID tag can comprise a unique identification code. Preferably, that code is transmitted upon interrogation and, for example, processed centrally to identify every individual element within a network.
While specific embodiments have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described in the foregoing without departing from the scope of the claims set out below. Reference signs in the claims should not be construed as limitations of the claims. Also, it will be appreciated that various parts, units and/or features of embodiments described can be combined with various other parts, units and/or features of other embodiments described, in various ways. In this application, the term “phase angle difference” can be used instead of “phase difference” as will be clear to the skilled person.

Claims (28)

1. Werkwijze voor het monitoren van elektrisch vermogen in een multifase elektriciteitsdistributienetwerk, waarbij een spanningswaarnemingseenheid (1) een spanning detecteert op ten minste één elektrische vermogenstransmissielijn (L), en een apart geplaatste stroomwaarnemingseenheid (2) geassocieerde stroom detecteert die door genoemde ten minste ene elektrisch vermogenstransmissielijn (L) vloeit, daardoor gekenmerkt dat ten minste één van de spanningswaarnemingseenheid (1) en de stroomwaarnemingseenheid (2) fasereferentie-informatie genereert, waarbij de fasereferentie-informatie wordt gebruikt om een faseverschil tussen genoemde gedetecteerde spanning en geassocieerde gedetecteerde stroom af te leiden.A method for monitoring electric power in a multi-phase electricity distribution network, wherein a voltage sensing unit (1) detects a voltage on at least one electric power transmission line (L), and a separately located current sensing unit (2) detects current associated with said at least one electric power transmission line (L) flows, characterized in that at least one of the voltage sensing unit (1) and the current sensing unit (2) generates phase reference information, wherein the phase reference information is used to complete a phase difference between said detected voltage and associated detected current lead. 2. Werkwijze volgens conclusie 1, waarbij de fasereferentie-informatie naar een signaalprocessor wordt gezonden, bijvoorbeeld een processor van de stroomwaarnemingseenheid in het geval dat de fasereferentie-informatie is gegenereerd door de spanningswaarnemingseenheid of een processor van de spanningswaarnemingseenheid in het geval dat de fasereferentie-informatie is gegenereerd door de stroomwaarnemingseenheid, waarbij de transmissie bijvoorbeeld wordt uitgevoerd door superpositie of het moduleren van een signaal in de overeenkomstige vermogenstransmissielijn, in het bijzonder een triggering of sync signaal.The method of claim 1, wherein the phase reference information is sent to a signal processor, for example, a processor of the current sensing unit in the case that the phase reference information is generated by the voltage sensing unit or a processor of the voltage sensing unit in the case that the phase reference unit information is generated by the current sensing unit, the transmission being carried out, for example, by superposition or modulating a signal in the corresponding power transmission line, in particular a triggering or sync signal. 3. Werkwijze volgens conclusie 1 of 2, waarbij genoemde fasereferentie-informatie een starttijd is of betreft van transmissie van een signaal, bijvoorbeeld een pseudoruissignaal, op een voorafbepaalde referentietijd van een fasespanning of van een stroom, bijvoorbeeld een tijd die samenvalt met een maximum van een fasespanning of een stroom, met een minimum van een fasespanning of een stroom, met een positieve nuldoorgang van een fasespanning of een stroom, of met een negatieve nuldoorgang van een fasespanning of een stroom.Method according to claim 1 or 2, wherein said phase reference information is or relates to a start time of transmission of a signal, for example a pseudo-noise signal, at a predetermined reference time of a phase voltage or of a current, for example a time coinciding with a maximum of a phase voltage or a current, with a minimum of a phase voltage or a current, with a positive zero crossing of a phase voltage or a current, or with a negative zero crossing of a phase voltage or a current. 