Stability criterion method suitable for multi-voltage-grade direct-current power distribution system

A multi-voltage level, DC power distribution technology, which is applied in the direction of DC network circuit devices, electrical components, circuit devices, etc., can solve the problems of not considering multiple voltage levels of the system, achieve the effect of wide application range and overcome limitations

Active Publication Date: 2019-05-10
SOUTHEAST UNIV
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Problems solved by technology

However, the above studies are all aimed at single-bus DC power distribution systems, without considering the system with multiple voltage levels, such as two-stage photovoltaic grid-connected systems, medium and low voltage DC power distribution systems, etc., DC buses of different voltage levels pass through DC Transformer for Interconnection

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  • Stability criterion method suitable for multi-voltage-grade direct-current power distribution system
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  • Stability criterion method suitable for multi-voltage-grade direct-current power distribution system

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Embodiment Construction

[0027] Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

[0028] Medium and low voltage DC power distribution system is a typical application of multi-voltage level DC power distribution system. Its topology is as follows: figure 1 As shown, it consists of a medium voltage DC bus and a low voltage DC bus. According to the definition of BVCC (bus voltage controlled converter, bus voltage controlled converter) and BCCC (bus current controlled converter, bus current controlled converter), its unified form can be obtained, such as figure 2 As shown, N 1 BVCC and N 2 BCCCs, N connected in parallel on the low-voltage DC bus 3 BVCC and N 4 A BCCC, a DC transformer realizes the interconnection of medium and low voltage DC buses, and plays the role of voltage matching and power exchange. In a broad sense, the medium voltage DC bus can represent the DC bus with a higher voltage level in the multi-voltage leve...

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Abstract

The invention discloses a stability criterion method suitable for a multi-voltage-grade direct-current power distribution system. The impedance criterion method comprises the following steps: firstly,according to the definitions of a control bus voltage type converter and a control bus current type converter, a unified expression form of the multi-voltage-grade direct-current power distribution system is obtained; secondly, small-signal modeling is performed on each converter, output voltage and output current control modes are adopted for a direct-current transformer, and a two-port small-signal model of the multi-voltage-level direct-current power distribution system in the unified form is built; thirdly, a transfer function from input variables to output variables of the system and anequivalent loop gain expression of the system are derived; and finally, the stability of the system is judged through whether the equivalent loop gain of the system meets a Nyquist stability criterionor not, and if the equivalent loop gain meets the Nyquist stability criterion, the system is stable, otherwise, the system is not stable. The impedance ratio criterion of an existing direct-current power distribution system is popularized to the multi-voltage-grade direct-current power distribution system, so that the application range is wider.

Description

technical field [0001] The invention relates to the technical field of DC power distribution systems, in particular to a stability criterion method suitable for multi-voltage level DC power distribution systems. Background technique [0002] With the development of new energy, DC load and power electronics technology, DC power distribution system has been widely used due to its advantages of flexibility and high efficiency. The DC power distribution system is composed of multiple feedback-controlled converters. Although each converter is stable when working alone, due to the negative resistance characteristics of its input impedance and the impedance mismatch of cascaded converters, the DC bus voltage is prone to low-frequency oscillation. Not even stable. Therefore, the stability of the DC power distribution system needs to be solved urgently. [0003] Scholars at home and abroad first studied the stability of simple cascaded systems such as single-source single-load, sin...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J1/00
Inventor 陈武潘鹏鹏
Owner SOUTHEAST UNIV
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