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My take is that in principle, loads should control themselves, and integrate their functional control goals with their power distribution context (price) and then determine how to operate.
Clearly today few devices can natively take in prices so we need external controls or software updates to do that, and a BMS could be such an external control - but it could be price-based. Occasionally a BMS system will co-optimize multiple end uses, such as deciding how much to use daylight vs shading and artificial light to illuminate a space, considering the HVAC context, but that is the exception, not the norm. Most end uses are independent.
Occasionally building controls need to consider power capacity - rarely because it is in short supply - more commonly due to EVIL demand charges. Most commonly the resource in question is energy.
If we can do everything with pricing alone, why not do that? What is the benefit of going to more complicated systems?
We can only determine the answer to that question with empirical experiments, but I don't think we should add complexity only on the theoretical possibility that is needed - we should only added when we are convinced by evidence that it is.
On Thu, May 6, 2021 at 2:14 PM James Kempf <kempf42@...
Yes, that's roughly correct. If the grid is connected, there may be other loads that might be controlled, like a hot water heater or pool pump.
Thanx for the link to the software controllable breaker, Levatron has a smart panel
. I think one issue with these devices is that the software is probably not very easy to use, which is where Span
has focused their efforts. Span's panel is a sort of nano grid controller, but they need to do custom, bespoke integrations with every battery and solar panel system due to the lack of a standard control protocol. I think they integrate with Tesla (the company was founded by former Tesla folks) and I think LG Chem.
Apologies for my answer delayed due to
“Golden Week holidays/National holidays in Japan”.
Thank you for your correction and detailed explanation about your view of load control. I have updated the meeting minutes. Please check it.
In addition to the correction, I have some questions about the way to prioritize. In short, you expect the microgrid controller or microgrid has the following functions :
The communication path to BMS (Building Management System) to control HVAC for load shading.
To control a breaker board to manage the load. Under the circuits below, the microgrid/nanogrid controller may control the connection /disconnection of the following circuits to copy with the generation
A Circuit is connected to a refrigerator and internet router
B Circuit is connected to a microwave
C Circuit is connected to a tv set.
Please suggest me if my understanding is correct.
BTW, The company named B!ixt provides software controllable breaker.
With best regards,
From: James Kempf <kempf42@...>
Sent: Saturday, May 1, 2021 2:41 AM
To: Jinushi, Kotaro (Sony CSL) <Kotaro.Jinushi@...>
Subject: Re: [hyphae-tsc] Hyphae TSC Meeting [Every Other Thursday] - Thu, 04/29/2021 6:00pm-7:00pm #cal-reminder
Thanx for sending out the meeting notes. I'd like to clarify my position w.r.t. load control.
It is not that I don't think load control is needed. Actually, it is important for a microgrid, especially one having exclusively renewable generators, to be able to shed load when grid disconnection happens. In addition,
even if the grid is connected, it is important to be able to schedule load when renewable generation is high on the grid or the TOU tariff is low and deschedule it when renewable generation is low or the TOU tariff is high. This allows such strategies as using
a building as a thermal battery by precooling it during the afternoon to below the ideal temperature when the grid has lots of solar generation and turning the HVAC system off in the evening when the solar resource starts to go away.
For this reason, I think having the microgrid be able to control prioritized circuits when the grid is down, and be able to control when HVAC equipment and hot water heaters run when the grid is up is necessary. The actual
prioritization and scheduling of loads should be done by the building energy management system not the microgrid controller, as these are functionally distinct. Soft circuit prioritization is also more desirable than hard circuit prioritization. Having the
priority controlled through a building energy management system allows the circuits that are energized to change during the day when the grid is down rather than having a critical loads subpanel where a fixed set of loads are backed up and the others are not.
I would like to have an OpenAPI 3.x REST API between the building energy management system and the microgrid controller for indicating which circuits are prioritized when the grid is down and when HVAC and hot water heater
loads should run. Also when to charge the battery and when not, but I think that is already covered by Hyphae. A separate API between the microgrid controller and load circuits and major loads turns prioritized loads on and off when the grid is down and the
HVAC equipment and hot water heater on and off for flexible scheduling. The latter might be available through protocols such as BACnet or Modbus, but having a REST API on top of those protocols would greatly enhance interoperability. Scheduling flexible loads
may not require the microgrid controller to talk directly to the HVAC equipment, it might just require the building energy management system to tell the microgrid controller when to run the HVAC.
What I don't think is necessary is fine grained load control of individual devices. For example: "I would like my porch light to be switched on and the stereo playing when I get home from work". That is basically a lifestyle
type function, and while I image it could be important, I don't see it as relevant to microgrids (though it is relevant to building energy management systems). My view is that the CHIP (Connected Home over IP) consortium is addressing such lifestyle/smart
home functions, since they say nothing about controlling batteries or DERs in their charter.
I have update the meeting minutes below. Should you have anything to add or modify, please proposed it.
Next time, we will discuss the use case scenarios which we would like to tackle with this project. These scenarios
will be posted to the ML before the call.
With best regards,
Reminder: Hyphae TSC Meeting [Every Other Thursday]
When: Thursday, 29 April 2021, 6:00pm to 7:00pm, (GMT-04:00) America/New York
Organizer: LF Energy Operations
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Topic: Hyphae TSC Meeting
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Meeting ID: 991 0311 4295
Bruce NordmanLawrence Berkeley National Laboratorynordman.lbl.gov
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