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Distributed Generation (DG) integration, especially based on renewable energy resources, has gained great attention by power utilities and frequently utilized in the electrical distribution systems. However, DG integration imposes some risks towards system stability which may lead to system blackouts. This mainly occurs when the grid is decoupled from a portion of the distribution system consisting DGs while the total load demand is greater than total DGs output power. In order to overcome this problem, load shedding technique can be adopted to stabilize the system frequency. However, existing load shedding techniques were unable to accurately estimate the power imbalance due the variation in system loading. This results in excessive/inadequate load shedding to stabilize the system frequency. Moreover, random selection of the loads without load prioritization might cause vital loads to be shed. Therefore, in this paper, a new load shedding strategy for islanded distribution system is proposed. Polynomial regression analysis estimates the power mismatch while MILP optimization estimates optimal load combination for shedding. Furthermore, load priority (i.e., vital, non-vital, and semi-vital) is also considered to avoid disconnecting vital loads. Efficiency of the proposed scheme is evaluated on three different test systems. Validation is performed by modelling the proposed load shedding on PSCAD/EMTDC software for dynamic analysis. From the results, it can be analyzed that the proposed technique is superior compared to other techniques proposed in the literature.

Interconnection of distributed generation (DG) in distribution system will result in formation of islands in the event of loss of main supply. This scenario is harmful to the power system, hence quick detection is critical to halt the formation of islands. Among the common passive and active detection methods available, the hybrid detection method is identified as the most reliable method. This paper proposes a new hybrid method using the combination of passive and active technique which is the rate of change of frequency (ROCOF) and load impedance, respectively. The passive method works when the value of ROCOF exceeds the threshold value which is set at 0.3Hz/s. The active method works when it detects low value of ROCOF and immediately inject a pre-specified load into the system to increase the ROCOF value up to its threshold value. Simulation study on different case studies is carried out on distribution test system to evaluate the performance of the proposed method. Results show that this method is effective in detecting any events that could result in islanding.

Electrical energy source in Malaysia is commonly from by fossil fuel such as coal, petroleum, LNG, LPG, kerosene, etc. However, these unrenewable sources of energy are neither economical nor favorable to the environment. Even though Malaysia produces enough electricity to meet current consumption levels, the reduction of electrical usage should be taken for us as a main consumer in this country in order to reduce energy consumption. Towards this end, solar energy seems to be a singularly legitimate and feasible source of alternative energy for heating water. Solar energy is permanently renewable, environmentally beneficial, and convertible to various energy forms. A solar water heating system is used to convert solar energy to thermal energy to heat water. This research investigates the application of solar energy to meet water heating needs especially in Malaysia and models the water heating system. Through modelling in the simulation, the average system efficiency for solar collector and thermal storage are determined as the total costs on a daily basis or monthly average.

The islanding operation of a distribution network connected with distributed generation may be a useful way to improve its power reliability. However, it requires a good control strategy for ensuring a safe operation of islanded system controlling voltage and frequency of the system within their permissible range. This paper proposed a centralized controller to coordinate the islanding operation with multiple islanding configurations for rotating type DGs. Multiple islanding configurations are introduced to maximize the benefit of islanded operation. The advantage of the proposed strategy is that DG will be able to operate in different islanding areas instead of energizing only one islanding area. The proposed controller regularly communicates with the governor and excitation controllers of the DG units with the utility grid to carry out action in case of an islanding event. The performance of the proposed controller is investigated for various simulations carried out on an existing Malaysia distribution network. The simulation results show that the islanding operation for each configuration is dynamically stable.

