Showing posts with label Solar Electrical Systems. Show all posts
Showing posts with label Solar Electrical Systems. Show all posts

Saturday, December 6, 2014

Towards a Design of a Parallel AC/DC Mains System for Single Residential Application

On a "research lark" about solar energy systems, today, I've found a resource published by Emerson Network Power, such that I would like to make a small note about, here in my DSP42 web log.

 Considering:
  • Solar energy systems produce DC signal -- as before any conversion to AC via diodes, inductors, transistor driven voltage regulators, etc -- as possibly before any conversion back to DC, then, as when for driving digital electronics and DC appliances
  • DC electrical signals may be suitable for decentralized applications not requiring any unspecific number of long-distance electrical transmission lines
  • That towards a design for a residential DC/AC parallel lines system, insofar as the DC line system, there may be an analogy found in data center architectures

Found Resources:
  • Murrill Mark  and B.J. Sonnenberg. "Evaluating the Opportunity for DC Power in the Data Center" Emerson. 2010
    • Notes
      • Modular Design
        • 480 V AC mains (common)
          • Step-downs to 208 V AC
        • Cooling system (p. 7)
        • PDUs, BDBC systems
          • Topology of power distribution network
          • Switched-mode power supplies may introduce harmonics of signals on AC lines (p. 6)
            • Affects accumulate in neutral line
              • Mechanical model: TBD
            • Desultory effects:
              • Power loss
              • Source of heat energy within data center/components
            • Related concept: Total harmonic distortion within power distribution network
          • Variations in system load 
            • At interfaces onto three-phase AC systems: Timing/scheduling of load changes within data center, onto phases of three-phase AC system (noted, p. 6) (?) ideal, to minimize power loss and generation of heat energy
              • Mechanical model: TBD (Three-phase AC)
            • See also: Phase Balancing: The Last Few Inches of a High-Efficiency Power System (referenced, p. 7)
            • Scheduable load changes (macro model):
              • Instance: Current loads induced for battery charging within uninterruptable power supply (UPS) systems
              • Instance: Current loads induced due to computing loads, in application of computing resources within batch computing models
            • Unschedulable load changes (macro model):
              • Instance: Computing loads resulting of direct user agent interactions
              • Mitigating concern: Interactive network services can be localized to individual data center elements
        • Energy consumption
          • Data center components - Digital computing
          • Battery charging in UPS systems
      • DC voltages
      • Safety and standards

Resources at a beginning of this research arc:
  • News article Worlds Largest Solar Plant Goes Online Using 9 Million Solar Panels
    • A large scale, grid-centric solar energy system recently developed by PG&E
  • Concepts towards applicability (residential energy systems): 
    • Concept: DC motors
      • (TBD)
      • Industrial applications
        • ShurFlo DC centrifugal pump, from ShuFlo industrial
          • Possible applications in decentralized solar/battery systems for agriculture, industry, and recreational maritime systems
      • Residential/Utility applications
        • Battery-operated/cordless home utility equipment and construction tools
    • Concept: DC appliances
      • (TBD)
      • Common:
        • Residential air conditioning and heating systems
          • Consdenser and motor in air conditioning systems
          • Heating coils
          • Swamp coolers (humidity)
        • Residential air circulation (e.g. ceiling fans)
        • Food refrigeration
        • Lighting appliances
          • Filaments (AC lighting)
          • "Warmth" of lighting model
    • Concept: DC power supplies within/for home entertainment systems
      • Video
      • Audio
      • (TBD)
  • Previous article in solar electrical series, here at my DSP42 web log

Thursday, November 27, 2014

Solar/Mains SSR-Switched Electrical System Design, Version 1 - Off-Topic Electrical System Design Idea Nr 4234

The following represents a second draft of my own written response to a discussion forum item, this evening. The initial question was, essentially, to illustrate an application of a comparator element, within an electrical circuit -- as in a context near to a discussion of op-amps, though of course a comparator is not essentially an op-amp.

Sure, the initial question sort of  asks for a response that would require a respondent to pull a design out of thin air. Having tried to find any sort of an interesting, practical application of this particular kind of electronic systems component to respond about, then, I had thought - at first - that a comparator could be used for a switched power supply. That's really a stretch, I know -- moreover, an instance of confusing a comparator with a switch -- but at least it fits the requirement of providing a practical example of a comparator, insofar as at least illustrating a hypothetical application of that one of many different types of electrical circuit element.

