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Power Flow Studies
Published in Syed A. Nasar, F.C. Trutt, Electric Power Systems, 2018
Remembering now that |Eg| increases as the field excitation in the synchronous machine is increased, it is a simple matter to raise or lower |Eg| by raising or lowering the generator or motor field current. If we now confine our discussion to reactive power flow only and neglect any real power flow, δ must be zero according to (4.7) and average reactive power flow is proportional to (|Eg|2 – 12) in accordance with (4.10). Therefore, overexciting (applying a large field current) in either a synchronous generator or an unloaded synchronous motor will result in a reactive power flow into the system bus. The effect of this reactive power flow is to raise the bus voltage (see Example 4.3). A synchronous motor applied in this manner is often called a synchronous condenser.
FACTS and HVDC
Published in Stuart Borlase, Smart Grids, 2018
Neil Kirby, Johan Enslin, Stuart Borlase, Neil Kirby, Paul Marken, Jiuping Pan, Dietmar Retzmann
While the synchronous condenser is not a new, high-tech device invented to contribute to the modern smart grid, it is worthy to consider that this may be the original Volt/VAr controller. Once commonly found in both industrial and utility applications, the number of synchronous condensers in operation has been on the decline. Simply put, the synchronous condenser is a synchronous motor without a load connected to its shaft. Or viewed in a way more familiar to the utility industry, a condenser is similar to a generator without a prime mover. The field is under- or overexcited to absorb or produce reactive power. The machine will absorb a small amount of real power to overcome losses. When equipped with a modern generator field exciter, the speed of response is reasonably fast.
6 Power Factor
Published in C. Sankaran, Power Quality, 2017
It was observed in Chapter 4 that capacitor banks must be selected and applied based on power system harmonic studies. This is necessary to eliminate conditions that can actually amplify the harmonics and create conditions that can render the situation considerably worse. One means of providing leading reactive power is by the use of synchronous motors. Synchronous motors applied for power factor control are called synchronous condensers. A synchronous motor normally draws lagging currents, but when its field is overexcited, the motor draws leading reactive currents (Figure 6.11). By adjusting the field currents, the synchronous motor can be made to operate in the lagging, unity, or leading power factor region. Facilities that contain large AC motors are best suited for the application. Replacing an AC induction motor with a synchronous motor operating in the leading power factor region is an effective means of power factor control. Synchronous motors are more expensive than conventional induction motors due to their construction complexities and associated control equipment. Some facilities and utilities use unloaded synchronous motors strictly for leading reactive power generation. The advantage of using a synchronous condenser is the lack of harmonic resonance problems sometimes found with the use of passive capacitor banks.
Linearization of a class of non-linear systems modelled by multibond graphs
Published in Mathematical and Computer Modelling of Dynamical Systems, 2019
Gilberto Gonzalez Avalos, Gerardo Ayala, Noe Barrera Gallegos, Aaron Padilla Jose
Synchronous generators form the principal source of electric energy in power systems, many large loads are driven by synchronous motors and synchronous condensers are sometimes used as a means of providing reactive power compensation and controlling voltage. These devices operate on the same principle and are collectively referred to as synchronous machines [26]. Figure 15 shows the schematic of the cross-section of a three-phase synchronous machine with one pair of field poles. The field winding carries direct current and produces a magnetic field which induces alternating voltages in the armature windings.