Distribution Feeder Voltage Control Using DER Integral Feedback
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Solution Overview
Problem
The integration of distributed energy resources (DERs) in distribution systems leads to voltage fluctuations that exceed or drop below allowed limits, necessitating active management, which is challenging due to the dynamic nature of DER integration and the difficulty in maintaining an updated power system model.
Innovation Solution
A method for integral voltage control in distribution feeders using feedback control with an integrator-based controller that generates control actions for controllable DERs to absorb or inject reactive power, and adjust active power, without requiring a power system model or additional hardware, ensuring voltage remains within defined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If DERs are integrated into the distribution system to increase renewable energy usage, then the quantity of energy sources increases, but voltage control becomes difficult and voltage violations occur
Solution Approach 1:
The patent implements a feedback control mechanism where voltage measurements from multiple locations along the feeder are continuously monitored, compared against voltage limits, and used to generate corrective control actions. The error between measured voltage and defined voltage limit is fed into an integrator that generates control actions to counteract voltage deviations, ensuring voltage remains within acceptable ranges despite high DER penetration.
Solution Approach 2:
The control system utilizes the existing voltage regulating capabilities of DER inverters themselves to maintain voltage. DERs are instructed to supply or absorb reactive power based on local voltage measurements and control signals, allowing them to self-regulate and contribute to voltage control without requiring external voltage regulation equipment.
2Reliability
If optimization-based voltage control methods are used, then voltage can be maintained within limits, but a power system model is required which is difficult to maintain updated
Solution Approach 1:
The control system utilizes the existing voltage regulating capabilities of DER inverters themselves to maintain voltage. DERs are instructed to supply or absorb reactive power based on local voltage measurements and control signals, allowing them to self-regulate and contribute to voltage control without requiring external voltage regulation equipment.
Solution Approach 2:
The patent changes the approach from using a complex power system model with multiple parameters to a simple feedback mechanism that only requires voltage measurements and voltage limits. By focusing on voltage magnitude as the key parameter and using an integrator to generate control actions, the system achieves voltage control without needing detailed power system models, thereby reducing complexity while maintaining effectiveness.
3Reliability
If DER inverters supply reactive power locally based on local voltage measurements, then voltage regulation is improved, but additional hardware or complex coordination is required
Solution Approach 1:
The patent makes existing DER inverters multi-functional by enabling them to perform both their primary function of active power generation and a secondary function of voltage regulation. By utilizing the existing reactive power capability of standard DER inverters and coordinating them through a centralized control system that distributes control actions, the system achieves voltage regulation without requiring additional dedicated voltage regulation equipment at each DER location.
Data Source
AI summary
A method for controlling voltage in a feeder of a distribution system having a plurality of DERs includes executing a feedback control using an integral controller. A voltage signal is generated using measured or estimated voltages at multiple locations along the feeder. An error is determined between the voltage signal and a defined voltage limit. The error is input to a controller including an integrator to generate a control action to counteract the error. The control action is distributed among at least some controllable DERs, from the plurality of DERs, that are capable of responding to the control action by generating actuation signals for absorbing reactive power from or injecting reactive power into the feeder, and/or for reducing active power or increasing active power in the feeder. The control action continues to increase until the voltage signal reaches the defined voltage limit, to thereby control voltage in the feeder.