Application of neural network observer for on-line estimation of salient-pole synchronous generators' dynamic parameters using the operating data

Parameter identification is critical for modern control strategies in electrical power systems which is considered both dynamic performance and energy efficiency. This paper presents a novel application of ANN observers in estimating and tracking Salient-Pole Synchronous Generator Dynamic Parameters using time-domain, on-line disturbance measurements. The data for training ANN Observers are obtained through off-line simulations of a salient-pole synchronous generator operating in a one-machine-infinite-bus environment. The Levenberg-Marquardt algorithm has been adopted and assimilated into the back-propagation learning algorithm for training feed-forward neural networks. The inputs of ANNs are organized in conformity with the results of the observability analysis of synchronous generator dynamic parameters in its dynamic behavior. A collection of ANNs with same inputs but different outputs are developed to determine a set of the dynamic parameters. The ANNs are employed to estimate the dynamic parameters by the measurements which are carried out within each kind of fault separately. The trained ANNs are tested with on-line measurements to identify the dynamic parameters. Simulation studies indicate the ANN observer has a great ability to identify the dynamic parameters of salient-pole synchronous generator. The results also show that the tests which have given better results in estimation of each dynamic parameter can be obtained

A statistical analysis on price elasticity of electricity demand using response surface methodology

For strategic planning under restructured environments, it is essential to assess how consumers respond to the price changes in order to increase the profits of supliers and customers. In this study, a case study based on Iran power system was collected to explore the effect of different factors including proportion of income spent-level (A), consumer academic-level (B), demand-types (C), demand time (D), possibility of postponing demand-level (E), price-level (F), demand-level (G) and awareness of participation benefits-level (H) on price elasticity of electricity demand. To achieve this, an nonlinear-empirical model based on Response Surface Methodology (RSM) is created. The statistical analysis reveals that factor A which represents proportion of income spent-level has the most significant effect on determination of the price elasticity of electricity demand while consumer academic-level (B) factor has the least effect. The results can be utilized as a tool for policy makers in developing an effective electricity pricing schemes

Line Differential Protection Modeling with Composite Current and Voltage Signal Comparison Method

This paper discusses the protection system which is the most important part in a power system. Increased protection system reliability determines to improve the performance of the entire electrical system. Differential scheme denoted a very reliable method to secure the protection zone. There have been some studies on this topic. However, still need further study in order to obtain a better system, simple and reliable. The resulting model is made in gradually. Each stage is verified to reduce operational errors. Validation was done using the composite method of current and voltage signals, and the sigma delta algorithm as the analog to digital converter. Numerous computing were done to simulate the differential protection system on the underground cable transmission line 420 kV along the 58.5 km, using Matlab / Simulink. The results showed that the proposed method is effective enough to minimize the percentage of errors

Application of Artificial Neural Network (ANN) for frequency response in power system dynamics

This paper presents a new application of Artificial Neural Network (ANN) for frequency response in system dynamics. In order to perform the ANN, the power flow solution is obtained first for the system to be studied. The purpose of load flow simulation is to get some operating parameters which influence the system frequency behavior. The transient simulation of a power system is then simulated by DigSilent Simulator to analyze the frequency response of the system when it subjected to a disturbance. Simulations were carried out on the IEEE 9-Bus Test System considering load injection on the system. The data collected from transient simulation are then used as inputs to the ANN while the frequency response of the systems as the ANN output. The Lavernberg–Marquardt optimization utilizing very fast propagation algorithm has been adopted for training feed–forward Neural– Network. To verify the effectiveness of the proposed application of ANN method, its performance is compared with the actual value obtained from transient simulation. The ANN provides promising results in terms of error estimation, accuracy and computation tim

Simulation of Distance Relay Operation on Fault Condition in MATLAB Software/Simulink

In this paper a distance relay is simulated in theproposed transmission line protection which is combinationof overhead line and significant part of underground cable.Transmission line is modeled as distributed parameter insteadof lumped parameter to have more accurate analysis compareto conventional analysis. Voltage and current are sampled atrelay point. But, high charging current of cable affects distancerelay operation. Using appropriate filtering can reduce chargingcurrent effect on distance relay. Simulated impedance will becompared with positive sequence impedance of power system inorder to evaluate simulated relay. The relay shows a good resultfor faults in zone 1, but high resistance faults force distance relayto mis-operation

Instantaneous protection scheme for backup protection of high-voltage transmission lines

