Simon Le Blond

Cost/Benefit Assessment of a Smart Distribution System With Intelligent Electric Vehicle Charging

In the near future, with more distributed generators connected and new demands arising from the electrification of heat and transport in the distribution networks, infrastructure will become ever more stressed. However, building costly new circuits to accommodate generation and demand growth is time-consuming and environmentally unfriendly. Therefore, active network management (ANM) has been promoted in many countries, aiming to relieve network pressure. Previous research in ANM was focused on distribution areas with significant renewable penetration, where ANM reduced network pressure through significantly enhanced generation curtailment strategies rather than adopting traditional asset investment. This paper proposes the use of electric vehicles (EVs) as responsive demand to complement network stress relief that was purely based on generation curtailment. It is achieved by allowing EVs to absorb excessive renewable generation when they cause network pressure, and it thus can provide additional measures to generation curtailment strategies. The approach is illustrated on a practical extra-high voltage distribution system. The analyses clearly demonstrate the combined management of demand and generation is superior to previous sole generation management. The combined management strategy can achieve 7.9% improvement in utilization of renewable energy, and subsequently increase the net investment profit by £566 k.

Design and application of superconducting fault current limiter in a multiterminal HVDC system

Voltage source converter based HVdc (VSC-HVdc) systems are prone to high short-circuit current during transmission line faults. The situation for multiterminal HVdc (MTDC) systems is worse. The characteristics of superconducting material are ideal to limit the fault current in HVdc systems. This paper presents a novel use of the resistive type of superconducting fault current limiter (SFCL) in the MTdc network with the function of limiting the high current. The working principles of fault current limiter and a three-terminal HVdc system are modeled in detail using PSCAD/EMTDC software. The hybrid operation of the SFCL in the three-terminal HVdc system is tested in this paper for the fault response of the MTdc system. The performances of SFCL under different fault conditions are analyzed. The simulation results show that the fault current is effectively restrained and the SFCL can act as an efficient protective device for VSC-based multiterminal HVdc systems.

Modeling and analysis of superconducting fault current limiters applied in VSC-HVDC systems

Direct current transmission based on Voltage Source Converters (VSC-HVDC) has a number of advantages compared with traditional HVDC systems. However, VSC-HVDC systems are subjected to high short circuit currents due to faults in the DC line, which may contribute negatively to the dissemination and advances of this technology. In this context, this paper analyzes the impact of superconducting fault current limiters on the system response due to faults in the DC line. An effective model for fault limiters is proposed, aiming at limiting the fault current to values below the short circuit withstand capability of DC breakers. The results show the effectiveness of the method and the advantages of using superconducting materials to minimize the impact of faults on VSC-HVDC lines.

Development of time-of-use price by clustering techniques

Active demand side response (DSR) from domestic customers can generate benefits in terms of reducing energy costs for customers and shaving peak demand for distribution network operators (DNOs). However, real-time price (RTP) is considered to be too dynamic for customers to response. Also, it is infeasible for most energy storage equipment to response to variable signals, such as RTP, as they can only charge/discharge a few cycles throughout a day. Due to these constraints, time-of-use (TOU) price is a more natural price signal for DMS. This paper proposes a novel statistical method to successfully convert RTP to TOU that captures the most significant price variations without comprising too much accuracy in total energy revenue from customers. The proposed method adopts hierarchical clustering techniques to group RTP into clusters, and each settlement period is assigned to one of the clusters to form a TOU pattern. For each cluster of the TOU tariff pattern, the tariff rate is determined by keeping the total customer revenue unchanged.

Control scheme for energy storage in domestic households

Distributed solar photovoltaic panels (PV) installed on the roofs of domestic houses generate electricity from sunlight, which is important for both decarbonization and electricity bill reduction. This paper proposes a new control approach to enable high density solar PV generation to be connected to low voltage (LV) networks more efficiently by working closely with in-home battery. The charging and discharging periods are crucially important for improving the efficiency of the PV battery. An optimal control scheme for energy storage systems in LV networks is introduced to facilitate demand response (DR). The method described also regulates thermal violation and voltage violation caused by PV generation. Finally, the paper uses a five node LV network and typical household profiles to demonstrate the effectiveness of the proposed control strategy. The benefits in terms of load shift are shown under three different configurations by using a selected lithium-ion battery.

Optimal flow of energy-hub including heat pumps at residential level

This paper presents a general approach to optimize the power and heat flow between houses based on the energy hub concept. An interconnected two energy-hub system including a heat pump, solar panels and boiler as hub elements and electricity and gas as input energy carriers is presented and the heat and power flow between each hub is optimized. The results illustrate the flexibility the energy hub approach can achieve when applied to optimal flow problems with systems including renewable energy. Moreover, it is shown that the total energy expense could be effectively minimized by adjusting the flow between the hubs, which demonstrates that the whole system, including the local renewable generation, can be optimized with an appropriate controller.

