Demand response potential of water heaters to mitigate minimum generation conditions

Abstract

During periods of low electricity demand, particularly when demand drops below baseload supply levels, a system operator can encounter difficulties in efficiently dispatching its generating units. Referred to as 'minimum generation conditions (MGC),' these states are troublesome because they can lead to increased greenhouse gas emissions, depressed electricity prices, or additional barriers to renewables integration. This work explores the potential of using electric water heaters (EWHs), in a demand response (DR) role, to mitigate the number and severity of these MGCs. A detection method for finding MGCs is first applied to the system in Ontario, Canada. At 2018 renewables target levels, it was found that most MGCs would occur in the early morning of spring and fall. To significantly address this issue next generation EWHs employing DR would need a deadband of 10 • C to enable the 800+ MW required.Index Terms-load management, renewable energy, smart grids, surplus baseload, water heating TABLE I NOMENCLATURE Sets and Parameters α 0 (t) Probability of q(t) changing from 0 to 1 (fraction) α 1 (t) Probability of q(t) changing from 1 to 0 (fraction) aRate of heat loss to surroundings (through insulation) (per min) A Rate of temperature loss when hot water is drawn ( • C/min) R Rate of temperature gain when element is on (Variables m(t) State of heating element (0-off, 1-on) q(t) State of water extraction (0-off, 1-on) x(t) Hot water temperature ( • C)

Managing electric flexibility from Distributed Energy Resources: A review of incentives for market design

“…Their availability depends a lot on the appliance considered: whereas electric space heaters have a good availability (0.4 oa r o1) due to the fact that they are turned on for long periods of time, washing machines have a very limited one (a r o0.1) as they are typically turned on once every two days for two hours [48,49]. Similar rationale applies for their predictability [41,50]. Heat pumps coupled with thermal energy storage stand out in this category; their max power temporal ratio can reach up to 3 h without any inconvenience for end-users [51], making those units suited for longer grid services such as peak shaving.…”

“…Differently, this could be directly to avoid reliability problems like network congestions [30]. In the PJM market, direct control is managed by the curtailment service provider [50]. This means that a central actor has direct access to the load and is able to reduce or increase this as required for the system and/or for portfolio management purposes.…”

Primary Frequency Control Contribution From Smart Loads Using Reactive Compensation

“…In this case, the compensator is required to inject about 10% of the rated voltage while the variation in voltage across the NC load is limited to ±10%. This transient voltage variation will not cause perceivable change in the performance of NC loads like heating [16], lighting (especially, LED lighting [17]), and small motors with no stalling problems (e.g., fans, ovens, dish washers, dryers) [18]. With normal loads (red traces), the mains voltage would increase (decrease) in the under-(over-) frequency case which aggravates the situation resulting in the poor frequency regulation.…”

“…The basic aim in all these methods is to control the system voltage within an allowable limit rather than controlling the frequency by manipulation of load. With certain types of voltage-dependant loads e.g., electric heating [16], lighting (especially, LED lighting [17]), small motors with no stalling problems (e.g., fans, ovens, dish washers, and dryers) [18], it is possible, in principle, to exercise a continuous variation in active power consumed by controlling the supply voltage [19]. However, it is neither straightforward (given the stiffness of even moderately weak systems) nor recommendable (as there are sensitive loads connected to the mains which require tightly regulated voltage) to vary the supply/mains voltage.…”

Demand response potential of residential HVAC loads considering users preferences

“…Nevertheless, recently there are a few papers in the literature that gave the attention to this area. For instance, reference [9] determined the DR potential of electric water heater to cope with minimum generation situation, while the work in [10] quantified the load reduction potential of space heating systems. However, neither of the works provides a comprehensive estimation of DR potential of residential HVAC loads.…”