Ching-Yin Lee

Study of Reconfiguration for the Distribution System With Distributed Generators

This paper proposes a reconfiguration methodology based on an Ant Colony Algorithm (ACA) that aims at achieving the minimum power loss and increment load balance factor of radial distribution networks with distributed generators. A 33-bus distribution system and a Tai-Power 11.4-kV distribution system were selected for optimizing the configuration and to demonstrate the effectiveness of the proposed methodology for solving the optimal switching operation of distribution systems. The simulation results have shown that lower system loss and better load balancing will be attained at a distribution system with distributed generation (DG) compared to a system without DG. Furthermore, the simulation results also satisfy and suitability reference merits of the proposal method.

Comparative Evaluation of the HVDC and HVAC Links Integrated in a Large Offshore Wind Farm—An Actual Case Study in Taiwan

This paper mainly focuses on the transient voltage and frequency responses of a large offshore wind farm integrated system in Taiwan. It adopts a simulation study by using different submarine cable technologies and wind turbine types, including high-voltage direct current (HVDC) link based on line-commutated converter (LCC), high-voltage alternating current (HVAC) link, and three types of wind turbines. In addition, it utilizes an actual system that connects the Taiwan grid and a 200-MW offshore wind farm in the Penghu area via two submarine cables. The aim of this paper is to analyze the transient characteristics of both the HVDC and the HVAC connected wind power systems. According to the simulation results, it shows that the HVDC link can provide better voltage and frequency responses, which are independent on the types of wind turbines. Moreover, the HVDC link can alleviate the effect of grid faults on the wind farm and provide the wind farm better voltage and frequency stability.

Effect of Low-Voltage-Ride-Through Technologies on the First Taiwan Offshore Wind Farm Planning

Penghu, Taiwan, has the potential to be one of the most valuable sources of wind energy in the world. A 59-km submarine cable that connects Taiwan to Penghu Island is currently in the planning phase, and a large-scale offshore wind farm around Penghu will be developed. This will be the first offshore wind farm to be planned in Taiwan and will have a significant role in the development of renewable energy in this country. In the initial planning phase, various transient impact analyses must be performed. Low-voltage-ride-through (LVRT) capability is one of the most critical items to be analyzed. The main target of this paper is to investigate the effect of LVRT technologies on the first Taiwan offshore wind farm planning. It begins by investigating the development of LVRT technologies, and then discusses the effect of grid strength on the preferred LVRT installation. The critical range of faults that can disconnect the wind farm from the grid with and without LVRT has been studied. Finally, the effect of LVRT characteristics on the transient stability of the power system in Taiwan is evaluated and the strategy of replacing the LVRT installations with reactive power compensation elements is proposed.

Taiwan's First Large-Scale Offshore Wind Farm Connection—A Real Project Case Study With a Comparison of Wind Turbine

The west coast and islands of Taiwan have abundant wind resource, which offers a great opportunity for large-scale offshore wind power generation. In Taiwan, the first stage of the offshore wind farms at the Jhang-Bin and Penghu areas has been planned. In particular, the Jhang-Bin wind farm will become the first and one of the largest wind farms in Taiwan. Therefore, its impacts on system operation and security have to be investigated and studied in advance. Following a general connection design discussion, this paper is consist of four major system impact analyses: load flow, fault current, voltage variation, and transient stability. Moreover, three types of typical wind turbines have been adopted in this paper in order to compare their performances on the wind farm integration system. From the simulation results, some significant conclusion and recommendations have been extracted, which would contribute to the first offshore wind farm development in Taiwan.

Optimization of the Wind Turbine Layout and Transmission System Planning for a Large-Scale Offshore WindFarm by AI Technology

The interest in the utilization of offshore wind power is increasing significantly worldwide. A typical offshore windfarm may have hundreds of generators, which is outspread in the range of several to tens of kilometers. Therefore, thereare many feasible schemes for the wind turbine location and internal line connection in a wind farm. The planner mustsearch for an optimal one from these feasible schemes, usually with a maximum wind power output and the lowestinstallation and operation cost. This paper proposes a novel procedure to determine the optimization wind turbinelocation and line connection topology by using artificial intelligence techniques: The genetic algorithm is utilized inthe optimal layouts for the offshore wind farm, and the ant colony system algorithm is utilized to find the optimal lineconnection topology. Furthermore, the wake effect, real cable parameters, and wind speed series are also considered inthis research. The concepts and methods proposed in this study could help establish more economical and efficientoffshore wind farms in the world.

