Wavelet Based Protection Scheme For Multi Terminal Transmission System

A Power system is an connection of generators to load centres. Through H.V. electrical lines & in general is controlled mechanically. It can be divided into 3 subsystems: Generation, X’mission and Distribution-systems. The electric power demand is Growing and building of new generating units & transmission circuits is becoming difficult because of environmental & economic reasons. So, power utilities are forced to depend on utilization of existing generating units and to load existing lines close to their heating limits.

measurements of three-phase voltage and current samples obtained from the PSCAD/EMTDC. Fig. 8 depicts the 220 kV, 50 Hz simulated system one-line diagram. The other related parameters of the simulated system are shown in Table 1, transmission lines are assumed completely transposed. Fig. 9 & 10 show 3ph voltages and currents waveforms for 3ph to ground fault at 50% of the second line without and with UPFC respectively. It is clear that when UPFC is involved in the fault loop, the the voltage and current signals would be deviated from the actual value.

A power system is always in a state of disturbance that may lead to instability in the system. The consequences of a major power supply interruption can prove to be so disastrous, that every effort must be made to reduce the impact of such a disturbance. The process of determining the steadiness of the power system following any upset is known as security assessment. In particular, MW security assessment is a process to evaluate the security of the power system following a disturbance. It is done considering the loading conditions in respect of MW power flow on the lines. Each line has a capacity to carry MW power up to transmission line design limits beyond which the lines may trip due to overloading. In this paper MW security assessment has

The DVR is one of the most common and effective solutions for protecting critical load against voltage sags [10] [11]. The DVR is a power electronic device used to inject three-phase voltages in series and in synchronism with the distribution feeder voltages in order to compensate for voltage sags. Moreover, it can be efficiently used to augment the fault ride through capability in wind applications. Detection time is an important factor in the voltage restitution process. Fast detection

Yan et al (2008) & Ebeling (1997), pointed out the purpose of maintenance is to extend equipment life and minimise the frequency of service interruption. Ebeling (1997) concluded that availability is the important index of the all indices for power availability. Several maintenance types or tactics have been suggested by many authors for example (Mowbray, 1991 and Kelly, 1997). There are mainly two types of maintenance practices and these are breakdown and preventive maintenance. Breakdown maintenance requires replacement of damaged part of the equipment during unscheduled maintenance while preventive maintenance requires replacement of the components at pre-determined intervals. Condition based maintenance is used to monitor the condition of the equipment using condition monitoring technique.

Problem statement: As the characteristics of the distribution network and high volume power electronics penetration into the network are significantly different from the conventional power system, several issues are raised. Some of the issues, which are a promising field for future research, are described shortly below:

The JV partner Engie Energía Chile S.A. (“EEC”) (BBB/BBB; SFS Equivalent 4-), is a subsidiary of Engie S.A. (Engie) (A-/A2/A-; SFS Equivalent 3-), and Red Eléctrica Chile (“REC”), subsidiary of Red Eléctrica Corporación S.A.U. (A-/Baa1/A; SFS Equivalent 3-). Both partners have significant experience in operating and managing a transmission grid. The risk designation of “Neutral/Standard” corresponds to the 4- equivalent

Easun Reyrolle, India is a leader in the field of electrical power management, a vibrant and growing industry. This is the parent company of the ERL group, which consists of ERL International Pte. Ltd: Singapore, ERL Marketing International FZE: Sharjah, ERL Phase Power Technologies Ltd: Canada, ERL Switchcraft Europe GmbH: Germany and ERL Electrical Distribution Solutions Pt Ltd: Australia. Executed by Easun Reyrolle Ltd to suffice the Energy Meter requirements of different electricity boards in India.

Moreover, when speed decreases during a disturbance, TII of the critical series components increases and does not provide accurate stability assessment. To overcome this issue, the local minimums of the TII are considered. When the present value of TII is lower than the previous local minimum value, it would replace the local minimum value. It means that the critical series component keeps its critical status until its next local minimum. When its local minimum increases, it means more stable case. To clarify this matter, TII and modified TII of transformer 11-32, the most critical series component, for previous fault are shown in Figure 4.4. Figure 4.4 shows that the system is first-swing stable as the modified TII increases with time.

