Generator Voltage Control for Engine Load Protection

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Solution Overview

Problem

In power generation systems, high load inputs can cause the target voltage of generators to become unnecessarily low, leading to excessive engine loads and hindering normal electric power supply to loads, which can result in engine operation failures.

Innovation Solution

A control device and method that adjust the target voltage of generators based on engine rotation speed or frequency, using a target voltage regulator to reduce voltage when loads are connected, maintain it at a lower limit for stable operation, and increase it back to rated levels when conditions stabilize, ensuring minimal engine speed reduction and rapid recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the target voltage of the generator is reduced in accordance with the decrease amount of the rotation speed of the engine, then the excessive load on the engine is avoided and the recovery time of the rotation speed is shortened, but the output voltage becomes unnecessarily low and normal supply of electric power to loads is hindered

Engineering Contradiction:
Improveengine protection from excessive loadVSAvoidelectric power supply to loads
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The invention changes the control parameter from directly reducing target voltage proportionally to rotation speed decrease to using a predetermined fixed voltage reduction value. This parameter change resolves the contradiction by preventing the target voltage from becoming excessively low while still providing sufficient voltage reduction to protect the engine from excessive load during sudden load input.

Inventive Principle:
Principle #35Parameter changes

2Speed

If the target voltage of the generator is reduced to protect the engine from excessive load, then the rotation speed reduction is suppressed, but the normal operation of loads is hindered due to insufficient voltage

Engineering Contradiction:
Improverotation speed recoveryVSAvoidvoltage for load operation
Core Design Contradiction:
SpeedVSPower

Solution Approach 1:

The invention changes the voltage reduction strategy from proportional reduction based on rotation speed decrease amount to a predetermined fixed reduction value. This ensures that the target voltage is reduced sufficiently to protect engine rotation speed while maintaining it above the level required for normal load operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention implements feedback control by detecting the actual rotation speed of the engine and comparing it with the rated rotation speed to determine whether to apply the predetermined voltage reduction. This feedback mechanism ensures voltage reduction is applied only when necessary (during sudden load input causing rotation speed decrease) and maintains normal voltage when the engine operates normally.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3570427B1Power generation system control device and control method
Publication Date: 2021.08.11 MITSUBISHI HEAVY IND ENGINE & TURBOCHARGER LTD
  • EP3570427B1 patent drawingFigure 1
  • EP3570427B1 patent drawingFigure 2
  • EP3570427B1 patent drawingFigure 3~4

AI summary

A control device 4 for a power generation system 1 includes a target voltage regulator part 43 configured to adjust the target voltage Vr of a generator 3. The target voltage regulator part 43 has: a voltage decrease function to reduce the target voltage Vr of the generator 3 in accordance with a decrease amount of a detection value Sm of a rotation speed S of a gas engine 2 or a frequency of the generator 3 if the detection value falls below an allowable variation value when a load is connected to the generator 3 via a circuit breaker 5; and a voltage decrease limiting function to maintain the target voltage Vr of the generator 3 at an allowable lower limit voltage determined on the basis of an output voltage V which is allowable to carry out normal operation of the load if the target voltage Vr of the generator 3 is lower than the allowable lower limit voltage.