P. Dong

Bio: P. Dong is an academic researcher from Hong Kong Polytechnic University. The author has contributed to research in topics: Stand-alone power system & Grid-connected photovoltaic power system. The author has an hindex of 4, co-authored 4 publications receiving 99 citations.

A Novel Detection Method for Voltage Sags

Abstract: Determining the start and end of the voltage sag event is very important for sag analysis and mitigation. There are several detection methods for voltage sags in which sag voltages are usually expressed in the terms of RMS. The RMS method represents one cycle historical average value, not instantaneous value which may lead to long detection time when voltage sag has occurred. This paper will proposed a novel voltage sag detection method based on miss voltage technique. Proper dead-band and hysteresis are used in the method. The actual instantaneous voltage is compared with certain percentage of desired grid voltage and certain percentage of the amplitude of the grid voltage. Through instantaneous value comparison, low instantaneous value of the grid is shielded which overcome the mishandling turnover of voltage sags. The approach is fully described, and the results are compared with other methods for marking the beginning and end of sag, such as RMS value evaluation method and Peak-value method and simulation result provides that the method is efficient and fast and can be used to determine the initiation and recovery of voltage sags accompanied by missing voltage technique.

The study of the energy management system based-on fuzzy control for distributed hybrid wind-solar power system

Abstract: An energy management system based on hierarchical fuzzy controller for the distributed hybrid wind-solar power system is designed Based on hierarchical fuzzy control, the energy management system switches the mode of power supply and controls the load share according to the condition of wind power, solar radiation and load requirement Through the suitable allotter of the generation ratio from wind power and photovoltaic cells, the distribution generation system, combined with battery bank, can provide user with reliable electric power The energy management system is implemented from microprocessor and data acquisition system This energy management system is applied in an experimental equipment The hybrid generation system controlled by the fuzzy energy management system, at the appearance of random variation of wind speed and solar radiation, supplies with stable electric power

The study of the energy management system based-on fuzzy control for distributed hybrid wind-solar power system

Abstract: An energy management system based on hierarchical fuzzy controller for the distributed hybrid wind-solar power system is designed. Based on hierarchical fuzzy control, the energy management system switches the mode of power supply and controls the load share according to the condition of wind power, solar radiation and load requirement. Through the suitable allotter of the generation ratio from wind power and photovoltaic cells, the distribution generation system, combined with battery bank, can provide user with reliable electric power. The energy management system is implemented from microprocessor and data acquisition system. This energy management system is applied in an experimental equipment. The hybrid generation system controlled by the fuzzy energy management system, at the appearance of random variation of wind speed and solar radiation, supplies with stable electric power.

General Discussion on Dimming Control Method Used for Discharge Lamp

Abstract: In order to reduce the energy, the dimming control is used in the lighting system. There are many different control methods in the fluorescent lamp, after comparing these methods, a research scheme of dimming control used in the HID ballast is proposed. In addition, the lamp model, dimming range and stability analysis are also analyzed in this paper.

A current and future state of art development of hybrid energy system using wind and PV-solar: A review

Abstract: The wind and solar energy are omnipresent, freely available, and environmental friendly. The wind energy systems may not be technically viable at all sites because of low wind speeds and being more unpredictable than solar energy. The combined utilization of these renewable energy sources are therefore becoming increasingly attractive and are being widely used as alternative of oil-produced energy. Economic aspects of these renewable energy technologies are sufficiently promising to include them for rising power generation capability in developing countries. A renewable hybrid energy system consists of two or more energy sources, a power conditioning equipment, a controller and an optional energy storage system. These hybrid energy systems are becoming popular in remote area power generation applications due to advancements in renewable energy technologies and substantial rise in prices of petroleum products. Research and development efforts in solar, wind, and other renewable energy technologies are required to continue for, improving their performance, establishing techniques for accurately predicting their output and reliably integrating them with other conventional generating sources. The aim of this paper is to review the current state of the design, operation and control requirement of the stand-alone PV solar–wind hybrid energy systems with conventional backup source i.e. diesel or grid. This Paper also highlights the future developments, which have the potential to increase the economic attractiveness of such systems and their acceptance by the user.

Low-Voltage Ride-Through Capability of a Single-Stage Single-Phase Photovoltaic System Connected to the Low-Voltage Grid

Abstract: The progressive growing of single-phase photovoltaic (PV) systems makes the Distribution System Operators (DSOs) update or revise the existing grid codes in order to guarantee the availability, quality, and reliability of the electrical system. It is expected that the future PV systems connected to the low-voltage grid will be more active with functionalities of low-voltage ride-through (LVRT) and the grid support capability, which is not the case today. In this paper, the operation principle is demonstrated for a single-phase grid-connected PV system in a low-voltage ride-through operation in order to map future challenges. The system is verified by simulations and experiments. Test results show that the proposed power control method is effective and the single-phase PV inverters connected to low-voltage networks are ready to provide grid support and ride-through voltage fault capability with a satisfactory performance based on the grid requirements for three-phase renewable energy systems.

Optimal Energy Management of Wind-Battery Hybrid Power System With Two-Scale Dynamic Programming

Abstract: This study is concerned with the optimal energy management for a wind-battery hybrid power system (WBHPS) with local load and grid connection, by including the current and future information on generation, demand, and real-time utility price. When applying typical dynamic optimization schemes to such a problem with a single time scale, the following dilemma usually presents: it is more beneficial to plan the (battery) storage setpoint trajectory for the longer horizon, while prediction of renewable generation, utility price, and load demand is more accurate for the shorter term. To relieve such conflict, a two-scale dynamic programming (DP) scheme is applied based on multiscale predictions of wind power generation, utility price, and load. A macro-scale dynamic programming (MASDP) is first performed for the whole operational period, based on long-term ahead prediction of electricity price and wind energy. The resultant battery state-of-charge (SOC) is thus obtained as the macro-scale reference trajectory. As the operation proceeds, the micro-scale dynamic programming (MISDP) is applied to the short-term interval based on short-term three-hour ahead predictions. The MASDP battery SOC trajectory is used as the terminal condition for the MISDP. Simulation results show that the proposed method can significantly decrease the energy cost compared with the single scale DP method.