LIXISE from diesel genset of rev. Stop, speed control, operation and remote control and so on typical automatic control process to detail, and describes the application of automatic control diesel generating set.Let us more profound understanding of diesel generating sets automatic control principle.

A, diesel generating sets the start/stop of the automatic control

In the automation of power plant, in order to make the diesel generator set automatically and put into operation, its primary job is to need to be able to start or stop the diesel generator set automatically according to instructions, or the first remote diesel generating set in the central control room to start or stop.Therefore, automatic control of diesel generating set is an important content of all kinds of power plant automation.

White to start and stop control of the generator, diesel engine, the control object, so should understand its working condition.Only from the Angle of operation control, first introduce below is how to start and stop the diesel engine.

Units of the diesel engine can be electric start and compressed air start in two ways.Electric start is commonly used in emergency generator prime mover, the battery power supply to the dc servo motor, drive diesel engine rotation until its start over: the main generator generally USES compressed air, compressed air entering the start valve diesel engine. Again by the air distributor of diesel engine control sequence of each cylinder ignition in turn compressed air into the cylinder, moves the pistons, turns the machine.Once the heat generated by the compressed air into the cylinder, self ignition after operation, immediately cut off gas source, diesel engine operating on its own.From diesel engine to start to work under rated speed need to pay attention to the following questions.

(a) prelubricated before the launch

Diesel engine has lubricating oil circulation system, including driven by their own power lubrication oil pump, pipeline, transition and cooler etc.At run time, the lubricating oil to establish their own pressure, guarantee its own oil circulation, so that the main lubrication parts have good lubrication;After downtime, lubricating oil system also stop working. Therefore, after a long time to stop, due before the start of prelubricated procedures, to ensure that when it starts, the mutual contact of the moving parts necessary lubricating oil, to avoid dry friction.Automatic control prelubricated with periodic automatic lubrication and one-time injection prelubricated in two ways.

Figure 1 －1 diesel engine start process control diagram automatically

1) periodic prelubricated automatically

Periodic prelubricated is outside of the diesel engine lubricating pump automatically, setting up an electric oil pump, as another source of power of diesel engine oil circulation system. The electric oil pump, will be able to realize automatic control, when the diesel engine after downtime, to begin to work, to ensure at regular intervals (e.g., 4 h) oil pump power supply is connected to work for a period of time (e.g., l0min), prelubricated periodically implementation, for start at any time.When the diesel engine operation, automatic control in the process of the lubricating oil pump power disconnect instantly, by diesel engine automatic lubrication.

2) a one-off injection lubrication

One-time injection lubrication is in diesel engine lubrication system, access to a plunger type lubricating oil pump, which filled with lubricating oil, when the machine been instructed to start, first role to plunger pump, compressed air moves the pistons, it will be what lubricating oil, oil pipe system, inject to various parts of the machine need lubrication, and then began to start.

3) starts the fuel oil control

Diesel engine fuel injection quantity is controlled by the governor and control handle.Startup, the normal work of the governor has not yet, at this moment controller to limit the amount of fuel available.

4) warm-up

When start after the success, the diesel engine will run on slightly higher than the lowest stable speed, known as the ignition speed, will be up later.Generally in order to reduce the thermal stress, let the machine run under medium speed for a period of time, this is the warm-up (or warming cylinder). The time needed for warm-up depends on models and auxiliary cooling system design is different. In the automatic power station, usually to the diesel engine cooling water piping system together as a whole, the operation unit of the cooling water (about 65 ` t) circulating in the cooling system of the spare machine, also make the spare units in the preheat condition.When the standby unit start-up

After the success of the move, can quickly to accelerate warming cylinder) (don't even have to run until the rated speed, to strengthen the function of automatic power station, continuity, reliability is of great help/very helpful to guarantee the power supply.

5) stop

Control of diesel engine when stop, need to cut off the fuel supply, Bai Hang stop machine.But also need to pay attention to, the different forms of machines may have different requirements.Suddenly stop, perhaps a diesel engine performance is unacceptable, it requires to run for a period of time under the medium speed, to gradually reduce temperature, then the oil is allowed to break down.

