Remote Power System Research Articles

Packet Routing and Energy Cooperation for RTU Satellite-Terrestrial Multi-Hop Network in Remote Cyber-Physical Power System

Packet Routing and Energy Cooperation for RTU Satellite-Terrestrial Multi-Hop Network in Remote Cyber-Physical Power System

A virtual synchronous generator control method for remote island power system considering dynamic voltage stability

Remote island power systems are difficult to install renewable energy sources (RES) because of the small system capacity and the large impact of intermittency of RES. Virtual synchronous generators (VSG) can equip inverters with the inertia of synchronous generators and can suppress frequency and voltage fluctuations. This paper proposes a VSG control method for dynamic voltage stability in remote island power systems. In conventional VSG control methods, the command of active and reactive power is determined by the Droop characteristics of frequency and transmission line voltage. However, the command are not based on dynamic voltage stability indices. Therefore, the compensation amount of active and reactive power is inappropriate. The proposed method determines the command of active and reactive power based on dynamic voltage stability indices. The dynamic voltage stability index considers the critical boundary index (CBI). The CBI is defined as the distance between the operating point of active and reactive power flowing through a transmission line and the stability limit curve calculated from the power flow between two bus lines. The proposed method improves dynamic voltage stability by determining power command so that the operating points of active and reactive power are closer to the origin direction. Simulation verification is performed for load increase and three-phase ground fault. In the three-phase ground-fault simulation, FRT requirements are considered to verify continued operation and the case of gate blocking. The conventional Droop control and the proposed method are compared for the case of continued operation with FRT requirements during load increase and ground fault. Simulation verification results show that the proposed method improves the dynamic voltage stability compared to the conventional method. Furthermore, it is shown that the proposed method is capable of stable continuous operation of the system even after a transmission line failure considering the FRT requirement.

Dynamic Voltage Stability Assessment in Remote Island Power System with Renewable Energy Resources and Virtual Synchronous Generator

Increasing the proportion of renewable energy generations in remote island power systems is becoming essential for realizing decarbonized society. However, since inverter-connected renewable energies have different generation characteristics from conventional generators, the massive penetration can adversely affect system stability. In particular, fault events in such weak remote systems can cause fast voltage collapse, and there is a need to assess dynamic voltage stability. This study attempts dynamic voltage stability assessment using the critical boundary index (CBI) and investigates the impact of the virtual synchronous generator (VSG) on dynamic voltage stability. A remote island power system and VSG are modeled, and time-domain simulations are conducted with case studies of fault events. The simulation results show the potential of CBI to use for dynamic voltage stability assessment. Furthermore, the VSG can provide suitable power output during fault events and improve dynamic voltage stability.

Two-stage framework for optimizing the operation of remote off-grid power systems under uncertainties

With the precipitated integration of intermittent renewable sources, operation optimization employed with uncertainty management strategies is imperative to ensure a reliable, cost-effective, and secure energy supply for the remote off-grid power systems. This paper presents a two-stage operation optimization process embedded in a model predictive control framework. The first stage decision variables are derived in a deterministic optimization framework to achieve minimum operational costs and emissions. The second stage uses a stochastic optimization framework to refine the first stage decision variables to achieve a feasible operation considering several candidate scenarios in a computationally inexpensive manner. Several measures are integrated to the proposed framework in order to address the operational requirements pertaining to remote off-grid power systems. The effectiveness of the proposed framework is demonstrated through numerical experiments for an isolated remote power system in Northern Canada for both summer and winter seasons. Quality of the obtained results as well as the computation efficiency of the overall framework has been verified compared to the existing energy management techniques. The overall result confirms the applicability of the proposed method in achieving a cost-effective and environmentally friendly operational trajectory while effectively accounting for the underlying uncertainties with a reduced computational burden.

Photovoltaic-driven transparent heater of ZnO-coated silver nanowire networks for self-functional remote power system

This work reports the first photovoltaic-powered transparent heater and the results suggest their potential for future smart window applications. Transparent heaters are of high interest for application in windows of buildings, automobiles, and aircrafts to ensure clear vision. Here, we propose the photovoltaic-transparent heater system to supply electric power for Joule heating of the transparent heater. The transparent heater is composed of silver nanowire (AgNW) networks to induce heat via the Joule effect. To ensure high stability, a ZnO film is applied as a transparent protection film to the AgNW networks, and it also serves as a thermal conductor for the transparent heater system. The proposed ZnO-coated AgNW transparent heater efficiently uses the Joule effect via the metal nanowire network, resulting in a high operating temperature >300 °C. The ZnO coating is also very effective in maintaining the optical transparency of the heater >67% in the visible spectral range. For on-site application, the ZnO/AgNW transparent heater is powered by photovoltaic cells and drives the heating temperature of 58 °C. The self-powered transparent heaters are therefore considered as suitable for application in transportation, buildings, wearables, and remote heating systems as a smart-window energy system.

