Parallel Generator Inverter Control for Stable Load Sharing
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Solution Overview
Problem
Existing systems with multiple generators mechanically coupled to a prime mover face challenges in deterministic power split and poor load sharing, especially during torque and speed changes, and fail to quickly respond to faults, leading to potential overload and damage.
Innovation Solution
A system comprising multiple processors and inverters, where each inverter is connected to a generator, receives a common speed command, adjusts it to create a droop, and determines a torque command to maintain load sharing and respond to faults by adjusting torque or disabling faulty generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If one inverter/generator is used as primary controller (speed mode) and others as secondary controllers (torque mode), then steady state load sharing is achieved, but load sharing becomes poor when torque and speed change
Solution Approach 1:
The patent implements dynamic role assignment where inverters switch between primary and secondary controller roles based on real-time system conditions. Each inverter can become the primary speed controller when needed, allowing the system to adapt to changing torque and speed conditions while maintaining proper load sharing. This dynamic switching resolves the contradiction by making the control architecture flexible rather than static.
Solution Approach 2:
The system changes control parameters dynamically - inverters switch between speed control mode and torque control mode based on system state. The primary controller uses speed references while secondary controllers use torque references, and this parameter switching allows the system to maintain both steady-state stability and adaptability during transients.
2Reliability
If primary controller fails, then system continues operation, but engine may be overloaded and potentially damaged due to reverse operation
Solution Approach 1:
The system pre-configures all inverters with the capability to become primary controllers, and establishes predetermined protocols for controller failure detection and role transition. When a primary controller fails, a secondary controller is already prepared and can immediately take over the speed control function, preventing engine overload before it occurs.
Solution Approach 2:
The system continuously monitors controller status and system operating conditions through feedback mechanisms. When a primary controller failure is detected, the feedback triggers an automatic role reassignment where a secondary controller becomes the new primary, ensuring continuous proper speed control and preventing harmful engine operation.
3Power
If multiple generators are mechanically coupled to the same output shaft, then power can be shared among generators, but deterministic power split and load sharing control becomes difficult
Solution Approach 1:
The patent segments the control function by assigning distinct roles to different inverters - one primary controller that manages speed and one or more secondary controllers that manage torque. This segmentation of control responsibilities simplifies the overall system while enabling deterministic power split, as each controller has a specific, well-defined function rather than all controllers attempting to manage all parameters.
Data Source
AI summary
A system for controlling load sharing between multiple generators mechanically coupleable to the output shaft of a prime mover is provided. The system may comprise a first processor; and at least two inverters operably connectable to at least two generators, respectively. The generators provide AC power to the respective inverter and each inverter provides DC power to a respective DC link. Each inverter may comprise a processor configured to control a respective generator. The processor may be configured to receive a common speed command from the first processor, adjust the common speed command based on a speed of the same output shaft to create a droop, determine a torque command based on the adjusted speed command and supply the determined torque command to the corresponding generator.