Wind Farm Black Start Control Using Converter Reactive Power Absorption
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Solution Overview
Problem
Existing methods for black start of offshore wind farms face oversizing issues with diesel generators, underutilization of external generators, reactive power overshoot, lengthy completion cycles, and excessive fuel consumption for auxiliary load supply.
Innovation Solution
A method for coordinating control of wind farms during black start by selecting conductors for connecting external generators to wind turbine converters, optimizing reactive power absorption, and operating within power limit curves to fully utilize generator capacity, reducing fuel consumption, and stabilizing voltage and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diesel generator sets are used to supply auxiliary loads during black start, then emergency power supply is ensured, but the diesel generator becomes oversized due to needing to absorb charging power from cable array
Solution Approach 1:
The patent divides the reactive power absorption function between two components: the diesel generator handles active power supply to auxiliary loads, while wind turbine converters handle reactive power absorption from the cable array. This segmentation allows each component to be properly sized for its specific function, eliminating the oversizing problem.
Solution Approach 2:
The wind turbine converters are made multi-functional by having them perform both their normal power conversion function and the additional function of absorbing reactive power from the cable array during black start, thereby eliminating the need for the diesel generator to be oversized for reactive power absorption.
2Quantity of substance
If wind turbine converters are used to absorb reactive power from cable system, then diesel generator sizing is optimized, but the black start completion cycle becomes relatively long
Solution Approach 1:
The patent applies preliminary action by pre-charging the cable array through the wind turbine converter before connecting to the diesel generator. This preliminary charging action prepares the system in advance, enabling faster synchronization and reducing the overall black start completion time.
3Reliability
If external generator supplies active power to auxiliary load, then power supply is ensured, but fuel consumption increases
Solution Approach 1:
The patent changes the operating parameters of the external generator by operating it in the operation region around the power limit curve rather than at fixed ratings. This parameter optimization allows the generator to supply the same active power to auxiliary loads while minimizing fuel consumption through more efficient operating points.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures full utilization of external generator capacity, prevents reactive power overshoot, reduces completion time, and minimizes fuel consumption while maintaining system stability.
Implementation Method 1
the charging power (capacitive reactive power) from the cable array still needs to be absorbed by the diesel generator
Data Source
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AI summary
A method for coordinating control of a wind farm (1) during black start of islanding operation, including: selecting a conductor in the wind farm (1) via which the external generator (9) is electrically connectable to auxiliary equipment of at least one wind turbine(10-15, 20-25, 30-35) of the wind farm (1) to deliver the active power to the auxiliary equipment of the wind turbine (10-15, 20-25, 30-35), wherein the selected conductor is electrically connectable to a converter (101-151, 201-251, 301-351) of the wind turbine (10-15, 20-25, 30-35); and choosing at least one of the wind turbines (10-15, 20-25, 30-35), wherein a converter (101-151, 201-251, 301-351) of the chosen wind turbine (10) can absorb a portion of an amount of reactive power generated by the selected conductor when voltage is applied between at least two parts of the selected conductor; operating an external generator (9) in an operation region around power limit curve to output energy; electrically connecting the output of the external generator (9) and the auxiliary equipment of the wind turbine (10-15, 20-25, 30-35) via the selected conductor; electrically connecting the output of the external generator (9) and the chosen wind turbine (10-15, 20-25, 30-35) converter via the selected conductor; and absorbing by the external generator (9) and the chosen wind turbine (10-15, 20-25, 30-35) converter (101-151, 201-251, 301-351) the reactive power generated by the selected conductor so that an operation point of the external generator (9) is kept within the operation region around the power limit curve. By having the method,the external generator's available capacity can be fully utilized.