In recent years significant changes in climate have pivoted the distribution system towards renewable energy, particularly through distributed generators (DGs). Although DGs offer many benefits to the distribution system, their integration affects the stability of the system, which could lead to blackout when the grid is disconnected. The system frequency will drop drastically if DG generation capacity is less than the total load demand in the network. In order to sustain the system stability, under-frequency load shedding (UFLS) is inevitable. The common approach of load shedding sheds random loads until the system&rsquo, s frequency is recovered. Random and sequential selection results in excessive load shedding, which in turn causes frequency overshoot. In this regard, this paper proposes an efficient load shedding technique for islanded distribution systems. This technique utilizes a voltage stability index to rank the unstable loads for load shedding. In the proposed method, the power imbalance is computed using the swing equation incorporating frequency value. Mixed integer linear programming (MILP) optimization produces optimal load shedding strategy based on the priority of the loads (i.e., non-critical, semi-critical, and critical) and the load ranking from the voltage stability index of loads. The effectiveness of the proposed scheme is tested on two test systems, i.e., a 28-bus system that is a part of the Malaysian distribution network and the IEEE 69-bus system, using PSCAD/EMTDC. Results obtained prove the effectiveness of the proposed technique in quickly stabilizing the system&rsquo, s frequency without frequency overshoot by disconnecting unstable non-critical loads on priority. Furthermore, results show that the proposed technique is superior to other adaptive techniques because it increases the sustainability by reducing the load shed amount and avoiding overshoot in system frequency.

Islanding detection is important for the protection of any distribution system supported by distributed energy resources. In this work, a number of islanding and non-islanding events are simulated to prioritise 16 different passive parameters on the basis of performance analysis. Among the parameters tested, the rate of change of frequency over reactive power (df/dq) attains the highest accuracy and consequently, a new passive technique is proposed that employs df/dq as discriminative feature. An extended study is carried out to further test the ability of the technique to differentiate the islanding from the non-islanding events of similar signatures, such as load variation, capacitor switching, faults and induction motor starting. The simulation results confirm that the technique is proficient enough to identify islanding from non-islanding events that cause minute disturbances in the power supply network.

This paper presents a load shedding scheme (LSS) based on system frequency and voltage stability (VS). In the proposed scheme, the amount of power imbalance is determined using a rate of change of frequency, and the load shedding priority is carried out based on a VS index. The load with the highest tendency for voltage collapse (based on the index value) is given first priority to be shed. Thus, by shedding the most sensitive load, the distribution system can be saved from power collapse and then the system can return to its nominal state after load shedding. The proposed LSS is validated through simulation using PSCAD/EMTDC software on a Malaysian distribution network that consists of two mini-hydro generators. The simulation results show that the proposed scheme manages to shed the optimal amount of load when compared to conventional and adaptive frequency LSS. Moreover, apart from frequency stability, the proposed scheme also shows a significant improvement in the voltage profile of the islanded system.

The increasing penetration of electric vehicle (EV) at distribution system is expected in the near future leading to rising demand for power consumption. Large scale uncoordinated charging demand of EVs will eventually threatens the safety operation of the distribution network. Therefore, a charging strategy is needed to reduce the impact of charging. This paper proposes an optimal centralized charging schedule coordination of EV to minimize active power losses while maintaining the voltage profile at the demand side. The performance of the schedule algorithm developed using particle swarm optimization (PSO) technique is evaluated at the IEEE-33 Bus radial distribution system in a set time frame of charging period. Coordinated and uncoordinated charging schedule is then compared in terms of active power losses and voltage profile at different level of EV penetration considering 24 hours of load demand profile. Results show that the proposed coordinated charging schedule is able to achieve minimum total active power losses compared to the uncoordinated charging.

This paper presents a new under-frequency load shedding technique based on the combination of random and fixed priority of loads. It has been observed that placing all of the loads in the distribution system with fixed priority results in un-optimum load shedding. On the other hand, designing the load priority with a combination of random and fixed priority provides the technique with some sort of flexibility in achieving the optimal load shedding. The validation of the proposed scheme on different scenarios proves that the proposed technique is capable of achieving the optimal load shedding and recovering frequency to nominal value without any overshoot.

This paper presents a voltage stability assessment based approach to determine the congested line with optimal sizing and location. FVSI, a voltage stability index is chosen as the indicator for congested line identification, while particle swarm optimization technique (PSO) is used for optimal location and sizing of FACTs devices installation. Congested line is identified by increasing the reactive load at chosen load buses until they reach the maximum loadability level. PSO is applied for identifying the optimal location and sizing of FACTs devices as the compensating device. Results obtained from the implementation on IEEE 30 Bus RTS revealed that the proposed technique can manage the congestion subject to various disturbances.

