Scale Power Grid Research Articles

An aggregating based model order reduction method for power grids

Simulation of power girds has become increasingly computationally expensive. In this paper, we propose a Model Order Reduction (MOR) method for power grids by extending the existing Aggregating based MOR (AMOR) method. In the proposed method, besides resistors and capacitors, current sources are also aggregated to improve MOR efficiency. Moreover, pre-partition and parallelization techniques are employed to decrease reduction time. Numerical results demonstrate that compared to original circuits, the scale of power grids is greatly reduced without much loss of accuracy. The reduced-order models are especially useful in the multiple simulations of different working modes or different environment corners.

Guest Editorial: Special Section on Large-Scale Grid Integration and Regulatory Issues of Variable Power Generation

The twenty-nine papers in this special section focus on the topic of large scale power grid integration and the regulatory issues involved. These include information on stochastic models of solar and wind power generation dispatch including case studies; transmission flexibility in accommodating more wind power; robust and optimal inertial control for frequency support; challenges associated with assessment, testing, and development inverter technologies for LVRT; inter-area oscillation of interconnected wind power plants; artificial intelligent applications in complex scenarios associated with futuristic plug-in hybrid vehicles; distributed energy storage for approaches for frequency support; and high penetration of variable power generation systems.

Credibility Theory-Based Available Transfer Capability Assessment

Since the development of large scale power grid interconnections and power markets, research on available transfer capability (ATC) has attracted great attention. The challenges for accurate assessment of ATC originate from the numerous uncertainties in electricity generation, transmission, distribution and utilization sectors. Power system uncertainties can be mainly described as two types: randomness and fuzziness. However, the traditional transmission reliability margin (TRM) approach only considers randomness. Based on credibility theory, this paper firstly built models of generators, transmission lines and loads according to their features of both randomness and fuzziness. Then a random fuzzy simulation is applied, along with a novel method proposed for ATC assessment, in which both randomness and fuzziness are considered. The bootstrap method and multi-core parallel computing technique are introduced to enhance the processing speed. By implementing simulation for the IEEE-30-bus system and a real-life system located in Northwest China, the viability of the models and the proposed method is verified.

The evaluation of adaptability among power source, power grid and load based on game theory

As the increase of the capacity of power source, the scale of power grid and load, and the internal and external factors of security and economy on large-scale grid, understanding of the interactions and effects of power source, power grid and load, has very important significance for establishing the evaluation theory system of the adaptability of large-scale power grid. In the aspect of construction and investment, power source, power grid and load belong to different; in the aspect of opration and income, the three must comply with uniform guidelines for the regulation of the power system, and their incomes for each connect by electricity and price. For the problems of investments and incomes of power source, power grid and load, the paper establishs models of substation capacity, generator capacity, load capacity and the relationship of their investment and income based on game theory; the paper also proposes investment and income algorithm of power source, power grid, and load based on the ISO scheduling model. Numerical result demonstrates the effectiveness of game models and the algorithm, at the same time, it also analyses the interaction and influence and finds Nash equilibrium point among power source, power grid and load. These explain behaviors of power source, power grid and load respectively. The evaluation of adaptability among power source, power grid and load is an important part of the evaluation of large scale power grid, the research work and achievements of this paper can analyse the interaction and influence among power source, power grid and load, and calculate the income of each investor under a variety of strategies. And these provide the basis for each investors decision.

Global Energy Cultures of Speed and Lightness: Materials, Mobilities and Transnational Power

Following aluminum as part of a material culture of speed and lightness, this article examines how assemblages of energy and metals connect built environments, ways of life, and ideologies of acceleration. Aluminum can be theorized as a circulatory matrix that forms an energy culture. Through a discussion of speed and social justice, the history of aluminium-based socioecologies reveals how the materiality of energy forms assemblages of objects, infrastructures, and practices. The article then traces the aluminum industry’s involvement in the production and distribution of energy itself both at the national scale of power grids and in the emergence of transnational transfers of energy, such as hydropowered smelters in Iceland. Finally, this analysis of deeply embedded energy cultures calls for a transnational approach to the accelerated socioecologies of aluminum production and consumption; and for energy transition theories to pay closer attention to the figured worlds and figuring work of the military-industrial complex.

Friendly Fast Poisson Solver Preconditioning Technique for Power Grid Analysis

Robust and efficient algorithms for power grid analysis are crucial for both VLSI design and optimization. Due to the increasing size of power grids, IR drop analysis has become more computationally challenging both in runtime and memory consumption. This paper presents a Fast Poisson Solver (FPS) preconditioned method for unstructured power grids with unideal boundary conditions. Unstructured power grids are transformed to structured grids, which can be modeled as Poisson blocks by analytic formulation. The analytic formulation of transformed structured grids is adopted as an analytic preconditioner for original unstructured grids, in which the analytic preconditioner can be considered as a sparse approximate inverse technique. By combining this analytic preconditioner with robust conjugate gradient method, we demonstrate that this approach is totally robust for extremely large scale power grid simulations. Theoretical proof and experimental results show that iterations of our proposed method will hardly increase with the increasing of grid size as long as the pads density and the distribution range of metal conductance value have been decided. We demonstrate that the run efficiency of our approach is much higher than classical incomplete Cholesky factorization preconditioned conjugate gradient solver and random walk-based hybrid solver.

