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电力电子器件的高渗透率与电网电压、电流的谐波以及电网本身的谐波阻抗相互作用而引起的公共低压电网的谐波不稳定。有必要进行全面的分析，以评估非线性装置的减振损失、谐波不稳定的风险以及由于装置数量的增加而引起的谐波共振的漂移和/或产生。与经典的稳态谐波研究不同，换流系统及其控制系统的抗扰度和发射的谐波行为是研究的重点。为了研究这一特定行为，需要详细的白盒模型。由于缺乏制造商的信息，特别是控制器的设计和模型开发的高度复杂性，目前还没有足够详细的换流系统的谐波模型。然而，大量并行运行的详细模型很快就会受到可用计算能力的限制，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、不同的时间尺度和对控制策略的不完全了解，将采用通用建模的方法来生成能够并行执行大量模型的降阶和简化的谐波黑盒模型。这些模型对于充分研究电力电子器件在低压电网中大规模实施时的谐波不稳定性、减振效应和谐振现象是必要的。为了对所建立的模型进行评估，需要对这些模型进行验证和参数化。每个白盒和黑盒模型都将基于实验室测量进行验证。因此，将实施带有适当测试信号的实验室测试。在几个模型并行运行的情况下，将执行一个简单的案例研究，以检验谐波黑箱模型在谐波潮流模拟中的功能性和适用性。本案例研究的模拟结果也将在实验室中得到验证。此外，所获得的结果还可用于开发特定于网格和设备的指标。它们可以用来近似和分类未来的谐波不稳定，并分别为电网规划和设备设计问题向DNO和制造商提供建议。市场上提供的转化器的评估模型和不同参数集将收集在模型库中。

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.