GB2205207A

GB2205207A - Electrical generator control system

Info

Publication number: GB2205207A
Application number: GB08812816A
Authority: GB
Inventors: Richard Dudley Payne
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-05-29
Filing date: 1988-05-31
Publication date: 1988-11-30
Also published as: GB8804091D0; GB8812816D0

Abstract

The frequency of a prime mover driven generator A, B is regulated by a control 2, eg. a microprocessor, which additionally provides other functions such as control, metering, warning and protection. Generator A is regulated during startup by controlling a valve 4a of a water turbine and by controlling a power absorber load 3.1, eg. an electrically heated water boiler, and a circuit breaker 5a is closed when the generator is up to speed. Power and speed are then regulated by controlling valve 4a and power absorber loads 3.1 and 3.2. Generator B may be similarly regulated by controlling valve 4b, and load 3.1 prior to closure of circuit breaker 5b when the voltage, frequency and phase of generator B match those on the common bus bar connected to load 3.2 and a consumer load 6. Control 2 can also connect the bus bar to the mains via circuit breaker 5c. Control 2 may measure and display voltage, current, power factor etc., and prime mover parameter such as water level and pressure may also be measured. Protection against over current, over- or undervoltage and reverse power may be provided. Control 2 may respond to an input from a power measuring device 7 to control valves 4a, 4b, and loads 3.1, 3.2 or consumer load 6 to achieve a particular operating point, eg. to minimise mains power input. The reserve generating capacity may also be determined by control 2. <IMAGE>

Description

INTEGRATED CONTROL METHOD FOR POWER SYSTEM MANAGEMENT The control system described herein comprises of an electrical power generating system having a controller receiving inputs from the electrical system and other devices and providing differing control and signal outputs as are required to regulate the system speed1 power and operation by working through suitable control means. The same controller is also used to provide functions such as metering, warnings and protection of the generating plant There are many methods in use for the management of power generating systems. These mostly comprise a multiplicity of individual controllers, measuring devices, meters and protective devices assembled together to obtain the overall desired performance. This results in extensive engineering, construction, wiring and commissioning costs.Also there is much duplication of common equipment This invention introduces a number of new techniques and collects all facilities into an integrated method providing greater benefits at reduced cost The drawing attached indicates a typical application utilising the main features of this invention. It this particular case, there are two or more hydro-electric generator sets using synchronous alternators operating either singly or in parallel with themselves or a network, and possibly supplying a consumer load 6. Typically the central device 2 could be a micro-processor unit and the load absorbers 3 being water heating boilers with electric heating elements. Other arrangements are however possible using diesel engines for example.

In the embodiment shown, an electrical signal from each set is connected to control device 2 through link 'x' via switch 1 which is interlocked with the alternator circuit breakers such that only one generator can be connected at any time. Control device 2 has another signal connection to the common busbar via link 'y'.

Outputs from 2 go to the water turbine regulating valve actuators 4a/4b and to the system circuit breakers 5a/5b/5c as well as to the regulating part of load absorbers 3.1/3.2 and the consumer load 6) The power connections to the load absorbers are shown seperately by solid lines.

Consider generator 'A' to run alone and supply to load 6 As the machine is started, then switch 1 will close to genr 'A' and controller 2 will regulate using local load absorber3.1 and actuator 4a to bring the set speed to the desired value at a suitable rate of acceleration. Controller 2 will then close circuit breaker 5a Whilst feeding the consumer load 6 the controller 2 will adjust either or both items 3.1/3.2 together with 4a so as to maintain control of speed and powerin the most efficient manner. Normally this being with minimum load dissipation in absorber 3.1/3.2 and with actuator 4a set to closely or exactly balance generator output Integrated control method for power systems management against the varying consumer load demand.The load absorbers, being electrical devices are generally used to control speed during transient load changes and actuator 4a used as follow up control for fuel economy.

Due to increasing consumer load, or other reason, it may become necessary to start generator 'B'.

As this is started then switch 1 will close to genr 'B'. Since generator 'A' is connected to the common bus through circuit breaker 5a then control of set 'A'is maintained using necessary elements of absorber(s) 3.1/3.2 and actuator 4a and monitoring link 'y'.

As machine 'B'is accelerated towards synchronous speed the controller 2 will adjust load absorber 3.1 and actuator 4b so as to hold the speed at synchronous and in the correct phase relationship to the common busbar. It is also possible that controller 2 be arranged to adjust voltage of the incoming machine so to exactly match that of the common busbar.

At synchronism, controller 2 will signal the incoming circuit breaker-5b to close thereby completing the synchronising procedure.

With the machines in parallel, then controller 2 can regulate both actuators 4 and absorbers 3.1/3.2 to share power and adjust output of the generator sets as desired.

