Liangju Zhang

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.

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.

The first digital reactor protection system in China

Abstract The reactor protection system (RPS) used in the 10 MW high-temperature gas-cooled reactor is the first digital RPS designed and operated in China. In order to ensure its safety and reliability and to reduce the development risk and cost, some measures had to be taken. The measures adopted in the development process include the architecture of defense-in-depth, commercial grade hardware, prototype development model, separation of safety class software and non-safety class software, deterministic behavior of safety software, etc. The measures adopted in the verification and validation (V&V) process include effective dedication on the commercial grade hardware, emphasis on the assessment of the requirements and specifications, emphasis on the demonstration and testing, thorough testing for the safety function, long period demonstration operation, application of automatic test system to improve the efficiency of V&V processes, etc. As a result, this first digital RPS has passed the safety assessment of the National Nuclear Safety Authority. Its performance and safety are proven to be confident and assuring through the demonstration and testing. Thus, the design and V&V process of the first digital protection system in China was successful.

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.

A Nodal Dynamic Model for Control System Simulation of the HTR-PM Reactor Core

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. China began to research the MHTGR technology at the end of the 1970s, and a 10 MWth pebble-bed high temperature reactor HTR-10 has been built. On the basis of the design and operation of the HTR-10, the high temperature gas-cooled reactor pebble-bed module (HTR-PM) project is proposed. One of the main differences between the HTR-PM and HTR-10 is that the ratio of height to diameter corresponding to the core of the HTR-PM is much larger than that of the HTR-10. Therefore it is not proper to use the point kinetics based model for control system design and verification. Motivated by this, a nodal neutron kinetics model for the HTR-PM is derived, and the corresponding nodal thermal-hydraulic model is also established. This newly developed nodal model can reflect not only the total or average information but also the distribution information such as the power distribution as well. Numerical simulation results show that the static precision of the new core model is satisfactory, and the trend of the transient responses is consistent with physical rules.Copyright

Output-Feedback Load-Following Control of Nuclear Reactors Based on a Dissipative High Gain Filter

Due to the existing serious climate and environment problems caused by burning fossil fuels, nuclear energy is now rapidly developed. Power-level control for nuclear reactors is significant for not only regular operating but also safety issues. The advances in computer technology, information processing, and control theory in the past decades allow the applications of advanced controllers with higher performance. In this paper, the separation principle for the recently established dissipation based high gain filter (DHGF) is presented, which guarantees the closed-loop stability of the system interconnected with a state-feedback controller and the DHGF. Then, the feasibility of applying the DHGF to the load-following control of nuclear reactors has then been verified. Finally, the DHGF with a well designed state-feedback power-level controller has been successfully applied to realize the load-following control for a nuclear heating reactor (NHR). Numerical simulation results has shown the high performance of the DHGF and the feasibility of the DHGF-based output feedback control strategy, and influence of the observer gain to the control and observation performance has also been analyzed.Copyright