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Get Up on the Fundamentals of Energy Management

Maxim Integrated has a new online course available called the Fundamentals of Energy Management. The course is presented by one of Planet Analog's well-known bloggers and former EDN editor, Bill Schweber.

The course doesn't deal with power generation, but jumps in after that point. Starting with distribution, Bill dives in with a discussion of the energy management chain: the electrical grid, grid storage, automation of the distribution network, and access points (where the users connect).

He looks at residential and commercial distribution and the way smart energy management can be applied. At the access point, that means smart meters. Smart meters monitor all three phases of the incoming AC line for commercial customers; and the two halves of a “split” phase for residential customers. That means monitoring the voltage and current.

Some issues to consider: battery life if the meter had battery back-up (to retain info during power outages); security; accuracy (0.1 percent accuracy over a 2000:1 range of power draw).

Bill discusses consumption — an obvious topic at first — but there are details to consider. If you are charging an electric vehicle, power draw can be very high for short periods of time. The power company wants to know when this is happening so they can perform load-leveling.

If there are streetlights, it would be good to know if they are overheating, drawing too much current, or not enough. A smart grid enables all this functionality.

The smart grid functionality needs a communications network. It's composed of a variety of links — 300/1200 Baud data links (possibly RS232), power line communications (PLC), fiber optics, ZigBee, etc.

There are multiple reasons why we want all this interconnectedness on the power grid: to save energy, balance the various loads via load shedding, anticipate and report problems, and reconfigure the system when problems occur.

Bill also discusses the need for galvanic isolation for the power and the communications link. He discusses security issues. He notes that they are underappreciated until something bad happens. He gives an overview of why it's important and how to do it.

Bill talks about standards and regulatory issues. He discusses how some products must comply with minimal standards (such as a wall thermostat) while others need to comply with much more rigid standards (if connected to high voltage or have security issues). And he reminds us that not all reference designs have been compliance/regulatory qualified.

For convenience, Bill lists some of the communications networks we are likely to encounter:

  • LAN: local area network;
  • WAN: wide area network;
  • HAN: home area network;
  • NAN: neighborhood or near area network.

Be aware of the standards that are applicable. Know who defines the standards. Know whether they are proprietary or open. A couple to become familiar with are ZigBee (a.k.a. IEEE 802.15.4) and IEEE P1901.2 (for PLC).

Are you working on any smart grid applications? What challenges are you dealing with and how have you overcome them?

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58 comments on “Get Up on the Fundamentals of Energy Management

  1. goafrit2
    October 2, 2013

    I was not expecting Maxim to have documents on this sector largely because I see them from the constructs of ASIC design. Energy management goes beyond ASIC to system integration. But it seems firms are moving both lateral and horizontal in efforts to become competitive in the market space. Good document on the fundamentals of energy management.

  2. goafrit2
    October 2, 2013

    >> Are you working on any smart grid applications?

    In our firm, smart grid was a huge buzz few years ago. But with this shale gas revolution and its readily abundant energy, it is affecting how far we take this. Energy is becoming cheaper in America and that is bad business for the smart grid sector!

  3. fasmicro
    October 2, 2013

    You must not underestimate the power of smart grid in the new industry. The world is moving in the domain of conservation and savings. Smart grid is good business whether you have abundance of resources or not. It is simple economics – money earned is one saved. If you have all the resources and burn them, nothing changes. But if you can conserve, you are in good shape.

  4. eafpres
    October 2, 2013

    @fasmicro–“Smart grid is good business whether you have abundance of resources or not”

    I agree with your point.  I also like the overview Brad gives of the Maxim courses; I'll go and look.  A lot of smart grid buzz these days is about the home.  Yes, that part of consumption is very important, but where there is a real leverage for technology is in the grid itself–generation, transmission, distribution, delivery.  Those measurement challenges are quite difficult–working at 500 kV poses some unique requirements.  Monitoring very large 3-phase transformers is not simple either.  A lot of the infrastructure that gets power to homes is largely unconnected.  As Steve Taranovich noted in his recent blog, power outages can be very expensive.  What many don't know is the generation and transimission companies often have delivery contracts with very large penalties for outages.  Monitoring and preventive actions via automaton and sensors can increase reliabilty at very modest cost.

  5. samicksha
    October 3, 2013

    @goafrit: Some components, like the power system stabilizers installed on generators are very expensive, require complex integration in the grid's control system, most utilities find it difficult to justify installing a communications infrastructure for a single application, although each utility has a unique set of business and regulatory drivers that guide its investments. Other than this current Smart Grid technology used by utility companies does not actually detect power theft or equipment failure.

