The open-phase fault in vector controlled drives is known as one of the most prevalent failures that require immediate detection. It is still challenging to develop a trustable fault diagnosis scheme at light load, transients, and low-speed regions. This paper presents a novel open-phase fault diagnosis strategy for three-phase induction motor drives over the entire speed range and for different load conditions. By taking advantage of the second-order rotational park transformation (SORP), new fault indices are proposed to identify the open-phase location without using any additional sensor or electric equipment. Comparing with root mean square (RMS) calculation based methods, the proposed method detects the fault at least twice faster, with minimal system resources. The presented scheme may be implemented simply and is robust against the operating point changes. Proof of the proposed fault detection and localization method has been shown through experimental tests on a 250-W three-phase induction machine which is controlled by TI-DSP F28335.

Energy storage systems (ESSs) bring various opportunities for a more reliable and flexible operation of microgrids (MGs). Among them, energy arbitrage and ancillary services are the most investigated application of ESSs. Furthermore, it has been shown that some other services could also be provided by ESSs such as power quality (PQ) improvements. This issue could be more challenging in MGs with widespread nonlinear loads injecting harmonic currents to the MG. In this paper, the feasibility of ESSs to act as coordinated active harmonic filters (AHF) for distributed compensation was investigated. An optimization model was proposed for the coordination of the harmonic compensation activities of ESSs. The model takes into account the various technical and systematic constraints to economically determine the required reference currents of various AHFs. Simulation cases showed the performance of the proposed model for enhancing the harmonic filtering capability of the MG, reduction in the compensation cost, and more flexibility of the distributed harmonic compensation schemes. It was also shown that ESS activities in harmonic compensation do not have much of an effect on the ESSs revenue from energy arbitrage. Hence, it could make ESSs more justifiable for use in MGs.

Storage systems play an important role in performance of micro-grids. Storage systems may decrease fluctuations caused by periodic and unpredictable nature of distributed generation resource. Some micro-grids are connected to the network via a grid-interface converter. The phase-locked loop (PLL) is a commonly technique for the grid synchronization of network-connected converters. Various parameters affect the stability of PLL (including the network-side and microgrid-side parameters). The effect of the micro-grid-side parameters on the stability of the PLL has not been studied so far. In this paper, the stability of PLL influenced by microgrid-side parameters has been evaluated after a detailed analytical modeling of micro-grid components (including the production power fluctuations, energy storage system, microgrid-side loads, controller parameters etc.). This paper proposes two new stability analysis criteria for PLL affected by micro-grid and hybrid storage system parameters. Using proposed criteria for stability of PLL, optimized rate of micro-grid and hybrid storage system parameters are obtained using statistical methods (Taguchi approach). Finally, behavior of PLL affected by hybrid storage system is investigated. The simulation results and eigenvalues analysis confirm the theoretical analysis and proposed criteria.

In this article, the planning and energy administration of energy hubs in electric, thermal and gas networks are presented, considering the resilience of the system against natural phenomena like floods and earthquakes. Each hub consists of bio-waste, wind and solar renewable units. These include non-renewable units such as boilers and combined heat and power (CHP) units. Compressed air and thermal energy storage are used in each hub. The design is formed as a bi-level optimization framework. In the upper level of the scheme, the energy management of networks bound to system resiliency is provided. This considers the minimization of annual operating and resilience costs based on optimal power flow equations in networks. In the lower-level model, the planning (placement and sizing) of hubs is considered. This minimizes the total building and operation costs of hubs based on the operation-planning equations for power supplies and storages. Scenario-based stochastic optimization models are used to determine the uncertainties of demand, the power of renewable systems, energy price and the accessibility of distribution networks’ elements against natural disasters. In this study, the Karush–Kuhn–Tucker technique is used to extract the single-level formulation. A numerical report for case studies verifies the potential of the plan to enhance the economic, operation and resilience status of networks with energy administration and the optimal planning of hubs in the mentioned networks. By determining the optimal capacity for resources and storage in the hubs located in the optimal places and the optimal energy administration of the hubs, the economic, exploitation and resilience situation of the networks are improved by about 27.1%, 97.7% and 23–50%, respectively, compared to load flow studies.

Increasing presence of non-linear and unbalance loads in electrical networks leads to severely distorted and unbalance voltage/current signals. Accordingly, the estimation of amplitudes and phase angles of symmetrical components are required in many power system applications, e.g. digital protection and power quality monitoring. We propose a complex Adaline based approach for fast and accurate sequences estimation. In this approach, three-phase signals are firstly simplified to a complex signal through the alphabeta transformation. Then, the transformed complex signal is fed to a complex Adaline processing unit to estimate embedded positive and negative sequences. This method directly estimates sequences of all individual harmonic components with low computational burden and high estimation speed, which is requested for on-line hardware implementation. Finally, two comparative case studies are conducted on the MATLAB and PSCAD/EMTDC to investigate the proposed method performance and compare it with another successful method, multi-output Adaline.