Leveraging smart meter data for economic optimization of residential photovoltaics under existing tariff structures and incentive schemes

© 2017 Elsevier Ltd The introduction of smart grid technologies and the impending removal of incentive schemes is likely to complicate the cost-effective selection and integration of residential PV systems in the future. With the widespread integration of smart meters, consumers can leverage the high temporal resolution of energy consumption data to optimize a PV system based on their individual circumstances. In this article, such an optimization strategy is developed to enable the optimal selection of size, tilt, azimuth and retail electricity plan for a residential PV system based on hourly consumption data. Hourly solar insolation and PV array generation models are presented as the principal components of the underlying objective function. A net present value analysis of the potential monetary savings is considered and set as the optimization objective. A particle swarm optimization algorithm is utilized, modified to include a penalty function in order to handle associated constraints. The optimization problem is applied to real-world Australian consumption data to establish the economic performance and characteristics of the optimized systems. For all customers assessed, an optimized PV system producing a positive economic benefit could be found. However not all investment options were found to be desirable with at most 77.5% of customers yielding an acceptable rate of return. For the customers assessed, the mean PV system size was found to be 2 kW less than the mean size of actual systems installed in the assessed locations during 2015 and 2016. Over-sizing of systems was found to significantly reduce the potential net benefit of residential PV from an investor's perspective. The results presented in this article highlight the necessity for economic performance optimization to be routinely implemented for small-scale residential PV under current regulatory and future smart grid operating environments

Applications of the direct space vector modulation controlled matrix converter as the unified power flow controller

© 2016, Institution of Engineering and Technology. All rights reserved. This paper investigates the matrix converter when working as the unified power flow controller which can regulate the active reactive power flowing in a transmission line. A conventional unified power flow controller usually has a DC capacitor; this is removed in the proposed controller. This reduces the volume, improves the efficiency and lifetime, and eliminates the DC voltage control. The detailed direct space vector modulation method for the matrix converter is described. Based on this modulation scheme, a PID controller is designed in order to control the power flow. Coupling effects are suppressed by feedback of the coupling components to the controller. The proposed strategy can control the active and reactive power efficiently and effectively. Simulations based on MATLAB/Simulink help verify the feasibility and effectiveness of the scheme

Wind farm grounding system analysis

© 2017 IEEE. this paper studies a real-case grounding system design for a wind farm and associated equipment. The design is based on the safety criteria provided by Australian and International guidelines listed in the references [1-5]. The wind farm grounding system consists of wind turbine generators, tower base padmounts, 33 kV cable screen and a primary substation. In this paper, grounding system and ground potential rise analyses are presented and discussed. In this study, the conventional earthing system of a wind farm is assessed. The impacts of turbines foundation reinforcement, tower base substation, inter-connection cables and mutual coupling between neighboring turbines grounding systems were simulated. Several methods of improvement are accordingly proposed. Since it is more likely to have farm animals in the vicinity of a wind turbine during the phase to ground fault, a new method for calculation of safe step voltage for farm animals is also proposed

Hysteresis band current controller based field-oriented control for an induction motor driven by a direct matrix converter

© 2017 IEEE. This paper presents work on the hysteresis band control for output current regulation in a direct matrix converter in order to drive an induction motor. The hysteresis band controller offers excellent dynamic performance. It has been extensively researched for the voltage source inverter and inverter based drive systems, but it has not been investigated within the context of a matrix converter or a matrix converter based motor drive. Firstly, this paper proposes a fixed-band hysteresis current controller for a matrix converter to track the prescribed current references, and then a sinusoidal-band hysteresis current controller is proposed. Both methods have fast dynamic performance and they inherently integrate the line modulation technique of the virtual rectifier stage into the overall modulation. The extra modulation stage is not required and the surge current is inherently prevented. The sinusoidal-band hysteresis controller demonstrates that it generates lower harmonic content at the expense of the higher average switching frequency. Following this, both methods are tested as a drive for an induction motor with field-oriented control. With the matrix-converter-based drive system, one significant benefit is that the braking chopper is removed due to the bidirectional feature. The methods are simple and have light computation burden. The obtained results demonstrate the effectiveness and feasibility of the proposed scheme. The experimental work is being carried out to support the proposed scheme

A novel sliding mode controller for DC-DC boost converters under input/load variations