  6. Davidled
    October 3, 2013

    There is so much development for outside components such as sensor, process, and power integration for a long time. As other viewpoint, I would like to point out the grid instability based on electrical transmission line. Grid would be instability due to the small frequency variation. I expect that someone audits electric transmission line map every state.

  7. samicksha
    October 4, 2013

    Your comment redirects me to one of the top social concerns about availability of electricity…

  8. Netcrawl
    October 4, 2013

    We're making huge advances in smart grid functionality, we are doing some pretty good in developing innovative, next-generation technologies and tools in the areas of transmission, distribution, energy storage, power electronics, and the advancement of precise time-synchronized measures of certain parameters of the electric grid. I believe this one could change the electricity landscape.

    Smart grid could give us two: consumption and distribution intelligence, generation is not a problem here we do have enough power sources to supply need, the real challenges here is on transmission and distribution. Wasted energy, we need to get rid of this.  

  9. Netcrawl
    October 4, 2013

    @fasmicro you're right, Smart grid could be the right tool in todat's never-ending struggle for meeting electricity challenges. Smart grid offer many benefits to utility companies and consumers – mostly seen in big improvements in energy efficiency on the electricity grid and in the energy users' homes and offices. Smart grid objective is savings and efficiency.

  10. Netcrawl
    October 4, 2013

    Yes there's so many development for outside components, Smart grid stands for “computerizing” the electric utility grid: from distribution to consumption. This includes adding two-way digital communication technology to devices associated with the utility grid, each device on the network can be given sensors to gather data (power meters, voltage sensors, fault detectors, etc.). A key feature of the smart grid is automation technology, which allows us to adjust and control each individual device or millions of devices.

  11. Brad_Albing
    October 4, 2013

    @goafrit2 – good observation regarding their (and other's) approach to this business sector. Companies have to keep changing the way they do business if they want to stay in business.

  12. goafrit2
    October 4, 2013

    >> Smart grid is good business whether you have abundance of resources or not

    Sure, I do agree that it is smart business. That is not in question. My only comment was there are companies I expect to be the players in this area. Good point that money saved is the one earned!

  13. goafrit2
    October 4, 2013

    >> Monitoring and preventive actions via automaton and sensors can increase reliabilty at very modest cost.

    That is true especially now most of the facilities cannot easily be  funded with budget crises if they go bad. The strategy will be to prevent them from going bad through preventive maintenance in the first place. Yet, except in the homes, the transmission and distribution aspect of the smart grid business is still primitive. I do not see that advancement yet.

  14. goafrit2
    October 4, 2013

    >>  Other than this current Smart Grid technology used by utility companies does not actually detect power theft or equipment failure.

    You have made the point excellently. They have done great works in the homes but in the transmission line, nothing has happened. I was expecting sensors that can detect severe wind and based on potential hazards will use redundant networks to provide power to people. But our systems do not have redundant lines so it does not matter. You cannot say that if the failure happens in the northern side of the city, it will automatically re-wire itself to give you power from the south. No way yet on that.

  15. goafrit2
    October 4, 2013

    @Daej >> Grid would be instability due to the small frequency variation.

    Could you explain this very well. Are you saying the 50 -60Hz frequency is enough to cause problem?

  16. goafrit2
    October 4, 2013

    >> This includes adding two-way digital communication technology to devices associated with the utility grid, each device on the network can be given sensors to gather data (power meters, voltage sensors, fault detectors, etc.)

    I am very curious. I have been living in America for years, cities to cities, but yet to see any of these smart grids. Even in Boston, it is not there. Can someone mention a city in America where we have this smart grid at work. 

  17. Brad_Albing
    October 4, 2013

    @goafrit2 – well, it's true that around the area of OH, PA, WV, and upstate NY, there are plentiful deposits of gas. But probably still a good idea to pursue the Smartgrid to reduce overall power consumption and greenhouse gas emissions. And if you consider power consumption in CA for example, its pretty high and electricity cost is pretty high. So that's a good place to be implementing the Smartgrid.

  18. Davidled
    October 4, 2013

    A generator that drops a certain frequency below 60 Hz would eventually generate heat of bearings and in consequence, drop the voltage in the transmission line of electric, as power supply instability such as phase and voltage fluctuations.

  19. fasmicro
    October 4, 2013

    @Daej, I do not think that is a real problem. Provided the frequency is not sporadic and random, a good designer can design it out of the system. It can be mitigated. Personally, I think the problem is not engineering but finance. Governments do not fund big projects any more – and no one should expect utilities to pull down cables to replace them with smartgrids without any govt subsidy. Wall Street will not be happy with them.

