Power-hardware-in-the-loop approach for emulating an offshore wind farm connected with a VSC-based HVDC

Abstract

Abstract-The real-world interaction of an offshore wind farm with a voltage source converter (VSC)-based HVDC is complex due issues such as noise, randomness of event timings, and hardware design issues that are not well explored. Numerical simulations are widely accepted and cost effective tool to test a wide variety of different cases, however, the fidelity of the results is difficult to assess. Higher fidelity can be obtained with scale-down experiments, however, this solution has a limited test coverage. The power-hardware-in-the-loop (PHIL) approach offers a good trade-off between test fidelity and test coverage. The hardware part allows a high fidelity of the results whereas, the software simulation part allows an extensive study of different cases at a reasonable cost. This paper presents a PHIL implementation of an offshore wind farm connected with a VSC-based HVDC. The offshore wind farm is emulated in a real time simulation environment, and a grid emulator is used as power interface between the emulated system and the hardware system, i.e. VSCbased HVDC substation. The interaction of real time models and hardware is demonstrated with experiment results.

A Physics-Informed Scaling Method for Power Electronic Converters in Power Hardware-in-the-Loop Test Beds

“…When reading the literature related to the emulation of FSCs with SDCs in PHIL tests, the following criticalities are found: an FSC or SDC is not a converter alone but a combination of the power converter and a passive (L/LC) filter or LC filter with a line frequency transformer (LFT) forming an LCL filter. There can be a difference in the passive filter topology of the SDC and FSC [9]. An available SDC in the laboratory is rarely an accurate linear scaleddown prototype of an FSC; thus, per unit values of the SDC will have a mismatch compared to the per unit values of the FSC.…”

“…Although this paper does not focus on interfacing methods, the critical point that needs to be highlighted here is that, despite having complete knowledge of the SDC, these methods ignore the impedance mismatch between the SDC and the emulated FSC. They alter the impedance further to improve the accuracy of the test, resulting in reduced power flow capability of the SDC, as mentioned in [9], [13]. With such changes, the emulation of the FSC in all four quadrants can be challenging, pointing towards the aforementioned research gap.…”

A Review of PHIL Testing for Smart Grids—Selection Guide, Classification and Online Database Analysis

“…For that reason, and considering the initial cost of the two main systems (DRTS and PA), laboratories need to clarify their objectives in order to find the best solution for them. Furthermore, the setting up of the experiments still has some difficulties [15].…”

Harmonic-Invariant Scaling Method for Power Electronic Converters in Power Hardware-in-the-Loop Test Beds

“…Although the focus of this article is not on interfacing algorithms, it is worth mentioning that some impedance-based interface algorithms alter the power circuit of the SDC [18] and this could further deteriorate the representation of the SDC as FSC for highfrequency transients including the ones related to pulse-width modulation (PWM) switching. Most of the PHIL results [13], [19], [20] do not present outcomes that match voltages and currents at the switching frequency range of the FSC. Hence, there is a research gap in validating SDCs as replicas of FSCs for both line frequency and harmonic interactions with PHIL simulations.…”

“…On one side, traditional scaling methods utilize rated values of voltages, currents and power of the SDC to directly normalize and match performance with the FSC [7], [13], [14]. In [7], for instance, a 300 MW wind farm is emulated by a reduced scale 3 kW permanent-magnet synchronous generator (PMSG) connected to a full-power back-to-back power electronic converter (PEC).…”