(2) diesel generator set automatic start and stop control

Diesel generator set automatic start and stop control should include the following functions.

1. Should be "automatic", "machine", "remote control" mode of operation of transformation, and can meet the "machine" prior to "remote control", "remote control" prior to "automatic", "automatic" refers to the engine operating mode switch in this position, diesel generator automatic control system to work, according to the established procedure, automatic start and stop the unit.

"Remote control" refers to the bridge or ecr with button controls opening and stop on diesel engine.

"Beside the machine" refers to the diesel engine by the conventional manual start-stop unit.

"Priority" is when the switch set "auto", also should be able to do a "remote control", or "machine"; "remote control", also can be real "by" operation, but can't have the function of the "automatic";"Machine", "auto" and "remote control"

Functions are cancelled.

2. Preparations for a variety of Settings to automatically start logic judgment and monitoring.Need to confirm the unit has finished repair, for example, switch in the "automatic", prelubricated, preheating, have enough startup power, the machine is in a stationary state, etc., can be started automatically.

3. Start instruction can automatically start diesel engine.When lubricating oil pressure and speed to achieve specified value, can signal started successfully.

4 a startup instructions, can allow three starts, if failed three times, should start failure signal is given, and report to the general logic control unit start "failure", in order to judge other measures by the "general".

5. Appropriate control starts to oil.The diesel engine ignition itself should be cut off after the launch power source.

6. "running at a moderate speed" and "speed" control.If the diesel engine needs to have a "warm cylinder run" program, the throttle control in the "warming cylinder speed should be carried out under the warming cylinder, and give the child a certain" warming cylinder time "control, after the time limit to be speed up again, until close to the rated speed.The machines don't need the warming cylinder can be directly step on the gas, make speed rapidly rising near the rated speed.

7. When speed up to 90% of the rating, can think the starting and accelerating the whole process is complete, should be automatically cut off the machine lubrication system, time limit for a project by the appropriate delay (about dozens of seconds), access to the machine hydraulic abundant monitoring.This is because the diesel engine's own oil pump in the lubricating system, it takes time to build up the necessary hydraulic has just started, lub oil pressure has yet to reach their values, don't like this is normal.If without delay access to monitor, it will immediately signal error of "low oil pressure", cause unnecessary alarm, automatic stop even.Other monitoring needed for the diesel engine without delay.

8. A overspeed protection.Namely when the diesel engine speed rating of more than 15%, 2 a 3 second delay, downtime, with signal alarm, when the ban on diesel engine starts up again.

9. Received the "stop" command, the unit that is according to the application of automatic stop, stop, after the completion of hair out of the "stop" signal, and shall be automatically switched on lubrication system, all set for the next start.

Because if the diesel engine itself fault (generally have a boot failure, lub oil low pressure, cooling water temperature is high, the high exhaust temperature, speed, etc.) caused by downtime, should be a "block" signals, make the machine start automatically control block, and send out sound and light alarm.For staff ruled out fault, after manual "unblocked", to resume the function of automatically.

10. Automatic start and stop the controller, it is better to have the function that "simulation", can make the operation and management personnel in the condition of not affect the original diesel engine, check the controller's job is normal.Usually use combination switch and lamp.Diesel generator set automatically start the program, which can be expressed in a block diagram 2 12.Figure included "warming cylinder" condition (box), the steps for some diesel engine may not need.In some systems, can also do the following processing. The "start" command arranged into one of two ways: one is the "normal boot" instruction, let the unit have "warming cylinder" condition, the other is a "emergency start" command, such as navigation eccn suddenly lost electricity, calls for immediate standby unit start power supply, when a program controller receives the instruction, can automatically remove "warming cylinder" program.Automatic stop the program block diagram is shown in figure 1 a 2.

Figure 1 －2 diesel engine automatic parking control block diagram

From what has been discussed above, diesel generators, stop procedures can be summarized as three basic principles: the KM, based on the principles of time control, which imitate the actual operation process, according to the time control program;(1) according to the principle of speed control, namely direct according to speed to control procedure: according to the oil pressure control, namely according to the changes of different speed lubricating oil pressure control program.Generally adopt integrated approach control, namely in the whole control system, all three of these control principle.