High Voltage Power Grid Research Articles

Traveling wave protection based on asynchronously sampled time difference of arrival of modulus traveling waves in per unit line length

Traditional traveling wave protection schemes are susceptible to many factors such as network topology change, environment interference and inaccurate identification of wave fronts, which may lead to mal-operation of protection. In addition, most traveling wave protection schemes need accurate synchronous measurement which adds to the implementation cost. This paper proposes a traveling wave protection for high voltage power grids based on the time difference of arrival (TDOA) of zero-mode and aerial-mode traveling wave. First, the time difference of arrival of the modulus voltage traveling waves (MVTWs) asynchronously sampled at each bus is captured. With the minimum TDOA, the key bus and fault area can be firstly determined. Then, the TDOA of the line in per unit length is defined as the ratio between the difference of the TDOAs at both terminal buses and line length. Finally, as for one case that key bus connects with no other bus, the line corresponding to the minimum TDOA of all the lines in the fault area is determined as the fault line. As for the other case, the calculated line length should be compared with the actual one to detect the fault line. PSCAD/EMTDC is used to conduct fault simulations and the calculation results verify that the proposed scheme is not affected by fault resistances, inception angles and distances. In addition, the operation time of the scheme does not exceed 20ms, which makes it applicable for actual power grid protection.

The Impact Analysis of the Electromagnetic Radiation from the Ultra-High-Voltage Transmission Devices on the Automobile Experimental Base

Through the measuring of the electric field, magnetic field intensity induced by ultra -high voltage power grid equipment, the paper aims to study the impact of these on the basic performance of the test vehicles, the physical health of the personnel and the communication reliability of intelligent network connection as well as to evaluate whether the electromagnetic environment of the experimental base reaches the automotive test standards. At the same time, it concluded the basic measurement and evaluation methods of electromagnetic environment in automobile test base.

Effect of disorder and noise in shaping the dynamics of power grids

The aim of this paper is to investigate complex dynamic networks which can model high-voltage power grids with renewable, fluctuating energy sources. For this purpose we use the Kuramoto model with inertia to model the network of power plants and consumers. In particular, we analyse the synchronization transition of networks of N phase oscillators with inertia (rotators) whose natural frequencies are bimodally distributed, corresponding to the distribution of generator and consumer power. First, we start from globally coupled networks whose links are successively diluted, resulting in a random Erdös-Renyi network. We focus on the changes in the hysteretic loop while varying inertial mass and dilution. Second, we implement Gaussian white noise describing the randomly fluctuating input power, and investigate its role in shaping the dynamics. Finally, we briefly discuss power grid networks under the impact of both topological disorder and external noise sources.

Characteristics of very fast transient currents in ultra high-voltage power system with Hybrid reactive power compensation

Hybrid reactive power compensation (HRPC) consists of a stepped controlled shunt reactor (SCSR) and a series compensation (SC), which will find applications in future ultra high-voltage (UHV) power grids to resolve the problems due to the frequent change of reactive power and bulk power transmission. However, very fast transient currents (VFTCs) are inevitably generated during switching, which would lead to insulation breakdown. In the present work, we first develop the equivalent model for HRPC, following which we deduce the expression of VFTCs in the time domain by using an inverse Laplace transform. The analysis indicates that the amplitude and frequency of VFTCs are both affected by the capacitance of the SCSR and of the SC, as well as the line length, stray capacitance, etc. The oscillating frequency, peak, and amplitude of the main frequency of the VFTCs in the substation can be modified by adjusting the silicon-controlled rectifiers in the SCSR when the disconnecting switch in gas-insulated switchgear is switched on. When the disconnecting switch in the SC is switched on, the VFTC oscillation frequency in SCSR decreases with increasing stray capacitance of SC, but the frequency and peak of the VFTC remains quite large. Increasing the line length between the SC and the SCSR suppresses the VFTC in UHV power systems. These results lay the foundation for developing HRPC methods to suppress VFTCs in UHV substations.

Effect of Geomagnetic Induced Current in Ethiopian Power Grid

It is important to determine the possibility of high risk value of geomagnetic induced current (GIC), accurately define the level of power grid GIC, understand the distribution characteristics of disaster GIC, to prevent, control and evaluate the impact of magnetic storm disturbance on the power grid. Based on the full node model, the long term performance of 2003-2017 geomagnetic disturbances in Ethiopia 400kV-230kV power grid is analyzed. The results show that the probability of GIC high risk value of low voltage power grid in Ethiopia low latitude region is not zero. The GIC values in the northwest, Southeast and central regions are larger, and the GIC values in the northeast and southwest regions are smaller. When evaluating GIC, 400KV substations named S1, S2, and S8, S10, S48 and 230 kV substations such as S42, S43, S17, S16 and S53 should be monitored intensively. To ensure the calculation accuracy of high voltage power grid GIC is a prerequisite for the evaluation and governance of GIC. For GIC node accuracy, it is only need to consider the effect of 230kV grid on 400kV power system; For line GIC precision, it need to consider the influence of 230kV grid on 400kV power system and 400kV grid on 230kV power system.