  20. Netcrawl
    October 5, 2013

    @fasmicro its all about funding? Is smart grid enough for today's grid challenges? yes therte' so many talking and buzz about smart grid but the reality is there's no blueprint for its development.

    I think we need is to modernize our electricity grid with a much larger capacity and the ability to manage graete fluctuations in supply and demand, and last but very important the security of supply. Smart grid is a cure for today's energy management challenges.

  21. Netcrawl
    October 5, 2013

    @Albing the would be great smart grid in CA, I think its much better if we combined that with clean energy such as solar power or wind enery, we're still in hot pusuit of energy efficiency savings, how do we start?

    I think we need to start from power generation then transmission and the smart grid, smart grid alone won't change the electricity landscape, it won't solve our problems. If we consider power consumption and savings I think we need to go much deeper, it doesn't start and end in transmission or power generation only, this is about the whole system, how do we get our power and how do we transmit it.

    CA is a good starting place for clean technology and smart grid implementation, the place is homed for some of the world's most powerful companies like HP and Google.  

     

  22. Netcrawl
    October 6, 2013

    @goafrit2 yes having two-way digital communication technology is a good idea, and I think we need also  to monitor transformer output allowing appropriate resourcing of maintenance and upgrades to the grid- the goal is to prevent transformer overload and some room for improvement.

  23. RedDerek
    October 8, 2013

    @eafpres – “power outages can be very expensive”

    Yes they can. When working at Supertex in Sunnyvale as the light rail was being put in, there were a few times where the power went out. Not a problem if it is just the office, but when the silicon wafer fab gets shut down and wafers are in the furnace, many tens to hundreds of thousand dollars in ICs were lost. It took two outages and then we got a huge generator to kick in – no trust in the power company while the rail was being built.

  24. Davidled
    October 8, 2013

    As Government is supporting the funding to power related project, Research Institute would improve cable material and design including high power transmission line with energy roadmap for each states.

  25. eafpres
    October 8, 2013

    @goafrit2–interestingly, I received an article just recently about the District of Columbia install automated meter reading for water meters.  We talk a lot about power etc. here, but a lot of the monitoring ideas and “grid” concepts apply to water delivery as well.  The article can be found here.  What they say, essentially, is that because the feedback loop using people to read meters was slow, and many times wildly inaccurate becuase if they could not easily get to the meter location, they simply estimated, the water company was losing lots of money and customers were all angry thinking they were being cheated.  Installing automated reading technology they get 2 readings a day and can spot leaks or unusual usage, and they can show customers where their bills come from.  I'm sure the system also helps them a lot by letting them see breaks in the “grid” as well; in the current water systems in most cities they know when they have a large break when the road caves in or a geyser appears in town.

  26. Netcrawl
    October 9, 2013

    Funding is a big problem, its a big issue in today's energy roadmap. We need funding to finance key projects and research works.We need to improve our transmission cables, we're seeing too much loss in transmission.  

  27. samicksha
    October 9, 2013

    @Netcrawl: I dont funding as problem here, rather complexity suits better here as an issue. What we need today is something simplified with better throughput. Yes your point on transmission cables really applies.

  28. BillWM
    October 9, 2013

    Power Factor Control can be a large cost savings for large and small business as well — just look at all the convienence stores running 24×7 with large walls full of coolers and a load that varys through the day and night, as well as heavy industry and even larger residences —  I even recall the shock of my first $600 electric bill as energy costs rose during the last decade and the decision to go with a more energy efficient residence

  29. Brad_Albing
    October 9, 2013

    @Will, I assume that means no more TV (just book readin' for entertainment); and a refrigerator powered via propane.

  30. fasmicro
    October 9, 2013

    >> yes therte' so many talking and buzz about smart grid but the reality is there's no blueprint for its development

    The real broken path why smart grid has not taken off is not the engineering or technology capability. Rather, municipals are broke to under-write these developments. In the past, the investments needed would have come from bonds – but most investors now run away from these “low-grade” products because they can blow up as Detroit.

  31. fasmicro
    October 9, 2013

    >> CA is a good starting place for clean technology and smart grid implementation, 

    It is working in CA because it is a very good tax and spend state. They know how to fund and build big infrastructure projects. It is not just CA, but most liberal states. They tend to have better infrastructure than the red states. I saw the best roads in MA, MD, CA than AL, GA and co.

  32. fasmicro
    October 9, 2013

    >>  “power outages can be very expensive”

    That is the simple reason why you may not have some big plants in some of the developing world unless you can develop your own power station. The reality is this – when you do not have power, there is no commerce. And in some countries, they look a significant part of their GDP growth due to inablity to provide electricity.