4. Werkwijze volgens conclusie 3, waarbij genoemde spanningswaarnemingseenheid tijden bepaalt en opslaat die samenvallen met een voorafbepaalde referentietijd van een fasespanning of een stroom, bijvoorbeeld met een maximum van een fasespanning of een stroom, met een minimum van een fasespanning of een stroom, met een positieve nuldoorgang van een fasespanning of een stroom, of met een negatieve nuldoorgang van een fasespanning of een stroom.The method of claim 3, wherein said voltage sensing unit determines and stores times that coincide with a predetermined reference time of a phase voltage or a current, for example with a maximum of a phase voltage or a current, with a minimum of a phase voltage or a current, with a positive zero crossing of a phase voltage or a current, or with a negative zero crossing of a phase voltage or a current. 5. Werkwijze volgens conclusie 3 of 4, waarbij genoemde voorafbepaalde referentietijd van een fasespanning of een stroom wordt afgeleid van een sample van een voorafbepaald aantal van genoemde vorige voorafbepaalde referentietijden van genoemde fasespanning of genoemde stroom.The method of claim 3 or 4, wherein said predetermined reference time of a phase voltage or a current is derived from a sample of a predetermined number of said previous predetermined reference times of said phase voltage or said current. 6. Werkwijze volgens één der voorgaande conclusies 3-5, waarbij genoemde stroomwaarnemingseenheid of genoemde spanningswaarnemingseenheid genoemde starttijd van transmissie van genoemd signaal bepaalt door een voorafbepaalde constante af te trekken van een signaaldetectietijd.The method of any one of the preceding claims 3-5, wherein said current sensing unit or said voltage sensing unit determines said start time of transmission of said signal by subtracting a predetermined constant from a signal detection time. 7. Werkwijze volgens één der voorgaande conclusies 3-6, waarbij genoemde voorafbepaalde referentietijd van een stroom en genoemde voorafbepaalde referentietijd van een fasespanning samenvallen met een zelfde type gebeurtenis, bijvoorbeeld met een positieve nuldoorgang van, respectievelijk, een stroom en van een fasespanning.A method according to any one of the preceding claims 3-6, wherein said predetermined reference time of a current and said predetermined reference time of a phase voltage coincide with the same type of event, for example with a positive zero crossing of, respectively, a current and of a phase voltage. 8. Werkwijze volgens één der voorgaande conclusies 6-7, waarbij een faseverschil tussen spanning en stroom wordt afgeleid van het kleinste verschil in absolute waarden tussen genoemde starttijd van transmissie van genoemd signaal en één van genoemde opgeslagen tijden die samenvallen met een voorafbepaalde referentietijd van een stroom of een spanning.A method according to any one of the preceding claims 6-7, wherein a phase difference between voltage and current is derived from the smallest difference in absolute values between said start time of transmission of said signal and one of said stored times coinciding with a predetermined reference time of a current or voltage. 9. Werkwijze volgens één der voorgaande conclusies, waarbij de stroomwaarnemingseenheid is geïntegreerd in een beschermend lichaam van een elektrische zekering, bijvoorbeeld een zekering die is geïnstalleerd in een distributietransformator eindstation, waarbij de stroomwaarnemingseenheid bijvoorbeeld een stroom bepaalt via een spanningsvalmeting over een smeltbare weerstand in de elektrische zekering, waarbij de weerstand bij voorkeur is ingericht om bescherming tegen overstroom te verschaffen.A method according to any one of the preceding claims, wherein the current sensing unit is integrated into a protective body of an electrical fuse, for example a fuse installed in a distribution transformer terminal, the current sensing unit determining, for example, a current via a voltage drop measurement over a fusible resistor in the electrical fuse, the resistor being preferably arranged to provide protection against overcurrent. 