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Demand Side Management and Differentiated Billing model developed in the 1990s.

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Joao Batista Gomes's picture
Consultant/Technical Manager Consultant Smart Grid

Development and Management of Projects and Products targeting the Distribution and Measurement of electrical energy. Defining characteristics and technical functions of Smart Meters and...

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  • Nov 3, 2019

The concepts and architecture of this project are still current, and in some ways still ahead of many current projects.
I was the Technical Manager of this project and for more information see the links below.



SIGED was jointly developed by SISTRON and the Minas Gerais Energy Company - CEMIG.

The purpose of this system is to automate billing-related processes (with the ease of applying Low Voltage Differential Charging in any configurations - including binomial tariff possibility), social cutoff ( 24 hs limitation of the maximum current supplied to the consumer unit from 1 A), Telemeasurement and Centralized Measurement, Load Management (in consumer units - with possibility of seasonal and selective application - and distribution transformers), Remote Cutting and Reclosing (offering reclosing 24 hours a day), loss control (loss energy balance by measuring each transformer secondary), load curve of transformers - BT and feeders - MT, voltage outage alarms (per phase), location consumer phase power supply and DEC / FEC of each transformer and feeder.

The basic assumptions considered were: multi - functionality, modularity, cost, integration into the dealership 's corporate system, ease of installation and compatibility with existing measuring equipment in the Brazilian market and with the various data communication means available (mobile phone and low-altitude satellites and radio). The system has four basic components.

The ETR, which is installed on the same pole as the transformer;

The REP, which is installed on the circuit posts;

The SX403 modules, which are installed in the metering boxes (connected to the meters) of the consumer units and the software, SCTDAcom , which can be installed in any system that has the configuration required by the system and which can reside in the integrated corporate system. routines already implemented, such as billing system, consumer information system, geoprocessed control systems , etc. The Remote Workstation - ETR commands, sends and receives information from the SX403 modules through the power grid with data transmission via P LC ( bidirectional power line carrier , via the PCL-NET protocol). ETR also sends and receives data (cut / reclose orders, invoice read / close orders scheduled through SCTDAcom ) from the Concessionaire, using the appropriate and available means of communication.

This project has been in operation since December 2001 in 14,300 homes in 3 primary circuits in Juiz de Fora, Alfenas and Contagem where, along with the billing sector of each location, COD and CAC are all scheduled system tasks (the links with ETRs are preferably done from 11 pm to 6 pm) and data collection. Either by changing meters (eliminating errors and frauds), the revenue saved by the practice of remote cutting and reading, the revenue obtained by the 24-hour emergency reclosure (through CAC), the immediate detection of non-technical losses (through change in the ratio of energy billed to the meters by the energy supplied by the transformer) the results obtained exceeded the expected return on investment made in the project design phase, making this technology feasible to be implemented for all CEMIG consumer units. For companies with high non-technical losses (over 4%), when combining this technology with the installation of measurements on the network and multiple pole or coaxial cable poles , the return on investment time may be less than 3 years. a capital cost of 18% pa.


Remote control . Telecorte . Energetic balance. Cargo management. Non-technical losses. Yellow fare


Since 1991 Cemig has been looking for solutions that allow an improvement in the load factor, especially regarding the demand profile presented by low voltage consumer installations. Considering the various household consumption and possession surveys conducted throughout Cemig's concession area and also the breakdown of the distribution load curve it can be identified that actions should focus on the impact caused by electric showers today with demand between 4,5 and 10 KW. According to the criteria stipulated by the company's tariff area, ways were studied that would make it possible, through a differentiated tariff incentive, for consumers to eliminate the use of the electric shower during the peak hour of the system, which generally represents the 17 : 00 at 19:00. Two main ways, aimed at low-income consumers (monthly consumption less than 180 kWh for the purposes of this study) and other consumers were more viable:

