Abstract: Problem statement: **The** **exact** **long** **transmission** **line** **model** consists **of** **the** lump **of** **the** series resistance, reactance and shunt capacitance. **With** **the** consideration **the** actual **long** **transmission** **line** **model**, it causes in **the** difficulty **of** deriving **the** mathematical **model**. Approach: This study investigates **the** **transient** **stability** **of** **power** **system** **with** consideration **the** **exact** **long** **transmission** **line** **model**. **The** concept **of** two-port network is applied in this study. **The** generator, transformer and short **transmission** **line** are represented by two-port networks. **With** **the** combination principles **of** **the** series and shunt connection, **the** mathematical **model** is achieved in a much simpler way. **The** proposed method is tested on **the** sample **system** and compared on various cases. Results: **The** first swing **of** rotor angle curve **of** **the** faulted **system** without **the** resistance is obviously higher than that **of** **with** **the** resistance whereas **the** second swing **of** **the** faulted **system** without **the** resistance is slightly less than that **of** **with** **the** resistance. **The** critical clearing time **of** **the** **system** **with** **the** resistance is better than that **of** **with** resistance. Conclusion: It was found from **the** simulation results that **the** resistance **of** **the** **line** provides **the** improvement **of** **the** first swing but not for **the** second swing. It was found from this study that for practical **long** **line**, **the** resistance is very import parameters to determine **the** critical clearing time **of** **the** single machine infinite **system** whereas shunt capacitance insignificantly affects on **the** critical clearing time **of** **the** single machine infinite bus **system**.

Mostrar mais
4 Ler mais

Abstract— In this paper, field measurements carried out in a suburban SFN network **with** two synchronized transmitters are reported. It is found that **the** radio signal coverage **of** **the** distributed **transmission** scheme is distinctly improved when compared to a single transmitter **system**. **The** path loss gain and improvement associated to **the** SFN scheme are obtained as well as **the** multipath channel parameters including **the** mean and RMS delay spread. A tapped delay **line** is used to **model** **the** average **power** delay profile (PDP) in **the** distributed **transmission** cases and shows rather different features than **the** single **transmission** case.

Mostrar mais
9 Ler mais

7 Ler mais

To study **the** **transient** **stability** phenomenon a simplest **power** **system** is analyzed by **the** utilization **of** SimPower **System** toolbox presented in **the** MATLAB/Simulink software environment. Fig.1 represents single **line** diagram **of** SMIB **system** which comprises **of** a **transmission** **line** connecting an AC **power** source at **the** sending end and a receiving side connected to a RL load. This arrangement is first studied without STATCOM using a generating source **with** 230 kV voltage which simulates a synchronous generator **of** 500MVA capacity **with** terminal voltage 11kV, and its associated step up transformer **with** 500MVA, 11/230kV rating. **The** real **power** flow and reactive **power** flow in this configuration and **the** associated sending end and receiving end parameters have been observed. In Simulink **Power** **system** blocks, **the** reactive and active **power** blocks are available for measuring **the** **power** flow both at **the** sending end and **the** receiving end.

Mostrar mais
11 Ler mais

Including monitoring and control equipment along **with** transformer switch gear protection. **Transmission** and distribution lines are designed for **transmission** **of** **power** from generating station to end user only. However, **transmission** lines, 66Kv and above are presently employed for audio communication between **the** operators at two ends **of** **the** **transmission** lines viz. Substation operators, carrier protection schemes and telemetry signal. These signals are modulated before sending on **transmission** lines in **the** frequency range **of** 100 KHz – 500 KHz for overhead **transmission** lines and 10 KHz – 100 KHz for underground cables. Such conventional modulated communication **system** over **power** **line** functions satisfactorily during normal operation **of** **power** **system**. However, during **transient** conditions when a fault occurs on **the** **transmission** lines, **power** frequency harmonics up to 100 KHz frequency are generated and distributed to **the** communication **system** [5]. It is, therefore required same methodology that **the** communication shall not be disturbed during **transient** and emergencies for **the** safe operation **of** **the** **power** **system**. Since **the** **power** wiring **system** was originally intended for **transmission** **of** AC **power**, **the** **power** wire circuits have only a limited ability to carry higher frequencies.

Mostrar mais
10 Ler mais

Abstract: Problem statement: **The** Static Var Compensator (SVC) have been widely investigated its effect on **transient** **stability** **of** Single Machine Infinite Bus (SMIB) **system**. **The** **exact** medium **transmission** **line** **model** in **power** **system** consists **of** **the** series resistance series reactance and shunt capacitance. It is not easy task to obtain **the** mathematical **model** **of** **the** SVC **with** **the** **exact** medium **transmission** **line** **model** for investigating **transient** **stability** performance. Approach: This study applied **the** concept **of** **the** two-port network to simplify **the** mathematical **model** **of** **the** **power** **system**. **The** full capacity **of** **the** SVC on **transient** **stability** improvement **of** **the** SMIB **with** **the** medium **transmission** **line** was then investigated. **The** proposed method was tested on sample **system** and compared on various cases. Results: **The** first swing **of** rotor angle curve **of** **the** faulted **system** without resistance was obviously higher than that **of** **with** resistance whereas **the** second swing **of** **the** faulted **system** without resistance was slightly less than that **of** **with** resistance. **The** **system** **with** a SVC could improve **transient** **stability** **of** **power** **system**. Conclusion: **The** SVC and resistance **of** **the** **line** can improve first swing **of** rotor angle. **The** resistance **of** **the** **line** provides negative effect on second swing **of** rotor angle. **The** simulation results indicate that for practical medium **line**, **the** resistance is very import parameters for evaluating **transient** **stability** **of** **power** **system**.