Interconnection of Distributed Generation (DG) in distribution system presents many potential benefits as well as drawbacks. The impacts of DG might vary with the types of generator. This paper presents a study on the impacts of synchronous DG's interconnection in distribution system. Steady state analysis is carried out to analyze the impact of DG on voltage profile and short circuit current considering before and after DG interconnection. Dynamic analysis is also performed for investigating the performance of DG when a part of distribution system is being islanded. Results show that the penetration of DG contributes to the changes of power flow in the system, hence give impacts to the overall system performance.

The exponential growth in electricity demand has driven the Distributed Generation (DG) technology a boost in the power system. The use of DG is beneficial to power utilities, DG owners׳, and end-users in terms of reliability, power quality, and economics. However, to fully utilize the benefits of DGs, some technical issues need to be addressed. Islanding condition is one of the most important issue in this context. Until now, several islanding detection techniques have been proposed for detecting the islanding condition. This paper presents a brief overview of existing islanding detection techniques with their relative merits and demerits. Apart from this, the paper presents an islanding detection strategy suitable for hybrid DG resources of mini-hydro and Bio-Mass. The proposed strategy uses average rate of change of reactive power and load shift strategy to detect islanding of the distribution network. The performance of proposed strategy is validated on various islanding and non-islanding events. The results of proposed strategy are compared with other existing techniques in terms of fast islanding detection, and non-detection zone. The simulation results show that the proposed strategy is effective in detecting islanding phenomenon possesses fast detection and negligible non-detection zone region compared to existing islanding detection techniques.

An islanding operation of a distribution network is a topic of interest due to the significant penetration of distributed generation (DG) in a power system network. However, controlling the frequency of an islanded distribution system remains an unresolved issue, especially when the load exceeds the generation. This paper presents a new technique for a successful islanding operation of a distribution network connected with multiple mini hydro based DGs. The proposed technique is based on three main parts. The first part uses an islanding detection technique to detect the islanding event correctly. The second part consists of a power imbalance estimation module (PIEM), which determines the power imbalance between the generation and load demand. The third part consists of a load shedding controller, which receives the power imbalance value and performs load shedding according to load priority. The proposed technique is validated on an 11 kV existing Malaysia distribution network. The simulation results show that the proposed technique is effective in performing a successful islanding operation by shedding a significant number of loads.

In many countries around the world, the electric power systems are operating in a deregulated environment where the generation, transmission and distribution systems owned by different companies will enhance intense competition in the electricity market among them in order to provide more reliable, cost effective and efficient electricity to the consumers. For that reason, the power system dynamic security assessment and control is becoming more challenging task in the transfer capability determination due to several new constraints, obligations and challenges that need to be encountered by the utility. Dynamic response of a system plays an imperative role in the analysis of system stability and blackout events that usually caused by the impact of enormous and unforeseen occurrence of fault, unexpected generation and load outages, and abrupt disengagement of loads. This paper presents a monitoring tool by using the Graphical User Interface (GUI) in order to monitor the frequency response of a power system due to the effect of contingency event. The proposed technique has been validated by using the IEEE Reliability Test System. This technique can assist the utility in order to monitor the stability of a power system in the event of contingency.

Power system is heavily loaded with increase in electricity demand. Frequency instability during islanding scenarios is an important issue to be addressed. Frequency instability happens when the power balance between generation and load demand is not met. During islanding, Under-Frequency Load Shedding (UFLS) technique is implemented to stabilize the system frequency and to ensure uninterrupted power supply to the customers. This paper proposes an optimal load shedding approach using Particle Swarm Optimization (PSO) technique for islanded mode of operation. The technique determines the optimal amount of load that needs to be shed considering power imbalance. The proposed load shedding approach is developed using MATLAB and is validated on distribution system modeled using PSCAD software. Simulation results show that the proposed PSO based approach was able to stabilize the system frequency by shedding the load optimally.

