A Flexible Compensation Strategy for Weak Grid-Tied Current Controlled Converters Under Unbalanced and Harmonic Conditions

With increasing changes in the contemporary energy system, it becomes essential to test the autonomous control strategies for distributed energy resources in a controlled environment to investigate power grid stability. Power hardware-in-the-loop (PHIL) concept is an efficient approach for such evaluations in which a virtually simulated power grid is interfaced to a real hardware device. This strongly coupled software-hardware system introduces obstacles that need attention for smooth operation of the laboratory setup to validate robust control algorithms for decentralized grids. This paper presents a novel methodology and its implementation to develop a test-bench for a real-time PHIL simulation of a typical power distribution grid to study the dynamic behavior of the real power components in connection with the simulated grid. The application of hybrid simulation in a single software environment is realized to model the power grid which obviates the need to simulate the complete grid with a lower discretized sample-time. As an outcome, an environment is established interconnecting the virtual model to the real-world devices. The inaccuracies linked to the power components are examined at length and consequently a suitable compensation strategy is devised to improve the performance of the hardware under test (HUT). Finally, the compensation strategy is also validated through a simulation scenario.

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VQ-oriented data hiding based on adjustable error compensation strategy

Connection Science ◽

10.1080/09540091.2021.1900073 ◽

2021 ◽

pp. 1-19

Author(s):

Chin-Chen Chang ◽

Ji-Hwei Horng ◽

Chia-Shou Shih ◽

Xu Wang

Keyword(s):

Data Hiding ◽

Error Compensation ◽

Compensation Strategy

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A Frequency Adaptive Scheme Based on Newton Structure of PRRC for LCL-Type Inverter Connected with Weak Grid

Energies ◽

10.3390/en14144225 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4225

Author(s):

Chengbi Zeng ◽

Sudan Li ◽

Hanwen Wang ◽

Hong Miao

Keyword(s):

Repetitive Control ◽

Harmonic Distortion ◽

Adaptive Scheme ◽

Computational Burden ◽

Weak Grid ◽

Control Scheme ◽

Sample Frequency ◽

Fractional Delay ◽

Pr Controller ◽

Online Tuning

Repetitive control (RC) is gradually used in inverters tied with weak grid. To achieve the zero steady-state error tracking of inverter current and compensate the harmonic distortion caused by frequency fluctuation, a frequency adaptive (FA) control scheme for LCL-type inverter connected with weak grid is proposed. This scheme adopts a proportional resonance (PR) controller in parallel with RC (PRRC) to overcome the disadvantages caused by RC inherent one-cycle time delay. A fractional delay (FD) filter based on the Newton structure is proposed to approximate the fraction item of fs/f, where fs and f are sample frequency and grid frequency, respectively. The structure of the proposed FD filter is relatively simple; moreover, coefficients of the filter maintain constant so as not to need online tuning even when grid frequency fluctuates, which decreases the computational burden considerably. The feasibility and effectiveness of the proposed FA control scheme, named as Newton-FAPRRC, are all verified by the simulation and experimental results.

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