大功率并网变流器离散域电流控制策略

doi:10.19595/j.cnki.1000-6753.tces.222309

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摘要

MW级大功率并网变流器的开关频率较低,延迟和离散化误差对控制性能影响较大,导致动态响应慢、电网背景谐波影响大等问题。因此,直接离散域控制系统设计成为必要。该文针对LCL滤波并网变流器建立离散域数学模型,并基于此提出桥臂侧电流和网侧电流融合的离散域电流控制器。同时,为了在不额外增加电流传感器和检测电路的情况下获取并网电流信息,设计电容电压微分器,实现网侧电流的估算,降低硬件复杂性和控制成本。研究表明,该文设计的离散域电流控制器,有着较好的动态性能和电网背景谐波抑制能力。最后,通过硬件在环半实物仿真系统对该文的分析和设计进行了实验验证。

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关键词 ： LCL型并网变流器, 低开关频率, 离散域控制, 背景谐波

Abstract：

For high power grid-connected converters, the switching frequency usually is low. Consequently, the negative effects enforced by the control delay and discretizing errors are heavy. However, traditional current control strategies generally ignored these negative effects and, hence, reducing the performance of the designed controller. Recently, some strategies were presented to compensate the control delay and the discretizing errors, but most of them suffered from the low dynamic response and the high sensitivity to the power grid harmonics. To address these issues, a current control strategy combining the bridge arm-side and the grid-side currents is designed directly in the discrete-time domain and pole-zero placement is used in synchronous coordinates. Meanwhile, a differentiator to the capacitor voltage is introduced to make estimation of the grid-side currents. Consequently, hardware complexity as well as the corresponding control cost is reduced.
Discrete-time model of the converter with LCL as output filter is built in synchronous coordinates, including the computational delay, firstly. Following that, the corresponding structure of the combining state-space control scheme is as follows: the harmonic control loop of the grid-side currents is constructed and combined with the fundamental current control loop on the bridge arm-side, which uses the full state-feedback control. And then, the integral controller is introduced for improved disturbance rejection and the reference-feedforward controller is designed to increase the reference-tracking dynamic performance. Consequently, the closed-loop transfer function of the system is obtained based on the discrete-time model and the control scheme, and then the state feedback function matrix and the feedforward module are optimized based on the pole-zero placement. Finally, a differentiator is introduced to make estimation of the grid-side currents, reducing the hardware cost.
Experiment results based on a hardware-in-loop simulator show: the response time of the bridge arm-side currents to a 1000A step-up change is about 4.5ms; the recovery time of the bridge arm-side currents facing a grid-voltage dip of 0.4 p.u.is about 10ms; and the total harmonic distortion of the grid-side currents is 2.28%, below the 5% limit given in standards, in the circumstances of 6% fifth and seventh harmonic components appearing in the grid voltage. Finally, to verify the robustness of the proposed strategy to the parameter deviations, the actual system parameters are deviated artificially from their nominal values. The experimental results show that the proposed strategy can operate satisfactorily in the range of ±40% parameter deviations and the influence of the parameter deviations is low.
The following conclusions can be drawn from the experiment results: (1) compared with the typical discrete-time state-space control strategy, the proposed strategy keeps the same great dynamic performance but achieves an improved capability of rejecting the grid harmonic-disturbance. (2) the proposed control strategy simplifies the design complexity based on the direct pole-zero placement and increases the degrees of freedom based on the combining design of fundamental current and harmonic control loops. (3) the differentiator to the capacitor voltage is designed to get knowledge of grid-side currents without additional current sensors and the corresponding sampling circuit required, reducing the hardware complexity and the cost.

Key words： Grid-connected converter with LCL as output filter low switching frequency discrete-time control grid harmonics

收稿日期: 2022-12-13

PACS:

TM464

基金资助:

安徽省科技重大专项资助项目（202003a05020029）

通讯作者: 杨淑英男,1980年生,教授,博士生导师,研究方向为风力发电系统、电驱动系统。E-mail：yangsyhfah@163.com

作者简介: 王旭男,1998年生,硕士研究生,研究方向为大功率风电变流器电流控制。E-mail：wx1998_wangxu@163.com

引用本文:

王旭, 杨淑英, 李典, 张兴. 大功率并网变流器离散域电流控制策略[J]. 电工技术学报, 0, (): 133-133. Wang Xu, Yang Shuying, Li Dian, Zhang Xing. Discrete-time domain Current Control Strategy for High Power Grid-connected Converters. Transactions of China Electrotechnical Society, 0, (): 133-133.