The aim of this research is to anticipate the stability status of a power system when the system is exposed to a change in frequency and rotor angle due to small disturbances. The proposed study was implemented on the IEEE Reliability Test System 1979 (IEEE RTS-79) which contains 24 buses, 38 transmission lines and 32 generators. Steady state stability limit of a system refers to the maximum amount of power that is permissible through the system without loss of its steady state stability. This research proposes the development of a Graphical User Interface (GUI) to observe the frequency and rotor angle stability due to the effect of small disturbances using the One Machine Infinite Bus (OMIB) technique. This proposed technique could ease the power system utility especially the power system operation to observe and examine the system frequency and rotor angle stability due to small disturbances. The findings from this research has proven that the proposed technique to observe the frequency and rotor angle stability due to small disturbances has successfully been developed using a GUI.

Accurate and fast islanding detection of distributed generation is highly important for its successful operation in distribution networks. Up to now, various islanding detection technique based on communication, passive, active and hybrid methods have been proposed. However, each technique suffers from certain demerits that cause inaccuracies in islanding detection. Computational intelligence based techniques, due to their robustness and flexibility in dealing with complex nonlinear systems, is an option that might solve this problem. This paper aims to provide a comprehensive review of computational intelligence based techniques applied for islanding detection of distributed generation. Moreover, the paper compares the accuracies of computational intelligence based techniques over existing techniques to provide a handful of information for industries and utility researchers to determine the best method for their respective system.

Events such as natural and manmade interference, line, transformer and feeder outages that occur in electric power distribution system negatively impact the continuity of power supply, thus affecting the power demand supply as well as customer’s satisfaction. In that cases, the restoration of power needs to be carried out immediately in order to guarantee the system’s reliability. The power flow path identification is considered as a difficult task especially in a huge system due to large number of switches. Kruskal’s algorithm is presented in this paper to find the minimum power flow path in a power distribution network. The comparison of performance between presented Kruskal’s algorithm and Binary Particle Swarm Optimization (BPSO) was made in solving a problem regarding network reconfiguration. The proposed load restoration approach is tested on IEEE 33-bus single feeder radial distribution system using MATLAB software. From the results, it is found that the presented Kruskal’s algorithm was able to search for the minimal power flow path that contribute to loss reduction for power restoration after the occurrence of fault.

Transmission line is one of the important elements in the process of power transfer from the source of generation to the consumer. In order to analyze the performance of a transmission line, it has to be represented by an equivalent model with suitable circuit parameters at a per phase basis. The line models are used to measure voltages, currents and the amount of power flow depending on the line length. Transmission line performance is determined by the voltage regulation and its efficiency under their normal operating conditions. In this study, a systematic approach was developed in order to assists the lecturers in teaching this important topic to the students despite so many complicated mathematical equations involved in the calculation. With the aid of Graphical User Interface (GUI), the performance of transmission line can be determined and monitored due to the change of line parameters. The results obtained could assist the lecturers in delivering the concept of engineering in a more systematic approach. On top of that, it could also assist the power system utility in planning the transmission line that needed to be installed in the system.

Technological advancement, environmental concerns, and social factors have made plug-in electric vehicles (PEVs) popular and attractive vehicles. Such a trend has caused major impacts to electrical distribution systems in terms of efficiency, stability, and reliability. Moreover, excessive power loss, severe voltage deviation, transformer overload, and system blackouts will happen if PEV charging activities are not coordinated well. This paper presents an optimal charging coordination method for a random arrival of PEVs in a residential distribution network with minimum power loss and voltage deviation. The method also incorporates capacitor switching and on-load tap changer adjustment for further improvement of the voltage profile. The meta-heuristic methods, binary particle swarm optimization (BPSO) and binary grey wolf optimization (BGWO), are employed in this paper. The proposed method considers a time-of-use (ToU) electricity tariff such that PEV users will get more benefits. The random PEV arrival is considered based on the driving pattern of four different regions. To demonstrate the effectiveness of the proposed method, comprehensive analysis is conducted using a modified of IEEE 31 bus system with three different PEV penetrations. The results indicate a promising outcome in terms of cost and the distribution system stress minimization.

