﻿ 基于遗传算法船舶新能源并网逆变器LCL滤波器设计
 舰船科学技术  2018, Vol. 40 Issue (1): 114-119 PDF

Design of LCL filter based on genetic algorithm for marine new energy grid - connected inverter
JING Zhen, XU He-li, GAO Lan
Key Laboratory of Marine Power Engineering and Technology, Ministry of Transportation, Wuhan University of Technology, Wuhan 430063, China
Abstract: In the trend of energy-saving emission reduction, people began to explore the development of new energy as an auxiliary power into the ship's power grid. Ship power grid is a limited power system, the higher the harmonic content of the grid .The grid-connected interface is the inverter. The pulse width modulation (PWM) technology makes the grid-connected inverter generate high-frequency harmonic current into the ship's power grid which will easily lead to ship power grid instability. There is a need to add in the inverter back-end to filter out high-frequency harmonics LCL-type filter, The design of LCL filter parameter of traditional grid-connected inverter on land is very difficult to meet the requirements of grid-connected inverter. In view of this, genetic algorithm is used to optimize the parameters of the LCL filter on the ship's power grid side, and the optimal solution of the LCL filter is considered synthetically. The optimal solution is obtained by considering the constraints of the ship LCL filter. The simulation results show that the filter with parameters optimized by genetic algorithm has good network side harmonic suppression ability, which provides theory support for the Ship new energy grid connection.
Key words: marine new energy     inverter and grid     LCL-filter     genetic algorithm
0 引　言

1 船舶新能源并网控制结构

 图 1 船舶新能源并网控制结构 Fig. 1 New energy grid-connected control structure for ships

 图 2 LCL滤波器单相等效电路 Fig. 2 LCL filter single-phase equivalent circuit

 $\left\{\!\!\! {\begin{array}{*{20}{c}}{{{{L}}_{1{{k}}}}\frac{{{\rm{d}}{{{i}}_{1{{k}}}}}}{{{\rm{d}}t}} = {{{u}}_{{k}}} - {{{u}}_{{{ck}}}}}, \\[8pt]{{{{L}}_{2{{k}}}}\frac{{{\rm{d}}{{{i}}_{2{{k}}}}}}{{{\rm{d}}t}} = {{{u}}_{{{ck}}}} - {{{u}}_{{{gk}}}}}, \\[8pt]{{{{C}}_{{k}}}\frac{{{\rm{d}}{{{u}}_{{{ck}}}}}}{{{\rm{d}}t}} = {{{i}}_{1{{k}}}} - {{{i}}_{2{{k}}}}}{\text{。}}\end{array}} \right.$ (1)

 $\left\{ {\begin{array}{*{20}{l}}{\frac{{{\rm{d}}{i_{1{\rm{d}}}}}}{{{\rm{d}}t}} = \omega {i_{1q}} - \frac{1}{{L1}}{u_{c{\rm{d}}}} + \frac{1}{{L1}}{u_{\rm{d}}}},\\[5pt]{\frac{{{\rm{d}}{i_{1q}}}}{{{\rm{d}}t}} = - \omega {i_{1{\rm{d}}}} - \frac{1}{{L1}}{u_{c{\rm{q}}}} + \frac{1}{{L1}}{u_q}},\\[5pt]{\frac{{{\rm{d}}{i_{2{\rm{d}}}}}}{{{\rm{d}}t}} = \omega {{\rm{i}}_{2{\rm{q}}}} + \frac{1}{{{\rm{L}}2}}{{\rm{u}}_{{\rm{cd}}}} - \frac{1}{{L2}}{u_{\rm{d}}}},\\[5pt]{\frac{{{\rm{d}}{i_{2q}}}}{{{\rm{d}}t}} = - \omega {i_{2{\rm{d}}}} + \frac{1}{{L2}}{u_{cq}} - \frac{1}{{L2}}{u_q}},\\[5pt]{\frac{{{\rm{d}}{u_{c{\rm{d}}}}}}{{{\rm{d}}t}} = \frac{1}{C}{i_{1{\rm{d}}}} - \frac{1}{C}{i_{2{\rm{d}}}} + \omega {u_{c{\rm{q}}}}},\\[5pt]{\frac{{{\rm{d}}{i_{c{\rm{q}}}}}}{{{\rm{d}}t}} = \frac{1}{C}{i_{1q}} - \frac{1}{C}{i_{2q}} - \omega {u_{c{\rm{d}}}}}{\text{。}}\end{array}} \right.$ (2)

 $\begin{split}{{{G}}_{{{LCL}}}}\left( {{s}} \right) \!= \frac{{{{{i}}_2}\left( {\rm{s}} \right)}}{{{{{v}}_{{{in}}}}\left( {{s}} \right)}} \!&=\! \frac{1}{{{{{s}}^3}{{{L}}_1}{{{L}}_2}{{C}} + {{s}}\left( {{{{L}}_1} + {{{L}}_2}} \right)}} \!=\\&\! \frac{1}{{{{s}}{{{L}}_1}{{{L}}_2}{{C}}{{{s}}^2}}}\frac{1}{{{{{s}}^{2 + }}{{\omega }}_{{r}}^2}},\end{split}$ (3)