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[1] Sharma H R, Suryawanshi H M, Chaturvedi P, et al.Implementation of passive damping technique in LCL filter for three-phase grid connected inverter[C]//2022 IEEE 2nd International Conference on Sustainable Energy and Future Electric Transportation(SeFeT), Hyderabad, India, 2022: 1-6.
[2] Li Xiaoqiang, Wu Xiaojie, Geng Yiwen, et al.Wide damping region for LCL-type grid-connected inverter with an improved capacitor-current-feedback method[J]. IEEE Transactions on Power Electronics, 2015, 30(9): 5247-5259.
[3] Xin Zhen, Loh P C, Wang Xiongfei, et al.Highly accurate derivatives for LCL-filtered grid converter with capacitor voltage active damping[J]. IEEE Transactions on Power Electronics, 2016, 31(5): 3612-3625.
[4] Pan Donghua, Ruan Xinbo, Wang Xuehua.Direct realization of digital differentiators in discrete domain for active damping of LCL-type grid-connected inverter[J]. IEEE Transactions on Power Electronic, 2018, 33(10): 8461-8473.
[5] Chen Chen, Xiong Jian, Wan Zhiqiang, et al.A time delay compensation method based on area equivalence for active damping of an LCL-type converter[J]. IEEE Transactions on Power Electronics, 2017, 32(1): 762-772.
[6] 方天治, 黄淳, 陈乃铭, 等. 一种提高弱电网下LCL型并网逆变器鲁棒性的相位超前补偿策略[J]. 电工技术学报, 2018, 33(20): 4813-4822.
Fang Tianzhi, Huang Chun, Chen Naiming, et al.A phase-lead compensation strategy on enhancing robustness of LCL-type grid-tied inverters under weak grid conditions[J]. Transactions of China Electrotechnical Society, 2018, 33(20): 4813-4822.
[7] 张森, 赵剑锋, 刘康礼, 等. 数字控制延时对电流环解耦有效性的影响[J]. 电工技术学报, 2020, 35(增刊2): 484-493.
Zhang Sen, Zhao Jianfeng, Liu Kangli, et al.Research on the impacts of digital control delay on the effectiveness of current loop decoupling[J]. Transactions of China Electrotechnical Society, 2020, 35(S2): 484-493.
[8] Dannehl J, Liserre M, Fuchs F W.Filter-based active damping of voltage source converters with LCL filter[J]. IEEE Transactions on Industrial Electronics, 2011, 58(8): 3623-3633.
[9] Nussbaumer T, Heldwein M L, Gong Guanghai, et al.Comparison of prediction techniques to compensate time delays caused by digital control of a three-phase Buck-type PWM rectifier system[J]. IEEE Transactions on Industrial Electronics, 2008, 55(2): 791-799.
[10] Corradini L, Stefanutti W, Mattavelli P.Analysis of multi-sampled current control for active filters[C]//2007 IEEE Industry Applications Annual Meeting, New Orleans, LA, USA, 2007: 1608-1615.
[11] 潘冬华, 阮新波, 王学华, 等. 提高LCL型并网逆变器鲁棒性的电容电流即时反馈有源阻尼方[J]. 中国电机工程学报, 2013, 33(18): 1-10, 21.
Pan Donghua, Ruan Xinbo, Wang Xuehua, et al.A capacitor-current real-time feedback active damping method for improving robustness of the LCL-type grid-connected inverter[J]. Proceedings of the CSEE, 2013, 33(18): 1-10, 21.
[12] Pan Donghua, Ruan Xinbo, Bao Chenlei, et al.Capacitor-current-feedback active damping with reduced computation delay for improving robustness of LCL-type grid-connected inverter[J]. IEEE Transactions on Power Electronics, 2014, 29(7): 3414-3427.
[13] 王林, 孙鹏菊, 薛统宇, 等. 一种提高LCL型并网逆变器电流控制性能的延时补偿方法[J]. 中国电机工程学报, 2020, 40(19): 6320-6330.
Wang Lin, Sun Pengju, Xue Tongyu, et al.A delay compensation method to improve the current control performance of the LCL-type grid-connected inverter[J]. Proceedings of the CSEE, 2020, 40(19): 6320-6330.
[14] Kukkola J, Hinkkanen M.Observer-based state-space current control for a three-phase grid-connected converter equipped with an LCL filter[J]. IEEE Transactions on Industry Applications, 2014, 50(4): 2700-2709.