A new reconfigurable multiband antenna is presented. The antenna operates in triple band and can be switched to operate either in single or dual band. The multifrequency band is achieved by using slots dipole antenna fed by a coplanar waveguide (CPW). Six switches are used and positioned at specific locations in the slots to achieve frequency reconfigurability. The antenna reconfiguration is realized when the dipole arms are coupled or decoupled from the slot edges. Three different sub-band frequencies (2.40, 3.50, and/or 5.20 GHz) are obtained. Measured and simulated results are presented. The proposed antenna may be suitable for future multimode applications such as cognitive radio systems. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:735–740, 2014

Cognitive radio CR enables spectrum sharing by allowing new unlicensed services from secondary users to operate in pre-allocated bands in an opportunistic manner. TV white space TVWS is a portion of the spectrum in ultra-high frequency UHF and very-high frequency bands, which is not utilised by primary users in specific time and location. It is envisaged that more spectrum will be available after digital switchover DSO TV transmission replaces the current analogue system. Recently, the regulators in the USA and in the UK have given approval for companies to operate new communication systems with the capability of utilising TVWS spectrum. This paper provides a comprehensive overview of the CR technology and quantifies the TVWS status in Malaysia to expose the spectrum reuse opportunities for future secondary user deployment. Taking the 18 major cities in Malaysia into consideration, we find that all seven TV stations utilise from two to seven of the UHF channels. In our analysis, three usage scenarios were considered, where the utilisation of the 40 UHF channels is full, half and a third. For each case, it was discovered that TVWS was 82.5%, 65% and 46.1%, which can be opportunistically utilised by CR users. Copyright © 2014 John Wiley & Sons, Ltd.

This paper prioritizes the different passive parameters on the basis of performance capability in selecting the parameters for intelligent islanding detection techniques. The responses of 16 different passive parameters are analyzed under all possible islanding and non-islanding conditions. As a result of this, it has been found that rate of change of frequency over reactive power shows the highest capability to distinguish islanding from other events of similar signatures followed by rate of change of reactive power and rate of change of power.

Under-Frequency Load Shedding (UFLS) is a common technique to maintain power system stability by removing the overload in some part of the system. The existing UFLS schemes operate successfully in the interconnected grid system. A particular approach of UFLS scheme is required for an islanded system which is known to be not as strong as the grid. This paper presents a new approach of UFLS scheme for the implementation in an islanded distribution system. The scheme is based on a combination of adaptive and intelligent techniques. The disturbance magnitude for response based and event based is treated differently: (1) event based is based on the power imbalance and (2) response based is based on the swing equation which relies on the frequency and rate of change of frequency measurement. Dynamic simulation on an intentional islanding operation is performed on an existing Malaysian network interconnected with a mini hydro generation. The objective is to investigate the effectiveness of the proposed scheme. The simulation results demonstrate that the proposed scheme is capable of improving the frequency response of the islanded system. A significant finding is that the scheme can successfully reduce the effect of power deficiency following the grid connected to islanding operation transition.

The successful islanding operation of distribution system requires an efficient islanding detection technique and under frequency load shedding scheme. The islanding detection technique is necessary to detect accurately the islanding phenomenon and under frequency load shedding scheme is essential to control frequency when the load exceeds the generation. This paper presents a new strategy for successful islanding operation of distribution system connected with rotating type DGs. The proposed strategy mainly consists of three stages. First stage uses an islanding detection technique to detect islanding event correctly. The second stage calculates the load amount to be shed. Finally, the third stage performs under frequency load shedding to recover the frequency to its nominal value. The proposed strategy is tested on an 11 kV Malaysian distribution system. The simulation results show that proposed strategy successfully performed the islanding operation by shedding accurate amount of loads.

