Heat Pump Water Heater Controller for Grid Stress Response
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Solution Overview
Problem
Heating systems face challenges in efficiently responding to grid stress events, balancing user needs with grid stability, especially with the transition from centralized to distributed renewable energy sources, where system inertia and reserve capacities are reduced, leading to fluctuations in demand and voltage frequency.
Innovation Solution
A heating system comprising a tank, a heat pump, an electric heating element, and a controller that detects grid stress events by measuring mains current frequency and voltage, determines a heat pump energy penalty, and adjusts power distribution between the heat pump and electric heating element to optimize energy usage and reduce wear and tear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the heat pump is used to provide heat in response to grid stress events, then energy efficiency is improved, but response time and reliability deteriorate due to the energy penalty and wear and tear
Solution Approach 1:
The system pre-heats the water tank before grid stress events occur by utilizing off-peak electricity or surplus renewable energy. This preliminary action ensures that sufficient hot water is available when grid stress events occur, allowing the heat pump to avoid rapid start-stop cycles and maintain reliable response while improving overall energy efficiency.
Solution Approach 2:
The water tank serves as a thermal intermediary between the heat pump and the heating demand. During grid stress events, the tank's stored thermal energy mediates the system response, allowing the heat pump to operate smoothly without rapid cycling, thereby maintaining reliability while achieving energy efficiency benefits.
2Ease of operation
If the heat pump operates frequently to meet heating demand, then user requirements are satisfied, but wear and tear increases reducing system longevity
Solution Approach 1:
The system performs preliminary heating of water during periods of low demand or off-peak electricity rates, storing thermal energy in the tank. This allows the heat pump to operate less frequently during peak periods while still meeting user heating requirements, thereby reducing wear and tear and extending system longevity.
Solution Approach 2:
The water tank provides self-service by storing thermal energy and delivering it to meet heating demand without requiring continuous heat pump operation. This reduces the operational frequency and wear on the heat pump while maintaining user requirement satisfaction.
3Speed
If the heating system responds quickly to grid stress events, then grid stability is improved, but energy efficiency deteriorates due to heat pump energy penalty
Solution Approach 1:
The system responds to grid stress events by drawing from pre-heated water in the tank rather than rapidly starting the heat pump. This preliminary heating action enables quick response to grid demands while avoiding the energy penalty associated with heat pump startup and frequent cycling, thus maintaining both response speed and energy efficiency.
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
The system enables efficient and responsive energy management during grid stress events, optimizing energy usage and reducing wear on the heat pump by dynamically adjusting power distribution based on detected grid conditions and user requirements.
Implementation Method 1
a heat pump arranged to provide heat to the tank
Implementation Method 2
an electric heating element disposed in the tank for heating water
Data Source
AI summary
A heating system (100), a controller (110) for a heating system and a method of controlling a heating system (100) suitable for responding to grid stress events are disclosed. A heating system (100) comprises a tank (104) for holding water; a heat pump (102) arranged to provide heat to the tank (104); an electric heating element (108) disposed in the tank for heating water; and, a controller (110) configured to: control electric power from an electric power grid to the heat pump (102) and the electric heating element (108); detect a grid stress event; determine a heat pump energy penalty for providing heat in response to the grid stress event under a present operating condition; and, vary, in dependence on the determined heat pump energy penalty, a power provided to the electric heating element (108).