Research On Stability Of Diesel Generator Sets Operating In Parallel

The diesel-generator set is the most common prime power generation mover in modernship power station. With the diesel engine technique continually updates and progress, theincreasing tonnage of ship, more and more high power loads are applied on board, the controlaccuracy requirements to the electronic governor of diesel engine and synchronous alternatorexcited system of ships is gradually becomes high. The traditional controller usually adoptPID as control law, the traditional PID controller can not satisfy the influence of nonlinearfactors and the load large scale change, the traditional PID has been difficult to ensure thesystem has a good dynamic and static performance.Firstly, the paper give a simple introduction to the traditional PID, then detailedintroduces the fuzzy control principle and the design of fuzzy controller. On the basis of theanalysis of two control methods with their respective advantages and the disadvantages, inorder to overcome the shortcomings of the two methods, the two control methods of thetraditional PID and the fuzzy control are combined, a new fuzzy-PID control method isdesigned. The fuzzy-PID control can control the control parameters online real-timeself-tuning. This control algorithm keeps the advantages of both of the traditional PID controland fuzzy control, which is simple and has high accuracy and good robustness characteristics.In this paper, the mathematical model of diesel engine speed regulation system of shippower station is deduced from the mathematical analysis of the diesel engine speed regulationsystem of ship power station, and the fuzzy-PID controller is used in the speed regulationsystem. Based on the simulation software of MATLAB, the diesel engine speed regulationsystem of the traditional PID and fuzzy-PID control simulation model is constructed inMATLAB, this paper simulates the processes of sudden increase and decrease100%ratedload of the synchronous machine under using different control strategies. Results ofsimulation proved that the fuzzy-PID control has superiority in steady-state performance anddynamic performance such as suppress overshoot, regulation time, Inhibition of oscillation.In this paper, the mathematical analysis of ship synchronous generator is given, on thebasis of the Parker equation, the equation is simplified and the practical five-order model ofthe electromagnetic transient process of the synchronous generator of ship power station isbuilt. The mathematical model of the voltage regulating system is designed, the simulationmodel of the voltage regulating is constructed by using MATLAB simulation software, thispaper analyzes both terminal voltage waveform in the condition of simulating the processes of sudden increase and decrease static load. The simulation results indicate that there are somany limitations when the traditional PID control applied to nonlinear, time-varyingcomplicated system, the fuzzy-PID control algorithm can overcome complicated systemlimitation and has a better effect on excitation adjustment of synchronous generator.Since the speed of the diesel engine of marine diesel-generator set and excitation voltagecoupling relations, the unified mathematical model of the diesel-generator set is establishedthat the aim is reducing the coupling relations of speed regulation system and excitationsystem. Based on a certain researching on single generator system, the simulation model oftwo parallel diesel-generating sets is constructed; the fuzzy-PID controller is used in thediesel-generating sets in parallel integrated control system. The simulation results show thatthe fuzzy-PID controller improves the stability of the system frequency in paralleldiesel-generating sets and effectively improve the uniform distribution of load power betweenthe dual machines.