Power station system with shared static starting device

Details Power station system with shared static starting device Power station system with shared static starting device

2001-02-23

2003-09-23

Picard, Leo (Department: 2125)

Data processing: generic control systems or specific application

Specific application, apparatus or process

Electrical power generation or distribution system

C700S297000

Reexamination Certificate

active

06625521

ABSTRACT:

This application claims priority under 35 U.S.C. §§119 and/or 365 to Appln, N. 100 08 457.5 filed in Germany on Feb. 23, 2000; the entire content of which is hereby incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to the field of power station technology. It relates in particular to a power station system having a number of identical subunits each including a turbine, and a generator/motor connected to the turbine, and a controller.
Such a power station is known, for example, from U.S. Pat. No. 3,764,815 (FIG. 6) or from U.S. Pat. No. 4,069,424.
DISCUSSION OF BACKGROUND
Static frequency converters (SFC) have been used in static starting devices (SSD) for several decades in pump storage power stations or gas turbine power stations, in order to accelerate the power station generators (gas turbine power stations or motors for pumps, turbines in pump storage power stations) from rest to a rotation speed at which they can continue to run on their own. During such a start, the synchronous generator is operated as a synchronous motor, with the electrical power required for the stator connections being provided at a variable frequency and voltage by the static frequency converter. In systems with a number of turbine/generator units, pump/turbine motor units (subunits), one static frequency converter is frequently used for a number of units in this case, in order to keep the system costs low. However, as a rule, this necessitates central control functions in order that the common static frequency converter can be used by the controllers for the connected subunits. In the past, such a central control function was always provided by a central controller which assigned the various digital and analog signals, and the signals transmitted on the bus, between the static frequency converter and the subunit to be accelerated.
FIG. 1
shows an example of one such central controller. In this example, six subunits with the associated controllers
14
a-c
(group
1
) and
15
a-c
(group
2
) are provided in the power station
10
. Each group has an associated static starting device
12
or
13
, respectively, and can interchange data and/or signals with the individual controllers
14
a-c
or
15
a-c
, respectively, in the group via appropriate connections. A connection between the two groups, which can be disconnected by means of a segment isolating switch
16
, also allows one of the static starting devices
12
,
13
to be connected to subunits in the respective other group as well, in an emergency. A central controller
11
determines which of the subunits or controllers
14
a-c
and
15
a-c
will be used for a starting process by one of the static starting devices
12
,
13
, and this central controller
11
interchanges information not only with the controllers
14
a-c
,
15
a-c
of the subunits but also with the static starting devices
12
,
13
.
A disadvantage of this known solution is that the additional central control function must be designed specifically for each specific system configuration. This relates, for example, to the number of static starting devices (primary and standby devices) per number of subunits which use the starting device normally and in an emergency when one of the starting devices has failed. Furthermore, during construction of the power station system, the central control needs to be continually modified to the latest standard in order to match the control logic to the system configuration existing at that time and to the availability of starting devices and subunits. This matching process has been found to be costly and time-consuming.
SUMMARY OF THE INVENTION
The object of the invention is thus to design the starting devices for a power station system such that the stated disadvantages are overcome and such that, in particular, the engineering and system costs can be considerably reduced by saving a central control function.
The essence of the invention is to use a decentralized allocation logic structure in each controller of a subunit in the same way, and directly to produce and to store information when the respective starting device is currently being used by a subunit and is thus not available for further use by another subunit, or is busy. The controllers of the other subunits then immediately know that the static starting device is currently unavailable for starting, and they can react accordingly. Since each subunit is always informed about the current availability of the associated starting device, there is no need for a central controller, or the complexity associated with it.
According to one preferred refinement of the invention, a busy signal (“flag”) is used to describe the availability of the static starting device and is set when one of the controllers initiates a start using the associated static starting device and is reset when none of the controllers initiates a start and the associated static starting device is freely available, with the busy signal being derived in particular from a function or unit in the power station system which allows reliable indication of the busy status of the static starting device at that time.
This can be done either by the static starting device producing the busy signal itself, or by the busy signal being produced by a component or a unit which is associated with the respective subunit and changes its status when a starting process is initiated. In the latter case, when a starting isolating switch is in each case provided for connecting the subunit and static starting device during a starting process and, as a high-voltage switch, connects the static starting device to the generator bus of the subunit, the busy signal is produced or derived from the starting isolating switches.
A further preferred refinement of the invention is characterized in that the subunits and their controllers are combined to form groups, and in that each group has its own dedicated static starting device for normal operation, in that each of the controllers in a group is connected to the associated static starting device via a first channel, in that each of the controllers in a group is connected to the static starting device of another group via a second channel and in that the connection via the second channels is activated only when the dedicated static starting device in the group is not available in an emergency.
The connection between the controllers and the associated static starting devices can be produced, in particular, by permanent wiring. However, it is also feasible for the connection between the controllers and the associated static starting devices to be produced via a data or signal bus.


REFERENCES:
patent: 3764815 (1973-10-01), Habock et al.
patent: 3908161 (1975-09-01), Messenger
patent: 4069424 (1978-01-01), Burkett
patent: 6333622 (2001-12-01), Fogarty et al.
patent: 6339316 (2002-01-01), Eguchi et al.
patent: 2001/0054823 (2001-12-01), Fogarty et al.

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