Richard Binns

Smart grids: energising the future

Electrical power systems are the backbone of industry, society and current civilisation. Power engineers have accumulated the necessary skills and procedures, to enable them to operate the system in the most reliable way possible. The main principles of system operation have not changed much, despite the rapid developments in power electronics, computing, information and communication technologies. This paper surveys existing power networks and their limits in meeting modern developments and environmental concerns. There is an evaluation of the impacts of deployment of new low carbon technologies such as distributed generation and electric vehicles on existing networks, together with the main drivers for change and features of the new concept of the ‘smart grid’. The paper also examines the challenges and benefits that the ‘smart grid’ will bring, and describes the enabling technologies.

Estimation of Solar Photovoltaic Parameters Using Pattern Search Algorithm

The interest towards solar Photovoltaic (PV) based power generation has increased worldwide due to climate change and depletion of fossil fuels. This has led to the need for accurate solar PV modelling under different environmental conditions. Since solar PV shows nonlinear characteristics, optimization technique is the best tool for modelling and estimation of PV parameters. Thus, in this paper, a Pattern Search (PS) algorithm is proposed to optimize the parameters of solar photovoltaic panels. The objective is to identify the parameters of single diode model based PV, in such a way that the difference between PV experimental current and simulated current is minimal. The effectiveness of the algorithms is investigated through simulation in MATLAB/Simulink environment at different solar irradiance and temperature and it is compared with the experimental data of solar module Kyocera – KC200GT 215. Results clearly reveal that the proposed technique shows better results in terms of its accuracy, convergence and CPU execution time.

Output observer for chaos synchronization applications

This article introduces the concept of output observer to chaos synchronisation applications. Here output observer is understood as a low order system designed to estimate a single measured variable of a higher order system only. In this work we show how this notion can be used to evaluate nonlinear systems with single output, being a chaotic state variable used as an example. Following this point a Duffing oscillator is used as a model. We show how a lower order observer can be employed to accurately estimate nonlinear time series dynamics.

The role of designer knowledge for circuit-level optimization within an analog synthesis system

This paper discusses techniques for circuit-level optimization within an analog synthesis system. Various strategies for adding designer knowledge to guide the optimization process are available-these range from rules for selecting design variables to use of design equations. An example is given of the strategies applied to a BJT VCO.

Analogue circuit design using the analogue design synthesis assistant (ADSA)

The analogue design synthesis assistant (ADSA) is presented as a tool for the automated design and optimisation of analogue integrated circuits. ADSA implements analogue design synthesis using optimisation within an abstraction-based design framework. The results demonstrate that ADSA assists analogue design synthesis from high-level descriptions to circuit-level designs.

Robust fault estimation for stochastic Takagi-Sugeno fuzzy systems

Nowadays, industrial plants are calling for high-performance fault diagnosis techniques to meet stringent requirements on system availability and safety in the event of component failures. This paper deals with robust fault estimation problems for stochastic nonlinear systems subject to faults and unknown inputs relying on Takagi-Sugeno fuzzy models. Augmented approach jointly with unknown input observers for stochastic Takagi-Sugeno models is exploited here, which allows one to estimate both considered faults and full system states robustly. The considered unknown inputs can be either completely decoupled or partially decoupled by observers. For the un-decoupled part of unknown inputs, which still influence error dynamics, stochastic input-to-state stability properties are applied to take nonzero inputs into account and sufficient conditions are achieved to guarantee bounded estimation errors under bounded unknown inputs. Linear matrix inequalities are employed to compute gain matrices of the observer, leading to stochastic input-to-state-stable error dynamics and optimization of the estimation performances against un-decoupled unknown inputs. Finally, simulation on wind turbine benchmark model is applied to validate the performances of the suggested fault reconstruction methodologies.