Power flow calculation is very important for power system operation, economic scheduling and planning. This paper presents a development of Power System Load Flow Analysis tool based on the Newton Raphson method by using a User Friendly Graphical User Interface (GUI) Matlab Program. This tool introduces a simple interface for the user to perform load flow analysis. It is also designed for a user to view power flow results for each iteration and thus will facilitate especially undergraduate electrical students to verify their manual calculation of load flow solution. By just point and click, the students will easily get the required solution. The load flow tool is evaluated by solving the load flow of several test systems including IEEE bus system. For such reason, the tools is designed specifically for 2, 3 and 14 buses systems. The result shows that all the answers/solutions displayed in GUI for every required calculation steps for Newton Raphson load flow are successfully verified with the manual calculation and load flow solution in Power World Simulator and VBA Excel. Thus, this tool helps student and lecturer to learn and verify their manual calculation and at the same time reduce their calculation time.

An effective islanding detection technique is extremely important in safeguard Distributed Generation (DG) from incur a great impact due to unintentional islanding. Among commonly employed techniques, passive detection is known as the simplest and cheapest detection technique, but suffers large Non-Detection Zone (NDZ). This paper present an evaluation on NDZ of passive islanding detection technique based on the combination of passive techniques i.e Rate of Change of Frequency (ROCOF) and Rate of Change of Voltage (ROCOV). The NDZ is identified by performing simulation study on a distribution system. A systematic approach to locate the specific zone is carried out by varying active and reactive power imbalance at the Point of Common Coupling (PCC) when the system is subjected to islanding. The performance of combination technique is compared with Over/Under Frequency (OUF) and Over/Under Voltage (OUV). The results show the combination technique has a smaller NDZ and is capable to detect islanding within a shorter time.

This paper presents a development of Visual Basic based Graphical User Interface (GUI) for an improved of Measurement and Verification Protocol (M&V) Whole Facility framework to quantify an investment in energy savings considering risks. Monte Carlo simulations are presented to assess the risks of an Energy Conservation Measure (ECM) project. The proposed M&V framework produces a continuous range of savings and rate of return of the investment with associated probabilities instead of a single value assessment without margin of error. The GUI was tested for a commercial building using three different variables that are affecting the energy use: 1) Cooling Degree Days (CDD), 2) Number of Working Days (NWD) and 3) Multi-Variable that combining CDD and NWD. From the findings, it shows that the proposed Visual Basic based GUI of M&V with Monte Carlo simulation provides a more comprehensive overview of energy savings investment in a building.

This paper presents an optimization framework to determine long-term optimal generation mix for Malaysia Power Sector using Dynamic Programming (DP) technique. Several new candidate units with a pre-defined MW capacity were included in the model for generation expansion planning from coal, natural gas, hydro and renewable energy (RE). Four objective cases were considered, 1) economic cost, 2) environmental, 3) reliability and 4) multi-objectives that combining the three cases. Results show that Malaysia optimum generation mix in 2030 for, 1) economic case is 48% from coal, 41% from gas, 3% from hydro and 8% from RE, 2) environmental case is 19% from coal, 58% from gas, 11% from hydro and 12% from RE, 3) for reliability case is 64% from coal, 32% from gas, 3% from hydro and 1% from RE and 4) multi-objective case is 49% from coal, 41% from gas, 7% from hydro and 3% from RE. The findings of this paper are the optimum generation mix for Malaysia from 2013 to 2030 which is less expensive, substantially reduce carbon emission and that less risky.

Monitoring fault current is very important in power system protection. Therefore, the impact of installing Distributed Generation (DG) on the fault current is investigated in this paper. Three types of fault currents which are single line-to-ground, double line-to-ground and three phase fault are analyzed at various fault locations. The optimal location of DG was identified heuristically using power system simulation program for planning, design and analysis of distribution system (PSS/Adept). The simulation was conducted by observing the power losses of the test system by installing DG at each load buses. Bus with minimum power loss was chosen as the optimal location of DG. In order to study the impact of DG to the fault current, various locations and sizes of DG were also selected. The simulations were conducted on IEEE 33-bus distribution test system and IEEE 69-bus distribution test system. The results showed that the impact of DG to the fault current is significant especially when fault occurs at busses near to DG location.