© 2015 IEEE. In this paper a simple sliding mode controller based on the averaging state space model is proposed for a DC-DC boost converter. It is demonstrated to be easily implemented and has time-variant sliding coefficients. The proposed controller can effectively regulate the output voltage by controlling the switch states (through the dynamic duty cycles) even when the input voltage, load or output command varies. Furthermore the controller is independent of the inductor current and the load, although the load value is needed when designing the sliding coefficients. The constant switching frequency is maintained thus simplifying the design procedure, enhancing the regulation properties and benefiting the filter design. The controller has good dynamic response, overshoot damping and robustness. Comparative simulations are carried in MATLAB/Simulink between the proposed approach and a widely used PID controller to verify the effectiveness and feasibility of the proposed method

Experimental Investigation of Ultracapacitor Impedance Characteristics

© 2015 The Authors. Published by Elsevier Ltd. Ultracapacitors (UCs) are being increasingly studied and deployed as a short-term energy storage device in various energy systems including uninterruptible power supplies, electrified vehicles, renewable energy systems, and wireless communication. They exhibit excellent power density and energy efficiency. The dynamic behavior of a UC, however, strongly depends on its impedance characteristics. In this paper, the impedance characteristics of a commercial UC are experimentally investigated through the well-adopted Electrochemical Impedance Spectroscopy (EIS) technique. The implications of the UC operating conditions (i.e., state of charge (SOC) and temperature) to the impedance are systematically examined. The results show that the impedance is highly sensitive to temperature and SOC; and the temperature effect is more significant. The experimental design and multi-condition impedance analysis provides prudent insights into UC system integration, dimensioning, and energy management strategy synthesis in advanced energy systems

Direct torque control with a modified switching table for a direct matrix converter based AC motor drive system

© 2017 IEEE. The direct matrix converter has been regarded as a promising AC/AC conversion topology and it is being researched. Motor drives are one of the main potential applications of the matrix converter. This paper carries forward the application of matrix converters in AC motor drives using direct torque control (DTC). In the common DTC scheme for the matrix converter, two vectors with the maximum amplitudes are used to control the torque and flux. In the proposed approach, the input voltage vector sectors are redefined, therefore a modified and simplified switching look-up table is obtained. In this case the most appropriate vector to be applied is uniquely determined and the number of switch actions are reduced. The excellent dynamic performance is obtained by selecting the maximum vector. Flux and speed are controlled effectively. Simulation work is carried out for an induction motor and results verify the effectiveness of the proposed DTC control in matrix converter based AC drive systems

Predictive voltage control of direct matrix converter with reduced number of sensors for the renewable energy and microgrid applications

© 2017 IEEE. This work proposes and investigates a renewable energy distributed generation system involving a matrix converter with an output filter working as a stable voltage supply. This is especially relevant for the stand-alone operation of a renewable energy microgrid where a stable sinusoidal voltage with prescribed amplitude and frequency under various load conditions is the main control objective. A controllable input power factor is preferred. In this paper, the model predictive control is employed to regulate the matrix converter output voltages which in turn are the supply for systems of the following stage. To reduce the number of required measurements and sensors, the work designs observers and makes use of the switch matrix. In addition to the regulation of the sinusoidal output voltages and input power factor, the control scheme deals with the common-mode voltage. The switching frequency is also considered in the controller to reduce the switching losses and keep the average switching frequency constant. In addition, the voltage transfer ratio can be improved at the cost of input current distortion. Supplying DC loads is feasible with this proposed control method. The controller is tested under various conditions including non-linear loads, DC loads and unbalanced input conditions to show it is effective, simple and easy to implement. Simulation results corroborate the effectiveness of the proposed controller and applications

Maximizing investment value of small-scale PV in a smart grid environment

© 2016 IEEE. Determining the optimal size and orientation of small-scale residential based PV arrays will become increasingly complex in the future smart grid environment with the introduction of smart meters and dynamic tariffs. However consumers can leverage the availability of smart meter data to conduct a more detailed exploration of PV investment options for their particular circumstances. In this paper, an optimization method for PV orientation and sizing is proposed whereby maximizing the PV investment value is set as the defining objective. Solar insolation and PV array models are described to form the basis of the PV array optimization strategy. A constrained particle swarm optimization algorithm is selected due to its strong performance in non-linear applications. The optimization algorithm is applied to real-world metered data to quantify the possible investment value of a PV installation under different energy retailers and tariff structures. The arrangement with the highest value is determined to enable prospective small-scale PV investors to select the most cost-effective system