Supervisory Control Unit Research Articles

Design and simulation of a TTRH-EV supervisory controller for a proton SAGA 1.3

This paper presents modeling and control design steps towards the vehicle hybridization process. The objectives are: a) to model a retrofitted proton SAGA, which is a through-the-road HEV; and b) to design and implement a supervisory control unit for this vehicle. The electric powertrain components required for conversion are sized using the ADVISOR software package. Physical models of both powertrains were modeled using the MATLAB Simscape toolbox and validated for their fidelity. A supervisory controller design and implementation for retrofitted TTRH-EV SAGA is based on the BSFC map and OOL of the engine. The control objective is to restrict engine operation within its optimum window. The controller was implemented using the MATLAB Stateflow toolbox. The complete model of the retrofitted TTRH-EV SAGA, together with the supervisory controller, was tested using standard drive cycles, and the results are presented.

Novel gas measurement based on pressure triggered release cycles for biochemical methane potential tests

Abstract This study aims to present a novel gas counter and to demonstrate its suitability for biochemical methane potential tests. In this system, the gas to be measured is collected in a chamber enclosed with two one-way solenoid valves and the absolute pressure is continuously monitored. After a trigger pressure is reached, a portion of the gas is released and the amount of the released gas is calculated according to ideal gas law and recorded. Three iterations of the supervisory control and data acquisition unit were constructed and tested for BMP measurement. Although it can be further improved and variations are possible, the presented final version works with eight reactors simultaneously and the recommended maximum gas flow is 1.24 mL/min. For those reactors, the measured/theoretical BMP ratio was 65.3% with 4.2% standard uncertainty, which is subjectively acceptable. Therefore, it can be concluded that the concept is valid and applicable to BMP tests.

Supervisory Nearly Constant Frequency Hysteresis Current Control for Active Power Filter Applications in Stationary Reference Frame

This paper proposes a new constant frequency space-vector hysteresis-band current control (CF-SVHCC) in the stationary reference frame (SRF) for three-level active power filter applications when applied to isolated neutral point (INP) systems. CF-SVHCC is designed based on two recognized modulation methods: 1) space-vector modulation and 2) adaptive hysteresis current control. The proposed technique consists of a simple circular hysteresis strategy around the current-error vector in SRF with the purpose of employing the zero- and nonzero-voltage vectors of the three-level voltage source inverter. CF-SVHCC continuously estimates an adaptive outer hysteresis-band in the SRF using the inverter switching signals by a simple and fast artificial neural network method called the adaptive linear neuron algorithm. The main part of CF-SVHCC is a supervisory control unit that operates in the SRF to avoid interphase dependency and systematically uses the voltage vectors associated with the estimated outer hysteresis-band to prevent a high switching frequency and, in turn, maintain the switching frequency constant. CF-SVHCC retains most benefits of the conventional HCC and also introduces additional advantages, including a constant switching frequency and the interphases independency in three-phase INP systems.

FPGA-based Centralized Controller for Multiple PV Generators Tied to the DC Bus

The integration of photovoltaic (PV) energy sources into DC grid has gained considerable attention because of its enhanced conversion efficiency with reduced number of power conversion stages. During the integration process, a local control unit is normally included with every power conversion stage of the PV source to accomplish the process of maximum power point tracking. A centralized monitoring and supervisory control unit is required for monitoring, power management, and protection of the entire system. Therefore, we propose a field-programmable gate array (FPGA) based centralized control unit that integrates all local controllers with the centralized monitoring unit. The main focus of this study is on the process of integrating many local control units into a single central unit. In this paper, we present design and optimization procedures for the hardware implementation of FPGA architecture. Furthermore, we propose a transient analysis and control design methodology with consideration of the nonlinear characteristics of the PV source. Hardware experiment results verify the efficiency of the central control unit and controller design.