Accounting for techno-economic parameters uncertainties for robust design of remote microgrid

This paper presents two different approaches to deal with uncertainties in the design optimization of renewable hybrid power systems in order to enhance the decision-making. The first one, Sensitivity Analysis Approach (denoted as SAA), takes the uncertainties into account after the optimization of the system. It permits first to evaluate the sensitivity on the static performances of the optimized system through uncertainty propagation. Secondly, it permits to identify the most influential uncertain parameters through Global Sensitivity Analysis (denoted as GSA). The second approach, called Robust Optimization (RO), integrates a Monte Carlo (MC) simulation into the process of optimization conducted with a Genetic Algorithm (GA). The two approaches have been set up and applied to a remote power system or microgrid, under uncertainties on techno-economic parameters. This illustrative case study is the electrical supply of a stand-alone application located in Nigeria, using photovoltaic production associated to a hybrid energy storage with a bank of batteries and a complete hydrogen chain (with an electrolyzer, a gas tank and a Fuel Cell (FC). Classically, the main source of uncertainties of such a system is associated to the temporal variation of renewable energy sources and load demands. Instead, this paper focuses on uncertainties of techno-economic parameters to improve the reliability of the optimization process for a stand-alone power system. Moreover, from a precise analysis of the state-of-the-art of such uncertainties, the authors propose to investigate complementarities of Sensitivity Analysis Approach and Robust Optimization. This study also aims to propose a methodological framework for any designer projecting to take into account uncertainties on techno-economic parameters. The results show the high interest to take into account such uncertainties for the decision-making and the ability of RO to limit their impact on system performance indicators.

Optimal Sizing and Performance Evaluation of a Hybrid Renewable Energy System for an Off-Grid Power System in Northern Canada

Sole dependence on diesel energy has imposed a wide array of problems upon the operation of off-grid power systems in Northern Canada. Hybrid Renewable Energy Systems (HRES) have been vehemently emerging as a feasible alternative to the existing diesel-based generation facilities. To maximize the intended benefits, proper component selection, optimum sizing of the grid configuration and performance evaluation in the economic, environmental and reliability paradigms become decisive steps in their designing process. This paper presents a HOMER software-based gird optimization study to optimally retrofit a remote off-grid power system in Northern Canada. Topologies like Battery-Diesel, PV-Diesel and PV-Diesel-Battery were assessed under different scenarios to find the optimum retrofit for a primarily diesel-based generation facility. Results reveal the competence of PV-Diesel-Battery topology at high renewable penetration levels in achieving the envisioned benefits. Around a renewable penetration level of 21%, fuel savings up to 22% is achievable along with 0–0.5% reductions in Levelized cost of electricity compared to the existing diesel-based power system. While diversifying the energy mix, the PV-Diesel-Battery topology considerably curbs the environmental degradation caused by the diesel-only operation and ensures the reliability, availability and security of the power supply.

Fuzzy logic-based energy management system of stand-alone renewable energy system for a remote area power system

ABSTRACTRenewable energy systems (RES) are being widely accepted as an alternative to standard conventional energy sources due to depletion of natural resources and their consequential environmental impact. One of the increasing uses of stand-alone RES is in powering the remote areas where grid power is significantly expensive due to transportation. However, the energy management of such systems is quite complex. This paper deals with fuzzy logic-based controller design for power management of a stand-alone hybrid renewable energy systems (HRES). The proposed intelligent energy management aims to minimise the operation cost and the environmental impact of a microgrid while significantly improving the economic and technical performance of power supply. The proposed fuzzy logic controller (FLC) ensures the power management between renewable energy generation, energy storage, and load. The simulation results clearly show that the controller demonstrated high performance under various load and generation conditions.