The eGo grid model: An open source approach towards a model of German high and extra-high voltage power grids

There are several power grid modelling approaches suitable for simulations in the field of power grid planning. The restrictive policies of grid operators, regulators and research institutes concerning their original data and models lead to an increased interest in open source approaches of grid models based on open data. By including all voltage levels between 60 kV (high voltage) and 380kV (extra high voltage), we dissolve the common distinction between transmission and distribution grid in energy system models and utilize a single, integrated model instead. An open data set for primarily Germany, which can be used for non-linear, linear and linear-optimal power flow methods, was developed. This data set consists of an electrically parameterised grid topology as well as allocated generation and demand characteristics for present and future scenarios at high spatial and temporal resolution. The usability of the grid model was demonstrated by the performance of exemplary power flow optimizations. Based on a marginal cost driven power plant dispatch, being subject to grid restrictions, congested power lines were identified. Continuous validation of the model is nescessary in order to reliably model storage and grid expansion in progressing research.

The effects of LED light sources on the parameters defining the quality of electricity

The article presents the regulations and standards relating to the quality of electricity, with special emphasis on higher current and voltage harmonics in high-voltage, medium-voltage and low-voltage power grids and the power factor (PF). The parameters defining the quality of electricity consumed by modern LED bulbs for lighting homes, industrial premises such as offices and production halls, as well as roads and yards were measured and analyzed. The current waveforms for LED lights were presented upon connection to the power grid.

Influence of disorder and noise in controlling the dynamics of power grids

Abstract We investigate complex dynamic networks which can model high-voltage power grids with renewable, fluctuating energy sources. The Kuramoto model with inertia is used to model the network of power plants and consumers. In particular, we analyse the synchronization transition of networks of N phase oscillators with inertia (rotators) whose natural frequencies are bimodally distributed, corresponding to the distribution of generator and consumer power. First, we start from globally coupled networks whose links are successively diluted, resulting in a random Erdos-Renyi network. We focus on the changes in the hysteric loop while varying mass of inertia and dilution. Second, we implement Gaussian white noise describing the randomly fluctuating input power, and investigate its role in shaping the dynamics.

Transmission Technologies and Operational Characteristic Analysis of Hybrid UHV AC/DC Power Grids in China

In order to solve the contradiction between demand and distribution range of primary energy resource, Ultra High Voltage (UHV) power grids should be developed rapidly to meet development of energy bases and accessing of large-scale renewable energy. This paper reviewed the latest research processes of AC/DC transmission technologies, summarized the characteristics of AC/DC power grids, concluded that China’s power grids certainly enter a new period of large -scale hybrid UHV AC/DC power grids and characteristics of “strong DC and weak AC” becomes increasingly pro minent; possible problems in operation of AC/DC power grids was discussed, and interaction or effect between AC/DC power grids was made an intensive study of; according to above problems in operation of power grids, preliminary scheme is summarized as fo llows: strengthening backbone structures, enhancing AC/DC transmission technologies, promoting protection measures of clean energ y accessing grids, and taking actions to solve stability problems of voltage and frequency etc. It’s valuable for making hybrid UHV AC/DC power grids adapt to operating mode of large power grids, thus guaranteeing security and stability of power system.

Vulnerability Analysis of Multiple Critical Fault Outages and Adaptive Under Voltage Load Shedding Scenarios in Marmara Region Electrical Power Grid

The utilization of electrical power system has been rising frequently from past to now and there is a need of dependable electrical transmission and distribution networks so as to ensure continuous and balanced energy. Besides, conventional energy governance systems have been forced to change as a result of rises in the usage of renewable energy resources and the efficiency of demand-side on the market. In this regard, electrical power systems should be planned and operated, appropriately and the balance of production and consumption demand should be provided within the nominal voltage limits. In this study, firstly, the current status of Marmara region interconnected power grid in Turkey is evaluated. Afterwards, the multiple cascading failure outages scenarios are modeled by “DIgSILENT Power Factory V14” software. The critical transmission line scenarios are implemented on the high voltage power grid model improved. These scenarios are based on the period of maximum and minimum production and consumption demand and the effects of demand response in this period. As a result of grid vulnerability analyses performed, several findings has been obtained about the impacts of different line scenarios on the high voltage transmission system, the optimization of power grid voltage profile and the role of production and consumption demand response on voltage regulation.