Comparative evaluation of the HVDC and HVAC links integrated in a large offshore wind farm - an actual case study in Taiwan

This paper mainly focuses on the transient voltage and frequency responses of a large offshore wind farm integrated system in Taiwan. It adopts a simulation study by using different submarine cable technologies and wind turbine types, including high-voltage direct current (HVDC) link based on line-commutated converter (LCC), high-voltage alternating current (HVAC) link, and three types of wind turbines. In addition, it utilizes an actual system that connects the Taiwan grid and a 200-MW offshore wind farm in the Penghu area via two submarine cables. The aim of this paper is to analyze the transient characteristics of both the HVDC and the HVAC connected wind power systems. According to the simulation results, it shows that the HVDC link can provide better voltage and frequency responses, which are independent on the types of wind turbines. Moreover, the HVDC link can alleviate the effect of grid faults on the wind farm and provide the wind farm better voltage and frequency stability.

Advanced Analysis of Clustered Photovoltaic System's Performance Based on the Battery-Integrated Voltage Control Algorithm

This paper summarizes international experience of significant clustered photovoltaic systems. Based on the operation experience, major system impacts and corresponding solutions have been studied. Among them, voltage raise of power distribution line due to the reverse power flow from the PV system has been one of the main problems. Therefore, this paper proposes the dynamic and steady-state simulations to evaluate the effectiveness of battery-integrated PV system on avoiding the over voltage problem. Furthermore, different types of battery control modes have been compared. In the simulations, the actual product specifications were adopted as the parameters of the component models, and the largest PV cluster system in Taiwan was chosen as the analyzed demonstration site. The simulation results reveal that the developed control algorithms could avoid voltage rise by setting appropriate control parameter values. In addition, these control algorithms could be applicable to other power grids if appropriate settings are made.

Study on voltage stability of island grid supplied by large grid with long submarine cables considering different load patterns

The voltage response characteristics considered different load patterns are studied in the paper. The effects of on-load tap changer (OLTC), over-excitation limiter (OLE), and high voltage direct current (HVDC) link on voltage stability are also analyzed. In which, the converter terminals of HVDC link are considered as a constant real and reactive power load under steady state and the effects of HVDC control modes on voltage stability are also studied. A practical system of larger grid (Taiwan grid) connecting to a smaller island grid (Peng-Hu grid) via two circuits of long submarine cables is used to study. The strategies for improving voltage stability include reactive power support and under-voltage load shedding (UVLS) are proposed. Based on the simulation results, it shows that the voltage response characteristics are affected significantly by different load patterns. The OLTC plays an important role during the load voltage restoration. The reactive power support devices and UVLS can improve the short-term voltage stability, which makes the power system achieve voltage stability operation. However, the interactions between OLTC and OEL under HVDC link connected operation would lead the power system to voltage instability. The constant current control mode of HVDC link has better effect on voltage stability. All of these studies are performed by software package, namely power system simulation for engineering (PSS/E) in this paper.

Onshore wind farm planning and system simulation analysis under low-carbon-island project at Penghu

Penghu is embarking on an ambitious plan to tackle global warming by controlling all aspects of the islands energy supply. The energy plan looks to tackle the islands dependence on fossil fuels and its carbon emissions via an increased uptake of renewable energy and low carbon usage. It will also help the island develop more and better low carbon technologies that will continue to stimulate economic growth. Among of these technologies, wind power definitely plays the most important role at Penghu Island because of its abundant wind energy resource. In the initial planning phase, additional onshore wind farms with a capacity of more than 100MW would be installed in this island. It would bring a severe challenge to the original power system. Therefore, it is necessary to perform various system simulation analyses, including the computations on steady-state power flows, fault currents, and transient stability. In this paper, the initial planning constructions on these wind farms and system simulation analysis have been performed. The results would provide significant references to the actual Penghu onshore wind farm planning.

Choice of interconnected points for large-scale offshore wind farms in Taiwan

Taiwan is developing the renewable energy actively, in which the wind energy is seen as one of the important resources. However, the suitable locations for wind farm constructions are less on the shore, and the trend of wind farm development in the near future will toward to offshore where the installation capacity of the wind farm could reach hundreds of megawatts. In this work, the choice of interconnected point of the large-scale offshore wind farm to the grid is investigated by using simulation analyses, in which the installation capacity of the offshore wind farm is assumed 864MW. The interconnected point is chosen on the extra-high voltage bus in the west coast of Taiwan. The short circuit current, short circuit capacity, and short circuit ratio (SCR) are used to determine the interconnected points. Besides, the impact of wind speed variation (gust, ramp-up, and ramp-down) on the voltage was also analyzed.