Smoothing of Wind Farm Output by Prediction and Supervisory-Control-Unit-Based FESS

This paper presents a supervisory control unit (SCU) combined with short-term ahead wind speed prediction for proper and effective management of the stored energy in a small capacity flywheel energy storage system (FESS) which is used to mitigate the output power fluctuations of an aggregated wind farm. Wind speed prediction is critical for a wind energy conversion system since it may greatly influence the issues related to effective energy management, dynamic control of wind turbine, and improvement of the overall efficiency of the power generation system. In this study, a wind speed prediction model is developed by artificial neural network (ANN) which has advantages over the conventional prediction schemes including data error tolerance and ease in adaptability. The proposed SCU-based control would help to reduce the size of the energy storage system for minimizing wind power fluctuation taking the advantage of prediction scheme. The model for prediction using ANN is developed in MATLAB/Simulink and interfaced with PSCAD/EMTDC. Effectiveness of the proposed control system is illustrated using real wind speed data in various operating conditions.

Low and high voltage ride-through of DFIG wind turbines using hybrid current controlled converters

Doubly fed induction generators have been recognized as the dominant technology used in wind generation systems. However, this type of wind generator is very sensitive to the drop/rise in the supply voltage and without efficient “ride-through” strategy, continuous operation of DFIG may fail due to destructive overcurrents in the rotor winding or large overvoltages in the dc-link capacitor. This paper introduces a hybrid current control scheme, implemented in the rotor-side and grid-side converters of DFIG, to enhance low and high voltage ride-through capacities of DFIG-based wind turbines. The proposed control scheme is constituted of two switching strategies integrated with a supervisory control unit: standard PI current controllers for normal operating conditions and vector-based hysteresis current controllers for DFIG protection during severe voltage sag/swell conditions. Time-domain simulation studies are carried out to examine the effectiveness of the proposed ride-through strategy under various types of grid disturbances. It is shown that the proposed controller constrains the rotor current and dc-link voltage within the safety limits of DFIG and as a result, the wind generator can comply with the strict low/high voltage ride-through requirements stipulated by modern grid codes.

Dynamic modelling of reconfigurable manufacturing planning and control systems using supervisory control

This research is concerned with studying the dynamic performance of reconfigurable Manufacturing Planning and Control (MPC) systems. Such goal requires two main tasks. The first task is to develop a dynamic MPC system model that has the ability to reconfigure to different MPC policies. The second task is to design a supervisory control unit that has as input the high level strategic market decisions and constraints together with a feedback of the current manufacturing system state and then select the optimal suitable operation mode or policy at these conditions. This paper addresses the first task of the proposed research and presents and analyses a dynamic reconfigurable MPC model. The response of the developed model to sudden demand changes under different parameters settings is analysed. In addition, the stability limits of the system are also studied. The results give a better understanding of the dynamics of reconfigurable MPC systems and the different trade-off decisions required when selecting an MPC policy and the limits for parameters settings. These results represent the first step towards designing the supervisory control unit which will be responsible for managing the reconfiguration of the whole system.

Voltage-injection control for switched-mode power-supply applications

As electronic systems become more complex, their power supplies require higher dynamic performance which is becoming increasingly difficult to meet. In many such applications the load is controlled by a supervisory control unit, so that a forthcoming load change can be anticipated. The paper proposes a new control method to enhance the dynamic response of power supplies that have a predictable load-switching pattern. By injecting a small voltage into the control loop in advance of the load application, it is shown that the dynamic response is greatly improved. Both experimental and simulated results are presented and demonstrate the robustness of the technique.

System Telemetering and Automation at Madison

This article describes the unusual central supervisory control, telemetering, and alarm monitoring of Madison, Wisconsin. During the last 10 years, Madison's population has increased by 40 per cent. At the same time, pumping facilities have increased by 60 per cent but automation has eliminated the need for additional operating personnel during the same 10 year period. The system's supervisory control unit is discussed, along with remote units, cost savings, and operation and maintenance.