Data encryption with chaotic Colpitts oscillators via power supply modulation

In this work we present numerical investigations for a simple data modulating technique employing Colpitts electronic oscillator models operating in the chaotic regime. The procedure includes a low amplitude half-wave rectified sinusoidal function on top of power supply terms, which acts as a message embedded data. We show how the suggested method does not take away the transmitters chaotic dynamics or the unidirectional complete chaotic synchronisation achieved. Advantages are in form of straightforward implementation that does not require hardware modifications as well as information recovery based on a simple subtraction. The proposed methodology can be applied to either positive or negative power supply. Traces of embedded data in the transmitted chaotic carrier cannot be spotted in time or frequency domain. In consequence the proposed method falls in the category of chaotic inclusion or embedding techniques but without requiring complex and computationally expensive left inversion protocols.

Simulation and evaluation of pulse-coupled oscillators in wireless sensor networks

ABSTRACT The clock in embedded systems usually is driven by a crystal oscillator and implemented via a counter register, such a crystal clock is non-identical and drifting due to the manufacturing tolerance and variation of working conditions. Thus, a common time among distributed wireless sensor nodes, also referred to as Time Synchronization, is required for many time-sensitive wireless applications, such as collaborative condition monitoring, coordinated control and localization. Inspired by fireflies’ behaviour, the Pulse-Coupled Oscillators (PCO) has been proposed for synchronization in complex networks. Since the concurrent transmission of PCO’s Pulses is impossible in Wireless Sensor Networks (WSNs), the desynchronization mechanism is adopted to ensure the implementation of PCO in WSNs. Moreover, due to the uncertainties in radio channels and the complexities of communication protocols and packet-exchange behaviours in wireless networks, it is challenging to have a closed-form solution to the performance of PCO synchronization in WSNs. The realistic software simulation, in particular, the discrete event simulator has been a powerful tool to exam the performance of communication protocols in various scenarios, since an order sequence of well-defined event in time is to represent the behaviour of a complex system. This paper presents the development of a pulse-coupled oscillators time synchronization simulator on the OMNeT++ platform for simulating and studying its behaviour and performance in sensor networks. A clock module with configurable phase and frequency noises, and adjustable and higher resolution is developed to mimic various crystal oscillators in embedded systems, for example, the real-time clock. The developed simulator also supports the full functions devices defined by ZigBee protocol, which allows realistic simulation of multi-hop IEEE 802.15.4 wireless networks. Finally, the intensive simulations of classical PCO with the refractory period in IEEE 802.15.4-based WSNs have been carried out to demonstrate the features and benefits of the developed simulator. It is shown that for the non-identical and time-varying PCO clocks in the WSNs, the achieved synchronization will lose gradually, and the time that maintained synchronization depends on the length of refractory period.

A simple all-fiber comb filter based on the combined effect of multimode interference and Mach-Zehnder interferometer

A polarization-dependent all-fiber comb filter based on a combination effect of multimode interference and Mach-Zehnder interferometer was proposed and demonstrated. The comb filter was composed with a short section of multimode fiber (MMF) fusion spliced with a conventional single mode fiber on the one side and a short section of a different type of optical fiber on the other side. The second type of optical fiber is spliced to the MMF with a properly designed misalignment. Different types and lengths of fibers were used to investigate the influence of fiber types and lengths on the performance of the comb filter. Experimentally, several comb filters with free spectral range (FSR) values ranging from 0.236 to 1.524 nm were achieved. The extinction ratio of the comb filter can be adjusted from 6 to 11.1 dB by varying polarization states of the input light, while maintaining the FSR unchanged. The proposed comb filter has the potential to be used in optical dense wavelength division multiplexing communication systems.

Indoor visible light communication localization system utilizing received signal strength indication technique and trilateration method

Abstract. Visible light communication (VLC) based on light-emitting diodes (LEDs) technology not only provides higher data rate for indoor wireless communications and offering room illumination but also has the potential for indoor localization. VLC-based indoor positioning using the received optical power levels from emitting LEDs is investigated. We consider both scenarios of line-of-sight (LOS) and LOS with non-LOS (LOSNLOS) positioning. The performance of the proposed system is evaluated under both noisy and noiseless channel as is the impact of different location codes on positioning error. The analytical model of the system with noise and the corresponding numerical evaluation for a range of signal-to-noise ratio (SNR) are presented. The results show that an accuracy of <10  cm on average is achievable at an SNR>12  dB.