Aggregate Load Control Using State-Space Thermostatic Models
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Solution Overview
Problem
Conventional load control strategies for renewable energy integration face challenges such as intermittency, stability issues, and complexity in managing thermostatic loads, particularly due to non-linear aggregate load models and refractory states, which limit their effectiveness in demand response applications.
Innovation Solution
The development of an aggregate load controller using discrete-time zero-deadband thermostatic controllers, which simplifies the control system by removing refractory states and employing a state-space model to manage thermostatic loads, allowing for precise control of electrical energy consumption through a reduced-order observer, direct load controller, and integral error feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional load control strategies are used to manage thermostatic loads, then the system can handle basic demand response, but the system exhibits instability and high sensitivity to modeling errors due to non-linear aggregate load models and refractory states
Solution Approach 1:
The patent transforms the non-linear aggregate load model into a linear state-space model by changing the mathematical representation parameters. This linearization eliminates refractory states and enables stable control while maintaining accuracy in tracking intermittent renewable generation.
Solution Approach 2:
The patent replaces the conventional non-linear control approach with a state-space control framework using reduced-order observers. This substitution provides a more robust mathematical foundation that reduces sensitivity to modeling errors and noise.
2Productivity
If direct load control strategies are implemented to track intermittent renewable generation, then the tracking capability improves, but the system becomes highly sensitive to modeling errors and noise
Solution Approach 1:
The patent implements feedback control through reduced-order observers that continuously estimate system states and compensate for modeling errors and noise. This feedback mechanism maintains accurate tracking of renewable generation while filtering out disturbances.
Solution Approach 2:
The patent introduces an intermediary state-space model that acts as a buffer between the intermittent renewable generation and the thermostatic loads. This intermediary representation smooths out modeling errors and noise while preserving the essential tracking capability.
3Stability of the object's composition
If multiple subgroups of responsive loads are dispatched in sequence to smooth load response, then the load fluctuations are reduced, but the control strategy requires detailed knowledge of aggregate thermal response and becomes more complex
Solution Approach 1:
The patent segments the aggregate load into controllable and uncontrollable portions using a state-space model. This segmentation enables smooth load response through coordinated control of controllable loads without requiring detailed thermal response knowledge of individual buildings.
Solution Approach 2:
The patent creates a universal control framework that handles both smoothing of load response and tracking of renewable generation through a single state-space model. This multi-functional approach eliminates the need for separate control strategies for different objectives.
Data Source
AI summary
Aggregate load controllers and associated methods are described. According to one aspect, a method of operating an aggregate load controller includes using an aggregate load controller having an initial state, applying a stimulus to a plurality of thermostatic controllers which are configured to control a plurality of respective thermostatic loads which receive electrical energy from an electrical utility to operate in a plurality of different operational modes, accessing data regarding a response of the thermostatic loads as a result of the applied stimulus, using the data regarding the response, determining a value of at least one design parameter of the aggregate load controller, and using the determined value of the at least one design parameter, configuring the aggregate load controller to control amounts of the electrical energy which are utilized by the thermostatic loads.