直流を介した商用電力とガスエンジンの負荷分担(FP5 レシプロエンジンの環境対応技術)

A new multi-port interline DC power flow controller for multi-terminal HVDC grids

Considering the increased interactions between power grids and natural gas grids, this study presents a chance‐constrained maintenance scheduling model for integrated gas‐electric grids with wind energy integration. Given the uncertainties of wind power, the loss of wind power probability is modelled as a chance constraint, ensuring the high utilisation of wind power. To overcome the adversities caused by the non‐linear and non‐convex models of natural gas systems, a piecewise linear approximation method is employed to transform the non‐linear models into a group of mixed integer linear models. A big‐M formulation method is used to construct inequality constraints for lines/pipelines to be under maintenance. In addition, unit commitment is also coordinated to achieve the best maintenance strategies. The proposed chance‐constrained stochastic programming model is converted into an equivalent deterministic programming model via a strong extended formulation for the sample average approximation by leveraging the star‐inequalities. Several tests on a four‐node natural gas system with a six‐bus power system and a 20‐node natural gas system with a modified IEEE 118‐bus power system demonstrate the effectiveness of the proposed model.

A second-order cone model of transmission planning with alternating and direct current lines

Gas engine power plant (PLTMG) is a power plant that uses a gas engine as the prime mover. Prime mover is equipment that has the function of generating the mechanical energy needed to rotate the generator rotor. The Arun PLTMG uses a type 20V34SG wartsila gas engine as the main engine. The 20V34SG type Wartsila engine has replaced several components but has not made the engine performance efficient again. One of the important components in supporting the electricity production process is the turbocharger. A turbocharger is a centrifugal compressor that gets power from a turbine whose power source comes from vehicle exhaust fumes. Usually used in internal combustion engines to increase power output and engine efficiency by increasing the air pressure entering the engine. The purpose of this paper is to calculate the efficiency of the equipment and analyze the results using the RCFA (Root Cause Failure Analysis) method to find out the basic problems that occur in the turbocharger. Based on the results of the calculation analysis showed that the lowest efficiency value for turbocharger A occurred in engine 14, which was 57%, and for turbocharger B efficiency, it was found in engine 13, which only reached 54%. By observing in the field there is oil seepage from the turbocharger which falls into the charge air cooler (CAC) area, wear and tear on the impeller mechanical sealing.

This paper on using gaseous biofuels from waste is from the proceedings of 14th international Conference on Urban Transport and the Environment in the 21st Century, which was held in Malta in 2008. The authors note that biomethane, which can be used in existing natural gas engines, supports vehicles with low environmental and toxicological impact, would be particularly suitable for urban area operation (fleets of cars, buses and trucks), and can satisfy the more stringent regulation limits that are being put in place worldwide. They maintain that on-site biomethane production, through anaerobic digestion or future gasification-methanization plants, will allow the problem of gas distribution to be overcome when a natural gas grid is not widely diffused. The capture and use of biomethane derived from the organic waste matter decomposition process allows a significant reduction of greenhouse gas emissions into the atmosphere. The authors also consider the problems of land use competition, the efficiency of biomass utilization, second generation technologies that leave edible fractions of plants for food use, improvements in hydrogen production by dark fermentation, the direct production of methane/hydrogen mixtures, and the development of gas engines with higher efficiency and further reduced emissions.

