In recent years, there is an increasing demand for ZEH equivalent houses as an initiative for housing to cope with global warming and decarbonization in Japan, which become increasingly intense and embodied. Under such circumstances, this article considers Next Generation ZEH based on the use cases related to HEMS and data driven control using locally predictable and correctable Meteo data on Outer Skin, Openings, HVAC, Lighting, Hot Water Supply etc as a smart system which responds to the reduction of primary energy consumption by energy generation, saving and storage and the measures against complex natural disasters in terms of architectural and MEP approaches.
Due to growing concerns over climate change, as well as to the recent cost declines, variable renewable energies (VREs), such as wind and solar PV, have seen rapid deployment over the past few years. High penetration of VREs, however, requires additional costs caused by the intermittency, e. g. those for grid expansion, for deploying power storage systems, and for power curtailment. Thus the total system cost becomes larger than the cost measured simply by the traditional metric known as the levelized cost of electricity (LCOE), which has long been used for estimating the economics of the power sector. This paper proposes a methodology to assess these additional “system integration costs”, as well as to decompose them into several subcategories, using two complementary mathematical optimization models. It also applies the methodology to Japan's power system in 2030, in the aim of obtaining insights into the key factors that determine the changes in the power sector under high penetration of VREs. The results show that in a case with a solar PV capacity of 64GW and a wind capacity of 10GW, the system integration cost divided by the total power supply amounts to 0.41JPY/kWh. Reduction in the load factors of conventional power generation facilities accounts for the largest part of the system integration cost at 0.30JPY/kWh, highlighting the need for appropriate policy measures that ensure the adequacy of power systems.
This paper presents that the phase characteristics in the current waveform at using home electric appliances were found. A current waveform consisting of a right triangle pulse waveform over a particular voltage phase range was focused. Then, the phase characteristics of the harmonic current of this waveform were investigated. θS(p) = θp + 360・Np for the phase valueθp at each harmonic order p (p = 1, 3, 5, ..., 39) of the measured waveform were calculated. Np is the smallest integer greater than or equal to 0 that satisfies θS(1) < θS(3) < θS(5) < ... < θS(39). The relationship between θS(p) and the harmonic order p is almost linear. An approximate equation of the harmonic order could be obtained using values of θS(p)/p. The phase values for simulation were derived from the values obtained by this approximate equation. Consequently, analyzed current waveforms using these phase values reproduced the measuredcurrent waveforms.
Due to the expansion of the photovoltaic (PV) power generation expected in the future, voltage fluctuations that occur locally in the distribution system are regarded as a problem. As one method of the suppressing this voltage fluctuations, Volt-var function of the smart inverter, that enables more flexible voltage control by reactive power output, is expected. The smart inverter not only just outputs photovoltaic power, but also has grid support functions that helps improve the stability of the grid. Considering new application of Volt-var control by smart inverter, it is necessary to construct a control system that sets appropriate control parameters according to the situation of the distribution line to which it is applied. The motivation of this research is to optimize the voltage control effect when the smart inverter is applied to distribution system with large amount of PV. Volt-var control behavior is defined by the curve point setting. It seems that the Volt-var curve setting could affect the behavior of tap changer control, and the reactive power output of the Volt-var control changes depending on the tap position. In this study, we propose a method for determining the Volt-var control parameters in consideration of the voltage control sharing with the tap changer control. And the effect of the proposed Volt-var control method is quantitatively evaluated by numerical simulation.
Renewable energy generation systems are promising energy sources, however, they have a problem that they do not have, in general, inertia and synchronous power. A system with low inertial and synchronization forces has low stabilizing capability, and such systems are vulnerable to network fault and can cause large frequency fluctuations. This paper focuses on a large storage battery and a permanent magnet synchronous generator (PMSG) based variable-speed wind power generator, and a new cooperative virtual inertia and reactive power control system between them which is based on Fuzzy Logic controller and asymmetric hysteresis deadband is proposed and designed. Its effectiveness on the system stability enhancement during a grid fault is confirmed by simulation analyses on PSCAD/EMTDC.
The Editorial Committee is working in planning and editing of the publication of Power and Energy Society. In this article, activities of the committee of the last term are reported, and recent trend and future problems are also discussed. The process of planning and editing of the publication, and the challenges to reduce the necessary months for reviewing papers and to increase the number of submitted papers are shown.