储能科学与技术 ›› 2020, Vol. 9 ›› Issue (6): 1982-1990.doi: 10.19799/j.cnki.2095-4239.2020.0103

• 储能测试与评价 • 上一篇    下一篇

基于载波移相调制的模块化多电平电池储能系统直流侧建模

田凯1(), 陈堃1, 陈满2, 凌志斌1()   

  1. 1.上海交通大学电力传输与功率变换控制教育部重点实验室，上海 200240
    2.南方电网调峰调频发电有限公司技术中心，广东 广州 511400
  • 收稿日期:2020-03-01 修回日期:2020-05-26 出版日期:2020-11-05 发布日期:2020-10-28
  • 作者简介:田凯（1995—），男，硕士，研究方向为电池储能系统，E-mail：tx327820@sjtu.edu.cn；联系人：|凌志斌，副教授，研究方向为储能工程，E-mail：lingzhibin@sjtu.edu.cn。
  • 基金资助:
    国家自然科学基金(51777125)

DC-side modeling of the modular multilevel battery energy storage system based on carrier phase shift modulation

Kai TIAN1(), Kun CHEN1, Man CHEN2, Zhibin LING1()   

  1. 1.Key Laboratory of Control of Power Transmission and Conversion, Shanghai Jiao Tong University, Shanghai 200240, China
    2.Technology Center of CSG Power Generation Company, Guangzhou 511400, Guangdong, China
  • Received:2020-03-01 Revised:2020-05-26 Online:2020-11-05 Published:2020-10-28

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摘要：

载波移相调制是模块化多电平电池储能系统中广泛应用的一种调制方式。本文针对载波移相调制和电池储能系统的直流侧进行了理论研究，提出了N+1调制和2N+1调制两种不同的载波移相调制方式的数学模型，发现载波周期内相开通模块数及其持续时间仅与调制比和桥臂模块数相关。基于此建立了模块化多电平电池储能系统直流侧的等效模型，发现系统直流侧可以用两个电压源和一个开关等效，其参数仅与调制比和桥臂模块数相关。在该模型的基础上，提出了一种桥臂电感取值的方法，可以在系统稳定状态下满足对直流电流纹波的设计要求。最后通过仿真验证了数学模型的准确性以及电感取值方法的有效性。

关键词: 模块化多电平电池储能系统, 载波移相调制, 直流侧等效模型, 桥臂电感取值

Abstract:

The carrier phase shift pulse width modulation (CPS-PWM) is a modulation method widely used in modular multilevel converter-based battery energy storage systems (MMC-BESS). At present, the mathematical modeling of MMC-BESS based on CPS-PWM is mostly concentrated on the AC side of the system, and its analysis of the output voltage waveforms is mostly focused on the frequency domain. The mathematical modeling for the DC side of the system and the time-domain analysis of the output waveforms has not yet been studied. Moreover, the instantaneous equivalent circuit for the DC side of MMC-BESS is still unclear. This study performs a theoretical research on CPS-PWM and the DC side of MMC-BESS. Accordingly, time-domain triangle wave mathematical expressions for the carrier waveforms are established, including the two most commonly used CPS-PWM (i.e., N + 1 and 2N+1 modulations). The intersection point sequence is proposed for a constant modulation wave and the carrier waveforms in a carrier period. The expressions of the intersection time interval and the number of sub-modules opened in a single phase, which are only related to the modulation ratio and the number of sub-modules in an arm, are then obtained. Based on this, an equivalent model of the DC side of MMC-BESS is established. We find that the DC side of the system can be equivalent to two voltage sources and one switch, and its parameters are only related to the modulation ratio and the number of bridge modules. Subsequently, the ripple expression of the DC current in the equivalent switching cycle is calculated based on this model. A method for determining the bridge inductance, which can meet the design requirements for the DC current ripple in the steady state, is also proposed. Finally, a three-phase 48-module MMC-BESS simulation model is built in MATLAB/Simulink. The simulation results of important system parameters, such as the number of open sub-modules, equivalent switching frequency and duty cycle, and DC current ripple, are consistent with the theory, thereby verifying the mathematical model accuracy. The simulation results of the current ripple can meet the design requirements when the method for choosing the bridge inductance is used. This also confirms the method effectiveness.

Key words: modular multilevel battery energy storage system(MMC-BESS), carrier phase shift pulse width modulation(CPS-PWM), DC-side equivalent model, bridge inductance

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