  33. fasmicro
    October 9, 2013

    >>As Government is supporting the funding to power related project, 

    I will guess Chinese government. I am not sure that is happening anywhere in U.S. Sure, there is the small credit govt gives to homes when you retool with renewal energy, that is a paltry way to jumpstart the new revolution we need to bring smart grid and renewals as the mainstream in our energy consumption.

  34. Davidled
    October 9, 2013

    Smart Grid impacts to EV charging of either HEV or Pure EV platform.  Any place n the USA has more EV charging station. Eventually, OEM sells more EV or HEV vehicle than gas type vehicle in the market, because as one of issues for alternative fuel type vehicle is lacks of infrastructure of charging station every place.

  35. goafrit2
    October 10, 2013

    @eafpres, sure when you have meters it makes everything better. In Scotland, they meter everything and it is done with the speed of light. In your house, if you do not  load the meter, no electricity. Nothing like waiting for the power man to give you a bill, you need to fund the meter before you can have light. 

  36. goafrit2
    October 10, 2013

    >>  What we need today is something simplified with better throughput. Yes your point on transmission cables really applies.

    I think some of the concepts are in the lab. They have been validated. The key issue now in some of these expensive area is commercialization. When you see the volume of research on nanotechnology that is waiting in the lab shelves to be commercialized, you will appreciate the need for government to take a big role in helping technology bloosom.

  37. fasmicro
    October 14, 2013

    >> I think we need is to modernize our electricity grid with a much larger capacity and the ability to manage graete fluctuation

    I think we agree in principles. My point is that modernisation costs money. And in this age of Google where one can invest in websites and hit millions of dollars, few will be ready to fund such projects. Only government can actually save the day. VCs and P/Es are looking for the next easy money and no one will commit to bankroll big projects like this modernization when governments expect banks to keep more liquid cash to pass through stress. That creates a problem – banks cannot get involved in big capital projects. That is why the bridges are falling and infrastructure is decaying.

  38. yalanand
    October 27, 2013

    Energy management is also often commonly used by precise commercial units to monitor, measure, and control their electrical construction loads. Energy management systems can be usage to centrally regulator devices like HVAC lighting systems across numerous locations, for example grocery, retail and restaurant sites.

  39. Brad_Albing
    October 29, 2013

    @fasmicro – sad but true.

  40. Brad_Albing
    October 29, 2013

    @yalanand – yes, we see energy management in the form of load sloughing (load shedding), but mostly with commercial customers.

  41. etnapowers
    November 26, 2013

    The voltage / current sensors are applied directly on the AC line, are these sensors protected from voltage or current spikes present on this line?

  42. etnapowers
    November 26, 2013

    Is there any filter for the signal conditioning between the voltage / current sensors and the ADC converter? The introduction of the filter purpose is to enhance the BER of the converter.

  43. etnapowers
    November 27, 2013

    The power meter block system could be powered by a rechargable auxiliary, which is supplied by rectifing the AC power sourge.

  44. Brad_Albing
    December 2, 2013

    @etnapowers – whenever you monitor voltage or current from a source that is likely to have high amplitude spikes, you need to add extra circuit components to protect the active devices doing the measurements (i.e., the op-amps and ADCs). So that means resistor/capacitors confib=gured as a low-pass network and clmp diodes and zeners to minimize high amplitude spikes.

    Unless you want to see and measure those spikes – then you have to attenuate the current and voltage waveforms more and make sure your ADC has enough resolution and range to measure the very small signals and the very large spikes. It's not easy to design such circuitry.

  45. Brad_Albing
    December 2, 2013

    @etnapowers – typically a low pass filter. You'd pick one with a corner frequency high enough to pass the fundemental frequency (50 or 60Hz) + enough of the harmonics to produce meaningful info regarding waveform distortion from the (nonlinear) loads. So perhaps 5th or 10th harmonic.

  46. Brad_Albing
    December 2, 2013

    @etnapowers – yes, there should be a battery to power the system during loss of power conditions. That way, data can be retained and (assuming there is an RF or power line communications channel) status can be transmitted to a central location indicating a power failure in certain areas. Then repair crews can be sent out.

  47. Victor Lorenzo
    December 3, 2013

    Battery backup can be used to keep powered some low power RAM so important measurements can be saved for long time periods. In fact, if the system is powered down (no AC line power) most surely we have nothing to measure.

