John E. Seem

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For simulation of centrifugal chiller system with differential algebraic equations (DAEs), consistent initial conditions are difficult to obtain due to the two-phase refrigerant cycle and the connections between several components. Existing rigorous initialization methods are generally not easy to apply and not suitable for the particular problem of(More)
To maintain the maximum achievable efficiency for the photovoltaic (PV) systems, it is crucial to achieve the maximum power point tracking (MPPT) operation for realistic illumination conditions. This paper presents the application of the adaptive extremum seeking control (AESC) scheme to the PV MPPT problem. A state-space model is derived for the PV system(More)
In this study, a multi-variable extremum seeking control (ESC) scheme is proposed for a variable-speed mini-split air-conditioning system. The control inputs are the evaporator and condenser fan speeds, respectively. While the total power consumption is used as the feedback. The multi-variable ESC can optimize the control inputs for each channel in(More)
Cooling towers are important equipments for the HVAC systems in commercial buildings, rejecting the process heat generation to the atmosphere. Dynamic modeling of cooling towers is beneficial for control design and fault detection and diagnostics of the chilled-water systems. This paper proposes a simple and yet effective dynamic model for a typical(More)
In this paper, the transient model of a water-cooled centrifugal chiller is developed in Modelica with Dymola and the TLK/IfT Library (TIL). The centrifugal compressor is modeled in detail based on the turbomachinery theory. The chiller capacity control is achieved by the combination of variable inlet guide vane (VIGV) and variable speed drive (VSD). The(More)
This paper presents a self-optimizing robust control scheme that can maximize the power generation for a variable speed wind turbine with Doubly-Fed Induction Generator (DFIG) operated in Region 2. A dual-loop control structure is proposed to synergize the conversion from aerodynamic power to rotor power and the conversion from rotor power to the electrical(More)