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电气专业英语翻译!高手帮忙!Voltage stability
Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the system under normal operating conditions and after being subjected to a disturbance. A system enters a state of voltage instability when a disturbance, increase in load demand, or change in system condition causes a progressive and uncontrollable drop in voltage. The main factor causing instability is the inability of a power system to meet the demand for reactive power. The heart of the problem is usually the voltage drop that occurs when active power flow through inductive reactances associated with the transmission network.
Progressive drop in bus voltages can also be associated with rotor angles going out of step. For example, the gradual loss of synchronism of machines as rotor angles between two groups of machines approach or exceed 180° would result in very low voltages at intermediate points in the network. In contrast, the type of sustained fall of voltage that is related to voltage instability occurs where rotor angle stability is not an issue.
Voltage instability is essentially a local phenomenon; however, its consequences may have a widespread impact. Voltage collapse is more complex than simple voltage instability and is usually the result of a sequence of events accompanying voltage instability leading to a low-voltage profile in a significant part of the power system. Voltage instability may occur in different ways.
For purpose of analysis, voltage stability is usually classified into the following two subclasses:
(1) Large-disturbance voltage stability is concerned with a system’s ability to control voltages following large disturbances such as system faults, loss of generation, or circuit contingencies. This ability is determined by the system load characteristics and the interactions of both continuous and discrete controls and protections. A criterion for large-disturbance voltage stability is that, following a given disturbance and following system-control actions, voltages at all buses reach acceptable steady-state levels.
(2) Small-disturbance voltage stability is concerned with a system’s ability to control voltages following small perturbations such as incremental changes in system load. This form of stability is determined by the characteristics of load, continuous controls, and discrete controls at a given instant of time. A criterion for small-disturbance voltage stability is that, at a given operating condition for every bus in the system, the bus voltage magnitude increases as the reactive power injection at the same bus is increased. A system is voltage-unstable if, for at least one bus in the system, the bus voltage magnitude decreases as the reactive power injection at the same bus is increased.
Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the system under normal operating conditions and after being subjected to a disturbance. A system enters a state of voltage instability when a disturbance, increase in load demand, or change in system condition causes a progressive and uncontrollable drop in voltage. The main factor causing instability is the inability of a power system to meet the demand for reactive power. The heart of the problem is usually the voltage drop that occurs when active power flow through inductive reactances associated with the transmission network.
Progressive drop in bus voltages can also be associated with rotor angles going out of step. For example, the gradual loss of synchronism of machines as rotor angles between two groups of machines approach or exceed 180° would result in very low voltages at intermediate points in the network. In contrast, the type of sustained fall of voltage that is related to voltage instability occurs where rotor angle stability is not an issue.
Voltage instability is essentially a local phenomenon; however, its consequences may have a widespread impact. Voltage collapse is more complex than simple voltage instability and is usually the result of a sequence of events accompanying voltage instability leading to a low-voltage profile in a significant part of the power system. Voltage instability may occur in different ways.
For purpose of analysis, voltage stability is usually classified into the following two subclasses:
(1) Large-disturbance voltage stability is concerned with a system’s ability to control voltages following large disturbances such as system faults, loss of generation, or circuit contingencies. This ability is determined by the system load characteristics and the interactions of both continuous and discrete controls and protections. A criterion for large-disturbance voltage stability is that, following a given disturbance and following system-control actions, voltages at all buses reach acceptable steady-state levels.
(2) Small-disturbance voltage stability is concerned with a system’s ability to control voltages following small perturbations such as incremental changes in system load. This form of stability is determined by the characteristics of load, continuous controls, and discrete controls at a given instant of time. A criterion for small-disturbance voltage stability is that, at a given operating condition for every bus in the system, the bus voltage magnitude increases as the reactive power injection at the same bus is increased. A system is voltage-unstable if, for at least one bus in the system, the bus voltage magnitude decreases as the reactive power injection at the same bus is increased.
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