Model and Analysis of Integrating Wind and PV Power in Remote and Core Areas with Small Hydropower and Pumped Hydropower Storage

Small hydropower (SHP) and pumped hydropower storage (PHS) are ideal members of power systems with regard to integrating intermittent power production from wind and PV facilities in modern power systems using the high penetration of renewable energy. Due to the limited capacity of SHP and the geographic restrictions of PHS, these power sources have not been adequately utilized in multi-energy integration. On the one hand, rapidly increasing wind/PV power is mostly situated in remote areas (i.e., mountain and rural areas) and is delivered to core areas (i.e., manufacturing bases and cities) for environmental protection and economic profit. On the other hand, SHP is commonly dispersed in remote areas and PHS is usually located in core areas. This paper proposes a strategy to take advantage of the distribution and regulation features of these renewable energy sources by presenting two models, which includes a remote power system model to explore the potential of SHP to smooth the short-term fluctuations in wind and PV power by minimizing output fluctuations as well as a core power system model to employ PHS to shift the surplus power to the peak period by maximizing the income from selling regenerated power and minimizing output fluctuations. In the proposed first model, the cooperative regulation not only dispatches SHP with a reciprocal output shape to the wind/PV output to smooth the fluctuations but also operates the reservoir with the scheduled total power production by adjusting its output in parallel. The results of a case study based on a municipal power system in Southwestern China show that, with the proposed method, SHP can successfully smooth the short-term fluctuations in wind and PV power without influencing the daily total power production. Additionally, SHP can replace the thermal power production with renewable power production, smooth the thermal output, and further reduce the operation costs of thermal power. By storing the surplus power in the upper reservoir and regenerating the power during the peak period, PHS can obtain not only the economic benefit of selling the power at high prices but also the environmental benefit of replacing non-renewable power with renewable power. This study provides a feasible approach to explore the potential of SHP and PHS in multi-energy integration applications.

State estimation for stochastic discrete-time systems with multiplicative noises and unknown inputs over fading channels

This paper deals with robust state estimation problem for a class of stochastic discrete-time systems with multiplicative noises and unknown inputs over fading channels. An unbiased unknown input insensitive filter is designed such that the variance of the estimation error is minimized in the sense of the so-called P-estimation. The filter gain matrix is derived through solving a recursive Riccati equation and a generalized Lyapunov equation. A necessary and sufficient condition that guarantees the existence of the filter is given, which establishes a fundamental limit on the mean square capacity of each fading channel. Unknown input estimation and finite horizon stability of the proposed filter are also discussed. To illustrate the effectiveness of the proposed approach, the proposed algorithm is applied to a faulty remote controlled uninterruptible power system, where both the state and the fault are estimated.

Fast Electromagnetic Transient Simulations of Power Systems Utilizing Single‐Phase Phasor‐Based Modeling of Remote Systems

SUMMARYElectromagnetic transient (EMT) simulations of relatively large power systems have become quite common, for instance, in the case where simulations of HVDC converters are carried out with large ac power systems connected to the converters. Thus, the increase in computation time is a serious concern. To reduce computation time, this paper proposes a method to reduce computational demand of a remote power system which is located far from the source of a transient event to be simulated. In the proposed method, the remote power system, which is supposed to be represented by a three‐phase EMT‐based model, is reduced to a single‐phase phasor‐based model, and the size of the circuit to be simulated is thus reduced and the dynamics calculations of inductors and capacitors included in the remote power system are neglected. The calculation algorithm of generator models included in the remote power system is also simplified. The proposed method has been applied to EMT simulations of the WEST 10 benchmark power system prepared by the IEEJ, and it has been shown that the computation time is remarkably reduced without significant loss of accuracy if the portion assumed to be the remote power system is sufficiently far from the source of a transient event.

A wireless transmission low-power radiation sensor for in vivo dosimetry

The aim of the paper is to illustrate the design and the performance of a microelectronic circuit composed of a dosimeter, an oscillator, a modulator, a transmitter and an antenna. The device was designed for specific in vivo dosimetry applications. However, the layout area of less than 1 mm2 makes it suitable for a large variety of applications, from spot radiation monitoring systems in medicine to accurate measurements of radiation level in high-energy physics experiments. Moreover, due to its extremely low-power budget, it might be also of interest for space applications. The chip embeds a re-programmable floating-gate transistor configured as a radiation sensor and a read-out circuit. Prototype chips have been fabricated and tested exploiting a commercial 180 nm, four-metal CMOS technology. Characterization tests of the performance of the Ultra-Wide Band transmission are summarized. The dosimeter prototype has an estimated sensitivity of 1 mV/rad within a total absorbed dose range up to 10 krad. The read-out circuit is powered with 3.3 V and the total power consumption is very low, i.e. about 165 μW, making it also upgradable with a remote power system.