Should synchronising with the mains or other network be required then a similar procedure will be followed insofar that controller 2 will adjust actuators 4a/4b and absorbers 3.1/3.2 so to match phase relationship and speed of the common busbar to that of the other supply.

At this point then controller 2 will cause the circuit breaker Sc to close thereby paralleling the two electrical systems.

A feature of this control method is the ability for the controller 2 to vary the generator loading intermittently during normal steady running of the generating plant. Typically this could be a load increase of 5% for 30 seconds each hour. The response of the electrical system is monitored by controller 2 and compared to a preset pattern. Should a deviation be noted, then a suitable alarm or other signal would be output from controller 2. Typically this may be used to warn of impending overload or blockage of the turbine water inlet screens. An alternative way of monitoring for system power reserve is to compare the opening of the prime mover fuel actuator 4 with the actual power being generated. Comparison with a preset pattern will indicate potential problems.

A major aspect of this invention is the measuring and calculating facilities provided within the controller 2. This allows measuring and display of all monitored values plus those derived therefrom by calculation (eg: Amps, volts, power factor, kWS, kVARS and others).

In addition these same values can be used to provide protection for the plant against such matters as overcurrent, over/under volts, reverse power, plus many others. Measurements may also be taken from parameters associated with the prime mover devices and other outside agencies. Integration of all these facilities within a single package offers appreciable cost effective benefits.

Integrated control method for power systems management In a further feature, controller 2 can be arranged to influence the consumer load 6 so as to adjust this either for prevention of generator overload or to maximise or give priority to the use of the power being generated. Typically this control is achieved by switching of the connected loads or by voltage control of heating loads.

A further feature is where the controller 2 receives an input from system device 7 and uses this to measure power at that point and adjust any of the control means 3.1/3.2, 4a/4b or consumer load 6 such that a particular operating point at the measuring point of 7 is obtained. This is typically used to minimise mains power input and prevent export penalties when operating in mains parallel on a 'Supply only tarriff'.

Similar inputs to the controller 2 may come from other measuring sensors in the system such as level or pressure or time clocks.

External signals such as representing future trends may also be accepted and acted upon as appropriate.

It will be seen from the above notes that the control method described provides speed governing, measuring, protection and new control features, all under the control of a single integrated controller.

Dependant on the particular installation it may be that there is no need of both control means of type 3 and 4 and of which only one may be fitted. The load absorbers 3 may be of any capacity but are commonly a total equal to about 20% greater than the alternator ratings. There are advantages in using the smallest possible size units and reduced sizes can especially be useful where the unit is used in conjunction with some other controlling device such as a flywheel, brake or other regulator. It should also be clearly understood that the load absorber, or such proportion of it as deemed appropriate, can be incorporated within and as part of the consumer load if so desired.

In the practical installations of the control system detailed in this application it is not a requirement that the various components be combined either in a single package or even at a single location.

As already mentioned it is also not necessary that every component be included in each and every system. Additionally there are further practical advantages emanating from the use of controllable load absorbers within a power generating system and reference is made to: UK Patent GB 2006998A EEC Application 83303020.8

where these further advantages are detailed and their benefit to this application can be realised.

Drawing of Invention 1 sheet is attached Integrated control method for power systems management

Claims

CLAIMS 1. An electric power generating system comprising of prime mover driven generators connected to a network with consumers and in which the frequency is regulated by a controller which additionally can provide control, metering, warning and protective functions as may be derived from measurements associated with the drive engines and generators supplying the electrical network, and the network parameters.
2. An electrical system as claimed in claim 1 wherein measurement is made of the reserve generating capacity
3. An electrical system as claimed in claim 1 or claim 2 wherein the frequency of a generating set or the electrical system is adjusted by the controller so as to vary its frequency and phase relationship and bring it into synchronisation with a second electrical system.
4. An electrical system as claimed in claim 1, 2 or 3 wherein the load on the generating set or the electrical system is influenced by the controller.
5. An electrical system as claimed in claim 1, 2, 3 or 4 wherein load absorbers are additionally supplied and influenced by the controller
6. An electrical system as claimed in any preceeding claim wherein the prime mover outputs are additionally influenced by the controller
7. An electrical system as claimed in claim 4, 5 or 6 where an external control signal can be applied in advance to increase the generator output and temporarily absorb excess power in said load absorber.
8. An electrical system as claimed in any preceeding claim wherein the load absorber may be in the form of any workable device whether using electrical, mechanical or fluid means in any combination.
9. An electrical system as claimed in any preceeding claim, wherein additional signals such as from a clock or additonal volts or amps are sensed.
10. An electrical system as claimed in any preceeding claim, wherein a parameter sensed may be water level or pressure.