[15] Kukkola J, Hinkkanen M, Zenger K.Observer-based state-space current controller for a grid converter equipped with an LCL filter: analytical method for direct discrete-time design[J]. IEEE Transactions on Industry Applications, 2015, 51(5): 4079-4090.
[16] Pérez-Estévez D, Doval-Gandoy J, Yepes A G, et al.Positive-and negative-sequence current controller with direct discrete-time pole placement for grid-tied converters with LCL filter[J]. IEEE Transactions on Power Electronics, 2017, 32(9): 7207-7221.
[17] 陈杰, 章新颖, 闫震宇, 等. 基于虚拟阻抗的逆变器死区补偿及谐波电流抑制分析[J]. 电工技术学报, 2021, 36(8): 1671-1680.
Chen Jie, Zhang Xinying, Yan Zhenyu, et al.Dead-time effect and background grid-voltage harmonic suppression methods for inverters with virtual impedance control[J]. Transactions of China Electrotechnical Society, 2021, 36(8): 1671-1680.
[18] 林丽娟, 贾清泉, 田书娅, 等. 基于一致性算法的配电网谐波分布式治理策略[J]. 电力系统自动化, 2022, 46(2): 109-117.
Lin Lijuan, Jia Qingquan, Tian Shuya, et al.Distributed harmonic mitigation strategy of distribution network based on consensus algorithm[J]. Automation of Electric Power Systems, 2022, 46(2): 109-117.
[19] 游小杰, 杨才伟, 王剑, 等. 一种适用于机车PWM整流器的比例积分-谐振电流控制器设计[J]. 电工技术学报, 2021, 36(23): 4926-4936.
You Xiaojie, Yang Caiwei, Wang Jian, et al.A tuning method for proportional integral-resonant current controller in locomotive PWM rectifiers[J]. Transactions of China Electrotechnical Society, 2021, 36(23): 4926-4936.
[20] 黄仁志, 全相军, 吴在军, 等. 基于多重谐振控制器的参考值前馈自适应控制[J]. 电工技术学报, 2022, 37(16): 4212-4224.
Huang Renzhi, Quan Xiangjun, Wu Zaijun, et al.A multiple resonant based on reference feedforward adaptive voltage control of three-phase inverter[J]. Transactions of China Electrotechnical Society, 2022, 37(16): 4212-4224.
[21] Xin Zhen, Mattavelli P, Yao Wenli, et al.Mitigation of grid-current distortion for LCL-filtered voltage-source inverter with inverter-current feedback control[J]. IEEE Transactions on Power Electronics, 2018, 33(7): 6248-6261.
[22] Zhao Rende, Li Qian, Xu Hailiang, et al.Harmonic current suppression strategy for grid-connected PWM converters with LCL filters[J]. IEEE Access, 2019, 7: 16264-16273.
[23] 谢震, 汪兴, 张兴, 等. 基于谐振阻尼的三相LCL型并网逆变器谐波抑制优化策略[J]. 电力系统自动化, 2015, 39(24): 96-103.
Xie Zhen, Wang Xing, Zhang Xing, et al.Optimized harmonic suppression strategy of grid-connected inverter with an LCL-type filter based on resonance damping[J]. Automation of Electric Power Systems, 2015, 39(24): 96-103.
[24] 徐健, 曹鑫, 郝振洋, 等. 基于电网谐波电压前馈的虚拟同步整流器电流谐波抑制方法[J]. 电工技术学报, 2022, 37(8): 2018-2029.
Xu Jian, Cao Xin, Hao Zhenyang, et al.A harmonic-current suppression method for virtual synchronous rectifier based on feedforward of grid harmonic voltage[J]. Transactions of China Electrotechnical Society, 2022, 37(8): 2018-2029.
[25] Li Weiwei, Ruan Xinbo, Pan Donghua et al. Full-feedforward schemes of grid voltages for a three-phase LCL-type grid-connected inverter[J]. IEEE Transactions on Industrial Electronics, 2013, 60(6): 2237-2250.
[26] Zhang Hao, Ruan Xinbo, Lin Zhiheng, et al.Capacitor voltage full feedback scheme for LCL-type grid-connected inverter to suppress current distortion due to grid voltage harmonics[J]. IEEE Transactions on Power Electronics, 2021, 36(3): 2996-3006.
[27] Franklin G F, Powell J D, Workman M L.Digital control of dynamic systems[M]. Menlo Park, CA, USA: Addison-Wesley, 1997.
[28] Hu Mingjin, Hua Wei, Ma Guangtong, et al.Improved current dynamics of proportional-integral-resonant controller for a dual three-phase FSPM machine[J]. IEEE Transactions on Industrial Electronics, 2021, 68(12): 11719-11730.