Voltage control of stand-alone wind and solar energy system

In this paper wind and solar based stand-alone hybrid energy system is presented for the remote area power system applications. The wind, solar, battery, fuel cell and dump load (i.e., aqua-electrolyzer) are connected to the common dc bus. An ac load is connected to dc bus through a pulse width modulation (PWM) based inverter. Ac voltage at load bus can be maintained at rated value by regulating dc-link voltage (Vdc) at its reference value and by controlling modulation index of PWM inverter. Novel control algorithms are developed to maintain Vdc at its reference voltage irrespective of variations in wind speed, solar irradiance and load. Along with the regulation of Vdc, dc–dc converter (connected between battery and dc-link) acts as a maximum power point tracker (MPPT) for photovoltaic (PV) array. Hence an extra dedicated MPPT circuit is not required to extract maximum power from PV. Control technique for the PWM inverter has been developed to make the line voltages balanced at the point of common coupling (PCC) when the load is unbalanced. Hence, efforts are made to supply quality voltage to the consumers through the stand-alone power system. Detailed modeling of various components of stand-alone system is presented. Extensive simulation results using Matlab/SIMULINK established that the performance of the controllers is quite satisfactory under balanced as well as unbalanced load conditions. Moreover, results with real time digital simulator (RTDS) are presented.

Techno-economic analysis of RES & hydrogen technologies integration in remote island power system

The main objective of the present study is the integration of hydrogen technologies as an energy storage medium in a hybrid power system. The existing power system of the island of Milos, which is based on fossil fuel generators and a small wind park, is assessed in the context of this paper. System level simulation results, from both technical and economic point of view, are presented for the currently existing and the proposed island's hybrid power system. The latter integrates a higher number of wind turbines and hydrogen technologies as energy storage medium, and the two system architectures are being compared taking into account not only technical and economic parameters but also Green House – Gas (GHG) emissions, fossil fuels consumption and Renewable Energy Sources (RES) penetration increase. Moreover, a sensitivity analysis has been performed in order to determine the contribution of hydrogen technologies equipment costs; with the cost of energy produced (COE) being the critical parameter. Results show that COE for the proposed power system is higher than the existing one, but on the other hand GHG emissions and fossil fuel consumption are significantly reduced. In addition, RES penetration increases dramatically and the sensitivity analysis indicates that a further reduction in hydrogen technologies equipment and subsidy on wind turbine costs would make RES & Hydrogen-based systems economically competitive to the existing power system of the island.

Dynamic Modeling and Analysis of a Remote Hybrid Power System with Pumped Hydro Storage

In this research, dynamic modeling of a remote hybrid power system and feasibility of a pumped hydro storage system is presented. Current hybrid system in Ramea, Newfoundland has an electrolyzer, storage and hydrogen generator system. This research proposes a pumped hydro storage as a replacement to the hydrogen system. Detailed MATLAB‐Simulink modeling has been done for every component of the Ramea hybrid power system. Incorporation of a pumped hydro system and some lead acid batteries will eliminate the low turn around efficiency of the electrolyzer and hydrogen generator system. The system dynamic model presented here is fast, accurate and includes dynamic and supervisory controllers. The proposed real time supervisory controller algorithm observes the available surplus/missing power in the system and regulates pump/turbine and charging/discharging of the battery bank to maintain a stable system frequency. This paper presents dynamic model, supervisory controller design and algorithm, six case studies and detailed simulation results.

