Local Power System Research Articles

FORMATION THE OPTIMAL STRUCTURE OF LOCAL POWER SYSTEM BASED ON VALUATION OF PROXIMITY PLACEMENT OF OBJECTS

In the article is considered the problem of energy efficiency in Ukraine. The advantages of creating intelligent networking technology Smart Grid, the use of renewable energy in local energy networks are identified. Formed requirements to distribution networks which are the most common in our country. Analyzed the issue of feasibility analysis of the effectiveness of the combined technologies in the power sector. The question of the use of cluster analysis in the modeling of the local power system are considered. Overview process modeling local power system is presented. It identifies a number of criteria for assessing the optimality of the local power system, which is a basic element in the process of improving the system efficiency. Was shown the application measures the proximity between different versions of the distribution of a finite set of objects into subsets that intersect. An algorithm for the formation of the optimal structure of the local power system was proposed.

Hybrid Transient Energy Function-Based Real-Time Optimal Wide-Area Damping Controller

This paper presents a real-time wide-area damping controller design based on a hybrid intelligent and direct method to improve the power system transient stability. The algorithm applied as a nonlinear optimal wide-area damping controller monitors the oscillations in the system and optimally augments the local excitation system of the synchronous generators. First, energy functions and Prony analysis techniques are used to identify these local or interarea oscillations and develop stability or damping performance index at a given time. Second, artificial neural networks are deployed to learn the dynamics of the system and energy functions based on supervised learning to construct an optimal control design. Then, using online reinforcement learning the quadratic objective function based on the stability index is estimated and optimized forward-in-time. Results on the IEEE 68-bus in Power System Toolbox and HYPERSIM real-time simulator show better transient and damping response when compared to conventional schemes and local power system stabilizers.

Shaping of PWM Converter Admittance for Stabilizing Local Electric Power Systems

This paper suggests the concept of shaping the pulsewidth-modulated (PWM) converter admittance. The analytic admittance matrix equation, which is derived from the small signal model of a PWM converter, is formulized. Based on the damping coefficient and the natural frequencies of phase-locked loop and dc voltage loop, the variations in admittance frequency responses are discussed. In addition, the frequency response can be adjusted through pole placement using the gain of the current controller. The controller gain for a stable operation is designed by detailed understanding of the frequency response shape. Furthermore, to stabilize the local electric power systems (EPSs) that invoke instability through the interaction between constant power load PWM converters, the admittance shaping loop is utilized for the distributed generator PWM converters. Through computer simulation and hardware experiments, the proposed shaping guidance can effectively stabilize local EPS.

Studying the effect of Ruthenium on High Temperature Mechanical Properties of Nickel Based Superalloys and Determining the Universal Behavior of Ruthenium at Atomic Scale with respect to alloying elements, Stress and Temperature

Any property of a material is a function of its microstructure and microstructure is a function of material composition. So, to maximize the desired properties of a material, one has to understand the evolution of microstructure which in turn is nothing but the reflection of the role of alloying elements. Research has not been done to understand the universal behavior of a certain base/alloying element. Let’s take the example of Cl- ion in HCl, we all know that in general, chloride ion can only be replaced by Fluoride or oxygen ion and that no other ion can replace it. But when you consider a metal like Ni, Co, Cr, Fe etc. there is no establishment that it behaves only in a certain way. Though I concord to the fact that discovery of universal behavior of Ni is lot complex than chloride ion, I think that future research should be focused in this direction also. Superalloys are the candidate materials required to improve thermal efficiency of a gas turbine by allowing higher turbine inlet gas temperatures. Gas turbines are the heart of local power systems, next generation jet engines and high performance space rockets. Recent research in superalloys showed that addition of some alloying elements in minor quantities can result in drastic change in properties. Such an alloying element is Ruthenium (Ru). Addition of Ruthenium to superalloys has shown improvement in mechanical properties by an order of magnitude. However reasons for such improvement are not known yet. Hence, there is a need to identify its role and discover the universal behavior of ruthenium to utilize it efficiently. In this proposal, we study materials with different compositions that are derived based on one ruthenium containing superalloy, and different thermomechanical history. Based on the evolution of microstructures and results of mechanical testing, we plan to determine the exact role of Ruthenium and prediction of its behavior with respect to other elements in the material such as Ni, Cr, Co, Mo, W etc. and stress and temperature. This helps us to determine the right quantity of ruthenium required for a given composition and operating conditions.

