WO2019139540A1

WO2019139540A1 - Improved electrical sub-metering system

Info

Publication number: WO2019139540A1
Application number: PCT/SG2019/050019
Authority: WO
Inventors: Aimin Wang
Original assignee: Sp Innovation Pte. Ltd.
Priority date: 2018-01-12
Filing date: 2019-01-14
Publication date: 2019-07-18
Also published as: SG11202006306RA; PH12020551065A1; CN111971566A

Abstract

An electric sub metering system for measuring and communicating power quality data, the system comprising: a plurality of metering node units, each comprising a metering node; at least one low voltage way electrically coupled to each of the plurality of metering nodes; wherein the plurality of metering node units are connected together in a linear series, commencing with a principal metering node unit.

Description

Improved Electrical Sub-Metering System

Field of the Invention

The invention relates to an electrical sub metering system directed to residential, commercial and industrial applications. In particular, the invention has applicability to single and 3 phase power systems requiring real time electric energy & power quality data and control.

Background

Sub-metering in order to manage and control networks typically require the use of individual arrangement for each low voltage way (LVW). To accommodate large numbers of low voltage ways, for complex networks in single-phase applications, will therefore involve substantial cabling, with the metering data processing at a centralized box. When applied to 3-phase networks, the infrastructure required is considerable.

Further, a centralized box will typically be configured to have a fixed LVW capacity. It follows that, in avoiding too small capacity, causes waste to customer when they purchase extra LVW capacity that is not used.

Summary of Invention

In a first aspect, the invention provides an electric sub metering system for measuring and communicating power quality data, the system comprising: a plurality of metering node units, each comprising a metering node; at least one low voltage way electrically coupled to each of the plurality of metering nodes; wherein the plurality of metering node units are connected together in a linear series, commencing with a principal metering node unit.

In a second aspect, the invention provides an electric sub metering system for measuring and communicating power quality data, the system comprising: a plurality of metering node units; each metering node units including metering node to which is connected a plurality of integration modules; each integration module having an array of current measurement devices coupled thereto; wherein the plurality of metering node units are connected together in a linear series.

The invention seeks to provide a cost-effective, scalable, low power, small form factor Power Quality (PQ) metering front-end system. Whilst it may be applicable to single phase applications, it may also suit 3-phase Low Voltage (LV) networks at grid edges such as distribution Boards (LVB) or Over Ground Box (OGB) pillars that commonly share the same busbar voltage with multiple feeders.

The invention may be suitable for low carbon technologies such as electric vehicles, heat-pumps, photovoltaic and energy storage systems, or micro-CHP. In general, by wiring a plurality of metering node units together in a daisy chain, commencing with a principal metering node unit, the system of the present invention reduces the volume of cabling required and occupies less space in the low voltage distribution board. Hence, the time required for carrying out maintenance work may be reduced.

In addition, the system of the present invention may enable the sharing of a single set of metering system power and synchronized-clock source, data concentration and take-out communication per low voltage distribution board or box. Further, the system may allow users to add additional low voltage ways by connecting one or more additional metering node units together in the daisy chain. This ultimately allows the users to customize the number of metering node units and low voltage ways required based on their design requirements. It will be appreciated that by using the term“low voltage way”, it may mean one set of feeder or power source conductors. For example, in a single-phase system the low voltage way has one conductor, however in a three-phase system it has four conductors.

In one embodiment, the sub metering processing such as voltage and current digitalization, power parameter calculation and signal processing may occur adjacent to the source of current sensing signal. The sub metering processing may therefore occur within 0.5 m in a distributed form.

In a further embodiment, a smart data concentrator gateway arranged to feed a lowered voltage signal in a differential signal form to the plurality of metering nodes may be provided. Such an arrangement may ensure a means of accurate time-sync mechanism between the smart data concentrator gateway and the metering nodes with zero crossing detection. Hence, with the presence of both real-time lowered voltage signal and the current sensing analogue signal at the metering nodes, the real-time metering processing may be distributed at every current sensing node in a synchronized way.

In addition, the present invention also mitigates and/or solves the problem of high signal loss and/or distortion caused by bringing in current sensing data from a distance.

Further, the system may allow integration of enhanced distributed intelligence into the low voltage distribution board. In particular, the smart data concentrator gateway may be pre-loaded with a distributed intelligence application so as to conduct real time analysis of the status of the low voltage distribution board, such as the power integrity analysis. Hence, by working together with the metering nodes, the smart data concentrator gateway can accurately monitor the performance of all low voltage ways. For example, the smart data concentrator gateway may detect, record and report any anomaly in real-time.

