Installation of an electricity metering system ASKUE in SNT

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In business associations and SNT, payment for electricity is made according to a single meter, while consumer metering units are not inspected, which makes it possible to steal electricity. The problem is solved by the organization of automatic control over the consumption of energy resources (ASKUE).

Installation of an electricity metering system ASKUE in SNT

ASKUE: what it is and how it works

The abbreviation ASKUE stands for an automated control and accounting system for energy resources. In fact, it is a distributed complex consisting of metering devices that transmit information about the operation of the system to a single dispatch center. At first glance, everything looks quite simple, but in reality, the operation of the system is provided by serious technical means. Because of this, the organization of ASKUE by people far from electrical engineering and information technology causes numerous difficulties..

An example of an ASKUE scheme: 1 – computer with software; 2 – electricity meter with RS-232 / RS-485 interface; 3 – PS-USB adapter; 4 – hub; 5 – RS-485 to Ethernet interface converter; 6 – GSM gateway; 7 – GSM modem

The unified metering system does not just collect data on energy consumption, it has a number of specific functions. First of all, it is work in real time: meter readings are transmitted several times per hour, due to which it is possible to build consumption diagrams and more efficiently use energy resources, optimize the operation of the entire power grid.

In addition, ASKUE conducts its work with a high degree of transparency. All information is stored in a single database, access to which is open to all users. Even more: the system allows you to remotely not only account, but also control power grid nodes. This, in particular, allows you to disconnect consumers in case of late payment or exceeding the consumption limit, and in a fully automatic mode..

Dispatch center of the ASKUE systemDispatch center of the ASKUE system

What are the alternatives

When it comes to horticultural associations and similar business associations, the introduction of a distributed metering system is the only way to truly distribute electricity bills fairly among consumers. The question arises: why organize AMR, if you can be content with transferring metering units from the direct access zone of consumers? After all, in terms of costs, both events are approximately comparable.

The first and main problem is the lack of an organized system for inspecting metering units. It is necessary to look for means of sealing, regularly conduct rounds with checks of the status of the installation boxes and take meter readings. And even then, the possibility of electricity theft is not completely ruled out..

Street electricity meters

When using ASKUE, there are no loopholes for unaccounted consumption. Any meter in the network will almost instantly notify the dispatch center about changes in the connection diagram. In addition, constant monitoring of the network parameters will make it possible to assess the natural parasitic losses during transportation, which ultimately will introduce each kilowatt under strict reporting..

Selection and installation of metering devices

For work within the framework of ASKUE, electronic meters are used that convert the current and voltage acting in the primary circuit into a sequence of pulses, the calculation of which determines the current consumption of electricity. However, not every electronic meter has the required set of functions, in particular, it is important to have a digital port (telemetry output) for connecting to data transmission devices.

Electronic electricity meter with RS-485 interfaceAn example of a meter with an optical port and RS-485 interface

Another nuance lies in the counter functionality. If requirements for remote control are imposed on ASKUE, the meter must be equipped with a built-in contactor. The function of parameterizing the device is also important for setting up interaction with other elements of the system. The latter depends on the software embedded in the controller and the capabilities of it.

In the simplest case, it can be practiced to retrofit meters with special sensors that read the number of pulses from a light indicator or monitor the frequency of rotation of the disk of induction meters. However, this approach is not very good from the point of view of unifying the system; moreover, the sensors do not allow remote control of energy consumption. For a cooperative organization ASKUE, the best option is the purchase of the same type of meters with the necessary set of functions..

Multifunctional electricity meter with communication interfaces: Ethernet, RS-232 and RS-485Multifunctional electricity meter with communication interfaces: Ethernet, RS-232 and RS-485

At the moment, almost all electronic meters have a telemetric output, so even those metering devices that have already been installed by consumers will be able to be introduced into the AMR. But you need to remember: attempts to combine disparate meters into a single network are always fraught with problems with interface coordination, signal coding and registration of indicators.

Communication devices

The digital telemetry ports of the meters use the RS-232 or RS-485 serial interface to transmit data to external devices; such meters simply have a built-in interface converter. The type of signal “current loop” is used less frequently and, as a rule, its presence usually indicates the possibility of switching to UART interfaces by means of manual parameterization of the meter, otherwise transmission via a special adapter is possible. For the simplest meters, the telemetry output has a discrete signal – that is, the frequency and duty cycle of the counting device pulses are simply transmitted.

Meter connection to GSM modemMeter connection to GSM modem

The main difficulty in organizing a communication system is that each meter and each adapter can generate different types of signals, depending on the capabilities and settings of the microcontroller. Problems are also added by the fact that initially the telemetry port is used for manual configuration and data retrieval with an individual connection through an interface converter, while data collection and transmission to the AMR requires bringing the entire network to a certain unified standard. As a rule, with the number of meters up to 32, the communication line is performed by wired RS-232, and with the number of subscribers up to 250 – RS-485. Thus, a group of devices is united by one switch using, for example, UART, but if some meters in this group do not support a common protocol, they are connected via interface converters. On the market, you can increasingly find equipment for data transmission over power lines.