20% discount on all energy consumption, for Customers classified as low-income, provided the Customer accepts, expressed through a contract signed with Cemig, not to exceed 15 Amps, for 2 consecutive hours, at tip (initially chosen between 5:00 pm and 7:00 pm , this range could vary for different sectors of the system); Application of the “time- of - using ” Tariff to the other Customers, and in the first instance the monomial tariff (only kWh) was tested in 2 tariff stations; This tariff composition, however, proved inefficient in terms of reducing demand during peak hours (the average result obtained did not reach 80 W per installed point); In this way a new binomial tariff composition (kWh and kW) was tested in 3 tariff stations: tip (17: 00/19: 00), complementary tip (16: 00/17: 00 and 19: 00/20: 00) and off-peak (20: 00-16: 00).

This new tariff showed results closer to the desired (around 200 W per installed point) despite the restriction imposed by DNAEE whereby each Customer was billed for the lowest value tariff mode (between the conventional kWh and the yellow in which naturally reduced the effects of load modulation in relation to a real situation in which to reduce the tariff the consumption habit should be changed. In addition to the possibility of a time-varying tariff structure , the development of the system should include the following characteristics:

Modularity: Be applicable to any secondary regardless of local structure. ÿ Low Cost: Systems then operating outside Brazil had costs incompatible with our reality.

Possibility of demand-type load restraint (high demand and low consumption over time, which must necessarily be done in the general input of the input pattern, as there are no thermally inertial loads to be cut for short periods of time.

Two-way communication to enable other business functions or not that increase the return on investment and are strategic. ÿ Compatibility with existing measuring equipment in the Brazilian market.

In this way, the development by SISTRON, together with CEMIG's Energy Company of Minas Gerais, started the system called SIGED.


This system uses "PLC - Power Line Carrier" transmission technology , for communication between the remote station installed on the pole where the distribution transformer of each secondary is and the modules. The unit installed on the pole, the Remote, can be accessed locally via conventional power grid (PLC) or remotely via fixed or cellular telephone line, fiber optic, radio or satellite.

The system has four basic components. The ETR, which is installed on the same pole where the transformer is located; REP, which is installed on the poles of the circuit due to possible need for PLC signal amplification; the SX403 modules, which are installed in the consumer metering box, and the SCTDAcom software , which can be installed on any system with the configuration required by the system operating in conjunction with the existing corporate system.

For loss control purposes, 3 BT CTs are installed in the secondary of each transformer and supply a meter installed in the ETR itself; A MT circuit measurement is also installed, connected to a specific ETR for this purpose at its very beginning, in order to obtain an energy balance of each feeder.

The system works as follows: Remote Workstation - ETR controls the SX403 modules through the power grid. The remote still sends and receives data from the Concessionaire, using satellite, radio, landline or mobile as a means of communication. Communication is bidirectional, ie both the module and the remote send and receive information with each other. The modules and ETR can still be accessed locally using a notebook.

An ETR is installed on the secondary of a distribution transformer. It follows a schedule developed by the Concessionaire that can manage consumer loads and store meter reading with pulse sensors, connected to the SX 403 Modules.

The ETR communicates with the SX 403 modules and the unit and PC / TP through the PLC -NET protocol , using the power grid as a physical means of data communication. The unit also monitors the state of the Modules, storing occurrences such as loss of communication (date and time), disk rotation reversal, and programming changes in memory.

The SX 403 Module receives an addressing code that will be used by ETR to request the accumulated values ​​when in a pooling system . The modules are autonomous, from the moment they are initialized and receive from the ETR, in pooling system , a synchronization signal that is sent every hour to set the internal clock of the modules and, when necessary, programming change or (daylight saving time and open / close command for cutting and reclosing, for example).

Using the PC / TP interface, data stored on the ETR can be downloaded via micro readers , notebooks or remotely by connecting the PC / TP interface to a modem and the telephone network. This same system will be used for switch programming.

SIGED can control peak demand through load modulation at predefined times for consumers (load management) or through the yellow / differentiated tariff; It can also cumulatively record energy consumption in kWh in three hourly segments. These segments are called Tip, Off Tip, and Reserved. It also allows monitoring the maximum demand in KW for these segments, enabling the implementation of tariff system with hourly binomial structure and informs if there was a power outage or lack of communication with the consumer.

