Xiaojin Huang

Water-Level Control for the U-Tube Steam Generator of Nuclear Power Plants Based on Output Feedback Dissipation

U-tube steam generator (UTSG) is one of the most important facilities in a pressurized-water nuclear reactor. The water level control of UTSG is crucial to secure the sufficient cooling inventory for the nuclear reactor and, at the same time, to prevent the damage of turbine blades. Because of high nonlinearity and nonminimum phase characteristics of steam generator dynamics, it is necessary to establish an effective nonlinear water-level controller. After establishing the state-space model of a UTSG, an output feedback dissipation control (OFDC) for nonlinear systems is presented, and then an output feedback dissipative L 2 disturbance attenuator is also proposed. The robustness of the OFDC is analysis through comparing the two controllers. Furthermore, the OFDC is applied to water-level control for the UTSG of a low temperature reactor (LTR). Numerical simulation results with comparison to a PID-like water-level controller show the high performance of the OFDC.

Dissipation-Based High Gain Filter for Monitoring Nuclear Reactors

Growing electricity requirement and the serious pollution caused by burning petroleum and coal give the current rebirth of nuclear energy industry. State observation is one of the key and basic technologies of system monitoring which is very necessary to the safe and effective operation of todays nuclear reactors. Since nuclear reactors are complex and nonlinear systems, it is quite necessary to design a nonlinear state-observer with high-performance for nuclear reactors. A dissipation-based high gain filter (DHGF) is presented for nonlinear systems in this paper, and robustness analysis is also given. The DHGF is then applied to the state-observation for a nuclear heating reactor (NHR), and simulation results show the feasibility of the DHGF.

Nonlinear Observer-Based Feedback Dissipation Load-Following Control for Nuclear Reactors

Nuclear fission reaction provides more and more energy required for generating electrical power in the world, and therefore load-following control has become an important technique for nuclear reactor regulation. A novel nonlinear controller called observer-based feedback dissipation controller for single-output-single-input (SISO) generalized Hamiltonian systems is presented in this paper. The observer has a dissipative Hamiltonian structure, and sufficient condition for closed-loop asymptotical stability is also derived. This novel control strategy is then applied to the load following control for nuclear reactors. Simulation results show that the control performance is high, and parameters of the controller have direct and close relationship with the rod speed and transient response of the nuclear power and coolant temperature.

Saturated Output Feedback Dissipation Steam Temperature Control for the OTSG of MHTGRs

The modular high-temperature gas-cooled nuclear reactor (MHTGR) is seen as one of the best candidates for the next generation of nuclear power plants. The once through steam generator (OTSG) is a crucial element for any MHTGR power plants with steam cycle. In order to guarantee the efficient and safe operation of the power plant, the outlet steam temperature of the OTSG should be well controlled. In this paper, a saturated output feedback dissipation control (SOFDC) law is presented for regulating the outlet steam temperature of OTSGs, and the corresponding robustness analysis is also given. In the numerical study, the SOFDC is applied to the outlet steam temperature control for the OTSG of Chinese high temperature gas-cooled reactor pebble-bed module (HTR-PM) project. Numerical simulation results show not only feasibility but also good control performance of this regulator, and the influence of its parameters to the regulation performance is also discussed.

Power-Level Control of Nuclear Reactors Based on Feedback Dissipation and Backstepping

Due to the existing serious climate and environment problems caused by burning fossil fuels, nuclear energy is now under rapid development. As a crucial technology in the field of nuclear energy, power-level control for nuclear power plants is significant for not only regular operating but also safety issues. A nonlinear controller based on feedback dissipation and backstepping (FDBC) is presented in this paper. This new controller can guarantee not only globally closed-loop asymptotic stability but also robustness to the uncertainties of the control rod dynamics. Numerical simulation results show the high performance of this controller. Moreover, this newly built controller is simplified to a proportional power-level controller under the assumption of no modeling error in control rod dynamics. The characteristics of these two power-level controllers are given by theoretic analysis and numerical simulation.

Operation and Control Simulation of a Modular High Temperature Gas Cooled Reactor Nuclear Power Plant

Issues in the operation and control of the multi-modular nuclear power plant are complicated. The high temperature gas cooled reactor pebble-bed module (HTR-PM) plant with two-module will be built as a demonstration plant in China. To investigate the operation and control characteristics of the plant, a simplified dynamic model is developed and mathematically formulated based upon the fundamental conversation of mass, energy and momentum. The model is implemented in a personal computer to simulate the power increase process of the HTR-PM operation. The open loop operation with no controller is first simulated and the results show that the essential parameter steam temperature varies drastically with time, which is not allowable in the normal operation. According to the preliminary control strategy of the HTR-PM, a simple steam temperature controller is proposed. The controller is of Proportional-type with a time lag. The closed loop operation with a steam temperature controller is then implemented and the simulation results show that the steam temperature and also other parameters are all well controlled in the allowable range.

Module Coordination Control of MHTGR-Based Multi-Modular Nuclear Plants

Based on the multi-modular scheme, modular high temperature gas-cooled reactor (MHTGR) can be used to build large-scale nuclear power plants with inherent safety feature at any desired power ratings. It is so clear that module coordinated control is very crucial for the safe and stable operation of multi-modular MHTGR plants, which induces the importance of the study in module coordination. Motivated by this, it is revealed in this paper that coordinated control of multiple MHTGR-based NSSS modules is essentially the flowrate-pressure regulation of a fluid flow network (FFN). A novel pressure-flowrate control with the proportional-integral (PI) form is then proposed for the FFN that couples

Coordination Control of SMR-Based NSSS Modules Integrated by Feedwater Distribution

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Reactivity Estimation Based on an Extended State Observer of Neutron Kinetics

MHTGR-based NSSS modules. This control provides the input-to-state stability (ISS) of the closed-loop system. Numerical simulation results not only verify the theoretic results but also show the satisfactory control performance.

Linear Representation and Sparse Solution for Transient Identification in Nuclear Power Plants

Due to its strong safety feature, the small modular reactor whose electric output is no more than 300MWe has been seen as a promising trend in nuclear engineering. By adopting multi-modular scheme, i.e. the superheated steam flows produced by multiple SMR-based nuclear heating system (NSSS) modules are combined to drive a common thermal load, the strong safety feature of a SMR can be applied to large-scale nuclear plants. To improve the economic competitiveness, it is meaningful to integrate multiple NSSS modules by the scheme of feedwater distribution, i.e. sharing a common pump and distributing feedwater by adjusting the opening of regulating valve of each module. The module coordination control of multiple SMR-based NSSS modules coupled by feedwater distribution is essentially the flowrate-pressure control of the common secondary-loop fluid flow network (FFN). In this paper, the nonlinear differential-algebraic model for the FFNs with a single feedwater pump is first given. A novel distributed adaptive flowrate-pressure control is proposed, which is then applied to realize the module coordination. Numerical simulation results in the case of coordination control of two MHTGR-based NSSS modules integrated by feedwater distribution scheme show the feasibility as well as the satisfactory transient performance of this newly-built coordination control law.