Harmonic assessment based adjusted current total harmonic distortion

Power systems suffer from harmonic distortion and extra ohmic losses associated with them. Moreover, all harmonic frequencies are mostly assumed to have the same effect on the system losses. However, the frequency-dependency of the resistances should be taken into account, so that the apparent power and the power factor have to considerably reflect power losses under nonsinusoidal conditions. In this paper, the difference between unweighted and weighted non-sinusoidal losses, is addressed. A new harmonic-adjusted total harmonic distortion definition is proposed for both voltage and current. Besides, a new formula that relates the proposed harmonic-adjusted total harmonic distortion and a generalised harmonic derating factor definition of the frequency dependent losses of the power transmission and distribution equipment, is derived. An optimal C-type passive filter design for harmonic mitigation and power factor correction based on the minimisation of the proposed harmonic-adjusted total harmonic distortion for a balanced nonsinusoidal system is introduced. A comparative study of the proposed filter design based on the new harmonic-adjusted definition, and a conventional filter design based on standard total harmonic distortion definition, is presented

Stochastic analysis results for coordination of single-phase rooftop PVs in unbalanced residential feeders

Installation of single-phase rooftop photovoltaic (PV) systems in low voltage (LV) residential feeders without controlling their ratings and locations may deteriorate the overall grid performance including reversed power flows, high losses and unacceptable voltage profiles. Therefore, in recent years the utilities have adopted limitations on the maximum allowable number of PVs in LV networks. To overcome these issues, this paper investigates the performance of a communication-based and intelligent voltage profile regulating technique under a Monte Carlo-based stochastic framework. This technique is applicable for LV residential feeders with single-phase rooftop PVs and relies on the availability of smart meters along the LV feeder to transmit phase voltage measurements to the controllers of the PV inverters. The objective of the voltage regulating technique is to minimize voltage unbalance along the feeder. The effectiveness and limitations of the voltage regulating method are investigated in this paper by the help of MATLAB-based simulation studies

Optimal siting and sizing of multiple active power line conditioners to minimize network THD considering harmonic couplings

Active power line conditioner (APLC) is an advanced shunt active filter that can limit the voltage total harmonic distortion (THDv) of the entire network or a designated area below 5% as recommended by most standards such as the IEEE-519. A research gap in design and implementation of APLCs is the consideration of harmonic couplings, which is an inherent characteristic of most realistic distorted networks. This paper proposes a particle swarm optimization (PSO) algorithm based on smart meter transmitted data for optimal siting and sizing of APLCs that include harmonic couplings of the nonlinear loads. The objective function of the proposed PSO is minimization of cost (associated with APLC size) and network THDv, respectively. For the nonlinear modelling of APLCs, a five-level neutral-point clamped (FL-NPC) inverter equipped with an adaptive hysteresis current control (AHCC) is used. Detailed simulations without and with harmonic couplings are performed in Matlab/Simulink to find the optimal locations and sizes of the APLCs in a 15-bus network with six nonlinear loads

Monte Carlo-based stochastic analysis results for coordination of single-phase rooftop PVs in low voltage residential networks

Installation of single-phase rooftop photovoltaic (PV) systems in low voltage (LV) residential feeders without controlling their ratings and locations may deteriorate the overall grid performance including reversed power flows, high losses and unacceptable voltage profiles. Therefore, in recent years the utilities have adopted limitations on the maximum allowable number of PVs in LV networks. To overcome these issues, this paper investigates the performance of a communication-based and intelligent voltage profile regulating technique under a Monte Carlo-based stochastic framework. This technique is applicable for LV residential feeders with single-phase rooftop PVs and relies on the availability of smart meters along the LV feeder to transmit phase voltage measurements to the controllers of the PV inverters. The objective of the voltage regulation technique is to minimize voltage unbalance along the feeder. The effectiveness of the voltage regulation technique are investigated in this paper by the help of MATLAB-based simulation studies

Impact of battery rating on performance of rooftop PV supporting household loads, regulating PCC voltage and providing constant output power to grid

The dependency rooftop photovoltaic generation system (rooftop PV) output power to environmental factors (sun radiation, panel temperature, passing clouds, etc.) and loading level (operating point on v-i characteristics) may result in sudden output power variations particularly during cloudy periods. This paper will first implement a rooftop PV with a battery storage energy management strategy (BS-EMS) to support the household loads and regulate the voltage at point of common coupling (PCC) while providing the grid with a constant output power during daylight. System operation is based on the power balance between rooftop PV, BS and grid which is achieved by dynamic control of the BS converter to assure constant output power to the grid during daylight. Then, the impact of battery rating on the performance of BS-EMS will be investigated for typical sunny and cloudy days in summer and winter