多逆变器混合运行模式系统的谐波谐振机理、评估与抑制

With the development of distributed renewable energy generation system, the harmonic resonance problem and stability problem of inverters and its component system have attracted much attention. Firstly, the complex network consists of the non-isolated parallel connection of distributed inverters, together with the large impedance of the power grid, can easily lead to harmonic resonance and even the instability of the system. Secondly, with the increasing penetration of renewable energy, the power grid is characterized by weak inertia and weak voltage support. Voltage-controlled virtual synchronous generator (VSG) algorithm has been gradually applied to distributed systems, thus constituting a multi-inverter hybrid operation mode system, which brings more severe challenges to the stable operation of the system. In this project a research on harmonic resonance mechanism, evaluation and suppression of multi-inverter hybrid operation mode system is intended to carry out, which mainly includes: studying the model of multi-inverter hybrid operation mode system that includes current control mode and voltage control mode, thus to obtain the harmonic resonance mechanism and resonance characteristics of different mixing ratios; studying harmonic resonance evaluation scheme of the multi-inverter hybrid operation mode system, as well as the system equivalence and similarity, to obtain the quantitatively express of harmonic resonance characteristics; studying the harmonic resonance suppression strategy based on evaluation adaptation, and the harmonic resonance optimization model predictive control strategy based on multi-sampling, to realize multi-harmonic resonance suppression of the multi-inverters hybrid operation mode system.

随着分布式新能源发电系统的发展，逆变器及系统谐波谐振与稳定性问题倍受关注。首先，分布式逆变器的非隔离并联连接构成了复杂电网络，加之较大的电网阻抗，易导致谐波谐振甚至系统的不稳定问题；其次，随着新能源渗透率不断攀升，电网呈弱惯性、弱电压支撑运行特性，电压控制型虚拟同步机算法逐渐应用于分布式系统中，从而构成了多逆变器混合运行模式系统，给系统的稳定运行带来更严峻的挑战。本项目拟开展多逆变器混合运行模式系统的谐波谐振机理、评估与抑制的研究。主要包括：研究包含电流和电压控制型的混合运行模式下多逆变器建模，得出该模式下谐波谐振机理及不同混合比的谐振特性；研究多逆变器混合运行模式系统的谐波谐振评估及系统的等值性与相似性，以对谐波谐振特性定量的表达；研究基于评估自适应的谐波谐振抑制策略和基于多采样的谐波谐振优化模型预测控制策略，以实现对多逆变器混合运行模式下多谐波谐振进行抑制。

随着新能源发电技术的持续快速发展，并网逆变器及系统的谐波、谐振与稳定性问题倍受关注。首先，逆变器的非隔离并联连接构成了复杂电网络，加之较大的电网阻抗，易导致逆变器谐波、谐振甚至系统不稳定；其次，随着新能源渗透率的不断攀升，电网呈弱惯性、弱电压支撑运行特性，采用下垂或虚拟同步机算法的电压控制型逆变器逐渐应用于并网系统中，从而构成了多逆变器混合运行模式系统，给系统的稳定运行带来更严峻的挑战。本项目重点研究了电流/电压控制型逆变器的建模方法，构建了统一模型框架，提出了分频谐波与集中等效的模型修正方法，建立了多逆变器混合运行模式下的系统模型。在此基础上，分析并揭示了电流/电压控制型逆变器及混合系统的谐波、谐振与功率振荡产生机理，结合仿真、实验数据从多角度对系统的稳定性及其谐波、谐振特性进行定性与定量描述。此外，研究了混合运行模式系统中传递函数矩阵的非特征值和系统中逆变器台数的等值性与相似性，证明了用4并联作为混合运行模式系统替代研究的有效性。为抑制混合系统中逆变器间的交互谐振，提出并研究了一种基于输出N阶微分加权反馈的有源阻尼算法并采用粒子群算法进行参数整定的方法，实现了逆变器间中、高频谐振的精准抑制；为提高电流控制型逆变器在弱电网下的稳定性，采用卡尔曼滤波改善锁相环以减小电网背景谐波对电流控制的耦合，提出基于多采样技术的滞环模型预测控制以减小输出电流低次谐波；为提高电压控制型逆变器的稳定性，提出并研究了基于双曲正切函数下垂控制结构和基于超前滞后串联的虚拟惯性结构，在提高了电压控制型逆变器响应的同时，减小了功率低频振荡。最后，基于MATLAB/Simulink建立了电流/电压控制型逆变器混合运行模式多逆变器仿真平台，并通过搭建4并联逆变器的物理平台共同验证了所建模型与谐波、谐振抑制方案的正确性。本项目的研究可为不同运行模式的逆变器建模、谐波交互分析、抑制控制技术的优化和运用提供理论基础及有效的解决方案。