John E. Seem

• Ph.D.
• Hedge Fund & Real Estate Investor at Private Investor

A major class of extremum seeking control (ESC) is based on the use of periodic dither perturbation of plant input for extracting the gradient information. Presence of the dither input into the steady state operation is undesirable in practice due to the possible excessive wear of actuators. It is thus beneficial to stop the dithering action after...

The Hybrid Ground Source Heat Pump (GSHP) systems combine the renewable geothermal energy and cooling tower for rejecting the cooling load, which is often adopted for high cooling demand. Model based control can be limited due to variations in ambient conditions, ground-loop heat exchanger (GHE) and equipment characteristics, cost and reliability o...

In wind farm operation, the performance and loads of downstream turbines are heavily influenced by the wake of the upstream turbines. Furthermore, the actual wake is more challenging due to the dynamic phenomenon of wake meandering, i.e. the turbine wake often demonstrates dynamic shift over time. To deal with the time-varying characteristics of wa...

This paper proposes a nested-loop extremum seeking control (NLESC) scheme for optimizing the energy capture of wind farm that is formed by a wind turbine array along the prevailing wind direction. It has been shown in earlier work that the axial induction factors of individual wind turbines can be optimized from downstream to upstream units in a se...

For wind turbine operation, wind variations around the rated wind speed can lead to frequent controller switching actions, which may result in significant fluctuation in power output and structural load. This paper presents a bumpless transfer scheme for the inter-region controller switching for variable-speed variable-pitch wind turbines, which ai...

This paper presents a multivariable Newton-based extremum seeking control (ESC) scheme for efficient operation of a chilled-water plant. A modelica-based dynamic simulation model of the chilled-water plant consists of one screw chiller and one counter-flow cooling tower was adopted for evaluation of proposed two-input Newton-based ESC controller. T...

Maximizing power generation efficiency and fault diagnosis are two important aspects for reducing the cost of energy (COE) for photovoltaic (PV) systems. In this paper, the extremum seeking control (ESC) scheme based on dither signals is applied to achieve the maximum power point tracking (MPPT) control and simultaneously to detect the change of in...

A system for operating a process includes a processing circuit that uses a self-optimizing control strategy to learn a steady-state relationship between an input and an output. The processing circuit is configured to switch from using the self-optimizing control strategy to using a different control strategy that operates based on the learned stead...

The chilled water system, typically consisting of chiller and cooling tower, plays a major role in the ventilation and airconditioning systems in commercial buildings. Due to the significant power consumption of such system, improvement of its efficiency would lead to significant benefit in energy saving. As the system characteristics and operation...

A system for controlling start-up of a feedback controller includes a memory device and a processing circuit. The processing circuit is configured to receive a gain parameter from the feedback controller and to store the gain parameter in the memory device. The processing circuit is further configured to multiply the stored gain parameter and to ca...

An extremum seeking control method optimizes a control process for a plant such as an air handling unit. The method improves the performance of an extremum seeking control strategy by limiting, removing or preventing the effects of an actuator saturation condition, particularly as the extremum seeking control strategy relates to HVAC applications.

An extremum seeking control method optimizes a control process for a plant such as an air handling unit. The method compensates for abrupt changes in the operation of the plant by resetting the extremum seeking control strategy in response to a detection of the abrupt change.

For offshore floating wind turbines, control of the platform pitch motion is of particular importance, especially due to the stability concern. This paper proposes an actuation scheme for stabilizing the platform pitch motion via an actively controlled horizontal vane. With the pitching moment on the tower-platform structure generated by the aerody...

Dynamic modeling of HVAC equipment is a subject of particular importance for control system design and fault detection and diagnosis, while the transient behaviors of the associated processes are, in principle, very complicated and feature strong interactions among multiple physical domains. Part I of this article reviews the research advancement i...