Centralized Control Architecture for Coordination of Distributed Renewable Generation and Energy Storage in Islanded AC Microgrids

The coordinated operation of distributed energy resources such as storage and generation units and also loads is required for the reliable operation of an islanded microgrid. Since in islanded microgrids the storage units are commonly responsible for regulating the voltage amplitude and frequency in the local power system, the coordination should consider safe operating limits for the stored energy, which prevents fast degradation or damage to the storage units. This paper proposes a centralized control architecture, applicable for local area power systems such as a small-scale microgrid. The centralized architecture is based on three supervisory control tasks which consider: active power curtailment of generation for avoiding overcharge of the storage units, load shedding actions for preventing deep discharge of the storage units, and equalization of the state of charge (SoC) among distributed storage systems for avoiding uneven degradation. The proposed equalization method has proved to be effective for equalizing the SoC of distributed energy storage systems and for ensuring uniform charge/discharge ratios regardless of differences in the capacity of the storage units. Additionally, the strategy is complemented with an optimal scheduling of load connection, which minimizes the connection and disconnection cycles of the loads within a time horizon of 24 h. The proposed architecture is verified experimentally in a lab-scale prototype of a microgrid, which has real communication between the microgrid and the central controller.

Adaptive system for automatic stabilization of the power factor for electric drives of separation device by means of serially connected capacitors bank

A method for designing adaptive systems for automatic extremum search to stabilize the power factor of local electric power system of electric is considered. It consists in application of the serially connected capacitors compensating the reactive component of the total electric power of in parallel connected centrifugal machines usually called as an aggregate. Operation of the system just demands measuring voltage at the output of the static frequency converter for electric drives. The proposed control system is designed to stabilize the power factor close to unity in a case of alteration of parameters of a separation cascade or a single separation device in an aggregate. Such system can be operated continuously or connected occasionally depending on a technological situation. In addition, it totally excludes the phenomenon of overcompensation.

The spatial dimension of the power system: Investigating hot spots of Smart Renewable Power Provision

The spatial dimension of the transition to a decarbonized power system becomes increasingly apparent with more than 1.5million renewable energy sources of electricity (RESE) plants operating all over Germany. The information regarding the spatial distribution of RES-E generation and power demand is still divers and not yet systematically used for the strategic planning of the energy transition and energy system modelling. The objective of this study is therefore to analyse the current power demand and RES-E supply spatially highly explicit with regard to their local interplay, annual balances and the share of volatile to flexible RES-E. This is achieved through the development and implementation of a general framework to analyse spatial patterns of the power system at different scales. The area of study is the Federal State of Germany, with the assessment of different spatial resolution ranging from federal state to community level. The resulting patterns are evaluated for their statistical significance through a hot spot analysis, followed by a correlation analysis to find possible reasons for their formation. The study shows a spatial dissonance between power demand and RES-E supply. This suggests that the design of the policy framework, focused on the levelized cost of electricity, led to a spatial distribution not oriented on local power demand but rather on economic optimality for the single power plant owner. By additionally differentiating between the RES-E technologies in terms of their intermittency characteristics, conclusions on the ability of regions at different scales for Smart Renewable Power Provision are drawn, measured by a set of proposed low carbon indicators. The spatially most detailed level reveals the diverse state of the regions with, on the one hand, already around 10% fulfilling the indicator limit of Smart Renewable Power Provision and, on the other hand, regions with no RES-E capacity installed. An algorithm for finding desirable trajectory pathways to a decentralized energy system is introduced, build on the knowledge of the current state of the local power system. Finally, the correlation analysis indicates that for the RES-E extension not only socioeconomic but also land use characteristics are important factors to consider.

