Diesel-Storage Microgrid Synchronization for Overcurrent Control
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Solution Overview
Problem
Existing diesel-storage independent microgrid systems face challenges in balancing power distribution during dynamic processes due to the inertia of diesel engines, leading to overcurrent issues and potential damage to power electronic equipment.
Innovation Solution
A method for calculating a dynamic synchronous torque damping coefficient is introduced, allowing for adaptive and dynamic adjustment of the virtual torque of an energy storage converter, even when the inertial parameters of the diesel engine are unknown. This method involves calculating the dynamic synchronous torque damping coefficient based on the angular accelerations of the diesel generator and the energy storage converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional droop-controlled energy storage converter is used in parallel with diesel engine, then parallel synchronous output is achieved, but power distribution becomes unbalanced during dynamic process causing overcurrent
Solution Approach 1:
The invention changes the control parameters of the energy storage converter from conventional droop control to virtual synchronous generator (VSG) control, simulating inertia and damping characteristics. This parameter transformation enables the energy storage converter to match the diesel generator's dynamic response, achieving balanced power distribution during transient processes and preventing overcurrent conditions.
Solution Approach 2:
The invention introduces virtual inertia and virtual damping coefficients as intermediary parameters that mediate between the diesel generator's mechanical inertia and the energy storage converter's electrical characteristics. These virtual parameters act as a bridge, enabling smooth power sharing and synchronized operation without causing harmful overcurrent effects.
2Reliability
If VSG simulates inertia of diesel generator, then multi-channel synchronous power supply is realized, but oscillation characteristic of synchronous motor rotor is introduced causing active power oscillation
Solution Approach 1:
The invention implements feedback control by continuously monitoring the active power output and adjusting the virtual damping coefficient dynamically. The feedback mechanism detects power oscillations and compensates for them by modifying the damping characteristics, thereby suppressing rotor oscillation effects and stabilizing active power delivery in the parallel VSG system.
3Stability of the object's composition
If existing oscillation suppression technology is used, then active power oscillation is suppressed, but virtual inertia introduced is far greater than system inertia causing equivalent inertia coefficients to be approximately the same
Solution Approach 1:
The invention makes the virtual inertia coefficient dynamic rather than fixed. The virtual inertia adapts in real-time based on system conditions, load characteristics, and the diesel generator's actual inertia. This dynamic adjustment enables proper inertia matching between the diesel generator and energy storage converter, preventing the virtual inertia from being excessively large while maintaining oscillation suppression effectiveness.
4Stability of the object's composition
If diesel engine parameters are fixed, then diesel generator operation is stable, but inertia matching of parallel system cannot be realized under high energy pulse load
Solution Approach 1:
The invention changes the energy storage converter's control parameters dynamically to match the fixed diesel generator parameters. By adjusting virtual inertia and damping coefficients based on real-time system state and load conditions, the energy storage converter adapts its characteristics to achieve inertia matching with the diesel generator, even under high energy pulse load conditions where the diesel parameters remain fixed.
Data Source
AI summary
A diesel-storage independent microgrid and a virtual dynamic synchronous control method and system are described. An adaptive dynamic synchronous torque and pre-synchronous compensation phase angles are introduced into a energy storage converter control system to realize output voltage and power synchronization before and after parallel connection of the system. By compensating the pre-synchronous phase angles, the phase angles of a diesel generator and an energy storage converter are kept consistent before parallel connection, which reduces current impact during the parallel process. By introducing the adaptive dynamic synchronous torque, after the parallel connection of the system, the virtual torque of the energy storage converter can be adaptively and dynamically adjusted according to the current accelerations of the diesel generator and the energy storage converter under the condition that the inertial parameter of a diesel engine is black-boxed.