New techniques for the assessment of harmonic stability in public low voltage networks with very high share of distributed power electronic devices

该研究的总体目标是分析公共低压电网中的谐波不稳定性，所述谐波不稳定性是由与电网电压和电流的谐波以及电网本身的谐波阻抗相互作用的电力电子设备的高渗透性引起的。为了评估非线性设备的阻尼损失、谐波不稳定性的风险以及由于设备数量增加而产生的谐波共振和/或偏移，需要进行全面的分析。与传统的稳态谐波研究不同，本文研究的重点是变流器系统及其控制的抗扰度和辐射特性。为了研究这种特定的行为，需要详细的白盒模型。由于缺乏来自制造商的信息，特别是关于控制器设计和模型开发的高度复杂性，变换器系统的足够详细的谐波模型还没有可用。然而，大量并行操作的详细模型的仿真很快受到可用计算能力的限制，并且需要过多的仿真时间。由于白盒模型的复杂性、元件的非线性、不同的时间尺度以及关于控制策略的通常不完整的知识，将使用通用建模的方法来生成能够并行执行大量模型的简化和简化的谐波黑盒模型。这些模型是必要的调查谐波不稳定性，减少阻尼效应和谐振现象的大规模实施的电力电子设备在低压grid. To评估开发的谐波模型，验证和参数化的方法，这些模型是必要的。每个白色和黑盒模型将根据实验室测量值进行确认。因此，将实施具有适当测试信号的实验室测试设置。将执行一个简单的案例研究，其中多个模型并行运行，以测试谐波黑箱模型用于谐波潮流模拟的功能性和适用性。本案例研究的模拟结果也将在实验室中进行验证。此外，所取得的成果可用于开发电网和设备的具体指标。它们可用于对未来谐波不稳定性进行近似和分类，并分别为DNO和制造商提供电网规划和设备设计问题的建议。评估的模型和市场上可用的转换器的不同参数集将被收集在模型库中。

The general objective of the study is the analysis of harmonic instabilities in the public low voltage grid caused by high penetration of power electronic devices interacting with the harmonics of the grid voltage and current and the harmonic impedance of the grid itself. A comprehensive analysis is necessary in order to assess the loss of damping by nonlinear devices, the risk of harmonic instabilities and shift and/or generation of harmonic resonances due to the increasing number of devices. Different to classical steady state harmonic studies the harmonic behavior concerning immunity and emission of the converter systems and its controls are in the focus of the investigation. In order to investigate this specific behavior, detailed white-box models are needed. Due to the lack of information from manufacturers, especially regarding the controller design and the high complexity of model development, sufficant detailed harmonic models for converter systems are not available yet. So, these models will be developed in this project.However, the simulation with a high amount of parallel operating detailed models is quickly limited by available computing power and needs excessive simulation times. Because of the complexity of the white-box models, the nonlinearity of the components, the different time-scales and the often uncomplete knowledge about the control strategy a method of generic modelling will be used to generate the reduced and simplified harmonic black-box models which are capable of the parallel execution of a huge number of models. These models are necessary to investigate the harmonic instabilities, reduced damping effect and resonance phenomena of a mass implementation of power electronic devices in the low voltage grid in a sufficient manner.In order to evaluate the developed harmonic models, methods for validation and parametrization of these models are needed. Each white- and black-box model will be validated based on laboratory measurements. Therefore, a laboratory test set up with appropriate test signals will be implemented. A simple case study will be executed with several models operating in parallel for testing the functionality and suitability of the harmonic black-box models for harmonic load flow simulation. The simulation results of this case study will be validated in the laboratory as well. Additionally, the achieved results can be used to develop grid and device specific indices. They can be used to approximate and classify future harmonic instabilities and to give recommendation to DNOs and manufactures for grid planning and device designing issues, respectively. The evaluated models and different sets of parameters for converters available on the market will be collected in a model library.