Grid-Forming Inverter Black Start for Multi-Microgrid Synchronization
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Solution Overview
Problem
Restarting a power grid from a blackout condition (black start) is challenging in systems with a high proportion of inverter-based resources due to complex synchronization and interconnection issues, particularly in microgrids with low inertia and susceptibility to cyber-physical attacks.
Innovation Solution
A minimum-resource, multiple-microgrid black start method using grid-forming inverters with intelligent synchronization units that enable autonomous synchronization based on terminal measurements, utilizing synchrobreakers to connect microgrids when voltage and phase angle differences are within specified thresholds, and requiring minimal communication with binary enable signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inverter-based resources are distributed across the power system to increase resilience, then resistance to cyber-physical attacks is improved, but the ability to perform black start operations deteriorates
Solution Approach 1:
The power system is divided into multiple independent microgrids, each capable of autonomous black start operations. Each microgrid contains distributed inverter-based resources that can independently synchronize and connect to the main grid, eliminating the need for centralized diesel generators while maintaining black start capability.
Solution Approach 2:
The microgrids are equipped with intelligent synchronization units that enable autonomous synchronization based on terminal measurements. The system self-regulates voltage and frequency matching without external control, allowing inverter-based resources to independently perform black start operations and connect to the grid without human intervention or diesel backup.
2Productivity
If microgrids are synchronized and connected during black start operations, then system restoration speed is improved, but voltage and frequency disturbances increase
Solution Approach 1:
The intelligent synchronization units continuously monitor and pre-adjust voltage and frequency parameters of microgrids before connection. By performing preliminary synchronization adjustments, the system ensures that voltage and frequency differences are minimized before the actual connection occurs, enabling rapid restoration while preventing harmful disturbances.
Solution Approach 2:
The synchronization system uses real-time feedback from terminal measurements to continuously adjust microgrid parameters. The intelligent synchronization units monitor voltage and frequency deviations and dynamically adjust inverter outputs to maintain synchronization accuracy, allowing fast connection without causing harmful transients.
3Loss of information
If autonomous synchronization based on terminal measurements is implemented, then communication requirements are reduced, but synchronization precision must be maintained
Solution Approach 1:
Each microgrid is equipped with an intelligent synchronization unit that autonomously performs synchronization using only local terminal measurements. The system self-determines voltage magnitude, frequency, and phase angle from local measurements without requiring communication with external control centers, thereby minimizing information loss while maintaining synchronization precision through advanced measurement algorithms.
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
This method enables rapid synchronization and connection of multiple microgrids, reducing frequency and voltage disturbances, minimizing power transience, and eliminating the need for diesel-based units, while ensuring robust and efficient black start operations.
Implementation Method 1
the first phase angle and the second phase angle are measured using phase locked loop
Data Source
AI summary
Methods for performing a black start in a power system and corresponding systems. A method (200) includes starting (100) a first anchor grid-forming inverter (122) in a first microgrid (110) and starting (100) a second anchor grid-forming inverter (122) in a second microgrid (120). The first microgrid (110) is connected to a first bus (118) and the second microgrid (120) is connected to a second bus (128). The method includes measuring (202) a first voltage at the first bus (118) and measuring a second voltage at the second bus (128), determining (204) a voltage difference between the first bus (118) and the second bus (128), and determining (204) whether the voltage difference is within a voltage difference threshold (350). The method includes measuring (206) a first phase angle at the first bus (118) and measuring a second phase angle at the second bus (128), determining (208) a phase angle difference between the first bus (118) and the second bus (128), and determining (208) whether the phase angle difference is within a phase angle difference threshold (360). The method includes, when the voltage difference is within the voltage difference threshold (350) and the phase angle difference is within the phase angle difference threshold (360), then operatively connecting (212) the first bus (118) to the second bus (128).