Novel strategy for suppressing bus voltage fluctuation of direct-current microgrid containing composite energy storage

Abstract

The invention discloses a novel strategy for suppressing bus voltage fluctuation of a direct-current microgrid containing composite energy storage. Photovoltaic power is used as a power supply, fluctuation is relieved through a composite energy storage unit composed of a super capacitor set and a storage battery set, load disturbance output is tracked in real time through a non-linear disturbanceobserver model, the system controls the direct-current microgrid by monitoring parameters of each module in the microgrid, and meanwhile the stability of the microgrid is guaranteed. Based on a traditional voltage and current double-closed-loop control strategy, the invention provides the novel strategy for suppressing bus voltage fluctuation of the direct-current microgrid containing composite energy storage. On the premise of fully utilizing plug-and-play of a distributed power supply and charging and discharging characteristics of a composite energy storage unit, a strategy of feedforward control of a nonlinear interference observer on the DC / DC converter side is utilized, the nonlinear interference observer is utilized to track load disturbance, and voltage fluctuation of a direct-current bus is suppressed through feedforward control, so that the electric energy quality is ensured.

Description

technical field [0001] The invention relates to the field of power system power quality analysis control and new energy technology, and in particular to a novel strategy for suppressing bus voltage fluctuations of DC microgrids with composite energy storage. Background technique [0002] Against the backdrop of ever-increasing requirements for energy utilization and environmental protection, distributed renewable energy generation and related technologies have attracted global attention. As a special form of microgrid, DC microgrid has better power quality and simpler structure. Compared with AC microgrids, it is much easier to achieve coordinated control of each component in the grid. In view of the intermittent and random output of distributed power generation such as wind turbines and photovoltaics, energy storage units have become a key part to maintain stable operation of the system, improve power quality and maintain uninterrupted power supply. [0003] For DC microg...

AI Technical Summary

Problems solved by technology

Due to the influence of solar radiation and the characteristics of photovoltaic panels, photovoltaic power generation is random, which directly affects the power generation in the photovoltaic system of the DC microgrid, which will cause the problem of DC bus voltage fluctuations

At the same time, the use of nonlinear and high-power power electronic equipment will cause problems such as harmonic interference and fault short circuits caused by voltage rise.

If these power quality problems are not improved, the service life of the DC microgrid system will be greatly shortened, and it will easily cause harmonic resonance in the distribution network, causing misoperation or damage to the relay protection device, resulting in instrument display failure and inaccurate data collection. And serious consequences such as communication network interference

Therefore, the status of the power quality in the DC microgrid is directly related to the high-quality operation of the system, and any power quality problems may bring immeasurable losses to the society

[0004] At present, some literatures have proposed the DC microgrid bus voltage layered coordinated control strategy and the hybrid energy storage coordinated control in DC microgrid, but they have not solved the problem of how to quickly stabilize the DC bus voltage when the system is disturbed or faulty.

Moreover, the actual output disturbance current value of the DC microgrid cannot be directly observed, and the observed output disturbance current value i cannot be calculated o * and the actual load current output value i o The error affects the control effect

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