Ke, Chiao-Yuan Hsu, Yen-Feng Yang, Jin-Shyr

Abstract

The microgrid is defined as a small-scale power grid which consists of one or more distributed generations, and which can be connected with a utility grid or be operated independently. A microgrid could be as small as a home, or as large as an industry or a commercial area. Distributed generation may consists of the small wind-turbine generations, solar PV power, energy storage and fuel cell. There are some advantages in the use of a microgrid, such as full utilization of renewables, cost reduction in transmission or distribution system, and enhancement of power quality and reliability. However, microgrids have not been widely used due to different reasons: necessity of making unique design to meet special engineering demand of customers and difficulty of reaching cost effectiveness in a specified case. At present, the microgrids are generally established by private organizations, not by a power utility. In spite of that, based on some considerations, the power utility may be able to build certain microgrid systems which are beneficial to customers and the power utility itself. Thus, there are also strategies and plan which have been developed for Taipower to build microgrids.

Lee, Yih-Der Jiang, Jheng-Lun Liu, Li-Yuan Chang, Yung-Ruei Fan, Jen-Li Hsu, Yen-Feng

Abstract

A microgrid system can be used to reduce the power generation costs, upgrade the power quality, and increase the share of renewable energies in an offshore island. However, considering the economic effectiveness, unlimited increase in the installed capacity of renewable energy in an offshore island may not be always beneficial. In order to entirely replace the traditional diesel generators with renewable energy, a large-scale energy storage system has to be installed to cope with system operation needs. Taking into account the cost of the energy storage system deployment, this solution is less economically competitive. This article proposes a method of evaluating the proper proportion of microgrids and the economic benefits in an offshore island. The Wangan Island in Penghu Area was taken as the example case study, with evaluation being focused on the proportion of renewable energy, capacity of the storage system installation, economic effectiveness, and the benefits in environmental protection. The actual costs of the fuels of Wangan power plant from 2013 to 2015 were used to make economic comparison and to verify the cost effectiveness of deploying a microgrids in the offshore island. An optimal allocation of the microgrid system was proposed to satisfy the system safety requirement, economic and environmental protection benefits.

Hsu, Cheng-Ting Chen, Chao-Shun Lin, Chia-Hung Hsu, Yen-Fong Yu, Hung-Yi Wang, Yaw-Ting

Abstract

This paper investigates the operation of Chi-Mei microgrid characterized by high penetration of photovoltaic (PV) generation system (PVGS). The power generation and load of existing system are investigated first. The power output and power variation of PVGS in different weather conditions are determined through the field measurement and tests. In addition, the dynamic control model for a battery energy storage system (BESS) with rated capacity of 250kW/300kWh is also built. By the way, this paper proposes an energy management system (EMS) for small island microgrids. To ensure the stable operation of Chi-Mei microgrid, this paper performs transient stability analysis of various scenarios, including instantaneous tripping of the largest PVGS, disturbance of different PV power variation and ramping rates (RR), diesel generator tripping and black start. In the meanwhile, the BESS is installed with frequency regulating mode to help the operation of Chi-Mei microgrid system.

Chen, Yen-Haw Lu, Su-Ying Hung, Yu-Lun

Abstract

In recent years, microgrid related technologies have turned to be mature and the cost of power supply using renewable energy is increasingly becoming competitive in the market under certain circumstances. Therefore, whether users are willing to install a microgrid system will depend on the generation costs and equipment warranty by manufacturers for the energy storage system to be installed. In this study, we collect several articles, both foreign and domestic, on the microgrid market development and equipment price trend of major microgrid equipment to analyze how the cost of power supply will influence the use of the microgrid. Then, the paper goes to discuss how this cost trend will impact its future market development. Finally, we suggest several microgrid development strategy for our industry based on the study analysis.

Chen, Chao-Shun Hsu, Cheng-Ting Lin, Chia-Hung Ku, Te-Tien Wu, Pin-Yi Yu, Hung-Yi

Abstract

This paper investigates the possible maximization of PV installation capacity by introducing smart inverters in the distribution feeders with high penetration of renewable energy. Various types of smart inverters control functions are analyzed to illustrate the ancillary services of reactive power control which PV systems can provide. The autonomous control mechanism which is considered suitable for adoption in Taiwan and the corresponding control procedure of PV smart inverters are proposed. Based on the computer simulation of distribution feeders, the implementation of smart inverters proves to be able to increase the PV penetration level, improve service voltage quality, and reduce PV generation curtailment. Finally, two distribution feeders of Yun Lin District in Taipower are selected for case study on power output response, reactive power compensation and voltage of PV systems using the autonomous control in the operation of load transfer between feeders.