10. Werkwijze volgens één der voorgaande conclusies, die de stappen omvat van: - het doorsturen van meetresultaten, of daarvan afgeleide resultaten, bijvoorbeeld bij ondervraging door een ondervragingsinrichting, naar een centrale monitorinrichting, die communicatief is verbonden via een communicatielink met een ondervragingsinrichting of met genoemde spanningswaarnemingseenheid en/of genoemde stroomwaarnemingseenheid; - het verwerken van de ontvangen data van de ten minste ene spanningswaarnemingseenheid en/of genoemde stroomwaarnemingseenheid.Method as claimed in any of the foregoing claims, comprising the steps of: - transmitting measurement results, or results derived therefrom, for example when interrogated by an interrogator, to a central monitoring device, which is communicatively connected via a communication link to an interrogator or with said voltage sensing unit and / or said current sensing unit; - processing the received data from the at least one voltage sensing unit and / or said current sensing unit. 11. Systeem voor het monitoren van elektrisch vermogen in een multifase elektriciteitsdistributienetwerk, bijvoorbeeld een systeem ingericht om een werkwijze uit te voeren volgens één der voorgaande conclusies 1-10, waarbij het systeem ten minste één elektrische vermogenstransmissielijn (L) omvat met een spanningswaarnemingseenheid (1) en een stroomwaarnemingseenheid (2) op afstand van genoemde spanningswaarnemingseenheid (1), daardoor gekenmerkt dat ten minste één van de spanningswaarnemingseenheid (1) en de overeenkomstige stroomwaarnemingseenheid (2) is geconfigureerd om fasereferentie-informatie te genereren met betrekking tot een waargenomen spanning en/of stroom, respectievelijk.A system for monitoring electrical power in a multi-phase electricity distribution network, for example a system adapted to perform a method according to any one of the preceding claims 1-10, wherein the system comprises at least one electrical power transmission line (L) with a voltage sensing unit (1) ) and a current sensing unit (2) remote from said voltage sensing unit (1), characterized in that at least one of the voltage sensing unit (1) and the corresponding current sensing unit (2) is configured to generate phase reference information with respect to a sensed voltage and / or power, respectively. 12. Systeem volgens conclusie 11, waarbij de eenheid die is ingericht om genoemde fasereferentie-informatie te genereren, ook is ingericht om die informatie naar een op afstand gelegen processor te zenden, in het bijzonder een processor die is ingericht om een faseverschil te bepalen tussen een waargenomen stroom en geassocieerde spanning, waarbij het systeem bij voorkeur een geheugen omvat om genoemd faseverschil op te slaan en/of het systeem bij voorkeur is ingericht om genoemd faseverschil naar een op afstand gelegen informatie-ontvanger te zenden.The system of claim 11, wherein the unit adapted to generate said phase reference information is also adapted to send that information to a remote processor, in particular a processor configured to determine a phase difference between a sensed current and associated voltage, the system preferably comprising a memory to store said phase difference and / or the system is preferably adapted to send said phase difference to a remote information receiver. 13. Systeem volgens conclusie 11 of 12, waarbij de stroomwaarnemingseenheid is geïntegreerd in een beschermend lichaam van een elektrische zekering.A system according to claim 11 or 12, wherein the current sensing unit is integrated into a protective body of an electrical fuse. 14. Systeem volgens conclusie 13, waarbij de stroomwaarnemingseenheid een Rogowski spoel (20) omvat, of een sensor (4) omvat ingericht om een spanningsval te meten over een weerstand, welke weerstand waarover een spanningsval wordt gemeten bij voorkeur een smeltbaar element van de zekering is.A system according to claim 13, wherein the current sensing unit comprises a Rogowski coil (20), or a sensor (4) adapted to measure a voltage drop across a resistor, which resistor over which a voltage drop is measured, preferably a fusible element of the fuse is. 15. Systeem volgens één der voorgaande conclusies 11-14, waarbij de spanningswaarnemingseenheid (1) is ingericht om spanningsfasereferentie-informatie te genereren met betrekking tot een waargenomen spanning, en om de fasereferentie-informatie naar de stroomwaarnemingseenheid (2) te zenden, waarbij de stroomwaarnemingseenheid (2) een processor omvat die is ingericht om een fase te bepalen van door de stroomwaarnemingseenheid (2) waargenomen stroom, waarbij de processor is ingericht om een bepaalde fase van de stroom te correleren of te vergelijken met een fase van een waargenomen spanning door gebruikmaking van de spanningsfasereferentie-informatie.The system of any one of the preceding claims 11-14, wherein the voltage sensing unit (1) is adapted to generate voltage phase reference information with respect to a sensed voltage, and to send the phase reference information to the current sensing unit (2), the current sensing unit (2) comprises a processor adapted to determine a phase of current sensed by the current sensing unit (2), the processor being adapted to correlate or compare a certain phase of the current with a phase of a sensed voltage by using the voltage phase reference information. 