Introduction The power grid controls their electric power supply by maintaining voltage, frequency, and transient stability, by predicting the electricity demand at any given time. However, recent large-scale implementation of photovoltaics (PV) makes it difficult to meet them because the gap between power supply and demand will be widening. The suppression of any power sources including solar power generation with sacrificing some electricity is sometimes adopted to avoid large-scale blackouts, and the situation is expected to be a common event at the 2030s. An effective solution to such situations is called as “leveling power”, which is the ability to maintain a balance between power supply and demand. Leveling power needs to be introduced not only into the centralized power grid but also into distributed energy systems. The major candidate of leveling power at distributed energy systems is electrochemical energy storage technology such as secondary batteries or hydrogen Power-to-Gas-to-Power (P2G2P). A smart energy system called Ene-swallow has been developed by our research group, and applied to Ookayama campus at the Tokyo Institute of Technology. This system manages 1400 kW-PV, 100 kW-FC, 70 kW gas engine and 100 kWh storage battery with a 10,000 kW-class electricity demand. Ene-Swallow also accumulates the power demand data in 1-sec intervals and PV power generation data in 1-min intervals. We previously carried out a techno-economic analysis of a hydrogen energy storage system to level the annual gap of power supply and demand [1]. Here we evaluated the potential of electrochemical energy storage as a leveling power with using the annual data from those data. Method We analyzed the current situation requirements for leveling power (analysis-1) and the applicability of a distributed energy storage system (analysis-2). For analysis-1, we analyzed 1-hour data of power generation and consumption published from power companies across Japan (Fig. 1a), and 1-min data of PV power generation (Fig. 1b) and 1-sec data of power demand (Fig. 1c) at Ookayama campus. For analysis-2, we set a tentative distributed grid with a 10,000 kW-class electricity demand, a given amount of primary power generation by PV and the power supply from the grid. In this work, we set no leveling power by the grid, which supplied constant power. Then, we determined the entire gap between power supply and demand during a single year based on the actual 1-minute data of PV power generation and power demand from April, 2017 to March, 2018. Then we estimated the required amount of energy storage, and thus determined the required number of P2G2P devices with alkaline electrolysis cell (AEC), solid oxide fuel cells (SOFC), H2 tanks and compressors, and lithium-ion batteries (LIB). In the system, the balance of power generation and consumption in a day is controlled as shown in Fig. 2. During the daytime, the surplus power from PV is leveled by an AEC. If AEC capacity is not sufficient, it is leveled by LIB. At night, the required power for demand is generated by an SOFC and/or an LIB. By optimizing the capacity of each component device in the distributed system, we evaluated the total system cost. We specified the expected technical parameters in the future (for the year 2030), such as unit price, efficiency and lifetime as shown in Table 1. Results From analysis-1, the 1-hour data showed that the supply fluctuation of PV power generation during the day strongly impacts the power grid when the energy mix ratio of PV to total annual demand reached about 10% when keeping nuclear power generation constant. The 1-minute data showed large fluctuations in PV generation within in a short time period (< 1 hr) during weather such as a cloudy day (Fig. 1b). Power fluctuations with different time scales have to be leveled by using electrochemical energy storage technologies. Analysis-2 showed that the total system cost could be reduced by using a combined system of P2G2P and LIB by utilizing their different characteristics. The combined system of P2G2P can reduce their total energy cost with dividing the role by power generation and the storage when the cost targets shown in Table 1 can be achieved. [Acknowledgements] A part of this study is supported by the New Energy and Industrial Technology Development Organization (NEDO) and MIRAI program of Japan Science and Technology Agency (JST). Reference [1] T.Okubo et al., 234th ECS Meeting AiMES 2018, (September 30-October 4, 2018) Figure 1

This paper presents a method of analyzing and predicting the electromagnetic environmental limit for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm \mathbf{2 0 0 k V}$</tex> overhead direct current (DC) lines. By employing analytical and empirical formulas, key parameters are analyzed such as the synthetic electric field intensity, audible noise, and radio interference under various conductor arrangements for the Yangzhou-Zhenjiang <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm \mathbf{2 0 0 k V}$</tex> DC project. The results demonstrate that for all conductor configurations considered, the synthetic electric field intensities remained well below the preset limit standards, while the levels of audible noise and radio interference were extremely low. This research underscores that under rational design, effective management, and strict control, the electromagnetic environmental impact of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 200 \text{kV}$</tex> overhead DC lines can be confined safely, offering robust support for the construction of an intelligent, efficient, and eco-friendly modern power system.

Multiobjective optimal operations for an interprovincial hydropower system considering peak-shaving demands

As the number of direct current (DC) customers is currently expanding, and distribution lines are changing from alternative current (AC) to DC accordingly, DC distribution lines with a radial structure are also becoming longer. This paper includes an analysis of the characteristics of fault currents in LVDC systems, and proposes a protective coordination method, utilizing AC/DC converters and protection equipment when a fault occurs in direct current lines with radial structure, that has been effectively demonstrated in field verification tests.

China′s energy infrastructure is predominantly fossil fuel based such as coal and petroleum, resulting in the deterioration of surrounding environments. The application of renewable resources, natural gas suppliers and distributed energy systems are a critical component in alleviating the present detrimental situation; by analyzing successful distributed power and micro grid systems internationally and applying it to domestic networks, these systems can be customized and calibrated to maximize efficiency. Furthermore, the demographics of distributed energy users is expanding from exclusive industrial consumers to commercial and residential customers, increasing demand for modular units, attracting the attention of the Chinese central government′s environmental policymakers. Within China, the implementation of distributed energy networks has been limited to industrial parks, economic and technological development zones. In this article, the characteristics of distributed energy networks is defined utilizing case studies involving the Sino German Eco-Park and Langfang City, introducing the mainstream energy networks including infrastructures, system hierarchy, its implementation methods and overall effects. In the Sino German Eco-Park, a distributed energy network is combined with a centralized system composed of one regional and six energy substations, providing electricity for blocks one through eight whose energy scheduling mode being divided into two inter-network and intra-network scheduling. Using the energy operations center, electrical transmission across the blocks is achieved via energy allocation between micro grids combined with the installation of natural gas, renewables and smart power grids; this enables the Sino German Eco-Park technical index to accomplish higher power distribution levels of efficiency. In Langfang City, the first city-level reconstruction and distributed energy project in China, the micro grid at New Chaoyang block is described in detail. Finally, the future of distributed energy network system is the energy internet as summarized an ecological, diversified and multilateral commodity whose logistics are intelligent and standardized.