A Novel Method of Static Security Analysis Based on Multithread Technology

With the UHV (Ultra High Voltage) power grid construction and the interconnection of regional power grids, the scale of power grids in China is increasing rapidly. At the same time, significant uncertainty and variability is being introduced into power grid operation with the integration of large-scale renewable energy in power systems. All of these pose an enormous challenge to the operation control of power systems in China. For a long time, online static security analysis, as an important part of EMS (Energy Management System), has been an effective tool for power grid operation. However, it is increasingly difficult for traditional static security analysis in serial computing mode to be online applied in bulk power grids in China. A new practical parallel approach for online static security analysis is put forward in this paper. A multithread parallelism is introduced into contingency screening, detailed contingency evaluation and decision support for reducing the execution time. By employing the multithread technology, the hardware resources of multi-processor/multi-core computer can be fully used and the program can be speeded up effectively. The performance of the parallel static security analysis is demonstrated by tests on two large-scale power systems. The test results show that the proposed method can be online applied in real bulk power grids.

Scalable Multilevel Vectorless Power Grid Voltage Integrity Verification

With the current aggressive integrated circuit technology scaling, vectorless power grid voltage integrity verification becomes key to designing reliable power delivery networks. To address the challenges of existing vectorless power grid verification methods that suffer from excessively long optimization time and poor scalability to large power grid designs, in this paper, we present a scalable multilevel vectorless power grid verification method which can efficiently tackle very large scale power grid verifications. By taking advantage of a series of coarsest to coarser grid verifications, the finest power grid verification can be accomplished in a more efficient way. To gain good efficiency, global and local “critical regions” for power grid verification are introduced, while power grid structure and electrical properties are exploited to facilitate identifying the worst case voltage drops across the entire chip. The proposed multilevel power grid verification algorithm allows more flexible tradeoffs between verification cost and solution quality, while providing the desired conservative upper/lower bounds for worst case voltage drops. Extensive experimental results show that our approach can efficiently handle very large power grid designs without sacrificing the final power grid verification accuracy. For example, finding the worst voltage drop for a flip-chip power grid design with one million nodes takes less than two hours.

Non-monotonic increase of robustness with capacity tolerance in power grids

The robustness of different scale power grids is analyzed based on complex network theory in terms of electrical betweenness and weighted efficiency. The robustness of a power grid does not always increase monotonically with the capacity. This property is different from the results obtained in previous studies, which have indicated that the robustness increases monotonically with capacity. To understand the non-monotonic phenomenon, the cascading failure is divided into several sub-stages, and we analyze the number of overloaded nodes and the average remaining load in each sub-stage. The results indicate that the increasing capacity is barely able to reduce the number of overloaded nodes at the beginning of malfunction, which may lead to more nodes being removed subsequently, including certain nodes with many connections or large load. More loads remain in the power grid such that certain nodes cannot take the load. This eventually causes overloading of more nodes and a decline in the robustness of the power grid. The conclusion may be useful for power grid planners seeking to design grids with cost-effective capacity.

Real-Time Power Dispatch Method under Wind Power Curtailed Conditions for Large Scale Power Grid

It is a great challenge to integrate more wind power generation to the power grid. A practical active power real-time dispatching method is proposed in this paper, which is used to reduce the curtailing amount of wind power in real time. Two optional solutions to estimate curtailed wind power generation are proposed in this paper. Based on the estimated results of curtailed wind power, a wind-thermal power coordinated dispatch algorithm is developed to improve wind power generation while considering security constraints. The on-site tests in Jilin provincial power grid prove the proposed method feasible.

The Maintenance Strategy of Electric Equipments Based on the Least Average Annual Cost

With the enlarging scale of power grids, the quantity of electric equipments is increasing and their quality is improving. Therefore, the optimizing management of equipments, which is an important act to reduce investment and increase economic benefit of power grids, has been paid more and more attention. This paper makes a comprehensive analysis of factors that influence the life cycle cost of electric equipments. Considering the risk of power grid caused by the fault of equipments and other relevant factors, the economic life model is established and the judgment about the optimal maintenance strategy is proposed. The proposed maintenance strategy is conducive to save the operating cost of power grids and optimize the investment. Also, it can promote the refined management and provide reference decisions for electric utilities to plan and adjust equipments operating better.

04/00766 Stability of interconnecting system between commerical scale HeCs MHD combined generation plant and power grid: Inui, Y. et al. Energy Conversion and Management, 2003, 44, (18), 2941–2952

04/00766 Stability of interconnecting system between commerical scale HeCs MHD combined generation plant and power grid: Inui, Y. et al. Energy Conversion and Management, 2003, 44, (18), 2941–2952