Grid-Frequency Motor Drive Control for Power-Limited Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The replacement of direct-on-line motors with drive control systems in electric grids leads to reduced grid stability during frequency decreases, as these systems consume constant power independently of grid frequency, failing to adapt and contribute to kinetic energy loss, necessitating load shedding or new power generation.
Innovation Solution
A control process that adjusts drive commands for motors and load systems based on grid frequency, including power, torque, and current limitations, or stop commands, to reduce power consumption and mimic direct-on-line motor behavior, thereby stabilizing the grid without external TSO commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If drive control systems with electronic switches replace contactors to control motors, then energy efficiency is improved, but electrical grid stability deteriorates during frequency decreases
Solution Approach 1:
The control system dynamically adjusts motor power consumption based on grid frequency conditions. During normal operation, the motor runs at optimal efficiency point with constant power. When grid frequency decreases, the control system automatically reduces power consumption to match the reduced kinetic energy available in the grid, thereby maintaining grid stability while preserving energy efficiency benefits during normal operation.
Solution Approach 2:
The invention changes the operating parameters of the motor control system based on grid frequency. The control system monitors grid frequency and adjusts motor parameters (power, torque, or current) accordingly. When frequency drops below a threshold, the system transitions from constant power mode to reduced power mode, changing the operational state to adapt to grid conditions and prevent further frequency deterioration.
2Productivity
If motors controlled by control systems operate at constant power independently of grid frequency, then optimal efficiency is maintained, but grid stability is reduced during frequency decreases
Solution Approach 1:
The control system implements feedback by continuously monitoring grid frequency and using this information to adjust motor power consumption. The control system receives feedback signals indicating grid frequency status and automatically modifies operational parameters to maintain both efficiency and stability, transitioning from constant power operation to adaptive power operation based on real-time grid conditions.
3Stability of the object's composition
If load shedding is implemented to balance production and consumption during incidents, then grid stability is improved, but productivity is reduced due to complete disconnection of loads
Solution Approach 1:
Instead of complete load shedding (100% disconnection), the invention applies partial action by reducing motor power consumption to a controlled level during frequency drops. The control system implements intermediate power reduction strategies (power limitation, torque limitation, or current limitation) that partially reduce load demand rather than completely disconnecting it, thereby maintaining some productivity while improving grid stability.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The present disclosure concerns a control process for a control system (60, 70, 100, 120) of a load system (30, 31, 32, 90) connected to an electric grid through said control system wherein said control process (40, 50, 41, 51, 42, 52, 43, 53) is configured to provide one or more adapted drive commands (Xlim, Ylim) to such control system dependent on the grid frequency (ω). The control system may comprise an inverter, a converter, a thyristor bridge or contactors ad the load may be a motor. The disclosure also concerns a control device for implementing the Control process.