Rupert Gammon

Effect of PV array emulator on power quality of PV inverter compared to a real PV array

In Solar Photovoltaic (PV) generation, an increasingly important issue is the reliability of electronics such as inverters, and how efficiently (and reliably) they interact with the local grid. Total Harmonic Distortion (THD) is increasingly important, relating as it does to efficiency and localised heating. PV is intermittent, so to design controlled experiments to evaluate power quality inverter performance, a reliable model of a PV array is needed. This paper describes a Photovoltaic Array Emulator (PVAE), with results compared to a physical array. The system numerical model includes the PV array, a grid connected inverter (and its controller) along with the grid. Some findings are then presented. The power quality of the commercial PV inverter improves with the PVAE compared to an actual photovoltaic array. However, this improvement of power quality does not comply with the IEEE-1547 standard. A bidirectional inverter with battery storage to improve power quality is proposed, which can provide fast active and reactive power to the load with a minimum THD of the output current to 0.64%.

Fower-to-hydrogen and hydrogen-to-X: Which markets? Which economic potential? Answers from the literature

With the expansion of renewable energys contribution to the energy mix, balancing the electricity grid is becoming increasingly challenging. Alongside other solutions, Power-to-Hydrogen concepts are gaining significant interest. In this paper, the “Task 38”, initiated by the Hydrogen Implementing Agreement of the International Energy Agency, presents the first of a two-step literature review regarding Power-to-Hydrogen and Hydrogen-to-X concepts with a focus on prospective market and economic potential. The study reveals a large scope of literature that shows a considerable variety of suggested implementation schemes. The transportation sector is identified as the most promising consumer market. Hydrogen-to-Gas pathways will require subsidies in order to be profitable. Hydrogen-to-Power becomes an economically promising option in the context of systems with high shares of renewables and a need for longer-term storages. Additionally, key enablers for Power-to-Hydrogen concepts are identified; namely support policies, concurrently with ongoing progress on the development and implementation of industry standard.

Dispatchable hydrogen production at the forecourt for electricity grid balancing

The rapid growth of renewable energy (RE) generation and its integration into electricity grids has been motivated by environmental issues and the depletion of fossil fuels. For the same reasons, an alternative to hydrocarbon fuels is needed for vehicles; hence the anticipated uptake of electric and fuel cell vehicles. High penetrations of RE generators with variable and intermittent output threaten to destabilise electricity networks by reducing the ability to balance electricity supply and demand. This can be greatly mitigated by the use of energy storage and demand-side response (DSR) techniques. Hydrogen production by electrolysis is a promising option for providing DSR as well as an emission-free vehicle fuel. Tariff structures can be used to incentivise the operating of electrolysers as controllable (dispatchable) loads. This paper compares the cost of hydrogen production by electrolysis at garage forecourts under both dispatchable and continuous operation, while ensuring no interruption of fuel sup...

Improving off-grid PV system power quality, and comparing with grid power quality

Developments in power electronics have enabled widespread application of Pulse Width Modulation (PWM) inverters, notably for connecting renewable systems to the grid. This study demonstrates a high quality power of a stand-alone inverter, whereby the comparison between the power quality of stand-alone inverter with battery storage (off-grid) and power quality of the utility network is presented. Multi-loop control techniques for a single phase stand-alone inverter are used. A capacitor current control is used to provide active damping and improve transient and steady state inverter performance. Capacitor current control is cheaper than inductor current control, where a small current sensing resistor is used. The output voltage control is used to improve the system performance and also control the output voltage. The inner control loop uses a proportional gain current controller and the outer loop is implemented using Internal Model Control Proportional-Integral-Derivative (IMC-PID) to ensure stability. The optimal controls are achieved by using the Sisotool in MATLAB/Simulink. The outcome of the control scheme of the numerical model of stand-alone inverter has nice dynamic performance but also strong robustness under load variations. The numerical model of the stand-alone inverter and its power quality are presented, and power quality is shown to meet IEEE 519-2014. Furthermore, the power quality of the off-grid system is measured experimentally and compared with the grid power, showing power quality of off-grid system to be better than that of the utility network.

Track C: Cyber-physical energy systems

Cyber-Physical Energy Systems address the merging of IT and energy infrastructures, with the aim of achieving more energy-efficient and sustainable lifestyles. The coordination of the various stakeholders involved in the future energy market raises many challenges, for example the dataintensive and complex event processing required.