Limit value management control method based on hybrid energy storage system

Abstract

The invention relates to a limit value management control method based on a hybrid energy storage system. A storage battery module, a super capacitor module, a power distribution module, a limit value management module, a storage battery charging and discharging control module and a super capacitor charging and discharging control module are adopted. According to the system, the vacancy or surplus power of the system is compensated through the super capacitor module and the storage battery module; the limit value management module can control the power limit value of the storage battery module and the operation of the super capacitor module in a set charge state interval; the power distribution module controls the storage battery module to bear a low-frequency power component and the super capacitor module to bear a high-frequency power component; when the charge state of the super capacitor exceeds a limit value and charging and discharging are continued, the storage battery only emits or absorbs the low-frequency power component, so that the storage battery is prevented from excessively bearing the high-frequency component and damaging an internal structure, and peak change of voltage and current at a starting moment is avoided. The system can control charging and discharging of the storage battery and the super capacitor to accord with the energy storage and discharging characteristics, and the service life of the energy storage system can be prolonged.

Description

technical field [0001] The invention relates to the technical field of electric energy storage systems, and in particular is based on a limit value management and control method for a hybrid energy storage system. Background technique [0002] With the development of the economy, the traditional energy is becoming more and more tense, and the problem of environmental pollution is becoming more and more serious. Countries have begun to focus on the development of new clean energy. The development of renewable energy power generation (Renewable energy power, REP) technology has become a solution to the problems brought by traditional energy. The inevitable choice of the problem. Microgrid technology is an important form of effective utilization of distributed renewable energy. However, distributed power generation is very different from traditional power sources. Its main feature is the randomness and intermittent nature of distributed power generation such as wind and light. ...

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Problems solved by technology

[0003] The domestic research status is as follows: some early literatures mainly researched based on a single energy storage configuration and mainly considered the impact of photovoltaic output. Some literature reviews stated that energy storage systems can be composed of a single energy storage form and multiple energy storage forms ; In the process of controlling the grid-connected power of new energy, comprehensively considering factors such as system cost and volume, it is required that the energy storage system has the characteristics of high power, high energy density, and long life; In the grid system, both energy storage structures are applied; in the small-scale connected microgrid, the energy storage unit is required to have a high energy density due to the intermittent nature of new energy generation, and at the same time, the rapid fluctuation of the load requires the energy storage unit It has high power density, therefore, the composite energy storage system composed of energy storage units with high power density and high energy density has broad application prospects in microgrid; The performance of the capacitor hybrid energy storage system is better than that of a single battery energy storage system; some literature shows that the battery-supercapacitor hybrid energy storage system not only has the characteristics of high energy density and high power density, but also can prolong the service life of the battery; some The literature has qualitatively analyzed the prolongation effect of the hybrid energy storage system on the power and service life of the battery; some literatures consider that the cost of the current energy storage device is high, and its power generation cost is higher than the grid price, and the economics of the microgrid are obviously insufficient. ; Some literatures proposed a stability criterion derivation method for droop control system based on mixed potential function theory, and obtained the stability criterion of DC microgrid; the criterion shows that the DC microgrid of droop control The large-disturbance stability of the power grid is related to the system parameters of each converter and the ratio of the output power of each power supply to the load power. The simulation verifies the accuracy of the proposed method and stability criterion; The energy storage system composed of energy medium, that is, the hybrid energy storage system (HESS); HESS takes into account the characteristics of high power density, high energy density and long operating life, and has received extensive attention in recent years; A hybrid microgrid segment coordination control strategy is proposed to deal with power fluctuations in the microgrid due to changes in micro-source output, load changes, and changes in charging and discharging power of energy storage devices due to state of charge.

[0004] The current status of foreign research is as follows: Some relevant literature proposes a dual-active full-bridge DC / DC converter, which uses a high-frequency transformer to achieve electrical isolation and increases system security. This structure has high symmetry, simple control methods, and variable voltage ratio The adjustment range is wide, but the cost of more components is relatively high; the DC microgrid can operate in two modes: grid-connected and off-grid; the stability of the DC bus voltage is the most important indicator for measuring power balance; when the DC microgrid is in In the grid-connected operation mode, the DC microgrid exchanges energy with the public grid through the grid-connected inverter, and the DC bus voltage is maintained by the grid-connected inverter; when the AC grid or grid-connected inverter fails, the DC microgrid Switching to the off-grid operation mode, the DC bus voltage is mainly maintained by the distributed power supply and the hybrid energy storage system; some literatures have proposed a decentralized HESS control method, and the battery and the supercapacitor use virtual resistors and virtual capacitors to droop respectively. Control, according to different virtual parameters to achieve power distribution between different and the same energy storage medium; some literatures use a control method including supercapacitor SOC self-recovery, when a step change occurs, the supercapacitor SOC can be restored to the initial value

Although this method can ensure that the supercapacitor operates in a safe range, it reduces the capacity utilization of the supercapacitor and is a passive control

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