It also enables centralized measurement and / or telemetering, and remote access, using fixed, mobile or satellite telephony, performs remote monitoring of the SIGED system.

For Centralized Measurement function and Telemetry is required to connect the module to a SX403 pulse measuring sensor . Pulses proportional to power consumption are accumulated by the module. Once a day, through a pooling system , the remote requests this data, updating its internal registers. In the module, differentiated pricing is performed through the programming of its internal registers (end, off end and complementary end).

The configuration of the system for telemetering is done through the interconnection of ETR with the Concessionaire's office, by normal telephone, cellular, fiber optic, satellite or radio. The Differentiated Tariff function - Yellow Tariff - enables multitarifation . There are three daily tariff stations for the BT consumer. The System works as follows: SX403 modules , connected to Pulse Sensor meters , accumulate data according to their own and ETR programmed times.

The load management system can be performed by two distinct systems:

A module with input for external pulses and relays is connected to a pulse sensor meter. The relays, if the load at rush hour exceeds the set peak value at peak time, are activated by the module and interrupt it. The module acts as a current supervisor that interrupts the power supply at short intervals (30 '', 1 ', 2' and 4 ') according to set current limits and restores power as the load exceeds the limit. is no longer requested.

Alternatively, through a module that has the “Shunt” board it is possible to monitor the current flowing through the Shunt resistor , so that no meter change is required (only for load management function) . When the current exceeds a predetermined value during rush hour, the power supply is interrupted at short intervals (30 '', 1 ', 2' and 4 '). Energy is returned as the load above the limit is no longer required.

Given that the management is performed in the low voltage consumer unit, the modulation of the load curve reflects in the distribution transformer, feeders, substations, transmission and generation.

Management intervals (tip) are determined based on the characteristics of the load curves of each part of the utility's electrical system.

The main components of the system are:

SX403 or SX403S (with shunt) - Module for Measurement, Charge Management and Differentiated Charging that is installed inside the consumer metering box. It is responsible for the activation and interruption of the load of the consumer (through specific relays and external to the module) or any electrical equipment fed through its contacts. The equipment is also responsible for storing consumption and demand metering.

The ETR - Remote Workstation is installed on the same post where the transformer is located. It is the equipment responsible for monitoring low voltage , with secondary measurement. It is also responsible for remote access of the SCTDA system.

The REP - Repeater is installed on the posts. It is the device responsible for maintaining the communication signal level throughout the distribution network.

The PC / TP is the interface responsible for the connection between RS232 and the power grid. It connects to programming and reading devices such as notebooks, microcolectors, and modems.

SCTDAcom is the software developed to access Remote, Central and Modules. The program runs in a Windows environment shared with the internal network where the other components of the corporate system (billing system, consumer information system and inspection order management system reside) .

The communication protocol used by the SCTDA is the PLC NET (Power Line Carrier-PLC) and allows the transmission and reception of logic signals through the power grid. The ETRs use the electricity grid already installed as a data / command transmission bus. The modules, also connected to the network (bus), perform the functions according to the command received, without the need for any other physical connection. The instructions between the ETR's and the modules are transmitted through digital codes. In the "basic control" register, the first 4 (four) bits represent the starting code. The next ones represent the address codes ( 9 bits) and the last ones represent the function envelope (11 bits). In most cases, a PLC NET command is transmitted with two distinct and consecutive "envelopes". The first contains the addressing code and the second the function envelope. The addressing code is made up of two parts. The first 4 bits represent the alpha part of the code (A ~ P) and the next 5 bits represent the numeric code (1-16).

Each receiver module is programmed with its address, eg: (A1, A2, A3, ..., P16). It is allowing to program up to 256 different addresses per bus. Modules with the same address can be placed on the same bus, but the command sent to one address will be executed by all modules that have it simultaneously.