  48. Victor Lorenzo
    December 3, 2013

    Well, it could be interesting (usually required) to log timing information for the time power supply is restablished. In that case the RTC (real time clock) should also be backed up by the battery.

    (nothing new for most EE, I suppose)

  49. Victor Lorenzo
    December 3, 2013

    @B_Albing, in case of long term power loss, some RFID products manufacturers are now providing kind of FLASH memories with dual interface, one SPI/I2C for reding/writing from MCU side and one RFID (ISO14443/ISO15693/NFC) for local wireless reading/writing with one RFID reader (no need to remove any SD or similar memory).

  50. Victor Lorenzo
    December 3, 2013

    @goafrit2, “Energy is becoming cheaper in America and that is bad business for the smart grid sector!

    In Europe it's more or less moving in the opposite direction. Some CEE projects have been funded focused on what is been called 'smart city'.

    Smart grids are mentioned in this excerpt from the European Initiative on Smart Cities http://setis.ec.europa.eu/set-plan-implementation/technology-roadmaps/european-initiative-smart-cities as part of the Energy Networks point.

  51. Victor Lorenzo
    December 3, 2013

    @Daej, “A generator that drops a certain frequency below 60 Hz would eventually generate heat of bearings and in consequence, drop the voltage in the transmission line of electric, as power supply instability such as phase and voltage fluctuations

    Small frequency variations around the 50/60Hz are allowed by regulations and should be taken care of by designers (electronics and mechanical).

    In the case of monophasic AC motors the rotating magnetic field vector does not describe a circle, but an ellipse, and that in fact conducts to bearing stress by vibrations, but that would be crytical only in case of having one operating point too close to the mechanical resonance frequency of the motor.

  52. Brad_Albing
    December 3, 2013

    @Victor – yes, ou're right — most engineers know to add a battery for powering the equipment during power-down times. Initially, it seems counter-intuitive to add a battery to a power meter. Like you said, if the power goes off, there's nothing to measure; any other time, you have the power you need available for your circuitry. But with the RF link, the power companies can get very accurate info on where power disruptions occur.

  53. Brad_Albing
    December 3, 2013

    @Victor – did not know about that type of dual port memory. Thanks.

  54. Victor Lorenzo
    December 3, 2013

    Hi @Brad,

    This page (http://www.st.com/web/en/home/catalog/mmc/FM76/CL1766/SC1412) lists some from STMicroelectronics. Security support is limited for these chips, once you crack the password all the security is compromised.

    TI has one Dynamic NFC transponder, perhaps with too many pins, that can be 'repurposed'. It is intended for storing NDEF messages for dynamic NFC pairing.

    Fujitsu is also entering the scene (http://www.fujitsu.com/downloads/MICRO/fme/ds-mb89r112.pdf), but it has almost no security at all.

    For more complex systems Atmel has one (http://pdf.datasheetcatalog.com/datasheet/atmel/DOC1943.PDF) RFID-to-EEPROM interface chip.

    In case you need one very secure system TI has one NFC reader/emulator chip (the TRF7970A) that can be combined with one ultra-low power MCU (with some hardware hacks/tricks both can be powered from the RF field and/or with local supply) to emulate ISO14443-A/B tags (all the cryptographic work must be done in the local CPU). Is is fairly easy to implement type-B emulation with this chip, but type-A emulation requires more skills and a more powerfull CPU (forget about the AVR/MSP430 and alike) in order to comply with ISO14443A timing specifications.

  55. Brad_Albing
    December 3, 2013

    @Victor – thanks for that info — that's practically a blog in itself.

  56. fasmicro
    December 12, 2013

    A lot of smart grid buzz these days is about the home.  

    It is the weakest and the easiest link. It is another beast to work at the industrial scale, so we can do smart-grid at homes and feel very good when one company in a city can consumer up to 90% of the city power. In the old America when govt had deep purse, they would have stimulated this to the next level.

  57. fasmicro
    December 12, 2013

    Other than this current Smart Grid technology used by utility companies does not actually detect power theft or equipment failure.

    Where I live in America, there is nothing smart about the grid. Personally, I am not overly worried because when an industry is regulated, I do not expect them to be agile. You cannot ask someone to invest in new technologies when he cannot increase price to recoup. Yet, it is bad to allow that company to be the only operating one.

  58. fasmicro
    December 12, 2013

    @Victor, Europe is a big different from U.S. First, most of their leaders unanimously believe that climate change is caused by human activities. In America, more than 50% of the leaders do not believe that. So, the game here is drill baby drill. Europe shows leadership in its home by using policy to change habits and influencing what companies do. Exxom Mobil enjoys tax credits in US despite having the largest revenue in America

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