 ${\omega _r} = \sqrt {\frac{{{L_1} + {L_2}}}{{{L_1}{L_2}C}}} {\text{。}}$ (4)

2 LCL滤波器分析 2.1 LCL滤波器谐振抑制

 图 3 LCL滤波器的幅频特性 Fig. 3 Amplitude-frequency characteristics of LCL filter

 图 4 谐振抑制幅频特性曲线 Fig. 4 Resonance suppression amplitude-frequency characteristic curve
2.2 LCL滤波器设计参数约束条件

 ${L_T} = \frac{{{E_m} \sin\varphi + U_m^2 + \sqrt {E_m^2{\sin^2}\varphi + U_m^2 - E_m^2} }}{{\omega {I_{mp}}}},$ (5)

 ${{{L}}_{{T}}} \leqslant \frac{{\sqrt {\frac{{U_{dc}^2}}{3} - E_m^2} }}{{\omega {I_m}}}{\text{。}}$ (6)

 $\Delta {I_{\rm ripple - max}} = \frac{{{U_{dc}}}}{{4\sqrt {3{L_T}{f_{sw}}} }},$ (7)

 ${L_T} = \frac{{{U_{dc}}}}{{4\sqrt 3 \Delta {I_{\rm ripple - {\rm max}}}{f_{sw}}}}{\text{，}}$ (8)

 $\frac{{{{{U}}_{{{dc}}}}}}{{4\sqrt 3 \Delta {{{I}}_{{\rm{ripple}} - {\rm{max}}}}{{{f}}_{{{sw}}}}}} \leqslant {{{L}}_{{T}}} \leqslant \frac{{\sqrt {\frac{{{{U}}_{{{dc}}}^2}}{3} - {{E}}_{{m}}^2} }}{{{\rm{\omega }}{{{I}}_{{m}}}}}{\text{，}}$ (9)

 ${\rm{C}} \leqslant 5\% \times \frac{P}{{3 \times 2 \times \pi \times {f_n}E_m^2}}{\text{，}}$ (10)

LCL型滤波器具有低通滤波器的特性，为了更好发挥LCL滤波器的优势，高效抑制高频谐波，且对开关频率控制并网逆变器不产生影响。则谐振频率fres取值设定式（11）约束范围。

 $10{f_b} \leqslant{f_{res}} \leqslant \frac{{{f_s}}}{2}\text{。}$ (11)

3 基于遗传算法LCL滤波器参数优化

3.1 染色体编码

LCL滤波器参数包括L1L2CRC，其中RC用于谐振抑制取RC=1 Ω，对另外3个参数采用遗传算法寻求3个参数最优解时，可将染色体表示为向量X=[L1 L2 C]。根据式子（9），式（10），式（11）确定的LCL滤波器参数的约束条件，对变量采用二进制编码的方式，将代表的个体表示为{0，1}二进制字符。

3.2 适应度函数建立

 ${{{f}}_{{{fitness}}}} = {{d}} = \frac{{{{{i}}_{\rm{g}}}\left( {{{{h}}_{{{sw}}}}} \right)}}{{{{i}}\left( {{{{h}}_{{{sw}}}}} \right)}} \approx \left| {\frac{{{{Z}}_{{{LC}}}^2}}{{{\rm{\omega }}_{{{res}}}^2 - {\rm{\omega }}_{{{sw}}}^2}}} \right|,$ (12)

 $Z_{LC}^2 = {({L_2}C)^{ - 1}},\;{\omega _{res}} = 2\pi {f_{res}},\;{\omega _{sw}} = 2\pi {f_{sw}}{\text{。}}$

 ${{{F}}_{{{fit}}}} = \left\{\!\!\!\! \begin{array}{l}{{\rm{f}}_{{\rm{fitness}}}}\;\;\;\;\;\;,\;\; x{\text{满足约束条件}}\\{{\rm{f}}_{{\rm{fitness}}}} - \infty \;\;\;,\;\; x{\text{不满足约束条件}}{\text{。}}\end{array} \right.$ (13)
3.3 遗传算法实现步骤

1）产生规模为NIND=70的初始种群；

2）经过研究比较，设定最大遗传代数MAXGEN=2 000，变异GGAP=0.1，交叉概率PM=0.8；

3）对种群中各个个体的适应度进行计算；

4）对群体进行选择运算；

5）对群体进行交叉运算；

6）变异运算，求得下一代种群；

7）终止条件判断。

 图 5 遗传算法流程图 Fig. 5 Genetic algorithm flow chart

 图 6 遗传算法寻求最优解变化图 Fig. 6 Genetic algorithm to seek the optimal solution change graph
4 仿真验证分析