Mostrar mais
4 Ler mais

techniques available in PSAT are **the** Euler and trapezoidal rule techniques. In this work, **the** trapezoidal technique is used considering **the** fact that it is widely used for solving electro-mechanical differential algebraic equations [12] . **The** type **of** contingency considered is **the** three-phase balanced faults created at various locations in **the** **system** at any one time. When a three-phase fault occur at any **line** in **the** **system**, a breaker will operate and **the** respective **line** will be disconnected at **the** Fault Clearing Time (FCT) which is set by a user. **The** FCT is set randomly by considering whether **the** **system** is stable or unstable after a fault is cleared. According to ref. [13] , if **the** relative rotor angles **with** respect to **the** slack generator remain stable after a fault is cleared, it implies that FCT<CCT and **the** **power** **system** is said to be stable but if **the** relative angles go out **of** step after a fault is cleared, it means FCT>CCT and **the** **system** is unstable.

Mostrar mais
8 Ler mais

FACTS controllers are capable **of** controlling **the** network condition in a very fast manner and this unique feature **of** FACTS can be exploited to improve **the** **stability** **of** a **power** **system** (Panda, 2010; Kumkratug, 2010). **The** detailed explanations about **the** FACTS controllers are well documented in **the** literature. Static Synchronous Series Compensator (SSSC) is one **of** **the** important members **of** FACTS family which can be installed in series in **the** **transmission** lines for applications such as increased **power** transfer, improved **transient** and small disturbance **stability** **of** **power** systems (Abido, 2009; Shakarami and Kazemi, 2010). SSSC is very effective in controlling **power** flow in a **transmission** **line** **with** **the** capability to change its reactance characteristic from capacitive to inductive.

Mostrar mais
6 Ler mais

7 Ler mais

4 Ler mais

It was found from **the** simulation results that **the** resistance **of** **the** **line** provides **the** improvement **of** **the** first swing but not for **the** second swing. It was found from this study that for practical **long** **line**, **the** resistance is very import parameters to determine **the** critical clearing time **of** **the** single machine infinite **system** whereas shunt capacitance would not affect on critical clearing time **of** single machine infinite bus **system**. It was also found in this study that **the** TCSC can enhance **transient** **stability** **of** **power** **system**.

Mostrar mais
5 Ler mais

Abstract: Problem statement: **The** enhancement **of** **transient** **stability** **of** **the** **power** **system** is one **of** **the** most challenging research areas in **power** engineer. Approach: This study presents **the** method to enhance **transient** **stability** **of** **power** **system** by Unified **Power** Flow Controller (UPFC). **The** mathematical **model** **of** **power** **system** equipped **with** a UPFC is systematically derived. **The** parameters **of** UPFC are modeled into **power** flow equation and thus it is used to determine control strategy. **The** swing curves **of** **the** three phase faulted **power** **system** without and **with** a UPFC are tested and compared in various cases. Results: **The** swing curve **of** **system** without a UPFC gets increases monotonically and thus **the** **system** can be considered as unstable whereas **the** swing curves **of** **system** **with** a UPFC can return to stable equilibrium point. Conclusion: From **the** simulation results, **the** UPFC can enhance **transient** **stability** **of** **power** **system**.

Mostrar mais
5 Ler mais

operation. More specifically keep voltages close to nominal values, reduce **line** currents and hence network losses. Reactive **power** compensation also contributes to **the** voltage **stability** margin enhancement. Compensation is provided by either capacitors installed in series **with** **transmission** lines or shunt elements connected to a particular load bus. In this study shunt compensation technique is adopted to improve **the** voltage **stability** margin.

4 Ler mais

13 Ler mais

Here 1013.25 is **the** pressure at sea level in mil/bar, z is **the** altitude in meters. Knowing p 0 ( z ) and **the** relation for resistance to flow, **the** pressure variation on **the** human body have been computed by **the** following method. We have

3 Ler mais

6 Ler mais

16 Ler mais

In **the** meanwhile, Fig. 8 shows that current rating is greatly influenced by wind direction, resulting in **the** changes **of** conductor temperature. However, this dependence disappears as **the** wind velocity is reduced to zero. During **the** situations in which **the** wind direction changes rapidly, **the** conductor temperature can be expected to reflect these changes. **The** actual response **of** **the** conductor temperature will be postponed from **the** variations in **the** weather conditions due to **the** thermal capacitance **of** **the** conductor. In Malaysia, there are 2 majors **of** vibration damage on **the** conductor. They are Aeolian vibration and sub-conductor oscillation, which cause by wind parameter (JMM, 1958).

Mostrar mais
12 Ler mais

4 Ler mais

7 Ler mais