A Real-Time Accurate Model and Its Predictive Fuzzy PID Controller for Pumped Storage Unit via Error Compensation

Abstract

Model simulation and control of pumped storage unit (PSU) are essential to improve the dynamic quality of power station. Only under the premise of the PSU models reflecting the actual transient process, the novel control method can be properly applied in the engineering. The contributions of this paper are that (1) a real-time accurate equivalent circuit model (RAECM) of PSU via error compensation is proposed to reconcile the conflict between real-time online simulation and accuracy under various operating conditions, and (2) an adaptive predicted fuzzy PID controller (APFPID) based on RAECM is put forward to overcome the instability of conventional control under no-load conditions with low water head. Respectively, all hydraulic factors in pipeline system are fully considered based on equivalent lumped-circuits theorem. The pretreatment, which consists of improved Suter-transformation and BP neural network, and online simulation method featured by two iterative loops are synthetically proposed to improve the solving accuracy of the pump-turbine. Moreover, the modified formulas for compensating error are derived with variable-spatial discretization to improve the accuracy of the real-time simulation further. The implicit RadauIIA method is verified to be more suitable for PSUGS owing to wider stable domain. Then, APFPID controller is constructed based on the integration of fuzzy PID and the model predictive control. Rolling prediction by RAECM is proposed to replace rolling optimization with its computational speed guaranteed. Finally, the simulation and on-site measurements are compared to prove trustworthy of RAECM under various running conditions. Comparative experiments also indicate that APFPID controller outperforms other controllers in most cases, especially low water head conditions. Satisfying results of RAECM have been achieved in engineering and it provides a novel model reference for PSUGS.

A Machine Learning-Based Model Predictive Control Method for Pumped Storage Systems

“…Zhou et al proposed a real-time accurate equivalent circuit model of a PSS via error compensation. This model reconciles the conflict between real-time online simulation and simulation accuracy under various operating conditions (Jianzhong Zhou et al, 2018).…”

Start-up process optimization of pumped-storage unit with Tilt–Integral–Derivative controller

“…Furthermore, apart from the characteristic model of the conduit system, the torque and discharge of the pump turbine are also calculated by means of the complete characteristic curves which reflect the static characteristic of the pump turbine obtained from the prototype. Li et al (2017a) and Zhou et al (2017) have given the detailed calculation processes of the torque and discharge, which are omitted here for space cause.…”

Optimization of Pump Turbine Closing Operation to Minimize Water Hammer and Pulsating Pressures During Load Rejection

“…However, the characteristic curves exhibit a reverse "S" shape, crossover, and overlap between each other (as shown in the ellipses in Figure 3), which may cause multi-value problems in the interpolation. Thus, an improved Suter transformation method in [23] is employed to exact the uneven characteristic curves.…”

“…By running the optimization model, the Pareto front plots were obtained as shown in Figure 17, and the fuzzy membership degree of each Pareto solution was then calculated using Equations (23) and (24). The objective function values as well as the µ values of partial Pareto-optimal sets are partially given in Table 5.…”