In order for photovoltaic (PV) systems to maximize their efficiency of power generation, it is crucial to locate the maximum power point (MPP) in real time under realistic illumination conditions. The current-voltage (I-V) characteristics of PV devices are nonlinear, and the MPP may vary with intrinsic and environmental conditions. Maximum power po...

This paper proposes a novel control approach for optimizing wind farm energy capture with a nested-loop scheme of extremum seeking control (ESC). Similar to Bellman’s Principle of Optimality, it has been shown in earlier work that the axial induction factors of individual wind turbines can be optimized from downstream to upstream units in a sequent...

Self-optimizing control methods have received significant attention recently, due to the merit of nearly model-free capability of real-time optimization. Of particular interest in our study are two classes of self-optimizing control strategies, i.e. the Extremum Seeking Control (ESC) and Simultaneous Perturbation Stochastic Approximation (SPSA). Si...

A major class of extremum seeking control is based on the use of periodic dither perturbation of plant input for extracting the gradient information. Presence of the dither input into the steady state operation is undesirable in practice due to the possible excessive wear of actuators. It is thus beneficial to stop the dithering action after the ex...

This paper presents a Maximum Power Point Tracking (MPPT) strategy for multi-string photovoltaic (PV) systems using the Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm. The multi-string PV system considered is a decentralized control configuration, controlling the voltage reference to each PV module but based on the feedback of...

A fault detection system for detecting a fault in a process system includes a first circuit configured to modify an input of the process system with a modifying signal. The fault detection system further includes a second circuit configured to receive an output from the process system and configured to determine whether the fault exists based on at...

Energy efficient operation of chilled-water systems is important for the energy saving of commercial buildings. This paper presents an extremum seeking control (ESC) scheme for energy efficient operation of chilled-water system, and presents a Modelica based dynamic simulation model for demonstrating the effectiveness of the proposed control strate...

Calculation of time derivatives of refrigerant pressures is important for dynamic simulation of heat exchangers in vapor compression cycles, i.e., typically the condenser and evaporator. This technical brief presents an experimental study on the pressure transient for the condenser and evaporator of a screw chiller with R134a, along with the analys...

This paper presents an extremum seeking control (ESC) scheme for energy efficient operation of chilled-water system, and Modelica based dynamic simulation models for demonstrating the effectiveness of the proposed control strategy. The simulated plant consists of a water-cooled screw chiller and a mechanical-draft counter-flow wet cooling tower. Th...

In wind farm operation, the performance and loads of downstream turbines are heavily influenced by the wake of the upstream turbines. Furthermore, the actual wake is more challenging due to the dynamic phenomenon of wake meandering, i.e. the turbine wake often demonstrates dynamic shift over time. To deal with the time-varying characteristics of wa...

For simulation of centrifugal chiller system with differential algebraic equations, 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 not suitable for the particular problems in centrifugal chiller simulation, such...

For wind farm operation, the performance and load of downstream turbines are strongly affected by the wake of the upstream units. Further, a more challenging reality is that the turbine wake often demonstrates dynamic shift over time, i.e. the so-called wake meandering phenomenon. This study investigates the design of load-reduction oriented indivi...

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 P...

Calculation of friction factor for smooth pipes in fully developed flow is important for heat transfer applications. Many different coefficients in the Prandtl equation (Prandtl, L., 1949. Führer durch die Strömungslehre. F. Vieweg & S, Braunschweig.), or PKN correlation [Kakac, S., Shah, R.K., Aung, W., 1987. Handbook of Single-Phase Convective He...

Individual pitch control (IPC) for wind turbine load reduction in Region 3 operation is improved when wake interaction is considered. The Larsen wake model is applied for composing the rotor wind profile for downstream turbines under wake interaction. The wind profile of the turbine wake was generated by modifying the NREL's TurbSim codes. The stat...

The photovoltaic (PV) systems are often subject to shading in practical operation, which often results in multipeak power-voltage (P-V) characteristics. Most existing maximum power point tracking (MPPT) control strategies are local-optimum oriented, based on the gradient search or its variations, e.g., perturb-and-observation (P&O) or extremum seek...