Power system security is an important aspect in the present generation. Power system security must also be economical. We can’t predict the fault at every time, so based on trend analysis method on load profile in this paper we are going to see the various methods which help for the protection of the power system. So we should carefully monitor the security. By these methods discussed in the paper we are to form security indices which helps us to calculate the faults in advance. With these methods when problem occurs in real time we will have the security indices to respond faster to find out the solution for the problem and also we can protect in advance.

In past 10 years, a lot of Plessey Data-term units are failure at multiple substations

After the real time data is collected from the sensors, the first important step for condition monitoring and faults detection is to develop efficient signal analysis algorithm that can be used to extract useful information from raw data for further diagnostic and prognostic purpose. Several useful algorithms that widely used for faults detection purpose will be discussed in this section which includes time-domain analysis, frequency domain analysis, time-frequency analysis and wavelet transform. These techniques are the fundamental of health monitoring methods.

Abstract— Voltage instability is one of the major power system problems which have appeared since the existence of the power systems. This paper investigates the performance of Recurrent Neural Networks (RNN) in voltage instability early prediction. Voltage instability early detection is necessary for avoiding voltage collapse which can lead to power system fast breakdown. In this research, the bus voltage phase is considered as the main factor of power system voltage instability early detection. Voltage instability leads to a considerable change in the difference between the consecutive buses voltage angles. A recurrent neural network trained with Particle Swarm Optimization (PSO) is proposed in this paper. The proposed method is examined on 14-bus and 30-bus IEEE standard systems. These systems are simulated using MATLAB/Power System Toolbox program. The performance of the proposed method is compared with Back-propagation (BP) training algorithm.

Moreover, the expected separation area(s), i.e., power system islands, and the critical series components, i.e., islands' boundaries using the equivalent of parallel components, are not accurately determined. The simplest example of the direct methods is the EAC. The EAC method is enhanced to be applicable to multi-machine systems, i.e., extended equal area criterion (EEAC) [82]. The EEAC method reduces the interconnected system into a two equivalent machine system or a single machine infinite bus. Hence, this method can be used only for the classical generator equivalent model, i.e., swing equation model or second-order model [76],[6]. An attempt has been made to overcome the limitations of both time-domain and Lyapunov-like functions by combining them, i.e., hybrid methods [6],[5]. The hybrid method also can be the result of combining time-domain and EEAC methods [83], i.e., Single Machine Equivalent (SIME) Method, to allow the use of detailed generator models. However, they are valid only for unstable cases and fault duration relatively close to the fault clearing time [76]. Also, all direct methods depend on the fault-on trajectory [84] which is not accurate for a fault followed by tripping a line and it is not valid for other contingencies not associated with faults. Machine learning/pattern recognition techniques also are used for transient stability

Feed forward control is a reliable for rejecting fast and dynamic voltage disturbances in the phase grid. Mainly in this scheme implemented in phase voltages of the Wyes connected configuration. Under this unbalanced and distorted grid conditions, the online conversion of line - to - line values into the phase value is unworkable. In order to an exploit full advantages of feed forward controller is a most appropriate modulator is needed. In this article the feed forward of grid line-to-line voltages is used in phase voltages. The introduced feed forward method is implemented in Implicit Zero Sequence Discontinuous Pulse Width Modulation (IZDPWM) technique that is compatible for grid connected inverters. Regarding in the IZDPWM grid topologies distorted the harmonics of the grid voltages. Hence, a sinusoidal current is injected to the grid. Moreover, the measuring grid line-to-line voltages two sensors are required; hence an overall system costs is reduced and control system reliability is increased. The time-domain simulations in MATLAB/Simulink and experimental results from a Hardware based laboratory prototypes are in good agreements,