The function envelope concentrates the 4- bit start code . The alpha part of the 4- bit addressing code follows, and finally the command code to be executed, with 5 bits. Examples of commands: turn off all units that have the same code, trigger, vary the intensity or require status of a specific module, among others.

Each day and at a predetermined time , ETR transmits a "SEND TOTALS" command to the SX 403 modules, installed next to consumer meters. The modules, in turn, transmit to ETR the accumulated maximum demand and read data, as well as the power outage and disk rollback status. Communications are always commanded by ETR.

ETR pooling time to modules is predetermined by checking available time "ranges". There is also the option to force pooling of all consumers or only pending consumers, executed a command via PC / TP and micro, through ETR software, at random times. At the end of each sequence of " pooling " of reading, ETR send a global command for the "TIME SYNC" and each module installed on the logical network synchronizes its clock clock inside. This command is also sent by the ETR every 58 minutes hour throughout the day.

Another "global command" is sent daily by ETR, at times set by the Concessionaire, indicating the beginning and end of the tariffs, eg ("YEAR START AND END"). Only modules programmed for this type of operation respond to the command. This command serves to confirm / change the times stored in the modules, facilitating the maintenance of schedules, since the programming will be changed only in the ETR. Regardless of being commanded by the ETR, the module performs the commutations according to its internal programming.

Both ETR and modules allocate message transmission times to meet information relay needs via REP repeaters before other messages are transmitted. The PC / TP interface is used to program the entire system as well as to receive the reading information accumulated by ETR. The communication between PC / TP and ETR is used to register or delete consumers, set the logic of the logical network, set date and time, set the start and end of different tariffs, the time of daily reading, among others.

The following information must be programmed when installing the SX 403 module using the PC / TP interface: Consumer Code; Logic network code; Yellow tariff start and end times; Start and end times of reserved rate; Read pulse rate per KWh ; Period for opening the load control relay (number of periods of 15 min. After entering the yellow tariff); Time of day

All messages transmitted over the power grid (physical bus) are encrypted using a 32 character cryptographic key. The switch is embedded in the firmware of all devices except the REP repeater and cannot be changed or read. When a message is transmitted, the sender randomly decides where in the data string encryption begins, sending this information at the beginning of each transmission. The preamble of each message is not encrypted , allowing the receiver to know which byte to begin decrypting .


Despite the fact that it represents a high initial investment, the automation of business, engineering and planning processes removes from electricity utilities a chronic and historical deficiency represented by the need to go to the field with teams and equipment whenever it is necessary to perform any task, since the most simple and repetitive (such as meter reading) as the most complex (locating non-technical losses). In addition to the more easily measurable gains such as the postponement of investments motivated by the sale of energy only at peak hours, there are other marginals such as the increase in energy sales due to the better voltage profile throughout the day, the increase in useful life and the reduction non-technical losses due to having properly sized transformers. All combined effects indicate a ' pay-back ' better than projected (4.5 years) and an internal rate of return 22% better than expected. There are also intangible gains such as increased customer satisfaction as a result of a shorter power recovery time due to the Remote warn voltage failure for each phase, allowing a better load distribution by identifying the phase (s). (s) of each consumer unit connection, give the option to provide any BT consumer unit with its daily load profile via the web tool and allow rational use of energy. Accordingly, it is recommended that the Dealers intend to make medium and long term investments that are structured to change their work methodologies, their traditional division of tasks and to offer a new range of services in their portfolio; of course, they will have to revoke old paradigms and attitudes by which we should only invest in greater production, transmission and distribution capacity and not invest in a more rational and economical use of existing assets already in place.



Abstract - The objective of this paper is to present a viable investment option as an alternative to conventional ways for repowering circuits and / or maintaining the quality of power supply in distribution circuits and which is also a tariff option for the low income population. .

Keywords - cargo management, tariff option

Keywords - demand side management, tariff option.