Analysis of low power wireless links in smart grid environments

Recently, wireless sensor networks (WSNs) have been used in various smart grid applications, including remote power system monitoring and control, power fraud detection, wireless automatic metering, fault diagnostics, demand response, outage detection, overhead transmission line monitoring, load control, and distribution automation. However, harsh smart grid environment propagation characteristics cause great challenges in the reliability of WSN communications in smart grid applications. To this end, the analysis of wireless link reliability and channel characterizations can help network designers to foresee the performance of the deployed WSN for specific smart grid propagation environments, and guide the network engineers to make design decisions for the channel modulation, encoding schemes, output power, and frequency band. This paper presents a detailed analysis of low power wireless link reliability in different smart grid environments, such as 500kV outdoor substation environment, indoor main power control room, and underground network transformer vaults. Specifically, the proposed analysis aims to evaluate the impact of different sensor radio parameters, such as modulation, encoding, transmission power, packet size, as well as the channel propagation characteristics of different smart grid propagation environments on the performance of the deployed sensor network in smart grid. Overall, the main objective of this paper is to help network designers quantifying the impact of the smart grid propagation environment and sensor radio characteristics on low power wireless link reliability in harsh smart grid environments.

Robust PI control of smart controllable load for frequency stabilization of microgrid power system

The intermittent wind power in a stand-alone microgrid power system may cause a serious problem of frequency fluctuation. Energy storage (ES) such as a battery, super capacitor, superconducting magnetic energy storage (SMES) etc., can be used to reduce the frequency fluctuation. However, ES is extremely expensive especially for developing countries. They still prefer to minimize the use of battery or apply cheaper technology to suppress the frequency oscillation such as controllable load. This paper proposes the design of robust PI controllable load to stabilize frequency fluctuation in a remote microgrid power system. The proposed controller is a conventional first-order PI controller. To guarantee the robustness of the proposed PI controller, an inverse additive perturbation is formulated as an optimization problem and a genetic algorithm (GA) is employed to tune and optimize the proposed PI control parameters. Simulation studies have been done to verify the performance and robustness of the proposed robust PI controllable load on remote hybrid wind-diesel power system against various disturbances and system uncertainties.

Wide area control for improving stability of a power system with plug-in electric vehicles

The integration of plug-in electric vehicles (PEVs) to power systems has impacts on the stability characteristics of the integrated systems. Wide area controllers (WACs) are used in power systems to provide auxiliary control signals to the generators or other devices in order to improve the stability of the system. The necessity of WACs becomes more relevant during grid-to-vehicle (G2V) or vehicle-to-grid (V2G) power transactions, that is, charging and discharging cycles of the PEVs respectively. The design of a WAC for providing damping to three generators in a 12-bus power system with PEVs is presented in this study. Each WAC signal is obtained based on the aggregation of modulated local and remote power system stabilisers' signals. The modulation indices associated with those signals are tuned using the particle swarm optimisation technique to provide the maximum damping to the three generators. The 12-bus power system with the PEVs and WAC has been implemented on the real-time digital simulator (RTDS). Typical results have been presented to show the improvement in the stability of the power system when PEVs are integrated using transient simulations and Prony analysis.

On line internet‐based multi‐location power system harmonics analysis and monitoring

AbstractTraditional methods to measure power system harmonics employ the power harmonic analyzer or a software package, such as Matlab or others, but they do have certain limitations in the graphical programming environment, applications for remote monitoring and control performance and for multi‐point harmonic measurement. In this paper, a PC‐based virtual instrument (VI) based on Fast Fourier Transform (FFT) to implement a remote multi‐point power system harmonics analysis and monitoring using LabVIEW is proposed. The nearby PC (Server) can collect real‐time waveform data from different multi‐locations and transmit it to remote PCs (Clients) for on line harmonic analysis and monitoring via the Internet. The history of Total Harmonic Distortion (THD) in the waveform signals from remote locations can be also recorded and tracked in the data base. The strategies and guidelines are also developed to enhance teaching and/or learning the basics of operating Internet‐based systems. Experimental results have testified its well performance and remote Web‐based capability. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 241–252, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20175

Application of decentralized control for remote power system stabilization by installing renewable energy power plant

AbstractThe generating power of wind turbines varies in proportion to the cube of wind speed, hence, they cannot supply constant power and this causes fluctuations in frequency and voltage. This article presents a methodology for controlling grid frequency, hydrogen volume, and terminal bus voltage. This system consists of diesel generators, wind turbines, and load. Aqua electrolyzer and fuel cells are introduced in order to control grid frequency, voltage, and hydrogen volume. By applying H∞ control, frequency, voltage fluctuation, and hydrogen volume, controls are achieved. H∞ decentralized controllers are designed and installed for diesel generators, aqua electrolyzers, and fuel cells in series. In order to verify the effectiveness of the suggested system, MATLAB/SIMULINK is used for simulation. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.