In addition, this also reduces the computational work of the backend server, while also increases the responsiveness of the grid operator. Brief Description of Drawings

It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

Figure 1A is a schematic view of a sub-metering system for a single-phase circuit according to one embodiment of the present invention, and;

Figure 1A is a schematic view

Figure 2A is a schematic view of a sub-metering system for a three-phase circuit according to a further embodiment of the present invention. Figure 2B is a schematic view

Figures 3A to 3F are a schematic views, and

Figure 4 is a schematic view of a metering node unit according to a further embodiment of the present invention.

Detailed Description

Figure 1A shows an LVDB Sub Metering System Illustration for single phase 10 according to one embodiment of the present invention. The system 10 connects to a headend data concentrated unit (HDCU) 72 that may receive data from one or more of said systems 10. The HDCU or data concentrator gateway 72 is connected via a power line (NLE) to a wall socket plug and wirelessly transmitted via wifi.. In a residential building, the data concentrator gateway may be installed in an enclosed Distribution Box (DB) that is enclosed in a metal cabinet that prevents wireless communications out of the DB box. The power line communications provides a hard- wired solution to overcome the limitation of a compromised wifi signal.

The electrical sub metering system 10, comprises a plurality of metering node units 40, 60 which are connected 65 to form a daisy chain of said nodes. Each metering node unit 40, 60, 62 which comprises a metering node or power quality node (PQN) 45 for receiving data from a plurality of current measurement devices 55, and communicating data to the metering node 45. In this case, the current measurement devices are

Rogowsky coils 55 arranged to engage with conductors (not shown) for s single phase circuit.. It will be appreciated that the current measurement devices may be any one of a number of known current measurement devices, which are capable of transmitting data to the metering node 45. Thus, each metering node 45 will receive multiple current channels associated with multiple of devices.

As mentioned, each of the units 40, 60, 62 receives data corresponding to low voltage way (LVW) which may include feeder or power source conductors such as a single conductor for a single phase system or four conductors for a three phase system. The units are arranged in data communication, through a communication bus 65, forming a daisy chain of units connected to a local data concentrated unit (LDCU) 15. Figure 1B shows one embodiment of the metering node connection bus for single phase, where“a” is a stepped down bus bar voltage analogue signal.

The principal metering node unit 40 is connected directly to the smart data concentrator gateway, which may include a local data concentrated unit (LDCU) 15 for receiving the individual data, and subsequently for communicate 20 to external sources 25.

The LDCU 15 may be further connected to a GPS (not shown) for retrieving time data and syncing the time across the entire system. To this end, the LDCU 15 will return the time data to each node to couple with the data received from each of said nodes. Figure 2A shows an LVDB Sub Metering System Illustration for 3 phase 80 according to the present invention, adapted for use with a three-phase circuit.

Here, a series of metering node units 85, 90, 95 are connected through a communication 100 with each in a daisy chain arrangement. Figure 2B shows one embodiment of the metering node connection bus for three phase, where“a”,”b” and”c” are stepped down bus bar voltage analogue signals. As with the embodiment of Figure 1A, each metering node unit 85, 90, 95 comprises a metering node 110 connected to a plurality of current measurement devices 120A to 120D. In this embodiment, the current measurement devices are Rogowski coils, which engaged with each of the four conductors 115A to 115D of the three-phase circuit. The Rogowski coils 120A to 120D measure current in the conventional manner and the data is communicated through the metering node 110 along the respective channels. A principal metering node unit 85 then communicates the cumulative data directly to the LDCU 130. The LDCU 130 subsequently communicates 135 the data to an external receiver

A further advantage of the sub metering system according to the present invention, being connected in series, is the convenience of having a single power supply to power the system. Here the terminal metering node 110 is connected to a power source 155, 160, 165 that supplies the remaining metering node units 85, 90. In an alternative arrangement, the LDCU 130 may be connected to a power source in order to supply the system.

Implementation of one embodiment of the present invention may include:

a. A low end Digital Signal Processor (DSP) at the core of the distributed metering node signal digitization and processing module that supports up to four (4) voltage channels and twelve (12) current channels with PQ standard based on IEC 61000-4-30 Class A; b. An Application Adaptation Board (AAB) that connects the DSP module for a specific product or application; c. In a further embodiment, the Rogowski coils may connect indirectly to the metering node through a Rogowski-coil Integration Module, being a multi channel Rogowski coil current sensor integrator The RIM has the dual role of being a junction box of the Rogowski coil sensors, as well as an integrator to provide the scalability and plug and play capability; d. The units comprising the metering nodes can be daisy chained, with a principal unit at the head of the daisy chain, in direct communication with the LDCU. The metering node units may be installed at feeder termination near the source of current signal. Every metering node may have a specific maximum current sensor fanout number, such as six channels according to the embodiment of Figure 1A or 12 channels according to the embodiment of Figure 2A. Figures 3A to 3F show a range of possible fanout embodiments for the metering node units. Whereby the various embodiments include three phase connections 170 and/or single phase 175 connections in communication with a metering node 180. The various embodiments include a dedicated single phase arrangement (Figure 3F), dedicated three phase arrangements (Figure 3A to 3C) and mixed application (Figures 3D & 3E);