DC Microgrid Protection: Using the Coupled-Inductor Solid-State Circuit Breaker

Since the great debate between Thomas Edison and Nikola Tesla, our nation's power system has operated on alternating current (ac). This was chosen over direct current (dc) because of the need to increase voltage with ac transformers to a high value using transformers for long-distance power transmission. The system has served its purpose well, but now, many energy sources, such as solar panels, fuel cells, and batteries, supply dc voltage. Also, dc/dc power converters are commonly used to transform voltage and to interface these dc sources with a larger system. Because of this, local dc power systems (or microgrids) have become popular topics in research literature. It also turns out that interfacing a wind power generator to a dc system is simpler than interfacing it to an ac system because ac/dc conversion is needed for the former and ac/dc/ac conversion is needed for the latter. Although energy sources and power conversion are readily available for dc power systems, some highperformance applications require fast-acting dc circuit breakers, which are currently in the experimental phase. This article discusses options for high-performance dc circuit breakers and specifically details the coupled-inductor dc breaker. This breaker is demonstrated for fault protection in a notional dc microgrid.

Modeling the Effects of Variable Tariffs on Domestic Electric Load Profiles by Use of Occupant Behavior Submodels

Emerging infrastructure for residential meter communication and data processing carries the potential to control household electrical demand within local power system constraints. Deferral of load control can be incentivized through electricity tariff price structure, which can in turn reshape a daily load profile. This paper presents a stochastic bottom-up model designed to predict the change in domestic electricity profile invoked by consumer reaction to electricity unit price, with submodels comprising user behavior, price response, and dependency between behavior and electric demand. The developed models are used to analyze the demand side management potential of the most relevant energy consuming activities through a simulated German household demonstrating that in the given scenario 8% of the annual electricity demand is shifted, leading to a 35€ annual saving. However, a 7% higher than average peak load results from the structure of the tariff signal modeled herein. A discussion on selected aspects for tariff design for categories of typical household appliances is included.

Induced sheath voltages in 110 kV power cables – case study

Abstract This paper considers electric shock hazard due to induced sheath voltages in 110 kV power cables. The purpose of this paper is to find an optimal configuration of the power cable system, taking into account electric shock hazard and ability of the system to transfer maximal power. A computer simulations on a computer model of the local power system, comprising high voltage power cables, were carried out. This model enables to analyse various configurations of the metallic cable sheaths bonding and earthing (single-point bonding, both-ends bonding, cross-bonding) and their impact on induced voltages in the cable sheaths. The analysis presented in the paper shows, that it is possible to find an optimal configuration of the complicated power cable system, in terms of electric shock hazard, maximal power transfer as well as economic aspects.

Sequential design and global optimization of local power system stabilizer and wide-area HVDC stabilizing controller

A sequential design and global optimization method is proposed to coordinately design local and wide-area controllers to enhance the overall stability of large-scale power system. The sequential design is used to assign the distributed local power system stabilizer (LPSS) and high-voltage direct current (HVDC) wide-area stabilizing controller (HVDC-WASC) to the concerned damping modes. The global optimization is used to simultaneously optimize all the overall control gains of LPSSs and HVDC-WASC. Moreover, the optimization model, which has an adaptive ability of searching and updating dominant oscillation modes, is established. Both the linear analysis and nonlinear simulation results verify the effectiveness of the proposed design method in enhancing the stability of large-scale power systems.

Impact of On-Grids Solar PV Rooftop on Low Voltage Grid Systems: A Case Study of PEA Udonthani, Thailand

This paper presents the impact of on-grid solar PV rooftop on local power systems of 10 kW - typical low voltage power rating for households campaigned by Thai Government. The overvoltage, frequency variation and harmonic contamination was investigated and analyzed. The condition of peak power generated from PV was also considered. The experimental data used for the analysis were collected by turning on and off the solar PV system of PEA power system on Udonthani province, Thailand for every hour with duration time between 6.00 AM and 6.00 PM. The results showed that the voltage at the connecting point of solar PV rooftop to the grid increases from 5-8 V (2.3-3.6%.).The frequency slightly increases from 49.97-50.06 Hz. In addition, the total harmonic distortion is not significantly different - varying in narrow range of 0.1-0.2 VTHD.