Proceeding as to refine the design I proposed in my response, I've been able to sketch up at least a high-level block diagram for ... some electrical things and stuff -- nothing competitive, but insofar as it would involve a circuit onto AC mains, nothing I'll share unless it was a thoroughly tested design.

The following is now my note's page for such a thing, which here I'll share for later reference.


A comparator may be applied as a voltage switch, perhaps in designing a circuit for a switched power supply of two possible voltage sources, wherein at least one voltage source may provide a varying voltage over duration of time. A single comparator would provide an output for a single voltage source providing an input of a higher voltage.  (Ed. Note: This is where I began confuse a comparator with a switch)

If a power supply would need to switch between more than two voltage sources, and only comparators would be available, then perhaps multiple comparators could be cascaded, with or without additional solid-state circuit elements in the cascade design.


Candidly, this may present an essentially crude design description. With some further refinement in the design, perhaps a comparator element could be of use for a battery switching circuit, such as in a solar electrical system -- namely as to provide a continuous output voltage and output current, across the output cycle of the solar cells and the charge cycle of any number of batteries. 

Alternately, a digital switching circuit could be applied, together with a programmed AVR microcontroller -- as in the Instructables items, below --implementing a PWM controlled charging model between the solar cells and the batteries, along with additional control and display functionality, in the solar/battery/load electrical system.

(Ed Note: The following paragraph represents, essentially, an instance of confusing a comparator with a switch)
Alternately, perhaps a comaprator circuit may be applied in a switching model for a combined grid/off-grid electrical system -- as for switching onto AC residential mains, outside the system's inverter, in case of battery under-voltage or other solar system failure, to the reference point of the inverter's output. In such an application -- in a simple view, albeit -- perhaps an AC coupled comparator would be applied, if having an input frequency range compatible with AC mains current. Perhaps a relay-driven switch with a solid state relay might be more readily applicable, for switching the input at a point beyond the inverter, in such a system.

Works Consulted:

[1] Radio-Electronics.com. Op-Amp Comparator Circuit
[2] Radio-Electronics.com. Op-Amp Schmitt Trigger Circuit 
[3] Instructables.  Arduino Solar Charge Controller (Version-1)
[4] Instructables. DIY Off-Grid Solar System 
[5] Texas Instruments.  AC Coupled Comparator Reference Design  (60 Hz not within input frequency range, component probably not designed for application on AC residential mains)
[6] Phidgets. Solid-State Relay Primer


DPDT solid state relay: Charter Electronics 38.21 

Residential/Household Electrical - Concepts and Standards
Comparators - Additional Reources:

Thursday, October 30, 2014

Figuratively Setting Point and Mark Onto: Further Research Regarding Household-Local Applications for DC Electrical Systems in a Contemporary Environment

The following is a response I'd written for a private discussion forum, today. This, effectively, is "Draft 1" of a thesis.

Insofar as in applying a power supply to an existing electrical circuit component -- in an instance of if there was not a power supply provided with the component, or if the provided power supply was unavailable -- I would first endeavor to read the specifications of the item, to see what type of current -- perhaps trivially, AC or DC -- and what amperage, and what voltage would be required by the component, so far as would be published by the component's manufacturer.

Offhand, I'm at last outwardly familiar with a "Wall wart" kind of power converter -- as would typically be provided with a laptop -- or an AC-to-DC-over-USB converter, as insofar as charging for mobile electronics from an AC electrical source. Of course, those are all designed for a single-phase household current, in a consumer electrical domain -- as namely for charging and for consistent power of digital electrical devices, each having an internal or detachable battery.  Of course, the battery in such a device, itself, would be a type of power source also.

So, as far as electrical sources and their corresponding power adapters, without seeking any too formal reference, offhand:
1) The AC-to-DC power converter in the form of a "Wall wart," so to speak (AC input, DC output)
2) The AC-to-DC power converter provided of an AC-to-USB power adapter (AC input, DC output)
3) Direct household AC electrical (AC input, AC output)
4) Three-phase industrial electrical. (AC input, three phase, AC output, three phase)
5) Rechargeable battery (DC input, DC output) 
6) Non-rechargeable battery (DC output)

Perhaps in a bit of a sidebar, as with regards to DC electrical systems:  Candidly, I don't imagine there's been as much standardization for DC power inputs, in digital devices -- as much as with regards to so much standardization as developed around household AC systems, regionally, and industrial AC systems, likewise. Perhaps there may ever be some more standards developed for DC power systems, however -- as could be developed in terms of ideal voltage and ideal amperage, such as for powering a heterogeneous range of DC powered devices, prospectively from a grounded household DC line, as might be run in parallel to a grounded household AC line, within a context of a single household?

