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Volt-per-hertz ($V/f$) scalar control is one the simplest control structures developed for operating induction motor drives. This paper presents the development and performance testing of a $V/f$ scalar control for induction motor drives that are fed by $3\phi$ wavelet modulated dc-ac power electronic converters. The wavelet modulation technique is typically characterized by the maximum resolution level ($J$) and scale-time interval factor ($\gamma$). The magnitude of the output voltage of a three phase wavelet modulated inverter is directly dependent on $J$, while the number of switching pulses, over a half cycle of the output voltage, is related to $\gamma$. These two factors of the wavelet modulation technique can be adjusted to implement a $V/f$ scalar control of induction motor drives. The $V/f$ scalar control of a wavelet modulated dc-ac PEC is implemented for performance testing using induction motor drives under different operating conditions. Performance results demonstrate stable, dynamic, and accurate responses, with minor sensitivities to the load torque and/or initial and final speeds. Furthermore, test results demonstrate the ability to enhance the efficiency using the tested scalar control.

Volt-per-hertz ($V\!\!/\!f$) control is one the simplest control structures developed for operating electric motor drives, including permanent magnet synchronous motor (PMSM) drives. This paper presents the development and testing of a $V\!\!/\!f$ control for PMSM drives that utilize a $3\phi$ wavelet modulated (WM) dc-ac power electronic converter (PEC). The wavelet modulation technique is characterized by the maximum scale ($J$) and scale-time interval factor ($\gamma$). The output voltage of a $3\phi$ WM dc-ac PEC has its magnitude directly dependent on $J$, while its frequency and phase are dependent to $\gamma$. These two parameters of the wavelet modulation technique can be used to implement a $V\!\!/\!f$ control for PMSM drives. The proposed $V\!\!/\!f$ control is featured with a stabilizing loop to correct the $V\!\!/\!f$ ratio, and improve the stability of the controlled PMSM drive. The $V\!\!/\!f$ control for a PMSM drive fed by a wavelet modulated dc-ac PEC, is implemented for performance testing using a laboratory 10$-hp$ PMSM drive under different operating conditions. Performance results demonstrate stable, dynamic, and accurate responses, with minor sensitivities to the load torque and/or speed changes. Furthermore, test results demonstrate the ability to enhance the efficiency using the tested control for PMSM drives.

The introduction of load-side control actions, to implement smart grid functions or integrate distributed generation units, has created a new source for power system dynamic events. Such events can have the capacity to adversely impact the stability in power systems. The growing interests in load-side control actions mandate the analysis and modeling of their contribution to voltage and frequency dynamics in power systems. This paper presents the analysis, development, and testing of a voltage-survivability based method for modeling the contributions of load-side control actions to power system voltage dynamics and stability. The developed method is structured using a voltage-survivability index $\boldsymbol{\Gamma}_{\boldsymbol{V}}$ that is defined at bus in terms of the difference in reactive power injection before and after a load-side control action. The boundary values of the index $\boldsymbol{\Gamma}_{\boldsymbol{V}}$ are derived in order to identify survivable and non-survivable load-side control actions. The voltage-survivability based method is implemented and tested for the Barbados power system. Performance tests are conducted for integrating distributed generation units, as well as implementing demand response at several load buses. Results of conducted tests demonstrate the ability of voltage-survivability based method to accurately model and quantify the impacts of load-sides activities on the bus voltages in the test power system.

The growing interests in utilizing Photovoltaic (PV) systems are usually faced with challenges of accurate and reliable protection of these distributed generation units. A desired protection of PV systems has to effectively and accurately detect and respond to internal faults (within the PV system) and external faults (in the host grid and/or fed loads). This article presents and tests the performance of a digital ground fault protection (DGFP) for grid-connected PV systems. The presented DGFP detects faults based on the energy contents of high frequency sub-bands of the ground current. These energy contents are extracted using the phaselet transform that can process signals with non-stationary variations in their phases. Energy contents of the high frequency sub-bands can provide accurate, fast, and reliable detection and identification of faults experienced by a PV system operated. The phaselet transform (PHT)-based DGFP is implemented for performance testing using PV systems that are operated in the grid-connected mode, and subjected to various fault and non-fault events. Performance results demonstrate accurate, fast, and reliable detection and response to different types of fault and non-fault events. Response features of the PHT-based DGFP are complimented with minor sensitivity to the level of power production and/or type and location of faults.

This paper presents the experimental performance assessment of the $\alpha \beta 0$-based bus differential protection (BDP). This protection is developed for buses that interconnect battery storage systems (BSSs). The tested BDP employs $\alpha \beta 0$ components of the apparent powers flowing in all branches that are connected to the protected bus. The $\alpha \beta 0$ components of apparent powers allow accommodating frequent changes in the direction of power flows due to the charging/discharging modes of the BSS operation. In each branch connected to the protected bus, the $3\phi$ apparent powers are determined using the measured branch currents and voltage (at the protected bus). The $\alpha \beta 0$-based BDP is implemented using a digital processing board for experimental testing for a laboratory setup. The test setup is composed of a bus that interconnects a 4 kW BSS, and feeds $3\phi$ linear and dynamic loads. The performance of the $\alpha \beta 0$-based BDP is assessed for responding to various internal and external faults occurring during the charging and discharging of the BSS. Experimental results reveal encouraging abilities of the tested BDP to initiate fast, accurate, and reliable responses to internal and external faults. Observed response features are complimented with a negligible sensitivity to the BSS mode of operation, fault type, and/or fault location.