All alternative techniques for troubleshooting should, under penalty of not moving from pure theory, provide cost-compensating benefit to the investor. Thus, it is necessary to look for new ways to address the serious issue presented in low voltage systems (with direct effects on subtransmission and transmission systems) by the significant increase in demand from 5:00 pm to 8:00 pm. Consumer units with demand above 500 kW are already covered by DNAEE Ordinance 1569/93 and, either by the blue or green tariff, have a load modulation appropriate to the needs of the electrical system. Units with demand between 75 and 500 kW of demand can opt for blue or green tariffs. For the units served at low voltage studies are being prepared for the establishment of the yellow tariff (time of use) and binomial tariff with the components of demand (limited by the circuit breaker) and energy consumption. Cargo management is therefore also a very suitable tariff option for low-income populations, as it guarantees the benefits of load modulation and the optimization of the installed system for the power supply and a reduction (today 20% of all energy consumed) to the Customer. Consideration should also be given to the fact that there is a natural growth in demand and, especially, a disproportionate growth in demand during peak system hours, the investments that are necessary to maintain the quality of the energy supply, whether in relation to the level of voltage or the number and duration of supply interruptions become very high; This is especially aggravated when it comes to power supply to small consumer units that have subsidized tariffs and have an average monthly bill that does not even support the basic costs of reading, issuing and billing.

Thus, as is already done in the area of ​​communication, with different tariffs in the various time segments, it seems very reasonable to find a solution to the problems related to energy quality and investment capacity of companies that seek the minimum profitability necessary for their survival. with the optimization of the installed system. This becomes especially important at this time of privatization / deregulation of the electricity sector where new entrants will not have the vision of “social” care for the low-income population. Another very important aspect which must be regarded with particular attention is to say respect to conservation will environment that gets delaying the need for more generating capacity. Looking at this aspect it is clear that the optimization that is sought does not cause losses in quality of life; In fact, there will be a small change in the consumption habit, mainly in relation to the use of the electric shower, which will bring a reduction in the value of the monthly bill of the Client and will allow a more rational use of natural and energy resources, with gains for all society.


The Valley is a large area (60000 km2, approximately 10% of the area of ​​Minas Gerais) made up of 54 municipalities ; It should be noted that this area has 800,000 inhabitants (5% of the state's population) with 90,000 consumers and represents for CEMIG 0.3% of its revenue. The Vale system in 1994 had the following configuration:

• 55 MVA capacity

• 59 MVA peak demand

• off-peak demand 25 MVA

• load factor 47%

• Cemig 80% average load factor

• residential load factor in Vale 30%

• at various points in the system at peak hours, the supply voltage was below the threshold set as precarious by DNAEE. Through research on consumption and possession of household appliances can confirm that:

• 90% of consumers (70 to 200 KWh / month) have electric showers;

• 57% use the shower at rush hours from 5 pm to 7 pm; This results in a coincident average demand of 0.49 KW per household for shower use; Thus, the maximum demand due to shower use in the Vale area can be estimated as 9719 KW for residential consumer units with monthly consumption of 70 to 200 KWh / month.


Considering the data of the subtransmission and distribution systems in the Jequitinhonha Valley area, it was decided to implement cargo management in the Salinas, Araçuaí and Almenara areas, covering a total of 11 municipalities. The SCTDA (Control System for Differentiated Pricing and Automation) uses programmable switches installed on the secondary of the distribution transformers that, through signals via carrier (using existing cables as propagation medium), control modules located next to measurement and overall protection of each consumer unit. With each Client who accepted the installation of the module in his / her home, an individual contract was signed with Cemig guaranteeing a 20% discount on the amount of energy consumed (this discount is shown monthly on the invoice ). In order to achieve load control and the consequent modulation in the demand curve, the general protection of each single-phase consumer unit was added with another circuit breaker (unipolar 15 A) connected in parallel with the existing one; at peak times every manager module indisponibiliza the old protection (single - pole circuit breaker 30, 35 or 40 A) and provides the circuit breaker 15 A, making it impossible to electric shower binding but allowing q ue the other loads are normally used to the limit of A. Both the manager module and the two circuit breakers are installed in the measuring and protection box (sealed and Cemig's exclusive access) in the input standard and the Consumer has access only to the circuit breaker handles to reset them in case of failure. overload or overcurrent operation .