Role of Local Energy Systems in Socio-Economic Development of Kostroma Oblast

The conceptual apparatus of the article is reviewed in the Introduction. The second part is devoted to the historical and geographical overview of the evolution of the power industry in Kostroma oblast. Topographic analysis of energy space of Kostroma oblast shows that three fourth of the area of Kostroma oblast will face problems in the case of system failure in the power system. Therefore, the traditional model of combining of different schemes of power supply is required. The development of gas turbine technologies determines the possibility of the formation of linear-nodal and areal-nodal types of local power supply systems, and the use of renewable energy sources gives the possibility of using of areal type power supply systems. Diversification of energy sources determines the growth of supply reliability. The main directions of combining of energy systems are presented as conclusions of the article. The sparsely populated rural areas of the Kostroma oblast (1.5 persons per square km) limit the feasibility of increasing of centralization of energy system. Local energy systems allow to solve energy and social problems of population. In the areas with a high share of small settlements (population density from 1.5 to 3.0 persons per square km) the reliability of power supply is dramatically reduced due to wear electricity distribution grids. The problem can be solved by combining the local and centralized power systems. Schemes of combining of local and centralized energy systems are also applicable in recreational and conservation areas. This direction is promising for areas that act as growth poles (in the Volga area). The scheme of the local energy system provides the operation of the small generation module as an integral part of a centralized system and increased synergies.

A Centralized Reactive Power Compensation System for LV Distribution Networks

A centralized reactive power compensation system is proposed for low voltage (LV) distribution networks. It can be connected with any bus which needs reactive power. The current industry practice is to locally install reactive power compensation system to maintain the local bus voltage and power factor. By centralizing capacitor banks together, it can help to maintain bus voltages and power factors as well as reduce the power cable losses. Besides, the centralized reactive power system can be easily expanded to meet any future load increase. A reasonably sized centralized reactive power compensation system will be capable of meeting the requirements of the network and the optimization algorithm proposed in this paper can help to find this optimal size by minimizing the expected total cost (ETCH). Different load situations and their respective probabilities are also considered in the proposed algorithm. The concept of the centralized reactive power compensation system is applied to a local shipyard power system to verify its effectiveness. The results show that an optimally sized centralized reactive power system exists and is capable of maintaining bus voltages as well as reducing the power losses in the distribution network. A significant power loss reduction can be obtained at the optimal capacity of the centralized reactive power compensation system in the case study.

Towards Smart Integration of Distributed Energy Resources Using Distributed Network Protocol Over Ethernet

The Distributed Network Protocol (DNP3) is the communication protocol standardized by IEEE for electric power systems (EPS) and it is a promising communication standard in the context of Smart Grids. This paper presents the Distributed Network Protocol over Ethernet (E-DNP3) using field programmable gate array (FPGA) technology as the first step to the EPS automation. The communication architecture improves the delivery time comparing with previous works and provides an adaptable solution for real-time information exchange in electrical applications such as management, control, and protection of power systems. The developed work allows the analysis of the feasibility of the proposed communication architecture in a real microgrid scenario. This implementation accomplishes a new technique for the communication architecture in order to integrate the distributed energy resources (DERs) to the local power system. The experimental results prove that the proposed architecture satisfies the communication requirements for real-time monitoring and control of EPS towards Smart Grid applications.

Novel Stability Enhancing Control Strategy for Centralized PV-Grid Systems for Smart Grid Applications

Inverter driven, inertia-less interface of a large photovoltaic (PV) source with power grid raises challenging penetration issues such as bus voltage fluctuation, active power variation, reactive power flow and poor system dynamics. Extensive efforts are underway to overcome these issues, which tend to put a limit on the maximum PV power injection capability for a given local area electric power system. This paper proposes a new control scheme that enables a centralized PV-grid system to damp out the low frequency power swings on the local area network as an ancillary activity apart from its regular function. The proposed scheme enhances the power system stability without incorporating any additional devices or systems (e.g., PSS). The analytical basis of the control law used in this scheme is derived from the structure preserving energy function (SPEF) model. A notable feature of the scheme that makes it highly feasible is that it requires only locally measurable signals. Further, it does not affect the MPPT control of the PV system in any manner. All these features make it highly relevant and suitable for smart grid applications. Relevant simulation results as well as key experimental results for a laboratory level hardware model are included.

