A Speed-Governing System Model with Over-Frequency Protection for Nuclear Power Generating Units

Abstract

Overspeed is more likely to occur in the process of load rejection or large disturbances for nuclear steam turbines due to the large parameter range and low steam parameters, as well as the power of the low-pressure cylinder accounting for a high proportion of the total power. It is of great significance to study the overspeed characteristics of nuclear power plants (NPPs) to ensure the safe and stable operation of the unit and power grid. According to the characteristics of NPPs, the overspeed protection model and the super-acceleration protection model were established, which were added to the speed-governing system model. The response characteristics of the reactor, thermal system, steam turbine and speed-governing system in the process of load rejection or large disturbances of the power grid were analyzed and simulated. The results were compared using the simulation software personal computer transient analyzer (PCTRAN). The simulation results showed that quickly closing both the high and medium pressure regulating valves could effectively realize frequency control when load rejection or a large grid disturbance occurred. The over-acceleration protection cooperates with the super-acceleration protection to avoid the repeated opening/closing of the valves due to overspeed protection. This could effectively reduce the impact of large disturbances on the reactor, thermal system, and turbine.

Analysis of Transient Interactions between a PWR Nuclear Power Plant and a Faulted Electricity Grid

“…A simple interconnection of the modelled PWR-type nuclear power plant connected to the electric grid is shown in Figure 1. The various subsystems of the integrated model have been considered in depth in [16,[23][24][25]. The integrated model has been analysed and verified with simulated as well as plant data in [26].…”

“…In some recent works [14][15][16][17], empirical formulation-based and first principles-based models have been proposed for power system analysis. An optimisation-based method has been put forward by Wang et al for power systems analysis in advanced pressurised water reactor (PWR) [14].…”

“…Wu et al studied the frequency and voltage excursions and discussed the coordinated control and protection of nuclear power plants and grids [15]. For the over-frequency protection of nuclear power plants, a speed-governing system model was also proposed [16]. Lately, a model for a small modular reactor was suggested to study the power system dynamics [17].…”

Modeling the Impact of Modified Inertia Coefficient (H) due to ESS in Power System Frequency Response Analysis

“…Conventionally, the objective of frequency regulation (FR) is achieved with the help of spinning and nonspinning reserves during normal conditions. However, to avoid larger blackouts, underfrequency load-shedding or overfrequency protection schemes are deployed during contingency stages [3][4][5]. There are several studies that explain the frequency regulation process in the conventional power systems (e.g., [1,6]).…”

Failure Modes Detection of Nuclear Systems Using Machine Learning

“…The dynamical model of a turbine consisting of the highpressure, intermediate-pressure, and low-pressure turbines is given by [37], (30) where the steam flow ism so =ṁ so /ṁ sor ,ṁ sor is the rated steam mass flow rate. The steam flow rate can be modified using the turbine-governor control valve coefficient (C tg ) aṡ…”