DC Grid Power Arbitration via Modular VSCs
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Solution Overview
Problem
The increasing demand for renewable energy and the expansion of solar power installations lead to conflicts over land use, particularly with agricultural areas, necessitating the exploration of alternative, ecologically friendly solutions for large-scale photovoltaic systems, such as utilizing linear surfaces like cycle paths and railway tracks, which require an optimized electrical architecture for interconnection with existing infrastructure.
Innovation Solution
An electrical architecture that includes a linear photovoltaic installation with a direct current network connected via DC/DC converters to a medium voltage direct current bus, interfaced with an alternating current network through modular multilevel voltage source converters, allowing for optimized power injection and distribution between multiple interconnection points to reduce losses and improve network quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large ground-mounted PV solar power plants are installed to meet renewable energy demand, then power generation capacity is improved, but land use conflicts with agricultural areas and biodiversity loss worsen
Solution Approach 1:
The patent transitions from traditional ground-mounted PV installations that occupy large horizontal areas to linear PV installations that utilize linear surfaces such as highway edges, railway tracks, and watercourses. This dimensional change allows PV panels to be arranged in linear configurations along existing infrastructure, generating power without consuming additional agricultural land.
2Area of stationary object
If linear PV installations are deployed to reduce land use, then land use conflicts are reduced, but electrical network interconnection complexity increases
Solution Approach 1:
The linear PV installation is divided into multiple groups of PV panels, each group connected to the DC network through DC/DC converters. The DC network itself is segmented into multiple sections that can be independently managed and connected to the AC network at different points, reducing the overall interconnection complexity.
Solution Approach 2:
The patent introduces a DC network as an intermediary layer between the PV panel groups and the AC transmission/distribution network. This DC network, equipped with DC/DC converters and voltage source converters, serves as a buffer and management layer that simplifies the interconnection process by handling power conversion and arbitration centrally before AC network injection.
3Adaptability or versatility
If multiple voltage source converters are used to connect DC network to AC network at different nodes, then power injection flexibility is improved, but system complexity increases
Solution Approach 1:
The voltage source converters in the patent are designed to perform multiple functions: they convert DC to AC for network injection, arbitrate power distribution among different AC network nodes, and can operate in various control modes (Vac/f, Vac-phi, Vdc-phi, Vdc-Q, PWM-phi, P-Vac, P-Q, Vdc-Vac, P-cos(f), Vdc-cos(f))). This multi-functionality reduces the need for separate dedicated devices for each function.
Solution Approach 2:
The control system dynamically adjusts the operation of multiple voltage source converters based on real-time AC network conditions. The converters can flexibly change their injection points and power distribution according to network needs, operating regimes, and loss minimization requirements, rather than being fixed to a single configuration.
4Device complexity
If power is injected at a single point in the AC network, then system simplicity is maintained, but network losses increase
Solution Approach 1:
Instead of injecting power at a single point, the patent segments the power injection across multiple AC network nodes through different voltage source converters. This segmentation allows power to be distributed to different parts of the network, reducing transmission distances and minimizing overall network losses.
Solution Approach 2:
The control system continuously monitors AC network conditions and uses feedback to optimize power injection distribution. Based on real-time information about network losses, operating regimes, and demand patterns, the control system adjusts the power injection levels at different nodes to minimize total network losses while maintaining simplicity in individual converter operations.
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 solution reduces land use, enhances the integration of renewable energy, improves network reliability and stability, and optimizes energy management by allowing flexible energy exchange between DC and AC networks, while minimizing the impact of intermittency and land use conflicts.
Implementation Method 1
at least one linear installation comprising at least one group of photovoltaic (PV) panels, adapted to produce a maximum total power P
Implementation Method 2
a direct current (DC) network comprising at least one bus to which the(s) are connected in electrical parallel groups of PV panels each via a DC/DC converter
Implementation Method 3
at least two voltage source converters (VSC), one of the two converters connecting the bus DC to a first node of the AC network, the other of the two converters connecting the DC bus to a second node of the AC network
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention essentially consists of setting up an architecture with at least one linear PV installation connected to a DC network and interconnecting this subset at at least two separate interconnection points with a preferably existing AC electrical network. Each interconnection point to a node of the AC network is a voltage source converter (VSC) capable of injecting from 0 to 100% of the maximum power P of the linear PV installations.