The alternative strategies of the development of the nuclear power industry in the 21st century

This paper emphasizes the urgency of scientific-and-technical and sociopolitical problems of the modern nuclear power industry without solving of which the transition from local nuclear power systems now in operation to a large-scale nuclear power industry would be impossible. The existing concepts of the longterm strategy of the development of the nuclear power industry have been analyzed. On the basis of the scenarios having been developed it was shown that the most promising alternative is the orientation towards the closed nuclear fuel cycle with fast neutron reactors (hereinafter referred to as fast reactors) that would meet the requirements on the acceptable safety. It was concluded that the main provisions of “The Strategy of the Development of the Nuclear Power Industry of Russia for the First Half of the 21st Century” approved by the Government of the Russian Federation in the year 2000 remain the same at present as well, although they require to be elaborated with due regard for new realities in the market for fossil fuels, the state of both the Russian and the world economy, as well as tightening of requirements related to safe operation of nuclear power stations (NPSs) (for example, after the severe accident at the Fukushima nuclear power station, Japan) and nonproliferation of nuclear weapons.

Development of Inexpensive Static Var Compensator Using PIC

This study presents the design and construction of an economical static reactive power compensator using inexpensive Peripheral Interface Controller (PIC), with the aim to add dynamic response to local distribution power systems. As FACTS devices have been more prevalent to perform instantaneous power compensation providing the enhancement of transient voltage and system stability. For some distribution networks, its price and complicated operation make FACTS devices unfavorable. The PIC is programmed as the heart of the overall control system for monitoring voltage, generating controlled signal and modulating PI feedback-loop. Simulation was carried out to guide the control design. Experimental results show the performance of the system response. This implies that the proposed compensator can be used for real applications and envisages the future replacement of mechanical- switched capacitor/reactor.

An Application of Developing Renewable Energy in an Extreme Arid and Energy-Scarce Area in Tarim Desert

This paper provides the systemic procedure to introduce local renewable energy into the local power system in the Tarim Desert and foot of the Kunlun Mountain. This research takes seven townships of Qira County as the research basis. By using forecast technique, the Intensive Load-Area was formed based on the forecasted local population and load condition by the year 2020. According to the local urbanization plan that is widely applied in Xinjiang Uygru Autonomous Region (XUAR), this paper defines the two types of rural power system namely township branch system and village terminal system. The optimal development procedure makes a small-scaled and weak power system expanded it's the ultimate ability to accept the capacity of renewable energy. According to national standard indexes, special simulation is used for testing stability of hybrid power system in normal operation and dynamic performance under the composed operational manners. The numerical statistics indicate the efficiency of saving energy and protecting the desert environment after introducing renewable energy.

Applicable Indices to Connecting Industrial Park Load and Renewable Sources to a Local Power System

This paper presents the applicable methods to connect industrial park load and renewable energy to a small-scaled power system. The connecting procedure consists of three items namely Optimal Order and Domain-Link Method and Weakness Degree in Energy Supply (WDES) as well. The optimal order makes dispersed hydropower and thermal power first developed to improve P-V nodes and capacity of small power system. The domain-link method can selects more stable buses that have multi-branch of power supply in order to connect industrial park and renewable energy. WDES shows weakness information of each bus to avoid connecting industrial park load and renewable energy to unstable buses in practical operation. To testify the operational characteristics, the system power flow is used to indicate the margin of buses voltage and carrying capacity of power lines after introducing industrial park and renewable energy. To elaborate on the application process in detail, this paper takes the several diagrams and tables as the theoretical basis and makes the all connection process more systematic.