In the present work, the authors have studied conductive surfaces on polyester fabrics by using two types of commercially available conductive polymers; polyaniline and poly (3,4-ethylenedioxythiophene)-poly (styrenesulphonate) (PEDOT: PSS) with 100 nm aluminium thin film evaporated on top of the polymer so the fabric becomes a conductive substrate for inorganic thin film solar cells. Conductive polymer surfaces on woven polyester fabrics were obtained by knife-over-table coating technique. Surface resistivities for polyaniline and PEDOT: PSS coated fabrics were measured and found in the range of 400 × 10³ and 1 × 10³ Ω/□, respectively. Thermal stability tests were carried out to evaluate the effect of specific periods of heal treatment at different elevated temperatures on resistance of polymer coated conducting textiles. PEDOT: PSS exhibited better stability than panipol. According to long term tests, PEDOT: PSS coated samples showed improvement in conductivity over 3 days whereas panipol showed the opposite. Transmission Line Model tests were performed to measure aluminium/polymer contact resistances which were found to be 120 × 10³ Ω for polyaniline and about 46.3 Ω for PEDOT: PSS. Mechanical bending tests for aluminium/PEDOT: PSS/fabric samples showed that the polymer can maintain the conductivity of samples by bridging micro-cracks in the metal film.

This study examines the cost-effectiveness of residential photovoltaic (PV) systems in the UK by considering the changes occurring in the supporting mechanism, the Feed-in Tariff (FiT). The metric used is the levelised cost of energy. The analysis stresses the importance of the FiT scheme and demonstrates the lowest cost of produced energy that domestic PV systems can achieve with the current policies. In this study, the term grid parity is used when the levelised cost of the PV generated energy is lower than the retail electricity cost that the consumer pays. It is observed that, for certain scenarios and in certain UK cities, a domestic PV system can reach grid parity without using the FiT scheme, but it might not constitute a sufficient reason to invest in a PV system.

Distributed electrical modelling and simulation plays an important role in investigating local operating points and the overall power generation of photovoltaic (PV) modules. A PV module is a three-dimensional device in which inhomogeneities can cause a non-uniform performance and hence, electrical mismatches which consequently reduce the overall power generation. Distributed modelling and simulation can be used to identify local electrical properties and their impacts on the power output. In this study, a flexible, distributed electrical network modelling approach is presented. The proposed approach introduces a hierarchical architecture built up from the diode model-based sub-cell level to the module level. A PV-oriented nodal analysis solver is developed to enable the spatially resolved quantitative analysis of electrical operating points by given local properties including irradiance, temperature, series resistance, shunt resistance and ideality factor. The approach has been verified by PSpice software. The case studies have shown that this modelling and simulation tool can be used to analyse spatially resolved characterisation results and to predict global and distributed operating points under different conditions.

This study introduces a new method for determining the spectral response of a photovoltaic (PV) device. Instead of illuminating the PV device under test with monochromatic beams at different wavelengths, the device is irradiated with different broadband spectra. Variations in the spectra are made by employing different types of polychromatic filters. The advantage of using these types of filters is the increase in the light intensity incident on the measurement plane, compared with narrowband filtered light. As a consequence, the spectral response measurement setup becomes very simple, comprising only a light source, a set of polychromatic filters, spectroradiometer and source-meter unit. The spectral response is determined by fitting the short-circuit currents measured under different spectra to a chosen spectral response model. The proposed method is verified by comparing the results to spectral response curves measured with a traditional monochromatic method, which show excellent agreement. From this analysis, it can be concluded that the proposed method is feasible as a new technique for determining the spectral response of a PV device.

This study presents the quantitative transient stability assessment and comparison for conventional synchronous generator (SG) and wind turbine generators (WTGs) by studying the impact of the fault clearing time, the grid coupling, the inertia constant, the generator terminal voltage sag and the slip on fault responses. The assessment and comparison is performed by evaluating the transient stability index through the modified transient energy function. Simulation results show WTGs exhibit different transient responses on the occurrence of faults as compared with conventional SG. This justifies the necessity of study in greater depth for reliable operation of conventional power systems with the integration of large wind power.

The authors propose robust non-linear controllers for a wind system. The proposed controllers are based on a combination of the block control linearisation and super-twisting algorithm, as a second-order sliding mode technique. The main control loop is designed to regulate the electromagnetic torque and stator power factor of a doubly-fed induction generator which is connected to the grid. The generator is mechanically coupled with a DC motor, which can emulate the wind turbine operation. Therefore, an auxiliary control loop is designed to control the DC motor velocity. Additionally, a grid-side converter controller is proposed to regulate the DC-link voltage into AC/DC/AC converter, and displacement factor of the energy flow between the rotor and the grid. A robust stability analysis of the complete closed-loop system under external disturbances is presented. The robustness of the proposed control schemes is validated in real time using a workbench, which consists of a motor–generator group, AC/DC/AC electronic drive and dSPACE DS 1104 controller boards.

This study suggests a moving horizon ℋ_∞ control scheme for variable speed wind turbines above the rated wind speed to maintain the output power at the rated value for variable operating points. A constrained ℋ_∞ control problem is solved at each sampling time with the update of not only the initial condition but also the prediction model based on different operating points. Closed-loop properties inclusive of ℒ₂ disturbance attenuation are discussed in the framework of dissipation theory. The moving horizon ℋ_∞ control considers the non-linear dynamic aspect of the wind turbine, the turbulent nature of the wind and actuator saturations. Analysis and simulation results for WD34 wind turbine show possible improvements on the output electrical power regulation performance for variable operating points, while respecting actuator saturation limits.