Synchrony-optimized networks of Kuramoto oscillators with inertia

We investigate synchronization in networks of Kuramoto oscillators with inertia. More specifically, we introduce a rewiring algorithm consisting basically in a {\em hill climb} scheme in which the edges of the network are swapped in order to enhance its synchronization capacity. We show that the the synchrony-optimized networks generated by our algorithm have some interesting topological and dynamical properties. In particular, they typically exhibit an anticipation of the synchronization onset and are more robust against certain types of perturbations. We consider synthetic random networks and also a network with a topology based in an approximated model of the (high voltage) power grid of Spain, since networks of Kuramoto oscillators with inertia have been used recently as simplified models for power grids, for which synchronization is obviously a crucial issue. Despite the extreme simplifications adopted in these models, our results, among others recently obtained in the literature, may provide interesting principles to guide the future growth and development of real-world grids, specially in the case of a change of the current paradigm of centralized towards distributed generation power grids.

Geomagnetically induced currents in Uruguay: Sensitivity to modelling parameters

According to the traditional wisdom, geomagnetically induced currents (GIC) should occur rarely at mid-to-low latitudes, but in the last decades a growing number of reports have addressed their effects on high-voltage (HV) power grids at mid-to-low latitudes. The growing trend to interconnect national power grids to meet regional integration objectives, may lead to an increase in the size of the present energy transmission networks to form a sort of super-grid at continental scale. Such a broad and heterogeneous super-grid can be exposed to the effects of large GIC if appropriate mitigation actions are not taken into consideration. In the present study, we present GIC estimates for the Uruguayan HV power grid during severe magnetic storm conditions. The GIC intensities are strongly dependent on the rate of variation of the geomagnetic field, conductivity of the ground, power grid resistances and configuration. Calculated GIC are analysed as functions of these parameters. The results show a reasonable agreement with measured data in Brazil and Argentina, thus confirming the reliability of the model. The expansion of the grid leads to a strong increase in GIC intensities in almost all substations. The power grid response to changes in ground conductivity and resistances shows similar results in a minor extent. This leads us to consider GIC as a non-negligible phenomenon in South America. Consequently, GIC must be taken into account in mid-to-low latitude power grids as well.

An Experimental Study of the Unbalance Compensation by Voltage Source Inverter Based STATCOM

This work presents an experimental study of the unbalance compensation caused by the high speed railway substations in the high-voltage power grid with a shunt voltage source inverter based STATCOM. This experimental study is realized on a reduced scale prototype. The Control of inverter is implemented in a DSP card. The practical results presented in this paper are shown the performance of unbalance compensation by VSI_STATCOM in static and dynamic regime.

Exploring the topological sources of robustness against invasion in biological and technological networks.

For a network, the accomplishment of its functions despite perturbations is called robustness. Although this property has been extensively studied, in most cases, the network is modified by removing nodes. In our approach, it is no longer perturbed by site percolation, but evolves after site invasion. The process transforming resident/healthy nodes into invader/mutant/diseased nodes is described by the Moran model. We explore the sources of robustness (or its counterpart, the propensity to spread favourable innovations) of the US high-voltage power grid network, the Internet2 academic network, and the C. elegans connectome. We compare them to three modular and non-modular benchmark networks, and samples of one thousand random networks with the same degree distribution. It is found that, contrary to what happens with networks of small order, fixation probability and robustness are poorly correlated with most of standard statistics, but they depend strongly on the degree distribution. While community detection techniques are able to detect the existence of a central core in Internet2, they are not effective in detecting hierarchical structures whose topological complexity arises from the repetition of a few rules. Box counting dimension and Rent’s rule are applied to show a subtle trade-off between topological and wiring complexity.

全国の電力基幹系統を考慮した最適電源構成モデルの開発と太陽光・風力発電大量導入に関する分析

This paper develops an optimal power generation mix model considering nationwide high-voltage power grid in Japan and aims to analyze the massive deployment of variable renewable (VR) such as PV and wind. The model is developed on the basis of linear programming and includes 200 million constraints and 100 million endogenous variables. The highlight of the model consists in the detailed geographical resolution derived from 135 nodes and 166 high-voltage lines and in the detailed temporal resolution derived from 10 minutes in a whole year. As energy storage technology, the model explicitly incorporates the possible deployment of sodium-sulfur battery and Li-ion battery as well as pumped-storage hydro power plants. Active power flow of the grid is considered through a direct current (DC) method. Simulated results reveal that the considerable deployment of PV and wind does not necessarily require the large-scale installation of rechargeable battery, because the intermittency of PV and wind is controlled by the inter-regional power flow exchange, the flexible operation of ramp generators and pumped-storage hydro and the utilization of VR output curtailments. In Hokkaido area where a large installable potential of wind power is expected, the time interval when a system non-synchronous penetration (SNSP) ratio exhibits more than 50 percent amounts to 1320 hours per annum, implying the requirement of advanced grid operation for the sake of power system security.