Ultra-fast basic geometrical transformations on linear image data structure

Abstract This paper presents a general, ultra-fast approach for geometrical image transformations, based on the usage of linear lookup hash tables. The new method is developed to fix distortions on document images as part of a real-time optical character recognition (OCR) system. The approach is generalized and uses linear image representation combined with pre-computed lookup tables. Backward mapping is used for generation of lookup tables, while forward mapping is presented as an alternative and more efficient mapping model for specific cases. Also, a theoretical space and time complexity analysis of the proposed method is provided. To achieve maximal computational performance, pointer arithmetic and highly-optimized low-level machine code implementations are provided, including the specialized implementations for horizontal mirror, vertical mirror, and 90° rotation. Also, a modified variant of the approach, based on auto-generated machine code is presented. Very high computational performances are achieved at the expense of memory usage. The performances from the perspective of time complexity are analyzed and compared with classical implementation, FPGA implementation, and other implementations of the image rotation. Numerical results are given for a set of different PC specifications to provide full insight into the implementation performances. The processing time for very large images are below 200 ms for backward mapping and below 100 ms for forward mapping for most machines, which is 30–60 times faster than the classical implementation, 5–20 times faster than the FPGA implementation, and up to 6 times faster than other implementations of image rotation. Original documents belonging to Nikola Tesla are used for visual demonstration of performance.

Investigation of energy storage and open cycle gas turbine for load frequency regulation

In power systems, load is continuously fluctuating and is difficult for slow generating units, such as coal-fired, nuclear and hydro power plants, to follow. Therefore, fast but expensive generation units like open cycle gas turbine (OCGT) are widely used to provide frequency regulation, maintaining system frequency within its specified limit. Owing to energy storage system (ESS)s zero-net energy and fast response nature, one of the applications of ESS in power system is to provide frequency regulation. This paper proposes a method of sizing OCGTs and advanced lead-acid batteries to provide frequency regulation under different types of load following patterns. The rain-flow counting algorithm is used for battery lifetime modelling. The cost and savings from displacing OCGTs with ESS are calculated and discussed. It was concluded that the system load following ability is the key factor when considering whether ESS is cost effective when providing frequency regulation in a control area. The method of battery and OCGT rating presented in this paper is applicable to the situation when regulation load requirement is known or can be estimated.

Low-Voltage Circuit Breakers Based on WBG Solid-State Devices

Conventional circuit breakers suffer from two main deficiencies: they are slow to operate and develop an electrical arc. These may be overcome by using solid-state switches which in turn introduce other problems, most significantly power dissipated while in the on-state. Nevertheless, a number of solid-state devices are candidates for implementation as low-voltage circuit breakers and there are several options based on the semiconductor material that may function as high-power switches. This paper presents a unique, extensive and systematic evaluation of these options. Voltage-controlled devices are selected due to the simplicity of the controlling circuit and their resilience to dv/dt-induced switching. Properties of fully solid-state circuit breakers are established and systematic comparisons are made among switches built of silicon and other wide bandgap (WBG) devices such as SiC MOS and GaN HEMT transistors. Using SPICE simulation it is shown that solid-state circuit breakers (SSCBs) based on WBG devices exhibit superior characteristics compared with silicon devices, with faster switching and higher voltage and current ratings. Hybrid circuit breakers, combining both conventional and solid-state switches, are discussed too and a new design circuit is simulated and compared to both conventional and fully solid-state designs.

Generalized N-way iterative scanline fill algorithm for real-time applications

A generalized iterative scanline fill algorithm intended for use in real-time applications and its highly optimized machine code implementation are presented in this paper. The algorithm uses the linear image representation in order to achieve the fast memory access to the pixel intensity values. The usage of the linear image representation is crucial for achieving the highly optimized low-level machine code implementation. A few generalization features are also proposed, and discussion about the possible real-time applications is given. The proposed efficient machine code implementation is tested on several PC machines, and a set of numerical results is provided. The machine routine is compared with standard and optimized implementations of the 4-way flood fill algorithm and scanline fill algorithm. The machine code implementation performs approximately 2 times faster than the optimized scanline fill algorithm implementation and 6 times faster than standard iterative scanline fill algorithm implementation on two-dimensional image data structure. Furthermore, the machine routine proved to perform even more than 15 times faster than the optimized flood fill algorithm implementations. Provided results prove the efficiency of the proposed generalized scanline fill algorithm and its advantage over the state-of-the-art algorithms, and clearly show that optimized machine routine is capable of performing the real-time tasks.