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Compensation in Power System
Published in Amitava Sil, Saikat Maity, Industrial Power Systems, 2022
Importance of reactive power: (i) voltage control in an electrical power system is important for proper operation for electrical power equipment to prevent damage such as overheating of generators and motors, to reduce transmission losses and to maintain the ability of the system to withstand and prevent voltage collapse; (ii) decreasing reactive power causes voltage to fall while increasing it causes voltage to rise. A voltage collapse may occur when the system tries to serve much more load than the voltage can support; (iii) when reactive power supply lowers voltage, as voltage drops, current must increase to maintain power supplied, causing system to consume more reactive power and the voltage drops further. If the current increases too much, transmission lines go offline, overloading other lines and potentially causing cascading failures; (iv) if the voltage drops too low, some generators will disconnect automatically to protect themselves. Voltage collapse occurs when an increase in load or less generation or transmission facilities causes dropping voltage, which causes further reduction in reactive power from capacitor and line charging, and still further voltage reductions. If voltage reduction continues, this will cause additional elements to trip, leading further reduction in voltage and loss of the load. The result in these entire progressive and uncontrollable declines in voltage is that the system is unable to provide the reactive power required supplying the reactive power demands.
Design, Construction, and Operation of Distribution Systems, MV Networks
Published in James Northcote-Green, Robert Wilson, Control and Automation of Electrical Power Distribution Systems, 2017
James Northcote-Green, Robert Wilson
Voltage Control by the Source Transformer Tap Changer. The voltage ratio of the source transformer that feeds an MV busbar is typically 110/20 kV. The incoming 110 kV is applied to the whole primary winding, and the secondary voltage is taken off the secondary winding. However, one winding can have a small number of additional turns at one end, such that, by switching the incoming supply to one of the additional sets of turns, a change in the voltage ratio is achieved in proportion to the additional turns. These additional turns are known as transformer taps and are usually fitted on the primary winding simply because the tap switching mechanism then operates on the lower current of the primary winding, at least for voltage stepdown transformers. Similarly, the taps are usually located on the “earthy” end of the winding so as to reduce the voltage capabilities of the tap changing mechanism.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Voltage control is required for proper operation of customer equipment. For instance, in the U.S., “voltage range A” for single-phase residential users specifies that the voltage may vary at the service entrance from 114/228V to 126/252V. Regulators, tap-changing under load transformers, and switched capacitor banks are used in voltage control.
Coordination of PV Inverters and Voltage Regulators Considering Generation Correlation and Voltage Quality Constraints for Loss Minimization
Published in Electric Power Components and Systems, 2020
Sarmad Ibrahim, Aaron M. Cramer, Yuan Liao
As a result of environmental pollution caused by conventional generation sources (e.g., fossil-based power generation), DGs, which can be installed by consumers or electric utilities, are considered a feasible technical solution to mitigate these unwanted impacts and support the voltage stability of distribution network [1]. The increasing penetration level of DGs in distribution systems has many benefits such as reducing system losses and increasing system reliability [2]. Nevertheless, primary technical challenges are voltage control problems such as a voltage fluctuation [3]. These significant technical challenges are associated with the integration of DGs due to the change in the DG power outputs both over the course of the day and over much shorter periods (e.g., due to cloud transients). The uncertain variation of the DG output powers can cause a considerable voltage magnitude variation across the distribution system. Such variations in PV power may lead to unfavorable operating conditions and power system failures. Such rapid variations in voltage magnitude can lead to inappropriate operation conditions of distribution system equipment and sensitive electronics, computers, and microprocessors [4, 5]. Accordingly, traditional voltage and reactive power control devices may suffer from excessive operations which may in turn lead to wear and tear of this equipment [6]. With rapid improvement of inverter-based DGs, these inverters have become the essential technical solution for distribution systems operators to perform fast and flexible voltage regulation to improve the system performance [7].
A Centrality Index Based Approach for Selection of Optimal Location of Static Reactive Power Compensator
Published in Electric Power Components and Systems, 2018
In power system network, reactive power is essential to maintain the voltage through the buses present in the system so that active power can be transferred. Voltage control in an electrical power system is important for proper operation of electrical equipments to reduce transmission losses and to prevent voltage collapse. Reactive power plays an important role in function of regulating voltage. While managing reactive power and voltage, main objective is to maintain adequate voltages throughout the transmission and distribution system in addition to minimize real power losses. In restructured electricity market, management of reactive power and its pricing is a separate service for system operator so that voltage stability should be maintained in any condition. Hence, it needs an intelligent planning and suitable procurement of reactive power.
Stability analysis of single area power system considering parameter uncertainties
Published in Australian Journal of Electrical and Electronics Engineering, 2020
Voltage control in power system is mainly concerned with the regulation of voltage at the terminals of equipments within acceptable threshold after a disturbance. System stability, on the other hand, is closely related to the optimum utilisation of transmission system along with associated system losses. Power system continuously experiences load changes due to inequality between generation and demand causing change in operating conditions. The change in operating condition results in small swings or oscillations in interconnected systems leading to collapse in voltage and steady-state power transfer across various networks (Prasertwong, Mithulananthan, and Thakur 2012).