In recent years, the introduction of electric vehicles (EVs) has been progressing worldwide in order to achieve carbon neutrality by 2050. EVs are a distributed energy resource, such as photovoltaics (PVs) and household battery energy storage systems, attracting attention as a means of ensuring power quality, enhancing resilience, and achieving energy independence. Alternatively, in the power distribution system, power flow is becoming more complicated due to the penetration of PVs and EVs. Thus, it requires reviewing the configuration of power network facilities and changing their operation methods. Therefore, in this study, the power flow is smoothed by optimizing the charge/discharge schedule of the transit electric buses.While many studies currently focus on private EVs, the study focuses on transit electric buses with a high certainty in operation. It constructs a bus model faithful to the actual operation. The reverse power flow (RPF) and normal power flow (NPF) were smoothed by charging/discharging using the proposed method, and the peak cut rate was 67.1% for RPF and 18.1% for NPF. Additionally, the proposed method utilizes the available battery capacity more effectively than the comparison methods and contributes to NPF and RPF smoothing.

Loss minimum reconfiguration technology, which aims to minimize distribution power losses by operating sectionalizing switches in distribution systems, has a certain significance to modern power systems. However, applying this technology requires detailed modeling that reflects the physical features of the actual system, making it challenging to deploy the technology overnight. Thus, for effective deployment of the technology, it is essential to prioritize systems likely to benefit from the loss minimization technology based on the features of systems where the technology has already been applied and statistical trends in loss reduction results. However, the complex behavior of power flow caused by the distributed energy resources makes it more difficult to estimate the expected reduction in distribution losses. This study proposes a framework for selecting systems that should be prioritized based on statistical trends in loss reductions of a small number of technology-applied systems and evaluates the usefulness of the framework.

With the widespread integration of renewable energy resources, the occurrence of electric power output control is increasing in Japan, especially for photovoltaic (PV) power plants. The practical application of smart inverters that can perform electric power output control more flexibly over the network has gradually progressed. Still, there is a remaining issue regarding how to determine the implementation method and scope of the cybersecurity evaluation for distributed energy resources (DER), including smart inverters. Therefore, we generated a set of security evaluation items, tools, and supporting environments. We validated these with academics, manufacturers, and electric power companies in realistic settings, after which we were finally able to arrange evaluation methods. In this paper, we describe how we performed the industrial demonstration experiments and what we learned through the trials.

The power hardware-in-the-loop (PHIL) simulation has become a popular testing approach due to the flexibility it provides and the high-fidelity of its results. It is expected to be utilized as an advanced laboratory testing scheme to validate the grid support functions of distributed energy resources (DERs) because it can evaluate the interaction between the power system and DERs. Despite the strong demand to utilize the PHIL simulation for such testing, the literature that elaborates on the practical design of PHIL simulation based testing (hereafter called "PHIL testing") environment including laboratory device setup, power system models, and test procedures is very limited. The simulation models, interfacing with the tested equipment, and data collection approaches are all different parameters that need to be fine-tuned for the successful execution of PHIL testing. It is vital for such successful test experiences to be shared to build universal knowledge around PHIL testing. In order to fill this knowledge gap, this paper presents such practical and essential techniques for the PHIL testing to share the knowledge for promotion of the PHIL simulation utilization. The development of PHIL testing environment to validate the smart inverter functions, i.e., volt-var function and frequency-watt function, is focused on in terms of laboratory setup, power system modeling, interfacing, and test procedure. The volt-var and frequency-watt functions of a 500 kW smart inverter of photovoltaic are validated on the basis of the presented techniques. Detailed test configurations, test procedures, and simulation models are presented along with obtained test results.

This article surveys background and consideration in California State of the United States as one example of oversea's Smart Inverter approaches. In addition, the outline of demonstration (Development of smart inverter & DERMS) that TEPCO is participating in is introduced.