Andrew W. Pike

State space generalized predictive control incorporating direct through terms

A new formulation of the multivariable state space generalised predictive controller is presented, which utilises a model with direct feed-through action. Such models can arise as a consequence of neglecting the fast dynamics of a system or as a consequence of discretization of continuous-time models. Implementation of the algorithm and application to upper level control of a power plant gas turbine simulation is discussed.

Power Generation Plant Control

The recent advances in information technology, increased market competition, the tightening of environmental regulations, the demand for low cost operation and energy efficiency have all influenced the need for new control design philosophies for complex industrial systems. The main features and impact of these changes on the plant-wide control methodologies are summarised below: New information technology and computing equipment is becoming progressively faster, more complex and has a shorter life cycle. Flexible and distributed plants are increasingly more feasible and demanded in the process industries. Total plant optimisation with efficient and reliable unit operation is essential for economic operation. The integration of control and instrumentation equipment manufactured by different vendors is a major issue in the control design for complex systems. The global coordination of management, operational control and maintenance functions is now an essential part of large scale plant computer control systems.

A Coordination Strategy for Integrated Operations Management and Control

Abstract Integrated operations management and control is described as an aspect of plant wide control consisting of planning, production scheduling, site-wide and interconnected process optimization and assessment. A framework is provided in the form of a hierarchical structure covering integrated operations management, plant optimization and assessment. A coordination strategy for use between the integrated operations management layer and the plant optimization layer is given particular attention

Constrained Control for Power Generation Plant

Abstract This paper is concerned with the design of advanced algorithms to optimally implement a desired set point change whilst satisfying operational variable constraints in large power plants. In common with many process control applications it is not possible to move from one power plant operating condition to another instantaneously. Previous ad-hoc methods to automate the transition usually involves ramping the setpoint over some pre-determined time horizon and implicitly satisfying the operational and safety constraints. The design of optimal methods for the implementation of future set points trajectories is addressed here using the techniques of Generalised Predictive Control (GPC) for large scale systems. A generic unit of Combined Heat and Power (CHP) unit is employed as an example.

Hierarchical Modelling and Interactive Simulation of Large Power Plants

Abstract The traditional approach to modelling complex power plants often leads to cumbersome, expensive and inefficient models. This paper is concerned with the development of a systematic, hierarchical and modular modelling procedure using state-of the art simulation tools and algorithms. Each component of the system is defined by a generic nonlinear dynamic structure of desired inputs, outputs, states and physical parameters. These components are then arranged in a hierarchical structure with the appropriate communication interface. Algebraic loops and hard nonlinearities are included as appropriate. The nonlinear dynamic model is then employed to produce steady-state models and linear models which can be used to investigate the transient characteristics, stability behaviour and control requirements. The result is an advanced toolbox which considerably enhances the modelling and simulation of complex power systems. A generic structure power plant simulation case study is presented to demonstrate the features of the proposed approach.

Hierarchical Simulation and Control of Power Plants: A Case-Study Approach.

Abstract The paper presents hierarchical approach to modelling, simulation and control of Combined Cycle power plants. For this purpose a fictitious case study example, named Skegton Unit, has been derived. The hierarchical structure of the system simulation model is presented and then the hierarchical structure of control is dicussed. A Model Based Predictive Control has been applied on the upper level of control hierarchy to provide optimal transition of the plant when moving to a new operating point. Simulation results show benefits of this approach against the case when only low level controllers are active.

OPTIMISATION OF SET-POINT TRANSITION IN COMBINED CYCLE POWER PLANTS USING PREDICTIVE CONTROL TECHNIQUES

Abstract The paper describes application of multivariable Generalized Predictive Controller to supervise the set-point transition in a Combined Cycle power plant. In power systems, all power generation units are usually supplied together with a proprietary low level control system. Thus, the GPC controller is located on the higher level adjusting setpoints to local control loops. Simulation results show that this approach enables significant reduction of transient period overshoots and may even compensate for inaccurate tuning of low level controllers.

Combined Cycle (CC) and Combined Heat and Power (CHP) Systems: An Introduction

Combined Cycle (CC) is a power plant system in which two types of turbines, namely a gas turbine and a steam turbine, are used to generate electricity. Moreover the turbines are combined in one cycle, so that the energy in the form of a heat flow or a gas flow is transferred from one of the turbines types to another. The most common type of Combined Cycle is where the exhaust gases from the gas turbine are used to provide the heat necessary to produce steam in a steam generator. The steam is then supplied to the steam turbine. However, as will be shown later, other connections between the gas turbine and the steam turbine are possible.