Asymmetric cascade multi-level hybrid energy storage control method

Abstract

The invention discloses an asymmetric cascade multi-level hybrid energy storage control method, and is suitable for phase splitting control of a single-phase cascade multi-level energy storage systemand a three-phase asymmetric cascade multi-level energy storage system. The method comprises the following steps of performing closed-loop control on a grid-connected current and a capacitor voltage,and determining an output voltage reference vector and a correction vector; determining a stable working range of the system according to the output voltage vector of the system, and by combining an inductor voltage, determining a steady-state working point; according to the steady-state working point, the output voltage reference vector and the correction vector, determining a battery link outputvoltage reference vector and a capacitor link output voltage reference vector; and determining a modulation wave according to the battery link output voltage reference vector and the capacitor link output voltage reference vector, generating a switch signal through SPWM, and driving an inverter to work. By virtue of the method, it can be guaranteed that the system can still operate stably in fourquadrants when a part of battery link breaks down, the control precision of the grid-connected current is improved, and the harmonic of the grid-connected current is reduced.

Description

technical field [0001] The invention relates to power electronics technology, in particular to an asymmetric cascaded multi-level hybrid energy storage control method. Background technique [0002] Modularization is a major feature of the cascaded multilevel circuit. When the energy storage battery fails in the cascaded multilevel circuit, the energy storage battery is removed by bypassing the link unit to form a battery based on the energy storage battery and capacitor. The asymmetric cascaded multi-level energy storage system can ensure the normal operation of the system, but it will cause the loss of the capacity of the energy storage system. For grid-connected asymmetric cascaded multi-level circuits, energy storage batteries and supercapacitors are used as the DC power supply of link units, and feedforward space vector modulation technology is used to realize the direct active power distribution of energy storage batteries and supercapacitors, but not It can realize th...

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Problems solved by technology

[0002] Modularization is a major feature of the cascaded multilevel circuit. When the energy storage battery fails in the cascaded multilevel circuit, the energy storage battery is removed by bypassing the link unit to form a battery based on the energy storage battery and capacitor. Asymmetric cascaded multi-level energy storage system can ensure the normal operation of the system, but it will cause the loss of energy storage system capacity

For grid-connected asymmetric cascaded multi-level circuits, energy storage batteries and supercapacitors are used as the DC power supply of link units, and feedforward space vector modulation technology is used to realize the direct active power distribution of energy storage batteries and supercapacitors, but not It can realize the continuous adjustment of active and reactive power of the system, and does not take into account the distribution of reactive power among the chain links; using energy storage batteries and photovoltaic cells as the DC power supply of the chain link units, it realizes the decoupling control of active power and reactive power of the system and the control of each chain The power distribution between the section units, but it ignores the stable operating range of the system, and is not suitable for all asymmetric cascaded multilevel circuits

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