A novel evaluation method of societal benefits of ultra high voltage power grid optimizing power energy allocation

Although Ultra High Voltage (UHV) power grid requires heavy investment, it can also produce vast social economic benefits by optimizing power energy allocation. Owing to the existing controversy over the economy of the UHV power grid, it is necessary for policymakers to propose a scientific method used to comprehensively analyze huge costs and benefits caused by the UHV power grid. In this paper, Life Cycle Cost (LCC) is introduced to analyze cost dimensions of the UHV power grid and shadow price theory is used to evaluate huge potential social benefits brought by UHV power grid. Based on these shadow prices, social benefits of UHV power grid are put forward from aspects of saving installation benefit, saving coal-fired benefit, power loss reduction benefit, short-circuit current reduction benefit, sustainable development benefit, and social resource distribution optimization benefit. Some evaluation indexes for social benefits based on input-output analysis table of the LCC mode are calculated to be comparable with those of the traditional cost mode. A certain UHV power grid of China is applied to verify the effectiveness and feasibility of the proposed evaluation method.

A Critical Review of Robustness in Power Grids Using Complex Networks Concepts

This paper reviews the most relevant works that have investigated robustness in power grids using Complex Networks (CN) concepts. In this broad field there are two different approaches. The first one is based solely on topological concepts, and uses metrics such as mean path length, clustering coefficient, efficiency and betweenness centrality, among many others. The second, hybrid approach consists of introducing (into the CN framework) some concepts from Electrical Engineering (EE) in the effort of enhancing the topological approach, and uses novel, more efficient electrical metrics such as electrical betweenness, net-ability, and others. There is however a controversy about whether these approaches are able to provide insights into all aspects of real power grids. The CN community argues that the topological approach does not aim to focus on the detailed operation, but to discover the unexpected emergence of collective behavior, while part of the EE community asserts that this leads to an excessive simplification. Beyond this open debate it seems to be no predominant structure (scale-free, small-world) in high-voltage transmission power grids, the vast majority of power grids studied so far. Most of them have in common that they are vulnerable to targeted attacks on the most connected nodes and robust to random failure. In this respect there are only a few works that propose strategies to improve robustness such as intentional islanding, restricted link addition, microgrids and Energies 2015, 8 9212 smart grids, for which novel studies suggest that small-world networks seem to be the best topology.

Optimal Placing of Wind Turbines: Modelling the Uncertainty

When looking at the optimal place to locate a wind turbine, trade-offs have to be made between local placement and spreading: transmission loss favours local placements and the correlation between the stochastic productions of wind turbines favours spreading. In this paper steps are described to determine the locations of new wind mills that minimize energy loss on the High Voltage power grid. A vindication of the used power grid model is provided, the simulation procedure for stochastic wind power is described and the required mathematical optimization models are described as well as implemented. Results are shown and their relation to real life problems is discussed. The analysis leads to the observation that in reality the entire Dutch coast is popular to locate wind turbines but the only region where this leads to actual reduction of the losses is the North (Groningen and Friesland). Next to this, at the current share of wind energy in the total network load, a spreading strategy to reduce variance of total wind power production does not seem advisable. At higher penetration (30% or more) spreading will become important.

Research of LED Solar Insecticides Lamp

In this paper, we design a modified insecticides lamp, LED the device by using solar battery as a power supply, high voltage power grid as a hunting tool, through the MCU drive different wavelength of LED strobe. Compared with ordinary insecticides lamp insecticide effect, improved the LED insecticides lamp peculiar four-color stroboscopic technology can be more traps in pests. By sampling clock chip and humidity sensitive resistor, the device will automatically work in spring and summer clear night, met YinYuXue fog and other adverse weather will automatically shut down. The device can be applied to farmland, orchards and other places of a large area of farming, and human nature, energy saving, environmental protection, for the development of LED insecticides lamp provides a new train of thought.

Dispatching Technology Application in India Large Scale Blackout

Scheduling technology plays an important role in avoiding the occurrence of large scope blackout. India "7.30", "7.31" blackout indicates dispatching mechanism is not reasonable. It is more important that it violates scheduling and supervision direction. The network defense mechanism is not perfect. It is lack of dynamic analysis and safety evaluation capacity. Dispatching technology can be a basis for China's high-voltage power grid construction, dispatching management and establishing a perfect accident recovery plan.