Test results of the main industrial prototype of energy storage system (ESS-10-1200-400) of nominal power 1200 kVA, energy capacity 400 kWh and voltage 10 kV based on lithium-ion batteries when operating in combination with gas engine generators (GEG) as a part of experimental power system with active abrupt variable load are given. Its structure, components and parameters, as well as the components and parameters of ESS are described. Tests have shown high operation capacity of the prototype tested, high efficiency of the implemented algorithms and confirmed the expediency of the use of ESS for smoothing power surges/sheddings in the GEG, thus preventing their emergency shutdown resulted from the power surge.

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;The transient operation of gas engines is of paramount importance to sustainable power generation as it increases the share of renewable energy. Fast-reacting and highly flexible power plants are an integral component of scenarios for the smart power generation of the future. Modern gaseous fueled large bore engines already adapt to fluctuating load demands quickly and also provide high efficiency throughout all load conditions. However, future energy systems that integrate predominantly fluctuating renewables will require even further improved transient capabilities of these engines. The goal is to be competitive with diesel engines in applications with the highest transient requirements and to meet the high transient requirements while simultaneously generating significantly less emissions than other fossil generation facilities to support the future sustainable power supply. This paper presents a hardware-in-the-loop (HiL) method that is capable of transferring the transient behavior of a multicylinder engine to a single-cylinder test bed so that transient multicylinder engine combustion and control strategies can be developed directly on the single-cylinder engine test bed. First, the required HiL components and their interactions are described in detail and an example is provided of a method for boost pressure control at the test bed. The required models and controls for operation in island mode and grid parallel mode are explained as well as their similarities and differences and the resulting challenges for real-time modeling. The basic functionality of the method was validated at the single-cylinder engine in HiL mode. It is shown that the simulation models and their real-time capability can correctly simulate the behavior of the system.&lt;/div&gt;&lt;/div&gt;

The power to gas (P2G) technology can realize the large-scale storage of electric energy in the form of natural gas, so that the power system and the natural gas system have the ability to flow energy, and the degree of coupling between the power system and the natural gas system is deepened. As the coupling between the power system and the natural gas system continues to increase, an integrated energy system (IES) with the power grid as the core has emerged. However, under uncertain conditions, the current planning methods still cannot guarantee the optimal interests of each manufacturer, so a collaborative planning method for gas-electric systems based on non-cooperative game theory is proposed. With each energy unit and electricity and gas network companies as independent interest groups, and with the maximum annual net income as the optimization goal, establishing a comprehensive non-combination of wind turbines, gas turbines, electric-to-gas turbines, transmission lines and natural gas pipelines in the gas-electric integrated system linear programming model. Aiming at the uncertainty of wind power and load, an improved two-stage robust optimization method is proposed. Finally, the modified IEEE 39-node power system and 20-node natural gas system gas-electric network verify the application value of the model and algorithm.

The "New Energy Plant" had been built at the Aichi EXPO. 2005 site as part of the "Demonstrative Project of Regional Power Grid with Various New Energies". The plant includes three types of fuel cells, a photovoltaic power generation system and a Sodium Sulfur (NaS) battery. One of the purposes of the demonstrative project is to achieve isolated operation of a micro grid without rotating generators. These new energy generators and battery are connected to the micro grid via inverters. In isolated operation, the system voltage and frequency are determined by four fuel cell inverters connected in parallel. This paper presents the control strategies, especially load share between inverters, for isolated operation of a micro grid configured with some new energy generators. Simulation results and verification test results are also shown in this paper.

Bioenergy is now an essential part of sustainable energy systems. In order to unlock the full potential of biomass resources, this research aims to develop a framework for biomass-to-power systems, benefiting from advanced technologies in heat integration and heat upgrading, particularly high-temperature heat pumps (HTHPs). The framework provides an opportunity to explore the performance of biomass-to-power systems utilising a wide range of biomass types as well as various operational conditions. A reduced-order model (ROM) is developed using the proposed model, which provides a reliable estimate of the power capacity and system efficiency for power generation. The investigation also identifies the contribution of the HTHP to energy efficiency and discusses its role in different scenarios. The present study reveals that biomass-to-power systems using gas engines achieve efficiencies ranging from 16% to 30%, and the sensitivity analysis shows that efficiency is highly influenced by the feed type and gasification temperature and the load of HTHP. The integration of the HTHP minimises the use of syngas for preheating the gasifier, thereby allowing more power to be delivered by the system. Despite the limited heat-delivery temperature of the HTHP and its consumption of about 5% of the gas-engine power output, it improves the overall power generation efficiency of the system by about 2%. • HTHP integration boosts net efficiency of bioenergy power generation by ~2%. • Up to ~5% of engine power to HTHP is thermodynamically feasible and beneficial. • Biomass-to-power efficiencies of 16–29% demonstrated across six typical biomass feedstocks. • Reduced-order model accurately predicts efficiency across wide feedstocks and operating ranges.