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Isolated network frequency control method and system based on double-loop PID composite control

A composite control and control system technology, applied in the direction of single-grid parallel feeding arrangement, reducing/preventing power oscillation, etc., can solve the problems of frequency instability, endanger the safe and stable operation of enterprises, etc., achieve small overshoot, maintain production safety, Precise control of effects

Active Publication Date: 2021-02-02
NR ELECTRIC CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the embodiments of the present invention is to provide a dual-loop PID composite control method and system for isolated grid frequency control, to optimize the anti-disturbance capability of the steam turbine DEH in isolated grid operation, improve the frequency dynamic performance of the isolated grid, and solve the problem of isolated grid frequency. In some unexpected situations, the network is prone to frequency instability, which endangers the safe and stable operation of enterprises.

Method used

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  • Isolated network frequency control method and system based on double-loop PID composite control
  • Isolated network frequency control method and system based on double-loop PID composite control

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Embodiment 1

[0046]Add a fast secondary frequency regulation function to the DEH system of an isolated generator set. The secondary frequency regulation function includes fuzzy self-tuning PID control of the outer loop and traditional PID control of the inner loop; when the speed deviation is greater than the switching threshold, the fuzzy self-tuning PID control is performed through the outer loop , when it is less than the switching threshold, the traditional PID control is performed through the inner loop.

[0047] Specifically, the following steps are included:

[0048] S1: Add the fast secondary frequency regulation function to the DEH system of the isolated generating set.

[0049] S2: Set the fuzzy subset, fuzzy reasoning and defuzzification rules of the fuzzy self-tuning PID controller of the DEH fast quadratic frequency modulation outer loop.

[0050] The fuzzy self-tuning PID control specifically includes the following steps:

[0051] S21: The speed deviation and the change rat...

Embodiment 2

[0063] figure 1 It is a schematic diagram of the isolated grid frequency control method provided by the dual-loop PID compound control provided by the embodiment of the present invention. When the enterprise operates in the isolated grid mode, the generator set no longer accepts the dispatched load command, and the frequency deviation cannot be completely eliminated by the primary frequency regulation function of the unit itself. Therefore, a fast secondary frequency regulation function is added to the DEH system to adjust the DEH power supply in real time. The fixed value balances the power generation and power consumption, and further realizes the stability of the frequency of the isolated grid. When the deviation between the isolated grid frequency fluctuation and the rated speed exceeds the first threshold E 1 When (in this embodiment, E 1 Take 15rpm), automatically switch to the fast secondary frequency regulation function, when the deviation between the isolated grid f...

Embodiment 3

[0071] Correspondingly, the present invention proposes a dual-loop PID compound control isolated grid frequency control system, and a fast secondary frequency modulation control unit is added to the DEH system of the isolated generator set, and the secondary frequency modulation control unit includes an outer loop fuzzy self-tuning PID control subunit , Inner loop traditional PID control subunit and switching subunit;

[0072] The switching subunit is used to enable the fuzzy self-tuning PID control subunit of the outer loop when the speed deviation is greater than the switching threshold, and enable the traditional PID control subunit of the inner loop when it is smaller than the switching threshold.

[0073] In a preferred embodiment, the fast secondary frequency regulation control unit further includes a fast secondary frequency regulation switching subunit, which is used to control when the deviation between the frequency fluctuation of the isolated grid and the rated speed...

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Abstract

The invention provides an isolated network frequency control method based on double-loop PID composite control. A rapid secondary frequency modulation function is added to a DEH system of an isolatedgenerator set, and the secondary frequency modulation function comprises outer loop fuzzy self-tuning PID control and inner loop traditional PID control; and when the rotating speed deviation is greater than a switching threshold value, the fuzzy self-tuning PID control is carried out through an outer loop, and when the rotating speed deviation is less than the switching threshold value, traditional PID control is carried out through an inner loop. The invention further discloses a corresponding control system. The fuzzy self-tuning PID has the advantages of being flexible in control and highin adaptability; the fuzzy self-tuning PID is switched into the traditional PID in an undisturbed mode under the assistance of small deviation so as to rapidly eliminate static errors, and therefore,the whole rapid secondary frequency modulation loop has the advantages of being rapid in dynamic response, small in overshoot, high in robustness, accurate in control effect and the like; frequency stability during isolated network operation is guaranteed; and production safety of enterprises is maintained.

Description

technical field [0001] The invention relates to the field of isolated network frequency control, in particular to an isolated network frequency control method and system for double-loop PID compound control. Background technique [0002] At present, the common problems in the enterprise power grid industry are weak connection with the large power grid, easy formation of isolated grids, and poor self-balancing ability of the power grid. For industries such as chemical industry that require high uninterrupted power supply and voltage quality, a short-term failure of a large power grid may directly lead to production interruption, resulting in serious economic losses and environmental pollution. Therefore, improving the safety and reliability of industrial enterprise power grids is an important issue that has attracted much attention. As one of the most important equipment in the entire power generation system, the steam turbine's control system (DEH) runs through the entire p...

Claims

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Application Information

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IPC IPC(8): H02J3/24H02J3/46
CPCH02J3/24H02J3/46
Inventor 宋诚骁牛洪海蔡丹李彦龙
Owner NR ELECTRIC CO LTD
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