Perhaps, if one may endeavor to develop any small effort towards a manner of standardization as such, perhaps it could be of some relevance with regards to development of solar electrical systems?

Candidly, I'm not sure of how well such a concept might be adopted in any single industry, however -- so, but perhaps one may endeavor to develop an initial "Proof of concept," a working prototype, sometime, for implementing a household DC line -- perhaps, towards a primarily DC electrical system extending of a solar electrical source, and safely so? Certainly, in a context of a household, a DC electrical current may not need to travel a really long distance -- with an apology, that I know this represents such that one may seek any number of formal references about, if one was to develop a complete thesis about such a concept.

Of course, there are applications for AC inductance, such as of any number of conventional AC devices -- as might typically be in regards to motors and heating elements -- such as may be powered indirectly from a household DC line, if not directly from a household AC line -- and of course, there could be a development of any number of standards as such, as  might be addressed firstly around paramount concerns for household safety, in applications, such as insofar as for ensuring a consistent ground, within a prospective, household DC electrical system.

Certainly, there are applications for AC inductance, in household and industrial electrical systems. In regards to industrial domains, certainly, I've read of a transition from DC electrical systems to AC electrical systems, in industry.[1] My not being immediately too familiar with the theoretical qualities of such a transition, but if there may have been, previously, any systems developed for DC power in regards to motors and heating elements, perhaps such old designs could be rennovated somehow, perhaps towards a contemporary application onto solar electrical systems, and broader DC electrical systems? Certainly, with digital systems being so broadly available in the consumer market -- assuming that any single digital system runs on a DC power supply, directly -- then if a DC electrical system could be developed as to support an adequate range of amperage and voltage ratings, among individual digital household devices, though it might seem to represent something of a shift away from conventional household and industrial electrical sources, but perhaps there might ever be an emerging market discovered for such technology.

Insofar as if one may find any applications for DC electrical systems -- such as for a simple feat of driving an electrical motor, for instance, from a DC current, such as for a household air conditioner, in its condenser and motor elements, or a household refrigerator, in a similar regards, or any motorized or heater-type household tools as in a proverbial electrical-powered shop  -- but if there may be any similar elements in industrial applications of DC electrical systems, perhaps there may be some similar works developed for household applications.

So, barring any lobbying to the contrary -- candidly -- perhaps there might be a broader application available for DC electrical systems, in household applications, focusing on essentially short-distance household wiring systems and their corresponding safety elements, as well as the solar domain of electrical sources? One might hope it would not seem like a devolution in electrical systems, however -- perhaps, rather towards something of a decentralization, in some regards?

Certainly, I've read of some of the press around households endeavoring to "Go" effectively "Off grid" with solar electrical systems. So, I would certainly not want to be too hasty in any of such a design then, certainly -- though it may seem somehow viable, theoretically, and perhaps none too problematic, electrically, if one may develop a system for a household DC current, and safely so?

Works Referenced:

[1]  Rockwell Automation. DC vs. AC drives: Why should I upgrade if it still works? Feb, 2014

Towards Draft 2 of this thesis, Ed. Notes:

  • This is not to revisit the War on Currents [Wikipedia] Certainly, the essentially decentralized nature of a solar-electrical system -- considered onto the open market, broadly in a global scale -- may permit for a warless development of a household DC electrical system. One might assume, furthermore, that there would not be any high-voltage lines implemented on Mars, at any time soon.
  • The decentralized character of a solar/battery systems may bear some specific note, as in regards to development of solar energy systems for rural applications
  • The International Space Station certainly would be using a lot of DC-signal energy also
    • Solar, perhaps together with fuel cells.
    • How does one ground an electrical system, in outer space?
  • Concept, version 2: Parallel-line AC/DC mains system for localized residential application
    • Safety concern: DC grounding
      • Common ground line for each of AC and DC household mains?
    • Technical question: Possible interference to DC mains lines, from AC mains lines?
    • Practical concerns: 
      • Differing DC current and voltage ratings in DC appliances
      • Block Diagrams
      • Proof of Concept - Case Studies
      • Specifications
      • Safety
  • See also: Next article in research arc