Chen, Chao-Shun Ku, Te-Tien Lin, Chia-Hung Yu, Hung-Yi Hsu, Dun-Kuai Chang, Wen-Yao

Abstract

To mitigate the impact on the distribution system service quality due to high penetration of PV systems, a Distribution Renewable Energy Advanced Management System (DREAMS) has been developed and installed at Feng Shan District of Taipower. The PV gateway and public 4G communication system are applied to monitor the power generation and voltage of 16 PV systems in Yun Lin County and to report the operation data to the master station with DNP3.0 protocol. When the problems of overvoltage occurs due to large amount of PV power output being injected to the power network, the power factor control or voltage setting autonomous control of smart inverter is activated to provide the reactive power compensations so that the impact of PV integration can be reduced. For the load transfer between too distribution feeders with high penetration of PV systems, the Dreams can derive the control strategy and perform the remote control of smart inverters according to the network reconfiguration, change of PV power output, and feeder loading.

Wang, Yung-Fu Wu, Chen-Han Liao, Ching-Jung Huang, Chih-Peng

Abstract

The stability of power system operation in Kinmen Island relies on operational flexibility of diesel engines. The quick response ability of the installed diesel engines there is currently able to maintain the balance between power generation and system’s load. However, loss of a very large power generation at a time may still trigger the under frequency load shedding relay. Currently, the penetration of Kinmen power system renewable energy is close to 27%. Without deployment of energy storage device in the Kinmen Island, power system stability has to heavily depend on diesel engine output adjusting capability, while there is no other way to control renewable energy generation for now. This paper focus on whether renewable energy generation deviation will exceed the diesel engine’s adjusting capability limit. By actual measured data and system simulation, we can assess the impact of power generation change on the power system frequency. On the other hand, we also calculate the acceptable limit of renewable output fluctuation under different unit generation schedule.

Hsiao, Tsun-Yu Chiu, Wen-Hsien Chen, Chien-Chung

Abstract

The revised Electricity Law Act was announced by the president and came into force on January 26, 2017. One of the major points in the Act revision is “Green Power Goes First”, which means that renewable energy will be given preferential benefit, flexibility and development space. Among others, article 8, part 1, states that “the transmission and distribution system operators are responsible for the electric power system control and dispatch tasks, and that under the condition of ensuring the security and stability of the power system, transmission and distribution system should give the highest priority to renewable energy in the network integration and dispatch”. According to the government, the development of the solar photovoltaics (PV) is projected to reach the target of 20 GW by 2025. However, it will be an extremely difficult task to ensure the security and stability of the power system if there is no accurate real-time PV generation data and proper forecasting capability. While PV is an intermittent and unstable power resource, most of the PV sites selected by the private investors have not sent their real-time operation information to Taipower. It will be a major problem to reasonably estimate PV real-time power generation information for system operators. This paper considers the concept of solar radiation zone and set up a real-time PV generation monitoring and estimation platform. The rationality and feasibility of the platform developed in this study has been verified by the statistical analysis data.

Wu, Yuan-Kang Huang, Si-Ru Wang, Yi-Wen

Abstract

The energy costs of an isolated islet system usually exceed those of a large power system because diesel engine power units installed there usually use high cost fuels. Accordingly, energy economics is a critical issue in the planning of power generation development for an islet power system. Taiwan has a number of small grid-independent islet power systems, with their systems very small and the generation costs extremely high. Consequently, it could be rather suitable for the construction of distributed energy based microgrid systems on those islets, including the development of renewable energy in combination with energy storage systems. This article takes Huayu Island as an example for the planning of a renewable energy system. First, this study collects the data of Huayu Island, including historical sunshine intensity system operational parameters, power output fluctuation of diesel engines, and the load and voltage at the main power buses. Then, this study utilizes OpenDSS software to implement steady-state power flow analyses after integrating the photovoltaic power into the system and analyses the influence of renewable energy on the bus voltages. Finally, for the problems related to voltage rise caused by the integration of solar power, this study offers suggestions on the use of smart inverters and energy storage systems to improve the voltage stability, and proposes the strategy of designing the optimal capacity for renewable energy generation and energy storage system.