Grid Power Command Correction for Frequency-Stable Renewable Integration
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Solution Overview
Problem
Existing grid systems face challenges in stabilizing frequency and voltage variations due to excessive power generation, leading to potential output fluctuations in both power generation and storage equipment, especially when renewable energy sources are integrated.
Innovation Solution
A grid system with a control device and method that includes power conversion devices and detection units to adjust power command values based on frequency variations at the power receiving point, prioritizing power storage device charging over reducing power generation, thereby stabilizing the grid frequency and reducing the influence of excessive power generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power storage equipment is used to control frequency variation caused by power variation in renewable energy, then grid frequency stability is improved, but when generated power is excessive the power generation equipment must be reduced which worsens productivity
Solution Approach 1:
The invention changes the control parameter from binary (reduce generation or not) to continuous (adjustment amount based on frequency deviation). The frequency-adjusted power command value dynamically modifies the power generation command according to the detected frequency, allowing proportional adjustment rather than abrupt reduction, thus maintaining productivity while ensuring frequency stability.
Solution Approach 2:
The invention implements a feedback mechanism where the detected frequency is fed back to adjust the power command value. The frequency detection unit continuously monitors grid frequency, and this information is used to modify the power command for both power generation and power storage equipment, creating a closed-loop control system that automatically responds to frequency variations without manual intervention.
2Reliability
If voltage variation at distribution impedance occurs, then temporary frequency variation happens which may change output of power generation or storage equipment, but suppressing this requires additional control complexity
Solution Approach 1:
The frequency-adjusted power command value mechanism serves multiple functions simultaneously: it controls frequency stability, manages excessive power generation, and suppresses temporary frequency variations from voltage changes. This single control mechanism handles multiple disturbances without requiring separate control systems for each issue, thereby avoiding additional complexity while maintaining reliability.
3Reliability
If power command value is corrected based on frequency detection, then influence of excessive power generation is suppressed, but measurement and control precision requirements increase
Solution Approach 1:
The invention applies partial correction to the power command value based on frequency deviation, rather than requiring perfect frequency restoration. The frequency-adjusted power command value provides proportional adjustment that is sufficient to suppress excessive power generation influence and maintain grid stability, without demanding ultra-precise frequency measurement and control that would be overly complex and costly.
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
The solution effectively suppresses the impact of excessive power generation on the grid and reduces output variations of both power generation and storage equipment, enhancing grid stability during frequency fluctuations.
Implementation Method 1
a first power conversion device provided between the power generation device and the power receiving point, and including a first power converter for converting output voltage of the power generation device to predetermined AC voltage
Implementation Method 2
a second power conversion device provided between the power storage device and the power receiving point, and including a second power converter for converting output voltage of the power storage device to predetermined AC voltage
Data Source
AI summary
A grid system includes a voltage source, a plurality of consumers connected to the voltage source via a distribution grid, and a grid control unit for transmitting a power command value to a device provided to each consumer. The consumer is provided with a power generation device, a power storage device, and power conversion devices for converting respective powers of the power generation device and the power storage device. The power conversion devices respectively include power command correction means for correcting the power command value from the grid control unit on the basis of the frequency of voltage at a power receiving point X2 which is a connection point between the consumer and the distribution grid. The power command value for the power conversion device of the power generation device is set to be greater than the power command value for the power conversion device of the power storage device.