Microgrid secondary frequency modulation method based on adaptive online model identification

Abstract

The invention discloses a microgrid secondary frequency modulation method based on adaptive online model identification, and the method comprises the steps: by obtaining the output power of each converter in a system, the reference power of a control center, the voltage frequency of a PCC (point of common coupling) of an island microgrid and other external characteristic information when the structure of the island microgrid changes, performing online adaptive optimization fixed-order black box modeling on power frequency characteristics of the microgrid, taking an obtained optimal power frequency characteristic equivalent model as a prediction model in dynamic matrix control, establishing a secondary frequency adjustment target function, solving the function through an intelligent algorithm to obtain a secondary frequency modulation power instruction, and issuing the secondary frequency modulation power instruction to each frequency modulation unit to achieve secondary frequency adjustment of the island microgrid. According to the method, the real-time adaptive modeling can be carried out on the power frequency characteristics of the island microgrid under different working conditions, and model parameters of a frequency modulation control algorithm are updated according to a real-time model, so that efficient and high-quality secondary frequency adjustment is realized.

Description

technical field [0001] The invention belongs to the field of new energy applications and relates to a secondary frequency adjustment method based on external characteristic measurement and self-adaptive online model identification. Background technique [0002] When the microgrid is running in an isolated island, the supporting energy storage converter usually adopts droop control, virtual synchronous generator control and related derivative strategies to maintain the voltage and frequency stability of the system. Disadvantages: Centralized secondary frequency control achieves frequency-free control through the central controller of the microgrid and the energy storage unit with frequency modulation function. Although this method is simple and effective, it is difficult for power generation equipment and loads to switch frequently, and the network structure is constantly changing. For microgrids, the model adaptability of the parameters of the secondary frequency modulation ...

AI Technical Summary

Problems solved by technology

Firstly, the parameters of commercial converters are commercial secrets and are generally difficult to obtain; secondly, as the number of converters connected and the network structure change, the network parameters and model structure of the island microgrid will also change; It is difficult to realize in the actual system of isolated island microgrid where converters are widely used

[0006] 3. In the current research results of using non-mechanism modeling methods to model the island microgrid, the power frequency model of the island microgrid adopts a fixed-order assumption, which cannot cope with the complex and changeable operating scenarios of the island microgrid. The model Due to the complexity and real-time variability of the model, the accuracy of the obtained model is low, and even the power-frequency characteristics of the island microgrid cannot be accurately described, which has a negative effect on the design of the frequency modulation controller.

[0007] 4. The secondary frequency modulation method of the isolated island microgrid generally adopts the PI control algorithm. The adjustment effect of this algorithm depends on the precise design of the parameters, and the parameter design depends on the accuracy of the secondary frequency modulation modeling. Therefore, the model of this method has poor adaptability and the parameter The setting is difficult, and it is impossible to ensure that the microgrid has a good frequency dynamic adjustment effect under all working conditions

[0008] 5. In the past, the frequency regulation strategy of isolated island microgrids generally combined the secondary frequency regulation modeling with the secondary frequency regulation method. A set of fixed frequency regulation parameters was given during system design to realize the frequency regulation function, which could not be implemented in each working condition. Adaptively adjust the frequency modulation parameters to obtain the best frequency adjustment effect

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