Energy efficient spectrum sensing and data communication to extend the lifetime of cognitive radio sensor network is becoming increasingly important due to resource constraint of CR-WSN inherent from WSN. This paper presents an energy-aware clustering (EAC) algorithm that enhances spectrum sensing performance and reduces network energy consumption thereby prolonging lifetime of the network. We derived network wide energy consumption model in terms of spectrum sensing energy consumption, intra cluster and inter clusters energy consumptions, and then determined the optimal number of clusters for the network. Through numerical analysis, we evaluate the effectiveness of the proposed algorithm in terms of minimizing network wide energy consumption and improving spectrum sensing performance.

One of the biggest challenge in an islanding operation is to sustain the frequency stability. A large power imbalance following islanding would cause under-frequency, hence an appropriate control is required to shed certain amount of load. Under-frequency load shedding (UFLS) scheme is commonly adopted for grid transmission system of which requires particular consideration for application on an isolated/islanded system. The main objective of this research is to develop an adaptive UFLS technique for an islanding system. The technique is designed considering response based for any disturbance during islanding operation. The disturbance magnitude is determined from the swing equation in which relies on frequency and rate of change of frequency measurement for shedding the required amount of load. The technique is modeled by using PSCAD simulation tool. A simulation study on a distribution network connected with mini hydro generation is carried out to evaluate the UFLS model. It is performed under different load condition: peak load, base load and overload scenario. The results have shown that the load shedding technique have successfully shed certain amount of load and stabilized the system frequency following overload.

This paper presents analysis of energy saving made by 16kWp grid connected photovoltaic (PV) system at Green Energy Research Centre (GERC), UiTM Shah Alam. The study is based on data collected from the PV system from May 2012 until April 2013. The data consists of solar irradiance, ambient and module temperature and output power of the PV system. The research investigates the effect of the PV system on the GERC building's daily load curve and maximum demand using the concept of residual load. The energy saving based on TNB tariff is compared with the revenue if the energy from the PV system would be sold to national grid at the FiT tariff. The CO2 emission avoidance provided by the PV system is also calculated. Analysis shows that there were strong correlation between the solar irradiance, ambient temperature and module temperature with the energy from the PV The energy from the PV reduced the daily energy consumption by 28.34% during the weekday. Total energy saving by the PV over the duration considered was 20,679.28kWh and this saved RM9,827 of electricity bill. On the other hand, if the energy from the PV would be sold to the utility grid, the expected payback period on the investment is 11 year.

Intentional islanding operation has recently been considered by some utilities to effectively use the available renewable energy generation. In this paper, an intentional islanding operation of hydro Distributed Generation (DG) is proposed. Governor and Automatic Voltage Regulation (AVR) are properly developed such that the DG exhibits a good dynamic response once a part of the network is islanded. A new adaptive load shedding scheme is also proposed to address the issue of overload or insufficient generation after the system is islanded. The scheme is based on a combination of adaptive and intelligent techniques. The disturbance magnitude of response based and event based is treated differently: 1) event based is based on the power imbalance 2) response based is based on the swing equation which relies on the frequency and Rate of Change of Frequency measurement. To investigate the effectiveness of the controller and the load shedding scheme, dynamic simulation on an intentional islanding operation is performed on an existing Malaysia network interconnected with mini hydro generation. The simulation results demonstrate that the island is successfully established with the frequency and voltage response during the islanding operation are within the acceptable limit.

This paper proposes a model to find minimum bid price for a generating company to bid in electricity auction for new power plants in Malaysia considering uncertainty. The model has been used for three most common generation technologies i.e. 1) coal, 2) gas-fired (CCGT) and 3) nuclear. It is important for generating company to determine the minimum bid prices that it should submit in the auction to ensure that the investment would be profitable and meet the Minimum Acceptable Rate of Return (MARR) aimed by the company. The uncertainty such as fuel cost, overnight cost, operation and maintenance (O&M) cost and utilization factor are the important factors that considered in the model. The effects of these uncertainties on the bid prices of the different technologies are studied using 1) sensitivity analysis and 2) probabilistic analysis. Results show that the bid prices of nuclear is more sensitive to the changes in investment cost, O&M cost and utilization factor and less sensitive to the fuel cost than coal and CCGT. On the other hand the bid price of CCGT is more sensitive to the fuel cost. The sensitivity of coal plant shows result somewhere in between the nuclear and CCGT.