The protection scheme focused on in this study is a typical protection system used in high-voltage systems such as 132 kV, 275 kV, and 500 kV. The research will analyze the existing protection scheme for transmission lines that the power utility has implemented and will propose a new protection scheme to improve the performance of the existing scheme. The existing protection scheme currently implemented by the power utility for backup protection operation has a longer fault-clearing time and no restoration time, and it does not utilize support relays. This study will focus on a backup protection operation on high-voltage overhead transmission lines, which take up communication when the main protection has failed to communicate, the relay has failed due to loss of DC supply, or the relay function itself has been blocked. Moreover, all the support relays will be utilized in order to improve the protection system. The improvement will consider three elements, which are the fault-clearing time, fast restoration time, and relay utilization. Each improvement to the protection system will have its own philosophy and concrete rationale, which have advantages or disadvantages for the transmission line. The effect of the improvement scheme will also consider the outcomes in other schemes to ensure that time coordination does not overlap. Every possibility of a fault will be analyzed in order to have a clear understanding of the effects of the three elements. CAPE software will be used as a tool for simulation and to analyze its compatibility with real applications. CAPE software is able to model a real-life transmission line and is also able to simulate faults in the tested area. The results of the simulation show that the backup protection operation improved fault-clearing time and restoration time. It also increased the network's system stability, particularly during the occurrence of maximum fault currents

Protection system analysis using fault signatures in Malaysia

a b s t r a c t Electrical power outages are major concerns to power utilities throughout the world. Unfortunately, power outages will continue to happen and they cannot be totally prevented. Outages could be due to lightning strikes, tree encroachments or equipment failures. However, the impact can be reduced if power system operators are equipped with appropriate tools to analyze the root causes of the outages. To ensure system operators have the system fault conditions immediately after a tripping has occurred, this paper discuses practical solutions to be applied in the control center. This paper presents a tool for analyzing protection system performance with special emphasis on the fault signatures using Digital Fault Recorders (DFRs)

Optimal economie dispatch for the nigerian grid system considering voltage and line flow constraints

The electric power industries worldwide have undergone considerable changes especially from vertical structure to full deregulated entities. These changes are now introducing new problems in terms of operations, controls and planning of the entire grid systems. This calls for a more reliable analytical tool ever than before. One feasible solution is to perform the Optimal Economic Dispatch (OED) paradigm on this restructured power system so as to provide fairness to all operators. In this paper, the economic dispatch problem with voltage and line flow constraints has been formulated for the hydro-thermal generating units feeding the Nigerian power system. In order to solve the arising power flow problem a MATLAB based simulation package, MATPOWER version 3.0 has been suitably modified to obtain feasible solutions for different loading system scenarios. The results obtained showed that the OED offered a better optimal power schedules, power loss minimization and reduced total fuel cost than earlier work based on Micro-Genetic Algorithm, (MGA) and Conventional Genetic Algorithm (CGA)

Effect of cross-country fault of distance protection in transmission line with different voltage levels

Transmission overhead line is one of the main elements in electric power system. Electrical power system comprises of generation, transmission and distribution. For transmission lines, it is used to transmit electric power to large load center. Nowadays, double circuit transmission lines on the same tower with a different voltage are widely used. This paper present the studies of the effect on distance protection, when fault that occur in the transmission line that have different voltages in the same tower. In this situation, PSCAD/EMTDC software has been used to simulate the output current and voltages in order to see the fault effect on distance protection. In the other words, the PSCAD/EMTDC software is used in model and analysis of the effect of cross-country fault on distance protection. In this paper, the result of cross-country fault on distance protection with different voltage levels is presented

On the policy of photovoltaic and diesel generation mix for an off-grid site: east malaysian perspectives

The recent policy of the Malaysian government to promote use of renewable, especially photovoltaic, energy has warranted a feasibility study on supplementing diesel generation in off-grid sites by solar (photovoltaic) electricity to be done in the Malaysian context. This paper addresses the technical viability and economy of using a photovoltaic (PV) system to supplement an existing diesel generator-based supply in a typical secondary school located at an interior, off-grid and rural site of Sarawak state in East Malaysia. The findings of the present study, would therefore, help the Government with a realistic picture of the techno-economic aspects in implementing its vision regarding renewable energy. Presently, a 150kW diesel generator supplies electricity to the considered school. The study required simulation of the load sharing pattern of the PV-diesel hybrid system taking into account varied weather and insolation conditions of the chosen site. Also, the purchase price as well as the size of the supplementing PV system that would give the lowest life cycle cost have been determined. The PV system was considered in both forms, i.e. with and without battery back-up. It has been found that if the market price for purchasing a PV system would drop to RM 11.02/WP (Ringgit Malaysia; US$1.00=RM 3.80) i.e. US$2.90/WP, a 35>kWP PV system without battery back-up in conjunction with the diesel generator would be able to supply the selected school's demand at a marginally lower energy cost than the existing diesel-only system. With continuous research and developments, PV price would keep falling in the near future so that a PV-diesel hybrid system with a higher sized PV is expected to be economically more viable. The reported feasibility study can serve as a guideline for making similar studies in the context of another off-grid site