Darmawan Sutanto

A Multi-Agent Solution to Distribution System Management by Considering Distributed Generators

A traditional distribution network carries electricity from a central power resource to consumers, and the power dispatch is controlled centrally. Distributed generators (DGs) emerge as an alternative power resource to distribution networks at a smaller and distributed scale, which will bring benefits such as reduced voltage drop and loss. However, because most of high penetration DGs are not utility owned and characterized by high degree of uncertainty such as solar and wind, the distribution network may perform differently from the conventionally expected behaviors. How to dynamically and efficiently manage the power dispatch in a distribution network to balance the supply and demand by considering the variability of DGs and loads becomes a significant research issue. In this paper, a multi-agent system (MAS) was proposed to solve this problem through introducing five types of autonomous agents, the electricity management mechanisms, the agent communication ontology, and the agent cooperation strategy. The simulation of the MAS by using InterPSS, JADE and JUNE well demonstrates the performance of the system on dynamic supply and demand balance by considering both efficiency and economy.

Distributed energy storage for mitigation of voltage-rise impact caused by rooftop solar PV

A high penetration of solar photovoltaic (PV) resources into distribution networks may create voltage rise problem when the generation from PV resources substantially exceeds the load demand. To reduce the voltage rise, the excess amount of power from the solar PV units needs to be reduced. In this paper, distributed storage systems are proposed for the mitigation of voltage rise problem. The surplus energy from the solar PV is used to charge the distributed storage units during midday, when the power from the solar PV would be typically higher than the load level. This stored energy is then used to reduce the peak load in the evening. An intelligent strategy for charging and discharging control to make effective use of the storage capacity is discussed. The proposed voltage rise mitigation strategy is verified on a practical low voltage distribution feeder in Australia.

Analysis of Nonstationary Power-Quality Waveforms Using Iterative Hilbert Huang Transform and SAX Algorithm

The nonstationary nature of power-quality (PQ) waveforms requires a tool that can accurately analyze and visually identify the instants of transitions. One of the recently reported tools available to analyze nonstationary complex waveforms with a very good time resolution is the Hilbert Huang Transform (HHT). However, HHT has difficulty in resolving waveforms containing components with close frequencies with a ratio of less than two, and similar to other waveform classification techniques, it has difficulty in resolving the instants of sudden changes in the waveform. To overcome the problem with components containing close frequencies, a novel Iterative Hilbert Huang transform (IHHT) is proposed in this paper. To overcome the problem in identifying instants of sudden changes in the waveform, a new method using the Symbolic Aggregate ApproXimation (SAX) method is proposed. SAX converts the signal into symbols that can be utilized by a pattern detector algorithm to identify the boundaries of the stationary signals within a nonstationary signal. Results from IHHT and SAX method to analyze and visually identify simulated and measured nonstationary PQ waveforms will be provided and discussed. The proposed method is particularly useful when investigating the behavior of the harmonic components of a particular PQ waveform of interest in a given interval of time, following a data-mining search of a large database of PQ events. It can be used to both identify, and later isolate unique signatures within a providers distribution system.

Classification of Power Quality disturbances using the iterative Hilbert Huang Transform

The Hilbert Huang Transform (HHT) is a powerful tool for Power Quality (PQ) classifications. One of the main advantages of the HHT is its ability to analyse non-stationary complex waveforms with very good time resolution. However, like other waveform classification techniques, it has difficulty in resolving the instant of sudden changes in the waveform. It has also difficulty with signals that have frequency components close together. This paper summarises the fundamentals of the HHT technique and its application to power quality classifications including its advantages and disadvantages. Two novel techniques to improve the performance of the HHT technique in analysing power quality problems will be proposed. Results from simulations will be provided and discussed.

Application of multi-agent system for preventing power interruption in a large power system

This paper presents an emergency control approach for preventing wide spread power interruption using multi-agent system. The proposed control algorithm is based on decentralized architecture of intelligent agents to achieve fast and accurate response when a catastrophic disturbance is identified in the system. By dividing the network into several areas, the voltage instability problem can be localized and countermeasures can be directed to the most affected area by the authorized local agent. This facilitates quick decision making within the system. The effectiveness of the proposed technique has been proved by a simulation of IEEE 57 bus test power system.

A decentralized multi-agent approach to prevent voltage collapse in a large power system

This paper presents a decentralized control system using multi-agent technology to prevent voltage collapse of a large power system following a catastrophic event involving multiple contingencies. The proposed automatic control system is employed to identify the affected region by the disturbances and to activate timely countermeasures. The modified IEEE-57 bus test power system has been used for simulation and the simulation was done in PSAT software. The multi-agent system has been implemented in Java language using JADE (Java Agent Development Framework). The results from the case studies indicate the efficiency of the proposed approach.

Hybrid fuel cell and energy storage systems using superconducting coil or batteries for clean electricity generation

This paper described a novel design of a hybrid fuel cell and energy storage system using high temperature superconducting energy storage system (HT-SMES) or batteries to meet fast changing load. The power electronic switches in the converter of the energy storage system are controlled in such a way that the amplitude and waveform of the inverter output current from the fuel cell is tightly regulated to follow a sinusoidal reference waveform. In this way, the energy storage system is used to supply the fast changing part of the load and the fuel cell system continuously supplies a constant full load demand. The SABER simulation results during motor starting will be presented and discussed.

SAX-based decomposition of non-stationary power quality waveforms

The Hilbert Huang Transform (HHT) is a powerful tool for Power Quality (PQ) classifications. One of the main advantages of the HHT is its ability to analyze non-stationary complex waveforms with very good time resolution. However, like other waveform classification techniques, it has difficulty in resolving the instant of sudden changes in the waveform. To overcome the above problems, SAX (Symbolic Aggregate ApproXimation) method is proposed to convert the signal into symbols which facilitates a pattern detector algorithm to identify the border of the stationary signals within a non-stationary signal. Results from simulations will be provided and discussed.