Without a proper islanding control strategy, islanding a part of a distribution network connected with Distributed Generation (DG) may presents risks and hazards. This paper presents a control strategy for islanding which has considered different islanding configurations/areas. A main controller was designed to coordinate these islanding configurations. Synchronization of the island and grid was controlled for a seamless grid reconnection. To achieve synchronization, the governor and exciter of the DG were properly designed to regulate the frequency and voltage of the system during islanding. The controller was modeled considering an existing Malaysia' distribution network of mini hydro power plant connected in parallel to the grid. To investigate the effectiveness of the controller, several case studies have been simulated. The dynamic response of the DG during islanding operation is observed. The results show that the DG is stable thoughout the islanding and the controller able to control the islanding operation for each of the configurations.

An intentional islanding operation or a planned islanding operation is feasible with the advance technologies introduced by a smart distribution system. This paper highlights a well planned islanding operation facilitating with an intelligent control strategy for a Distributed Generation (DG) to operate islanded and cater the issue of different islanding area. For radial system network, the DG could be serving several islanding areas as a result of different fault locations. For each islanding area, the governor's controller is properly designed such that the DG exhibits a good dynamic response once a part of the network is islanded. A means to automatic synchronized the islanded network with the grid for reconnection process is also considered in the controller. The controller has been modeled considering the existing Malaysia' distribution network of mini hydro power plant connected in parallel to the grid. The transient stability response of the generator is observed particularly on the frequency not to exceed the maximum allowable protection setting. The results proved that the DGs are feasible to operate in the islanded system despites slow dynamic response of hydro turbine to reach steady state. In addition, the slow transient response of hydro governor turbine has given a challenge in designing the controller algorithm.

This paper presents an alternative fault location algorithm to estimate short-circuit faults location in electrical distribution networks using only voltage sags data. The proposed algorithm uses voltage sags profile as a means to locate fault. The possible fault locations is estimated by incorporating the measured voltage sags magnitude and its corresponding phase angle into an equation of voltage sag as a function of fault distance. A ranking procedure is also introduced to rank possible fault locations due the same electrical distance. The uncertainty of fault resistance is also considered in this algorithm. The performance of the technique is presented by testing it using an actual underground distribution network. The simulation results indicated a possibility of practical implementation.

Providing end-to-end communication in heterogeneous Internet working environments is a challenge. Handover delay is one of the problematic issues that users are face in the heterogynous networks. However, in the case of both WiMAX and WiFi technologies located at the same base station (BS); the vertical handover (VHO) delay will be less compared with two conventional WiMAX/WiFi heterogonous networks with two different wireless Internet service providers (WISP). However, protocol conversion is still adding delay and jitter for data exchange between the needed two technologies. In this paper, In order to reduce the delay in protocol conversion, a new design for WiWi (WiMAX and WiFi) adaptation layer is proposed. The realization of the interworking between these two standards is discussed and evaluated.

Ac contactor has been identified as one of the devices vulnerable to the effect voltage sag. We studied the performance of an ac contactor during voltage sags to identify its susceptibility level by determining its voltage sags ride through characteristics. An experiment was conducted to test the ride through capability of a typical contactor when subjected to voltage sags. From the experimental results, the ride-through capability curve is constructed to identify its susceptibility area. However it is important that the characteristics can be simulated without having to perform laboratory experiments so that a simulation of a system that has contactors can be carried for any type configurations. For that purpose, this paper presents the development of an ac contactor model using digital simulation software. The simulation results compared well with the curve obtained experimentally and thus validating the model to be used for any type of voltage sag simulation, which involves a contactor.

Efficient subband structures that aim at fast adaptation of fractionally spaced equalisers (FSE), by exploiting the 'prewhitening' effect that a subband decomposition has on the spectral dynamics of the equaliser input are discussed. Two novel FSE structures are proposed, which differ in the extent to which the feed-forwars and feed-back sections of the FSE are implemented in the subband domain, with distinct impacts on the updating. Improved convergence is achieved at a reduced computational cost compared to a fullband benchmark.