This paper presents an initial investigation on improving individual pitch control (IPC) for wind turbine load reduction for Region 3 operation with the wake interaction included under the context of wind farm operation. The Jensen wake model is applied for composing the rotor wind profile for downstream turbines under wake interaction, and switche...

Multi-string configuration is commonly seen in practical photovoltaic (PV) applications, to secure the Maximum Power Point (MPP) for each string, individual string is equipped with its own DC-DC converter for voltage regulation. This study presents an integrated framework that achieves dual purposes simultaneously: maximum power point tracking (MPP...

Individual pitch control (IPC) for wind turbine load reduction in Region 3 operation is improved when wake interaction is considered. The Larsen wake model is applied for composing the rotor wind profile for downstream turbines under wake interaction. The wind profile of the turbine wake was generated by modifying the NREL’s TurbSim codes. The stat...

Regarding the reduction of the cost of energy (COE) for photovoltaic (PV) systems, two important issues are maximizing the efficiency of power generation and fault diagnosis. This study presents an integrated framework that achieves both maximum power point tracking (MPPT) control and diagnosis of change in internal resistance simultaneously. An ex...

As the heating, ventilating, and air conditioning (HVAC) systems accounts for a major sector of energy consumption for commercial buildings, there has been a greater demand for improving the efficiency of such systems. The air-side economizers have been developed as a class of energy-saving HVAC devices that may increase the energy efficiency by ta...

This paper describes two new strategies for controlling air economizers. The model-based control strategy uses a model to estimate the load on the cooling coil for 100% outdoor air and minimum outdoor air and transitions dampers between these two positions to minimize the load. The optimization-based control strategy uses a cooling coil model and a...

For heating, ventilating, and air-conditioning (HVAC) systems for commercial buildings, the cooling coils in air-handling units (AHUs) account for a significant fraction of total building energy consumption and have a major impact on comfort conditions and maintenance costs. Development of cost-effective advanced control strategies will enhance the...

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 typic...

The photovoltaic (PV) systems are often subject to shading in practical operation. Non-uniform shading for PV array with bypass diodes leads to mismatch in power generation, and thus resulting in multi-peak power-voltage (P-V) characteristics. Most existing maximum power point tracking (MPPT) control strategies are local optimum oreinted, as based...

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 e...

This paper presents a study on the dynamics of a water-cooled centrifugal chiller from two aspects: dynamic simulation modeling and stability analysis. First, the transient model 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 capacit...

Economizers have been recognized as a class of energy-saving devices for heating, ventilating and air conditioning (HVAC) systems that may increase the energy efficiency by taking advantage of outdoor air during cool or cold weather. There has been a tremendous demand for reducing energy consumption of HVAC systems in commercial buildings. However,...

Maximizing energy capture has become an important issue as more turbines are installed in low wind areas. This paper investigates the application of extremum seeking control (ESC) to maximizing the energy capture of variable speed wind turbines. The optimal control torque and pitch angle are searched via ESC based on the measurement of the rotor po...

A new method for integrated control and fault detection of air-handling units (AHUs) is described in this paper. The method uses sensors commonly installed in AHUs and collects much of the key diagnostic information at times when steady-state conditions are imposed on the AHU by the sequencing logic, thereby eliminating the need for a steady-state...

For the heating, ventilating, and air conditioning (HVAC) systems for commercial buildings, the cooling coils in air handling units (AHU) account for a significant fraction of total building energy consumption and have a major impact on comfort conditions and maintenance costs. Development of cost-effective advanced control strategies will enhance...

Maximizing wind turbine energy capture has become an important issue as more turbines are installed in low wind areas. This paper investigates the application of extremum seeking control (ESC) to maximizing the energy capture of variable speed wind turbine. The optimal control torque and pitch angle are searched via ESC based on the measurement of...

This paper describes a novel method for detecting abnormal energy consumption in buildings based on daily readings of energy consumption and peak energy consumption. The method uses outlier detection to determine if the energy consumption for a particular day is significantly different than previous energy consumption. For buildings with abnormal e...