e. Further, it may include the DSP and AAB in a miniaturized enclosure to be installed at the feeder power cable termination. The system may be scalable with savings received through less wiring number/total wiring running length, cutting financial cost in over capacity and installation cost. For instance, one (1) metering node may measure a feeder and its immediate adjacent left or right two (2) feeders; f. A smart data concentrator gateway in the form of a Local Data Concentrator Unit (LDCU) that identifies, configures and manages its cluster of metering node chain. The LDCU may virtualize the whole dynamic cluster as a single “physical” meter and provide an open reading and reporting interface to meter headend system that connects to backend. The LDCU provides attenuated and isolated analogue voltage signal, power and time sync to all metering nodes. It provides power to the metering node chain and optionally to the HDCU as well. It divides the busbar phase-neutral voltage to analogue voltage signals that are shared by all metering node via the daisy chain cable for PQ parameter data acquisition and processing. This way, it may avoid the need to connect every metering node directly to a busbar or feeder voltage. On the other hand, since the voltage signal is analogue, so it is real time compared to digital voltage signal (digital network packet delay uncertainty); The Power Quality Edge Sensing contains a plurality of metering node units integrated with RIM’s with FRC, LDCU and Daisy Chain Cable (DCC). In one embodiment, the system according to the present invention may provide scalability from one (1) feeder to twelve (12) feeders that share the same busbar voltage. The overall sizing may also be designed to fit into the OGB and LVB grid edge assets. The LDCU manages the virtualization of the edge PQ meter system, records the PQ parameter, event, waveform and system logging into local non-volatile memory and presents a unified, open interface to backend (headend) system as if it is a single giant multiple feeder/multiple channel PQ meter serves the grid edge.

Figure 4 shows a further embodiment of a metering node unit 190. In this embodiment, the metering node unit includes a metering node 195, from which project a plurality of current sensor fanout connections 200, in this case four current sensor fanout connections. How the current sensor fanout connections of Figure 4 vary from those of other embodiments is the use of a Rogowsky Integration Module (RIM) 210 intermediate the Rogowsky coils 205 and the metering node 195. The RIM 210 senses the various inut signals from the coils 205 for communicating these to the metering node 195. The RIM therefore acts to configure the arrangement, and particularly configure the use of the coils 205 for the application in question, allowing for easier adaptation to the sub metering system.

Claims

1. An electric sub metering system for measuring and communicating power

quality data, the system comprising: a plurality of metering node units, each comprising a metering node; at least one low voltage way electrically coupled to each of the plurality of metering nodes; wherein the plurality of metering node units are connected together in a linear series, commencing with a principal metering node unit.

2. The electric sub metering system according to claim 1, wherein the plurality of metering node units are arranged to act as both a current sensor fanout connection node and a metering processing node.

3. The electric sub metering system according to claim 2, wherein each of the plurality of metering node units supports more than one low voltage way current sensor fanout.

4. The electric sub metering system according to claim 2 or 3, wherein the low voltage way current sensor fanout includes at least one Rogowsky coils for the measurement of current.

5. The electric sub metering system according to claim 4, wherein the at least one Rogowsky coils are in data communication with a Rogowsky Integration Module, said Rogowsky Integration Module in data communication with said metering node.

6. The electric sub metering system according to any one of claims 1 to 5, further comprising a smart data concentrator gateway in data communication with the principal metering node unit, said smart data concentrator gateway arranged to feed a lowered voltage signal in a differential signal form to the plurality of metering node units.

7. The electric sub metering system according to claim 6, wherein the smart data concentrator gateway is arranged to receive data with having a time stamp from the plurality of metering node units.

8. An electric sub metering system for measuring and communicating power quality data, the system comprising: a plurality of metering node units; each metering node units including metering node to which is connected a plurality of integration modules; each integration module having an array of current measurement devices coupled thereto; wherein the plurality of metering node units are connected together in a linear series.

9. The electric sub metering system according to claim 8, wherein the array of current measurement devices includes between one and four current measurement devices.

10. The electric sub metering system according to claim 8 or 9, wherein the current measurement devices are arranged to measure current of low voltage way.

11. A power quality edge sensing system, the system comprising:

a headend data concentrated unit, said headend data concentrated unit in data communication with a plurality of smart data concentrator gateways; each of said smart data concentrator gateway in data communication with an electric sub metering system according to any one of claims 1 to 3 and 8 to 10.