Wireless networks are configured differently. The protocols can be very different: GSM, Wi-Fi, radio communication – in all cases, the transceiver is set individually for each meter. Each communication point communicates with a kind of base station, and modems can work not only in direct transmission mode, but also as repeaters.

Electricity meter Single-phase electricity meter with additional plug-in modules for transmitting telemetry information

In both cases, there is one unifying link that acts as a root hub and transforms data for transmission to the dispatch center. As a rule, we are talking about using the Ethernet interface familiar to many, that is, this node already belongs to Internet technologies. This part of the system is intended for communication between the AMR and the server where the remote dispatching software is installed. A PC located directly in the coverage area of ​​the system can be used as a server; data transfer to a remote server is also practiced, but a backup channel is required for a reliable connection. The “cloud” option is good for the ability to access from anywhere in the world, while the wired network requires the installation of additional equipment.

Organization of a dispatch center

Difficulties in mutual integration of meters from different manufacturers (and sometimes even simply different models) into AMR appear mainly at the stage of organizing the third level of the system – a single dispatching and control center. At the physical level, this part occupies the extreme branch of the topology, the PC communicates with the hubs through an RS-USB interface converter or similar, the server – through a switch installed as part of the communication complex.

USB-RS485 interface converterUSB-RS485 interface converter

Most of the problems are in the custom software. Leading trade marks of electricity meters – “Energomera”, Nik, “Mercury” – all are accompanied by software administration systems, free for non-commercial use. But for the purpose of deunification, it has been done so that everything will work correctly only if all the meters in the system are only of this manufacturer and preferably of the same model. Otherwise, you have to modify open products and operating system tools, connect each subscriber individually and conduct continuous administration.

It is especially important that when using proprietary software, unauthorized entry into the system is impossible: the source code of the programs is closed and difficult to crack, besides, in fact, the data is stored in the memory of the counters themselves, the server simply duplicates and organizes them. The memory on the meter is protected from writing by a password, which cannot be changed during a remote connection – there are simply no necessary privileges. So, for reliable protection against changes, you just need to set up regular database rewriting. What is no less interesting, the system works “out of the box” and is easy to study, you don’t have to make any major modifications, and therefore perfect command of the operator in programming and OS administration skills is not required.

Installation and adjustment of the system

Each ASKUE subscriber is connected individually. The person in charge of this process must have an Excel file with the consumer base. This database contains the name and contact information of the subscriber, as well as the model and serial number of the meter. If the meter has a digital telemetry port, write down the address of the network device. If the output is a discrete signal, a sensor of the corresponding type is installed, to which the network address is manually set and also entered into the database.

The meter or a sensor installed on it is connected to the system’s hub directly via a wired connection. This is what the UART protocol is good for: the cable can be laid from subscriber to subscriber at a distance of up to a kilometer, it is only important to proportionally reduce the transmission speed. Communication methods in AMR can be combined, for example, connecting remote subscriber groups via a radio point or via GSM. In the end, everything turns into only additional costs for equipment for communication and signal conversion, as well as the choice of appropriate program settings. The subscriber connection method must be entered into the base in the notes field.

ASKUE system

Before installing the meter, parameterize it: reset the settings, synchronize the real-time clock, generate the correct type of signal at the output and communication settings – a step-by-step procedure according to the user manual. When using interface converters, they must first set the address in accordance with the network topology, as well as study the operating instructions and configure the communication parameters according to the current protocol. Since the core of the system is nevertheless connected by a serial interface, you can connect to it at any point. That is why all the equipment installed on the customer’s side can be pre-installed on the stand for adjustment and testing in convenient conditions, and then transferred to the installation site almost completely assembled. In the database of the administration complex, the subscriber connection settings do not need to be changed..

The cost of switching to automated accounting

It rarely makes sense to independently engage in the installation and adjustment of ASKUE, usually such projects are created on a cooperative basis with the involvement of a third-party contractor. Prices for equipment and installation differ from region to region, on average the project budget is 6–10 thousand rubles for each consumer. There is a significant difference in the number of subscribers: the more there are, the ultimately cheaper, and the density of meter placement in the area is also of great importance. The more complex the network hierarchy, the higher the project cost..

We must not forget that the initial expenses are almost always not the only investment. If the number of subscribers is more than 100 or using complex communication topologies, you will need to pay for the services of a remote administrator. If GSM is used for communication, the subscriber will have to pay for each communication session with the system, which is almost 50 CSD requests or SMS per day.

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