Seem (1998) described a pattern recognition adaptive controller (PRAC) that tunes PI controllers. PRAC has successfully been used in over 500,000 controllers for heating, ventilating, and air-conditioning equipment. However, there have been three reported problems: 1) PRAC will detune under capacity systems that are repeatedly restarted, 2) PRAC ma...

This paper describes a pattern recognition algorithm for determining days of the week with similar energy consumption profiles. The algorithm determines energy use features, such as average daily consumption or peak daily consumption, from time series of energy use. Features are transformed to remove the effects of seasonal variation that may be pr...

AGENDA: Adaptive Feedback Control -- Fault Detection and Diagnostics -- Sequencing Control -- Energy Optimization Control.

Traditional air-handling unit (AHU) control systems link the position of the exhaust, recirculation, and outdoor air dampers. Laboratory tests of a variable-air-volume AHU using the traditional damper control approach revealed that outdoor air could enter the AHU through the exhaust air damper. This can negatively impact indoor air quality. This pa...

Air-handling unit (AHU) controllers commonly use sequencing logic to determine the most economic way to use the components of the AHU to maintain the supply air temperature at a setpoint value. The objective of this paper is to introduce the finite state machine (FSM) sequencing control strategy for AHUs and to compare this strategy with a traditio...

This paper describes a novel method for automatically adjusting the gain and integral time of proportional-integral controllers based upon patterns that characterize the closed-loop response. The method was developed for self-regulating systems that can be modeled as first-order plus dead-time systems. This new pattern recognition adaptive controll...

This paper presents a new algorithm for controlling the peak electrical demand in buildings below a target level through load shedding. The algorithm uses statistical methods to determine the load shedding requirements, without unnecessarily shedding loads. Specifically, a random walk model is used to forecast the uncontrolled electrical demand, an...

A finite-difference model is used to predict the steady-state and dynamic thermal performance of thermal bridges in a typical office building. The thermal bridges evaluated include a built-up roof system with ceiling fasteners, a roof/wall interface, an insulated masonry cavity wall with metal studs, a floor slab that penetrates wall insulation, an...

This paper presents a simple algorithm for forecasting the electrical demand in a building. The algorithm should also be applicable for forecasting cooling loads. The algorithm has application in dynamic control strategies that use chilled water, ice, or building thermal mass as a thermal storage medium. Parameters of the forecasting model are adju...

Transfer function methods are more efficient for solving long-time transient heat transfer problems than Euler, Crank-Nicolson, or other classical techniques. Transfer functions relate the output of a linear, time-invariant system to a time series of current and past inputs, and past outputs. Inputs are modeled by a continuous, piecewise linear cur...

This paper describes a method in which the transfer functions describingheat flow in building elements can be combined into a single tranfer functionfor an enclosure, referred to as a comprehensive room transfer function (CRTF).The method accurately models long-wave radiation exchange and convection in anenclosure through an approximate network, re...

Finite difference or finite element methods reduce transient multidimensional heat transfer problems into a set of first-order differential equations when thermal physical properties are time invariant and the heat transfer processes are linear. This paper presents a method for determining the exact solution to a set of first-order differential equ...

This paper has presented and compared seven different equations for determining the time to return from night or weekend setback. For nights that required cooling to return, the most accurate forecasts were obtained from a quadratic relationship between return times to both the outdoor temperature and the room temperature provided the best forecast...

For the heating, ventilating, and air conditioning (HVAC) systems for commercial buildings, there has been a greater demand for reducing energy consump-tion. The economizers have been developed as a class of energy saving devices that may increase the energy efficiency by taking advantage of outdoor air during cool or cold weather. However, in prac...

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 suitable for the particular problem of centrifugal chiller...

Typescript. Thesis (Ph. D.)--University of Wisconsin--Madison, 1987. Vita. Includes bibliographical references (leaves 159-163).