Power Supporting Arrangement With Segmented Phase Arms
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Solution Overview
Problem
Power grid systems face challenges with low inertia and short-circuit levels due to increased renewables and decommissioned traditional generation, necessitating the provision of additional reactive power beyond the real power rating, which is costly for some energy storage systems.
Innovation Solution
A power supporting arrangement with multiple groups of phase arms connected in wye-configuration, utilizing a DC network and energy storage units to provide both active and reactive power, allowing for increased apparent power rating without proportional increases in energy storage system capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrochemical or dielectric energy storage systems are used to provide fast frequency and synthetic inertia response services, then the response speed and grid stability are improved, but the system cost increases significantly
Solution Approach 1:
The invention segments the energy storage system into multiple independent phase arms (first, second, and third groups), each capable of operating semi-independently. This segmentation allows the system to provide fast frequency response services using a smaller, more cost-effective energy storage capacity while meeting grid requirements through coordinated control of the segmented arms.
Solution Approach 2:
The invention introduces a third dimension to the conventional two-level hierarchy by adding a neutral point connection that enables independent reactive power control. This dimensional addition allows the system to simultaneously provide active power for frequency response and reactive power for voltage support, reducing the total energy storage capacity needed compared to traditional single-hierarchy systems.
2Ease of manufacture
If the real power rating of the energy storage system is reduced to lower costs, then the system becomes more economical, but the apparent power capability is insufficient to provide required reactive power
Solution Approach 1:
The invention makes each phase arm multi-functional by enabling it to simultaneously or independently provide active power, reactive power, and voltage support. The third group of phase arms connected to the neutral point can provide reactive power without requiring proportional increases in energy storage capacity, as the reactive power is drawn from the grid through the wye-configuration rather than from the energy storage medium itself.
Solution Approach 2:
The neutral point acts as an intermediary that decouples the reactive power provision from the energy storage system. By connecting the third group of phase arms to the neutral point, the system can exchange reactive power with the grid through this intermediary without depleting the energy storage medium, thereby maintaining apparent power capability while using a smaller, more cost-effective storage capacity.
3Power
If multiple groups of phase arms are added to increase apparent power and reactive power capability, then the power supporting capability is improved, but the device complexity increases
Solution Approach 1:
The invention merges multiple phase arm groups into a unified modular structure with common DC links and coordinated control. The first, second, and third groups of phase arms are integrated through shared DC voltage sources and a common control system, reducing overall complexity compared to separate independent converters while maintaining enhanced apparent power capability.
Solution Approach 2:
The invention implements dynamic control of the phase arms where the neutral point potential can vary independently based on grid conditions. This dynamic capability allows the system to adapt its configuration - the neutral point can be at different potentials relative to the DC lines, enabling flexible operation modes that simplify control while providing enhanced power supporting capability across different operating scenarios.
Data Source
AI summary
A power supporting arrangement includes a DC network having a first DC line with a first DC potential, a second DC line with a second DC potential, and an energy storage system that includes a first energy storage unit connected in a branch between the first and the second DC lines. A first group of phase arms is connected in a wye-configuration between the power grid and the first DC line and a second group of phase arms connected in a wye-configuration between the power grid and the second DC line. The first and second groups of phase arms are controllable as a voltage source converter. A third group of phase arms is connected to the power grid in a wye-configuration. The third group of phase arms have a neutral point and being controllable to support the power grid with reactive power.