 图 7 基于LCL滤波器船舶新能源逆变并网仿真系统 Fig. 7 Grid connected simulation system of new energy inverter based on LCL filter

 图 8 传统算法并网电流波形 Fig. 8 Traditional algorithm grid - connected current waveform

 图 9 遗传算法并网电流波形 Fig. 9 Genetic algorithm and grid - connected current waveform

 图 10 传统算法谐波分析 Fig. 10 Traditional algorithm harmonic analysis

 图 11 遗传算法谐波分析 Fig. 11 Genetic algorithm harmonic analysis
5 结　语

1）本文针对船舶新能源并网系统会产生大量谐波，对本身就不稳定的船舶电网造成谐波污染的问题，采用遗传算法对其LCL滤波器参数通过编码、交叉、变异，择优进行参数最优化，最后搭建了仿真模型，比较传统算法和遗传算法优化参数得到的谐波含量，遗传算法优化的滤波器得到的并网电流谐波含量低且符合船舶新能源并网要求。

2）先前有过采用自适应遗传算法对陆地风力发电逆变并网LCL滤波器参数进行优化设计，本文采用遗传算法是对船舶新能源逆变并网LCL滤波器参数进行优化，并提出一种电容并联电阻的无缘阻尼谐振抑制的方法。

3）本文采用遗传算法对船舶新能源逆变并网LCL滤波器参数优化，最后逆变器输出电流经滤波后谐波含量降低且符合并网要求，为船舶新能源并网提供理论支持。本文只是一个仿真实验，还需要进一步通过对实船新能源逆变系统设计来验证。

 [1] 严新平. 新能源在船舶上的应用进展及展望[J]. 船海工程, 2010, 39 (6): 111–115. YAN Xin-ping. Progress review of new energy application in ship[J]. Ship & Ocean Engineering, 2010, 39 (6): 111–115. [2] 孙义存. 船舶新能源动力系统现状与发展趋势[J]. 中国水运, 2012, 12 (7): 87–88. SUN Yi-cun. Present situation and development trend of marine new energy power system[J]. China Water Transport, 2012, 12 (7): 87–88. [3] 陈姝慧, 王红梅. 基于电网电压前馈的三相LCL并网逆变器电流控制方法研究[J]. 电气工程学报, 2016, 11 (1): 24–31. CHEN Shu-hui, WANG Hong-mei. Research on current control scheme based on grid voltage feed forward for three-phase LCL-type grid-connected inverters[J]. Journal of Electrical Engineering, 2016, 11 (1): 24–31. [4] 张勇. 分布式发电系统中的LCL滤波器性能分析和设计[J]. 电力电容与无功补偿, 2013, 34 (6): 29–32. [5] 韩琳, 陈柏超, 陈晓国. 三相整流电路谐波注入滤波器方法[J]. 高电压技术, 2003, 3 (33): 42–46. [6] 李永辉. 船舶并网逆变器控制策略的研究[D]. 大连: 大连海事大学, 2014. [7] 陈东, 张军明, 钱照明. 带LCL滤波器的并网逆变器单电流反馈控制策略[J]. 中国电机工程学报, 2013, 33 (9): 10–16. [8] 张宪平, 李亚西, 等. 三相电压型整流器的LCL滤波器分析与设计[J]. 电气应用, 2007, 26 (5): 51–53. [9] 陈伟, 韦徵. 三相并网逆变器LCL滤波器的研究及新型有源阻尼控制[J]. 电工技术学报, 2014, 29 (6): 71–79. [10] J DANNEHL, FW FUCHS, S HANSEN, et al. Investigation of active damping approaches for PI-based current control of grid-connected pulse width modulation converters with LCL filters[J]. Energy Conversion Congress and Exposition, 2009, 46 (4): 1509–1517. [11] 阮新波, 王学华, 潘东华, 等. LCL型并网逆变器的控制技术[M]. 北京: 科学出版社, 2015: 60–71. [12] PEÑA-ALZOLA, et al. Analysis of the PassiAnalysis of the passive damping losses in LCL-filter-based grid convertersve Damping Losses in LCL-Filter-Based Grid Converters[J]. IEEE Transactions on Power Electronics, 2013, 28 (6): 2642–2646. DOI: 10.1109/TPEL.2012.2222931 [13] . 三相并网逆变器LCL滤波器的简明设计[J]. 通讯电源技术, 2012, 29 (2): 47–49. [14] 雷英杰, 张善文. MATLAB遗传算法工具箱及应用[M]. 西安: 西安电子科技大学出版社, 2014: 55–59. LEI Ying-jie, ZHANG Shan-wen. MATLAB genetic algorithm toolbox and its application[M]. Xi’an: Xi'an University of Electronic Science and Technology Press, 2014: 55–59.