Observer-Based Pulsed Signal Injection for Grid Impedance Estimation in Three-Phase Systems

Garcia, J.; Sumner, Mark; Navarro-Rodríguez, Ángel; Guerrero, Juan Manuel; Garcia, P.

doi:10.1109/tie.2018.2801784

Cited by 57 publications

(28 citation statements)

References 49 publications

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“…Using that approach, and assuming there is no cross-coupling between the phases, the impedance can be represented by (5). In the case cross-coupling is considered, it will be represented by nondiagonal terms [32]. However, it should be noted that crosscoupling impedances in low-voltage distribution networks have, generally, a negligible value compared to the phase impedances [33].…”

Section: Rg Lgmentioning

confidence: 99%

Sensorless Unbalance Modeling and Estimation as an Ancillary Service for LV Four-Wire/Three-Phase Power Converters

Suárez

Garcia

Navarro-Rodríguez

et al. 2019

IEEE Trans. on Ind. Applicat.

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This paper describes a method to provide LV four-wire three-phase power converters with the capability of unbalance estimation as an ancillary service to the main role that they play in the distribution system (distributed generator, energy storage system, drive, etc). Typically, dedicated grid/load current sensors are needed to effectively comply with unbalance compensation tasks, increasing system cost and reducing reliability. This is due to the difficulties that arise in the extraction of the zero and negative voltage components from the voltages at the point of common coupling, such as the inadequate resolution of full-scaled voltage sensors and limited spectral separation. In this paper, the proposed method does not rely on additional sensors to those typically used in VSCs, and in any case, those sensors are limited to the point of connection of the power converter. Impedance estimation only using converter-side current sensors is implemented by adding a high frequency voltage excitation over the fundamental command. A new model approach is proposed for the real-time extraction of system impedance using a complex-valued compact form. Considering the voltage source at that frequency to be unique in the grid, it will be proved the impedance can be estimated and, thus, the resulting negative sequence current which is used for unbalance compensation. For the zero sequence, a special arrangement of the converter voltage sensors together with a repetitive controller is used.

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Section: Rg Lgmentioning

confidence: 99%

Sensorless Unbalance Modeling and Estimation as an Ancillary Service for LV Four-Wire/Three-Phase Power Converters

Suárez

Garcia

Navarro-Rodríguez

et al. 2019

IEEE Trans. on Ind. Applicat.

Self Cite

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“…Several methods for estimating the grid impedance have been proposed, see [3]- [20] and the papers cited therein. For the impedance estimation, grid converters have been utilized to inject an excitation signal to the grid [3]- [16]. On the contrary, the impedance has been estimated passively using existing power system disturbances [17], [18].…”

Section: Introductionmentioning

confidence: 99%

Real-Time Grid Impedance Estimation Using a Converter

Kukkola

Routimo

Hinkkanen

2019

2019 IEEE Energy Conversion Congress and Exposition (ECCE)

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This paper presents two real-time methods for estimating the grid inductance and resistance using a three-phase converter. In the methods, a single-frequency rotating voltage signal with a small magnitude is injected to the converter voltage reference. The converter measures the currents and voltages at the point of common coupling (PCC). The grid impedance is estimated from the measured data using two alternative methods: an estimator based on the sliding discrete Fourier transform (SDFT) and an adaptive grid observer. Dynamic performance of these methods is compared by means of simulations and experiments in the case of a changing grid impedance.

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“…of the grid impedance, e.g., [8]- [13]. The identification has been carried out using Fourier analysis [8], recursive parameter estimation [9], [10], model predictive control [11], extended Kalman filter [12], and wavelets [13].…”

Section: Introductionmentioning

confidence: 99%

Real-time Identification Method for LCL Filters Used With Grid Converters

Pirsto

Kukkola

Rahman

et al. 2019

2019 IEEE Energy Conversion Congress and Exposition (ECCE)

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This paper presents a real-time algorithm for identifying the inductance and capacitance values of LCL filters used with grid converters. As a side product, the grid inductance seen from the point of common coupling is also estimated. A wideband excitation signal is added to the converter voltage reference. During the excitation, the converter currents and the converter voltage reference are sampled. The samples are preprocessed in real time by removing DC biases and significant grid-frequency harmonics. Parameters of a discrete-time model are estimated at each sampling instant with a recursive estimation algorithm. The model parameter estimates are translated into inductance and capacitance values. The method can be embedded to a control system of PWM-based converters in a plug-in manner. Only the DC-link voltage and converter currents need to be measured. Simulation and experimental results are presented for a 12.5-kVA grid converter system to evaluate the proposed method.

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Observer-Based Pulsed Signal Injection for Grid Impedance Estimation in Three-Phase Systems

Cited by 57 publications

References 49 publications

Sensorless Unbalance Modeling and Estimation as an Ancillary Service for LV Four-Wire/Three-Phase Power Converters

Sensorless Unbalance Modeling and Estimation as an Ancillary Service for LV Four-Wire/Three-Phase Power Converters

Real-Time Grid Impedance Estimation Using a Converter

Real-time Identification Method for LCL Filters Used With Grid Converters

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