CEMIG made several measurements to evaluate the results obtained with the implementation of the SCTDA; Thus, voltage level and demand measurements were made on the secondary transformers of distribution over 1 year and the table below illustrates one of the measurements. Although not specifically monitored , secondary circuit disconnects are known to fall significantly after the use of SCTDA, especially in the colder months.


The cost of the deployed system, including all personnel, vehicle and material expenses, was around R $ 400.00 for each kW taken out of the system at peak hours and on average, according to previous studies, a 450 W of demand at peak hour per installed point. This value can be directly compared to the cost of R $ 2000.00, which represents the general investments required to supply each kW for low voltage consumer units. The graphs below show the gains made in the system as a whole.


Following the installation of the load manager and the implementation of other measures (such as free replacement of incandescent bulbs with compact fluorescent bulbs), the Customer satisfaction level was constantly monitored; Through survey, it can be highlighted that 79% of Clients intended to continue with the installed manager. It is observed, today, in practice, that is already being made a thickening of the system with approximately 100% index (being the majority of cases by request of Consumers), ie: where there were n points installed, other n points were marketed on the same secondary circuits using the same plants already installed.

• centralized measurement;

• control of public lighting;

• telemetering ;

• data acquisition for management / control of primary and secondary distribution networks; It was recommended to use it in other areas of CEMIG, prioritizing those considered critical from the point of view of ability to meet new demands; Other supplemental applications to load management were also prioritized. Thus, today we have the SCTDA as a management instrument that, depending on the peculiarities of


After the first year of operation of the system and also considering the following potentialities of the SCTDA (Control System for Differentiated Billing and Automation) developed in conjunction with SISTRON:

• binomial differentiated pricing;

• telecut ;

• prepayment without card or numeric code;

• loss control;

• provision of services and sending messages to the consumer;

The position of ELETROBRÁS regarding load management should be taken as an indication of the energy sector policy regarding the rationalization of the use of electricity since this body is implementing demand side management projects throughout the Brazilian territory, having been estimated. a potential market of two million managed points for years to come. Regarding the use of SCTDA in areas where care is not critical, we propose to add to management the other facilities that the system offers and which will certainly make investments more profitable. This can be seen from several aspects but we can exemplify the higher return on investments by simply postponing the need for new resources for repowering secondary distribution circuits to supply the vegetative growth of areas not fully urbanized. As the implementation of other functions can be exemplified by the implementation of remote sensing that, as a result , allows the implementation of other forms of differentiated charging. Thus, the characteristic of punctual application in each distribution transformer secondary is the differentiating fact that allows the application of SCTDA in the exact dosage of the needs of each company, requiring neither the application of the solution in large areas nor very high investments .

Spell checking: Press the CTRL or COMMAND key then click on the underlined misspelled word.
Matt Chester's picture
Matt Chester on Nov 4, 2019

Joao-- what would you say are the main takeaways here (for those of us that can't read Portuguese!)?

Dr. Amal Khashab's picture
Dr. Amal Khashab on Nov 4, 2019

First , it is very old experience 16 years ago , things must have changed and what were applicable in 2003 could not in 2019.

Second . How many people can read Portugese ? Three handereds million ,not more . We appreciate giving an English summary . Thanks in advance

Joao Batista Gomes's picture
Joao Batista Gomes on Nov 4, 2019

Dear Matt and Amal,
Frankly, at this time, you can't get a translator from Portuguese to English.
This project in its topology and architecture is very current.


Joao Batista Gomes's picture
Joao Batista Gomes on Nov 4, 2019

Matt and Amal,

Sorry for any inconvenience, the English version is now available.




Matt Chester's picture
Matt Chester on Nov 5, 2019

Thanks for the translation, Joao. Though I'm still curious if, as an expert in the field, you can provide what you think are the one or two most important takeaways-- what makes you most excited about this model?

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