Characterization of Time Delay in Power Hardware in the Loop Setups

Abstract

The testing of complex power components by means of power hardware in the loop (PHIL) requires accurate and stable PHIL platforms. The total time delay typically present within these platforms is commonly acknowledged to be an important factor to be considered due to its impact on accuracy and stability. However, a thorough assessment of the total loop delay in PHIL platforms has not been performed in the literature. Therefore, time delay is typically accounted for as a constant parameter. However, with the detailed analysis of the total loop delay performed in this paper, variability in time delay has been detected as a result of the interaction between discrete components. Furthermore, a time delay characterization methodology (which includes variability in time delay) has been proposed. This will allow for performing stability analysis with higher precision as well as to perform accurate compensation of these delays. The implications on stability and accuracy that the time delay variability can introduce in PHIL simulations has also been studied. Finally, with an experimental validation procedure, the presence of the variability and the effectiveness of the proposed characterization approach have been demonstrated. Index Terms-Time delay, power hardware-in-the-loop, delay identification, real-time simulation, component testing. NOMENCLATURE Abbreviations AC Alternating current. ADC Analog to digital converter. DAC Digital to analog converter. DC Direct current. DRTS Digital real time simulator. FPGA Field-Programmable Gate Array. GPS Global positioning system. HUT Hardware under test. IA Interface algorithm. ITM Ideal transformer method.

Real-Time Coupling of Geographically Distributed Research Infrastructures: Taxonomy, Overview, and Real-World Smart Grid Applications

“…6) Time Delay Determination and Compensation: The exchange of interface signals between the two subsystems introduces delay. In monolithic PHIL setups, the delay is variable yet deterministic [47]. However, for GDS setups where communication is over the Internet, the delay is non-deterministic and time varying.…”

“…Interface Algorithm [30] A review and comparison of IAs [31] Voltage-current decoupling pattern IA [12] Extension of IA proposed in [30] with capability to handle missing data [34] Generalized coupling scheme IA [35] ITM IA [15] Use [9] Platform that supported orchestration of experiments across multiple RIs [26] Open source orechestrator platform JaN-DER [29] Latency analysis of JaNDER [13] Requirements of orchestrator platform [19] Open source orchestrator platform VILLAS [44] Improvements to VILLAS platform reported [36] VILLAS platform for FPGA developed Cyber-Security [19] Analysis of impact of VPN on latency Time Delay Compensation [47] Time delay characterization of PHIL [48] Lead filter compensation [20] Delay compensation with linear predictor [49] Phase-shift delay compensation [28] Estimator-based delay compensation IV. CASE STUDIES In this section, four selected case studies, encompassing different geographical, taxonomical, and technological options are presented.…”

“…Simultaneously, novel time-delay compensation techniques that can improve the fidelity of GDS with the limited bandwidth available should be explored. A careful characterization of latency within a setup, as presented in [47] for monolithic setups, can be extended to GDS. This can form a basis for innovative compensation techniques such as probabilistic compensation or data-driven compensation to ensure higher fidelity and accuracy.…”

Advanced Laboratory Testing Methods Using Real-Time Simulation and Hardware-in-the-Loop Techniques: A Survey of Smart Grid International Research Facility Network Activities

“…The communication over long distances between geographically separated assets is the key characteristic that differentiates monolithic HIL simulations from GD simulation. For feasibility purposes, communication generally takes place over the Internet with time delays depending on the available network infrastructure between the sites and in contrast with monolithic setups present non-deterministic time delays [78]. Latencies over the Internet between different cities have been evaluated in [69,72].…”

Facilitating the Transition to an Inverter Dominated Power System: Experimental Evaluation of a Non-Intrusive Add-On Predictive Controller

“…DPSL comprises equipment representing both conventional and non-synchronous generation, static and dynamic loads, arranged in such a way as to be able to run as three independent islands (or cells, as in Figure 2a) or brought together in any combination as a single system. State-of-the-art HIL techniques such as seamless initialization and synchronization of large test setups [51], experimental setup time-delay characterization [52] and measurements delay identification [53] and compensation [54] enable the realization of a high fidelity systems-level testing facility able to robustly de-risk novel control solutions for emerging power systems.…”