Hot-Water Heater Load Scheduling for Late-Night Peak Suppression

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Solution Overview

Problem

Existing water heaters, even with peak-shifting techniques, continue to cause peak power issues during late-night hours as their number increases, leading to elevated electricity rates and operational inefficiencies, particularly in condominiums and smart-towns with collective high-voltage power reception.

Innovation Solution

A hot-water storage type water heater with control means that alternates between high-capacity and low-capacity operations based on predetermined operation patterns, with patterns assigned based on serial numbers or other unique identifiers to distribute load evenly among multiple units, thereby reducing peak power demand.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If water heaters perform water-heating operation during late-night time period with inexpensive electricity rate, then operational cost is reduced, but peak power arises during late-night hours when multiple water heaters operate simultaneously

Engineering Contradiction:
Improveoperational costVSAvoidpeak power demand
Core Design Contradiction:
Use of energy by moving objectVSPower

Solution Approach 1:

The water-heating operation is segmented into multiple operation patterns (first operation at high capacity, second operation at low capacity) that are alternately executed. This segmentation distributes the power demand across different time slots within the late-night period, preventing simultaneous high-capacity operation of multiple water heaters and thus suppressing peak power while still utilizing inexpensive electricity rates.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control means implements periodic action by alternately switching between first operation (high capacity) and second operation (low capacity) according to predetermined operation patterns. This periodic alternation creates a staggered operation schedule across multiple water heaters, smoothing out power demand fluctuations and eliminating peak power surges during late-night hours.

Inventive Principle:
Principle #19Periodic action

2Power

If peak-shifting technique is used to postpone start time of water heater operation, then peak power around start time is suppressed, but peak power still arises later when enough water heaters begin operation

Engineering Contradiction:
Improvepeak power suppressionVSAvoiddelayed hot water availability
Core Design Contradiction:
PowerVSLoss of time

Solution Approach 1:

The system dynamically adjusts operation capacity rather than simply delaying start time. By switching between high-capacity first operation and low-capacity second operation based on predetermined patterns, the system maintains hot water availability while distributing power demand dynamically, preventing both early and late peak power formation.

Inventive Principle:
Principle #15Dynamics

3Power

If collective control of water heaters is implemented on per-condominium or per-region basis to suppress peak power, then peak power is suppressed, but control complexity and operational burden increase significantly

Engineering Contradiction:
Improvepeak power suppressionVSAvoidcontrol system complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

Each water heater is equipped with autonomous control means that independently determines and executes operation patterns based on predetermined settings. This self-service approach eliminates the need for centralized collective control systems, reducing control complexity while achieving peak power suppression through distributed autonomous decision-making at each unit.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively suppresses peak power emergence with a simplified and convenient structure, reducing peak power by approximately 25% compared to conventional methods, while maintaining efficient water heating operations.

Implementation Method 1

a hot-water storage type water heater includes a hot water tank and a control means, the hot water tank storing preheated water

Methodology Applied
Scientific EffectThermal Energy Storage: Thermal Energy Storage

Data Source

PatentEP3382297B1Hot-water supply unit and hot-water supply system
Publication Date: 2021.08.04 MITSUBISHI ELECTRIC CORP
  • EP3382297B1 patent drawingFigure 1
  • EP3382297B1 patent drawingFigure 2
  • EP3382297B1 patent drawingFigure 3

AI summary

A settings data storage (41) stores unique serial numbers and information regarding a plurality of patterns for alternately switching between normal operation for operating at high capacity and suppressed operation for operating at low capacity each unit time. A pattern specifier (43) determines information for a pattern set in accordance with even and odd serial numbers. A water-heating heat amount determiner (45) determines a heat amount necessary for water heating. A water heating scheduler (46) establishes a water heating plan based on information regarding the pattern determined by the pattern determiner (43) and the water-heating heat amount as determined by the water-heating heat amount determiner (45). A water heating controller (47) alternately switches between normal operating and suppressed operation to heat water in accordance with the water heating plan established by the water heating scheduler (46).