Local Voltage Control via EV Charging Power Adjustment
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Solution Overview
Problem
The integration of large-scale electric vehicles into the power grid exacerbates voltage security issues, as existing under-voltage load shedding technologies are reactive and economically inefficient, failing to prevent voltage declines and restore loads effectively.
Innovation Solution
A method and device that monitor and control the voltage at local transformer substations by determining control strategies based on predetermined threshold values for voltage enhancement and under-voltage load shedding, adjusting the charging power of electric vehicle charging stations to stabilize the power grid voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If under-voltage load shedding technology is applied to respond to voltage security issues, then the power grid can be restored from dangerous state, but the shed load cannot be restored and the control is not economic
Solution Approach 1:
The patent implements preventive control by monitoring voltage values and comparing them with threshold values before voltage collapse occurs. When voltage drops below the threshold, the system proactively adjusts electric vehicle charging power to prevent further voltage deterioration, rather than waiting for dangerous conditions to develop and then shedding loads.
Solution Approach 2:
The system dynamically changes the charging power parameter of electric vehicles based on real-time voltage conditions. By adjusting the charging power within acceptable ranges, the system maintains voltage security while avoiding complete load shedding, thus preserving load restoration capability.
2Reliability
If under-voltage load shedding technology is used to eliminate dangerous states, then voltage security is temporarily improved, but economic efficiency deteriorates due to irreversible load loss
Solution Approach 1:
The system performs preventive control by detecting voltage deviations early and adjusting EV charging power before the grid enters a dangerous state. This avoids the need for reactive load shedding that would cause irreversible energy loss.
Solution Approach 2:
Electric vehicle charging stations serve dual purposes: they consume power for charging while simultaneously acting as controllable loads that can be adjusted to support grid voltage stability. The system leverages the flexibility of EV charging to self-regulate and maintain voltage security without external load shedding.
3Object-affected harmful factors
If large-scale electric vehicles access the power grid for charging, then transportation environmental performance is improved, but voltage security issues are aggravated
Solution Approach 1:
The system implements dynamic control of EV charging power based on real-time grid voltage conditions. When voltage is stable, EVs charge at higher rates; when voltage drops below thresholds, charging power is reduced or curtailed. This dynamic adjustment allows large-scale EV adoption while maintaining voltage security.
Solution Approach 2:
The system continuously monitors voltage values at the transformer substation and uses this feedback to adjust EV charging power. The control strategy is determined by comparing real-time voltage with predetermined threshold values, creating a closed-loop control system that balances EV charging demand with grid voltage stability.
Data Source
AI summary
A method and a device for controlling a local voltage are provided. The method includes: obtaining a first voltage value of a high-voltage side bus in a local transformer substation; determining a control strategy according to a starting threshold value for a voltage enhancement control, a starting threshold value for an under-voltage load shedding and the first voltage value of the high-voltage side bus; and performing the control strategy to control a charging power of an electric vehicle charging station corresponding to the local transformer substation, so as to control the local voltage of the local transformer substation.