16. Systeem volgens één der voorgaande conclusies 11-15, omvattende drie elektrische vermogenstransmissielijnen corresponderend met drie verschillende fases, waarbij elk van de drie elektrische vermogenstransmissielijnen een spanningswaarnemingseenheid (1) en geassocieerde stroomwaarnemingseenheid (2) omvat.A system according to any one of the preceding claims 11-15, comprising three electrical power transmission lines corresponding to three different phases, wherein each of the three electrical power transmission lines comprises a voltage sensing unit (1) and associated current sensing unit (2). 17. Systeem volgens één der voorgaande conclusies 11-16,waarbij de spanningswaarnemingseenheid en/of de stroomwaarnemingseenheid een signaalgenerator (5, 6) omvatten die is ingericht om een signaal bovenop genoemde elektrische vermogenstransmissielijn te zetten, in het bijzonder een signaal dat genoemde fasereferentie-informatie verschaft.A system according to any one of the preceding claims 11-16, wherein the voltage sensing unit and / or the current sensing unit comprise a signal generator (5, 6) which is arranged to place a signal on top of said electrical power transmission line, in particular a signal that said phase reference information provided. 18. Systeem volgens één der voorgaande conclusies 11-17,waarbij genoemde stroomwaarnemingseenheid en/of genoemde ten minste ene spanningswaarnemingseenheid detectiemiddelen (7, 8) van fasereferentie-informatie omvatten die zijn ingericht om genoemde referentie-informatie te detecteren.A system according to any one of the preceding claims 11-17, wherein said current sensing unit and / or said at least one voltage sensing unit comprises detection means (7, 8) of phase reference information which are arranged to detect said reference information. 19. Systeem volgens één der voorgaande conclusies 11-18,waarbij genoemde spanningswaarnemingseenheid een datageheugen (9) omvat ingericht om de spanningswaarnemingseenheids metingen op te slaan en/of voorafbepaalde fasespanningsreferentietijden, bijvoorbeeld fasespanningsnuldoorgangstijden.A system according to any one of the preceding claims 11-18, wherein said voltage sensing unit comprises a data memory (9) adapted to store the voltage sensing unit measurements and / or predetermined phase voltage reference times, for example phase voltage zero transit times. 20. Systeem volgens één der voorgaande conclusies 11-19,waarbij genoemde stroomwaarnemingseenheid een datageheugen (10) omvat ingericht om de metingen van de stroomwaarnemingseenheid en/of voorafbepaalde stroomreferentietijden, bijvoorbeeld stroomnuldoorgangstijden, op te slaan.A system according to any one of the preceding claims 11-19, wherein said current sensing unit comprises a data memory (10) adapted to store the measurements of the current sensing unit and / or predetermined current reference times, for example current zero transit times. 21. Systeem volgens één der voorgaande conclusies 11-20, waarbij genoemde spanningswaarnemingseenheid een besturings-eenheid (11) omvat, bijvoorbeeld een microcontroller of een microprocessor, ingericht om een functioneren van de spanningswaarnemingseenheid te besturen.A system according to any one of the preceding claims 11-20, wherein said voltage sensing unit comprises a control unit (11), for example a microcontroller or a microprocessor, adapted to control a functioning of the voltage sensing unit. 22. Systeem volgens één der voorgaande conclusies 11-21,waarbij genoemde stroomwaarnemingseenheid een besturings -eenheid (12) omvat, bijvoorbeeld een microcontroller of een microprocessor, ingericht om een functioneren van de stroomwaarnemingseenheid te besturen.A system according to any one of the preceding claims 11-21, wherein said current sensing unit comprises a control unit (12), for example a microcontroller or a microprocessor, adapted to control a functioning of the current sensing unit. 23. Systeem volgens één der voorgaande conclusies 11-22,waarbij de spanningswaarnemingseenheid is ingericht