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Using ultra high voltage (UHV) disconnector to switch the fixed series compensation capacitors platform may induce fast transient phenomenon and repetitive breakdown of disconnector, adjacent capacitor voltage transformer (CVT) will suffer from repetitious transient overcurrent. The high amplitude and steepness current may damage adjacent CVT. In order to reduce the transient impulse current amplitude,...
System stability and protection from any disturbances are significant problems in power system especially in a distribution system with dispersed generation. Superconductivity is expected to be a powerful controller to stabilize and protect the power systems. SMES is effective to damp the power swing Improvement transient stability SMES not able to absorb enough energy during fault. In order to enhance...
STATic synchronous COMpensator (STATCOM) can be integrated into electric transmission systems to provide reactive power compensation and grid voltage support for achieving high-efficient and reliable Flexible AC Transmission Systems (FACTS). An emerging solution for STATCOM with modular structure and multilevel voltage output, named as modular multilevel STATCOM (mmSTATCOM) shows its great advantages...
Historically, failures of distribution transformers due to transient overvoltage phenomena has led to the development of Resistor-Capacitor snubber circuits for the protection of the transformer and winding insulation. These transients are most often observed when dry-type transformers are close coupled to vacuum switching devices. Typically, snubber circuit design has been specific for the particular...
Recently, two Modular Multilevel Converter (MMC) projects are under construction in China. Since these are the first two multi-terminal MMC projects in the world and the controllers are sophisticated, a real time simulation platform becomes critical to enable hardware-in-the-loop (HIL) test and validation of the MMC controllers in various scenarios, before applying them in the field. This paper presents...
One of Saudi Aramco's gas exploration expansion plans consists of powering an offshore platform via a 13.8 kV, 56 km subsea cable. Under various loading conditions on the offshore platform, voltage fluctuation and control becomes problematic. The installation of a 13.8 kV shunt capacitor bank (SCB) and shunt reactor bank (SRB), was initially introduced to remedy voltage control. During transient analysis,...
Series capacitors compensation plays a more and more important role in long-distance and large-capacity transmission system, whose model has a significant impact to system stability study. Firstly, both gap protected SC model and linearized model is applied into the available power transmission capability and system stability study in electromechanical transient simulation in this paper. Secondly,...
This paper presents high performance control algorithms for a 100 kVA three-phase four-wire online voltage regulator. The 100 kVA voltage regulator is composed of a PWM rectifier, a center-tapped DC bus, and an inverter. The rectifier connects with the grid through an LCL filter, providing power factor correction and DC-link voltage regulation. The inverter output power is fed forward to the rectifier...
This paper proposes an algorithm based on the use of the S-transform for time-frequency analysis of the capacitor-switching transients. With no prior knowledge about system parameters, the time-frequency analysis of the voltage and current transient signals due to switched capacitor banks are used to simply but accurately estimate the relative location of the switched capacitor whether it is upstream...
The operation of PWM motor drives with long cables results in several undesired phenomena. In order to avoid them all, it was proposed in a previous work that the long cable be used to connect the rectifier to the inverter, which would then be placed beside the motor, thus establishing a DC line transmission. In the mentioned work, the additional benefit of the proposal, which is the reduction of...
Power Transmission Systems have predominantly inductive loads, so that the systems themselves must supply the reactive power consumed. The most practical and efficient way for the utility to supply the reactive power demanded is through the installation of Mechanically Switched Capacitors (MSCs), more common know as shunt capacitor banks. The installation of MSCs brings benefits concerning the reduction...
This paper proposes an identification scheme of capacitor switching transients using Approximate Entropy (ApEn) approach. Detailed procedures of the proposed scheme are presented. Simulation and real results indicated that the scheme is feasible for classification of power event signals.
More and all-electric aircraft (AEA) carry many loads with varied functions. In particular, there may be large pulsed loads with short duty ratios which can affect the normal operation of other loads. In this paper, a converter with spilt capacitors and a simple adaptive controller is proposed as a Voltage Bus Conditioner (VBC) to mitigate the voltage transients on the bus. The proposed converter...
A capacitive sensor has been developed for the measurements of very fast transient over-voltages (VFTO) in GIS. Step response measurement was performed on the sensor. It is shown from the test that the settling time is less than 20 ns and the response time is less than 2 ns, suitable to the IEC1321-1. The sensor has been calibrated by power frequency voltage, impulse voltage, the division ratio of...
Summary form only given. This paper proposes applying the 2-stage diagonally implicit Runge-Kutta (2S-DIRK) method of numerical integration to the calculation of electromagnetic transients (EMTs) in a power system. The accuracy and the numerical stability of 2S-DIRK are almost the same as those of the trapezoidal method, while 2S-DIRK does not produce sustained numerical oscillation due to a sudden...
Three-level (TL) switch unit is produced by two-level switch unit connected together in series manner. Combination mode TL AC-AC converter is proposed. The principle is investigated. In order to keep the balance of the claming capacitor voltages, mixed staggered complemented control strategy is proposed. Transient voltage feedback control strategy is taken in the proposed converter and principle diagram...
Controllable series capacitors have been utilized to damp swings resulted from large transient disturbances in power systems, and the switching time of the capacitors has distinct influence on the swings of the machines. The reason that different switching time of the series capacitor brings out different stability of the system is analyzed in this paper, a method for calculating the optimal switching...
In this paper, application of SVM to classify disturbances in power quality is discussed. Power system transient can pose a serious threat to the reliability of power system apparatus and sensitive loads. There are numerous causes of power system transient namely short circuits, capacitor bank switching, switching of large inductive loads that include motors and transformers as well as lightning....
Based on a hydro-energy storage station, the very fast transient over-voltage in GIS is calculated and simulated using the FORTRAN language and Matlab program. The node with the maximum of the VFTO is found. The suppression effect of cable and SF6 busbar is discussed, and the influence the shunted capacitor is analyzed in the paper. It is indicated that the VFTO peak-values may be restricted by increasing...
The transient caused by capacitor switching is an important power quality (PQ) problem. Switching the capacitor may cause a disturbance to a voltage-sensitive load or a resonance in the system. This paper presents a new method to identify the positions of the transients caused by capacitors through the PQ monitoring system. The discrete wavelet transform is used to extract the features of transients...
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