Hierarchical Power Supply Demand Control for Microgrid Balancing
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Solution Overview
Problem
Small-scale power systems, such as microgrids, face challenges in achieving supply-demand balancing due to fluctuations in natural energy generation and limited demand, making it difficult to maintain constant electric power flow and balance between estimated and actual load and power output values within short time periods.
Innovation Solution
A power supply and demand control apparatus and method that includes a long-cycle and short-cycle control unit to adjust power output of distributed variable output power sources, using a power generation planning unit, load power estimating unit, natural energy output estimating unit, and economical load dispatching to ensure supply-demand balancing at a linking point between a microgrid and a commercial power system, with the ability to correct power flow targets every few minutes to maintain balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power supply and demand control methods are used in small-scale power systems, then the system can operate with distributed power sources including natural energy generation apparatus, but it cannot achieve supply-demand balancing within short time periods due to fluctuations in natural energy generation and limited demand
Solution Approach 1:
The control period is segmented into multiple sub-periods, with intermediate target values set for each sub-period. This allows the system to achieve supply-demand balancing in shorter time intervals by breaking down the overall balancing task into manageable segments, rather than attempting to balance over a single long period.
Solution Approach 2:
The control device calculates intermediate target values in advance for each sub-period before the actual power generation and consumption occur. By pre-calculating these targets based on predicted natural energy generation and demand patterns, the system can proactively adjust power distribution to prevent imbalances, achieving faster response times.
2Reliability
If the control period is extended to accommodate natural energy fluctuations, then supply-demand balancing can be achieved, but the responsiveness to actual power flow deviations is reduced
Solution Approach 1:
By dividing the control period into multiple sub-periods with intermediate targets, the system maintains reliability through comprehensive balancing while improving response speed. Each sub-period represents a shorter time window that requires faster adjustment, thus enhancing overall responsiveness without sacrificing balancing accuracy.
Solution Approach 2:
The control device operates periodically by setting and adjusting target values for each sub-period in sequence. This periodic adjustment mechanism allows the system to maintain continuous responsiveness to power flow deviations while ensuring supply-demand balancing is achieved across the entire control period.
3Adaptability or versatility
If multiple distributed power sources including natural energy generation are integrated, then the system becomes more versatile and sustainable, but the complexity of power output control increases
Solution Approach 1:
The control device acts as an intermediary that manages the complexity of coordinating multiple distributed power sources. It calculates intermediate target values for each sub-period and communicates these to the respective power sources, simplifying their control tasks while maintaining overall system versatility and enabling integration of various natural energy generation types.
4Measurement precision
If the system uses detailed estimation and calculation for each distributed power source to achieve precise balancing, then the accuracy of power flow control is improved, but the computational burden and system complexity increase
Solution Approach 1:
The control device segments the calculation process by determining intermediate target values for each sub-period separately. This segmentation allows for precise control calculations to be performed in smaller, more manageable steps, maintaining high accuracy while reducing the overall computational burden compared to calculating everything in a single complex operation.
Data Source
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AI summary
A power supply and demand control apparatus includes a power generation planning unit that calculates one day's power outputs of multiple distributed power sources and a power flow target of a linking point to another power system, a long-cycle control unit having a long-cycle supply-demand balancing control unit that performs control every few minutes so as to ensure the supply-demand balancing of electric energy in a given amount of time at the linking point in order to perform control for making deviations between total power output calculated by the power generation planning unit and load power in the power system constant, and a short-cycle control unit having a short-cycle supply-demand balancing control unit that performs similar control every few seconds. In the power supply and demand control apparatus, the long-cycle control unit and short-cycle control unit perform the supply-demand balancing control in a hierarchical fashion to determine output assignments of the distributed power sources.