om, bijvoorbeeld bij ondervraging door een ondervragingsinrichting (13), een signaal te zenden dat meetresultaten omvat, of daarvan afgeleide resultaten, van de spanningswaarnemingseenheid naar een ondervragingsinrichting, waarbij de spanningswaarnemingseenheid bij voorkeur een zender (14) omvat om zulke informatie te zenden.A system according to any one of the preceding claims 11-22, wherein the voltage sensing unit is adapted to, for example when interrogated by an interrogator (13), send a signal comprising measurement results, or results derived therefrom, from the voltage sensing unit to an interrogator, the voltage sensing unit preferably comprises a transmitter (14) for transmitting such information. 24. Systeem volgens één der voorgaande conclusies 11-23,waarbij de stroomwaarnemingseenheid is ingericht om, bijvoorbeeld bij ondervraging door een ondervragingsinrichting (13), een signaal te zenden dat meetresultaten omvat, of daarvan afgeleide resultaten, van de stroomwaarnemingseenheid naar een ondervragingsinrichting, waarbij de stroomwaarnemingseenheid bij voorkeur een zender (15) omvat om zulke informatie te zenden.A system according to any one of the preceding claims 11-23, wherein the current sensing unit is adapted to, for example when interrogated by an interrogator (13), send a signal comprising measurement results, or results derived therefrom, from the current sensing unit to an interrogator, the current sensing unit preferably comprises a transmitter (15) for transmitting such information. 25. Systeem volgens één der voorgaande conclusies 11-24,waarbij de spanningswaarnemingseenheid RFID zendmiddelen omvat, bijvoorbeeld een sensor-ingeschakeld RFID label, en waarbij de ondervragingsinrichting is ingericht om de RFID zendmiddelen van de spanningswaarnemingseenheid draadloos te ondervragen.25. System as claimed in any of the foregoing claims 11-24, wherein the voltage sensing unit comprises RFID transmitting means, for example a sensor-enabled RFID label, and wherein the interrogating device is adapted to wirelessly interrogate the RFID transmitting means of the voltage sensing unit. 26. Systeem volgens één der voorgaande conclusies 11-25,waarbij de stroomwaarnemingseenheid RFID zendmiddelen omvat, bijvoorbeeld een sensor-ingeschakeld RFID label, en waarbij de ondervragingsinrichting is ingericht om de RFID zendmiddelen van de stroomwaarnemingseenheid draadloos te ondervragen.26. System as claimed in any of the foregoing claims 11-25, wherein the current sensing unit comprises RFID transmitting means, for example a sensor-enabled RFID label, and wherein the interrogator is adapted to wirelessly interrogate the RFID transmitting means of the current sensing unit. 27. Systeem volgens één der voorgaande conclusies 11-26, verder omvattende een op afstand gelegen centrale monitorinrichting die communicatief is verbonden via een communicatielink met de ten minste ene ondervragingseenheid, waarbij de centrale monitorinrichting is ingericht om van de ten minste ene ondervragingsinrichting ontvangen data op te slaan en te verwerken.A system according to any of the preceding claims 11-26, further comprising a remote central monitoring device that is communicatively connected via a communication link to the at least one interrogation unit, the central monitoring device being adapted to receive data received from the at least one interrogation device to store and process. 28. Elektriciteitsdistributienetwerk dat ten minste één distributietransformator eindstation omvat in de buurt van een pand van een klant en ingericht om een relatief hoge transmissiespanning, bijvoorbeeld middenspanning, te transformeren naar een voor huishoudelijke toestellen aangepaste spanning, bijvoorbeeld rond 230V of rond 115V, waarbij het distributietransformator eindstation een systeem omvat volgens één der voorgaande conclusies 11-27.An electricity distribution network comprising at least one distribution transformer terminal near a customer's premises and adapted to transform a relatively high transmission voltage, for example medium voltage, to a voltage adapted for household appliances, for example around 230V or around 115V, the distribution transformer terminal comprises a system according to any one of the preceding claims 11-27.
NL2016237A 2016-02-08 2016-02-08 Method and system for monitoring electric power in a multiple phase power distribution network. NL2016237B1 (en)

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