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In the demand-side management (DSM) context, some appliances are remotely controlled by the utility or by end-users based on the expected aggregated consumption profile or day-ahead electricity rates. The main objective of these actions is to shift the load from critical to off-peak periods. This article proposes a novel approach to estimate in real time the load as seen by the distribution power network. The only requirement to perform this online estimation is the voltage measurement at the electrical board panel of the end-user building. The proposed method combines digital filtering, statistical process, and transient analysis to make possible the accurate identification of the corrective actions introduced by the voltage regulation system of the distribution network. Hence, this identification permits the estimation of the aggregated load profile. The method provides real-time information that can be used by the end-user or an automated energy management system to initiate demand response actions depending on the state of the grid, e.g., shaving, shifting, or modulation of the local load. Experimental data of three different locations permitted the validation of this novel approach, which enables the implementation of grid-friendly home energy managements systems with DSM functions at a very low cost for the utilities and end-users. [ABSTRACT FROM AUTHOR]

Paralleled operation of voltage-source inverters (VSIs) is currently achieved by using voltage/frequency droop control techniques which requires the knowledge of the system parameters. Otherwise, centralized control techniques with robust communication among VSIs controllers are also used. This paper presents a new control strategy which allows the load sharing between the power sources of an ac microgrid without centralized controller or any communication among the VSIs; only local measurements of voltage and output current are used. The dispatchable sources (e.g., fuel cells) of the microgrid are operated using voltage control with a direct droop scheme, and the nondispatchables or intermittent ones (e.g., wind turbine generators) are operated using power control with a complementary inverse droop scheme (D-Droop + I-Droop). The number of operating sources can be changed online without any modification needed on the VSI controllers. The proposed VSI controllers are based on the variable frequency adaptive linear neuron with frequency-locked loop for the VSIs system synchronization, voltage/power and signal estimation. Experimental results using field-programmable gate array devices for the implementation of each VSI control in the microgrid test bench demonstrated the validity of the proposition. [ABSTRACT FROM PUBLISHER]

The novel scenario of power systems with massive utilization of distributed generation (DG) imposes that islanding detection methods for voltage source inverter (VSI)-interfaced DGs must be evaluated taking into account multi-inverter configurations. This paper presents the experimental validation of an active islanding detection algorithm for multi-inverter systems proposed by the authors in previous work. Field programmable gate array implementation of power control and islanding detection algorithms has been used to test this proposition in a multi-inverter system based on grid-connected insulated gate bipolar transistor VSIs. The proposed islanding detection algorithm offers a very low impact on power quality and rapid and efficient islanding confirmation which is demonstrated by simulation and experimentation. The performance of the algorithm was tested under critical conditions as resonant load with high quality factor and unity power factor and also for cases where load and VSI powers are matched. [ABSTRACT FROM PUBLISHER]