The transient stability analysis incorporating wind power intermittency and volatility is studied in this study. The wind turbines with doubly fed induction generator (DFIG) and direct-driven permanent magnet synchronous generator (PMSG) are considered, respectively, during analysis. In modelling of DFIG and PMSG, the default GE wind turbine model and the Western Electricity Coordinating Council generic wind turbine model are employed, respectively. Based on the Jensen model, which is applied to describe the wake effect in a wind farm located on flat terrain, an equivalent simplified model of a wind farm is established regarding wind farm layout. On the basis of the built wind farm model, the Monte Carlo simulation technique combined with two evaluation indices, namely angle-based margin index and critical clearing time (CCT) is applied on the IEEE 10-generator-39-bus test system and a real-sized China-Jiangxi power grid as a benchmark to exploit and explore the effects of wind power intermittency and volatility on power system transient stability. The frequency distributions of transient stability evaluation index, CCT, probability of system transient instability and the range of wind speeds causing system transient instability are simulated. In addition, the influence of wake effect on transient stability is discussed as well.

In electricity generation, one of the direct benefits of exploiting wind energy is reducing the atmospheric emissions due to using conventional fuels. An emission mitigation model for oxides of nitrogen has been developed with short-term wind statistics, based on the Beta distribution. The probability infeasibility of random wind behaviour is taken into account. An optimisation model, based on economic dispatch models, is developed to minimise the impact caused by the oxides of nitrogen emissions.

Controlling the frequency of power systems with high wind power penetration is more difficult due to the high variability of the wind power. One possible mainstream energy carrier in the future, particularly for the transportation sector, is Hydrogen, and water electrolysis is one of the most attractive ways to produce it. In this study, a detailed model of a steam turbine generator has been produced in MATLAB Simulink and used to investigate a scenario in which there is a 25% penetration of wind power. To improve the frequency stability of the power system, large scale alkaline electrolysers used in future Hydrogen filling stations could adjust their load with respect to the frequency deviation from nominal and can significantly reduce fluctuations in system frequency. For the case examined, five times less spinning reserve is required in order to maintain the power system frequency within operational limits when electrolysers are utilised as a form of demand side management (DSM), compared to the base case where no electrolyser DSM plant is available. Actual operational data from a pressurised alkaline electrolyser is used to evidence the fast load changing capability of such electrolysers.

This study presents a new methodology to solve the wind turbine modelling based on doubly-fed induction generator (DFIG) technology. The proposed solution allows us to simulate simultaneously a significant number of individuals DFIG submitted to different wind-speed profiles, minimising the computational time costs and avoiding excessive simplifications in comparison with previous solutions. For this proposal, a third-order induction generator model has been considered by the authors. The rotor current-control loops have been modelled through standard PI regulators, discussing in detail rotor voltage expressions and values of the parameters. The global non-linear equation system has been rearranged in state-space forms, by means of local linearisations and using two different software-packages that enable symbolic computation in a collaborative manner. The analytical results have been compared facing a traditional discretised solving methodology to assess the suitability of the proposed solution under different wind-speed conditions. Indeed, simulated and real-measured wind profiles have been considered for this purpose. Finally, a comparison of computational time costs for different time steps, including the effect of the number of wind turbines, is also included in this study.

The no-load losses represent one of the most important problems for flywheels energy storage systems (FESS) which produce electrical energy from the kinetic energy stored with long waiting times between charging and discharging. This study presents a novel modular stator for use in synchronous permanent magnet (PM) electrical machine coupled to a FESS. The modular stator includes several sections of retractable yoke stator, displaceable in the radial direction. Each stator segment is composed of several coils, teeth and its corresponding back iron section. A removable back iron yoke stator allows reducing the iron losses in the ferromagnetic core of the PM motor/generator during stand-by operation mode in FESS. In stand-by mode, with the stator in a retracted position, the iron losses are reduced up to 95% when the air gap length is increased 20 mm.

The growth of wind power in some power systems is hampered by the system requirement for emergency reserve to cover loss of the biggest infeed. The study demonstrates that reserve provision from the wind sector itself has economic and operational benefits. A heuristic algorithm has been developed that can model the relevant aspects of emergency reserve provision in a system with both thermal and wind generations. The proposed algorithm is first validated by comparing its performance with established economic scheduling methods applied to a representative power system. The algorithm is then used to demonstrate the economic benefit of reserve provision from the wind sector. It is shown that such provision reduces wind energy curtailment and thermal unit ramping. Finally, it is shown that a wind sector capable of providing emergency reserve can expand economically beyond the capacity limit that would otherwise apply.

This study presents a novel coordinated secondary voltage control (CSVC) and reactive power management scheme for efficient utilisation of distributed energy resources in a smart distribution network. The proposed controller is developed to achieve efficient voltage regulation and to maximise the dynamic reactive power reserve in a distribution network to react during system contingencies. The simulated distribution system, including an on-load tap changer (OLTC) and distributed energy resources, is implemented using PSCAD/EMTDC. The CSVC is designed to provide slow and medium speed responses, using low-pass filters for OLTC and diesel generators, respectively, and a fast response by utilising inverter-based distributed energy resources. Therefore it applies a control strategy with different bandwidth dedicated by the decentralised voltage controllers and reactive power management scheme. The CSVC is used to enhance the bus voltage control by utilising the reactive power loading capabilities among distributed energy resources and on-load tap changers of the substation transformer. A comprehensive simulation has verified the superior performance of the proposed coordinated secondary voltage control with the reactive power management scheme for enhancing the voltage profile and the fault ride-through capability, ensuring higher dynamic reactive power reserves in a distribution network, and improving the transient stability margin.