Patent GB-871617-A (GB)
Title: Improvements in or relating to computers for power plants
IPC: G06G7/635
Filed: 1957-07-17
Abstract: 871,617. Electric analogue calculating. SIEMENS-SCHUCKERTWERKE A.G. July 17, 1957 [July 17, 1956], No. 22652/57. Class 37. A computer determining the most economical division of total load among plural generating stations of a power supply system for minimum total production cost comprises for each generating unit a function potentiometer providing a predetermined voltage output curve which supplies an output as a function of the instantaneous station loading to represent the differential production cost or incremental cost #Ki - (where Ni is the load and Ki the operating #Ni cost of a station i); there being associated with each potentiometer a current summation circuit for the outputs of individual first multiplication elements, each comprising a resistance of admittance representing a coefficient Bik supplied with voltages Nk representing the load on a station k to pass a current representing BikNk to produce an output current representing the function #BikNk for a given load network, which output current is applied with added constants to a second multiplying circuit for multiplication by a current representing the load/cost factor A of the system as a whole, dependent on the total system loading #Ni; the output of each individual summation arrangement and multiplication circuit representing #(1 - 2#BikNk) being fed to a comparator together with a voltage or current representing the differential production #Ki costs - to produce an error signal controlling #Ni a servosystem regulating the setting of the associated function potentiometer until the error signal is reduced to zero, whereby the most economical output for each generating unit is determined by the appropriate potentiometer setting in relation to the specific cost factor # for the total load. Fig. 5 shows a computer wherein A, C are simulating units representing thermal generating stations and B is a simulating unit for a pumped storage hydroelectric station capable of generating or absorbing power; the stations being connected to a common network. Units A, C incorporate double-tapped autotransformers energized from a standard alternating voltage source giving analogue voltages of station power Nk while unit B incorporates a similar autotransformer giving analogue voltages of power absorbed or generated in corresponding phase sense. Each unit incorporates in addition a pair of function generating potentiometers each having a slider and plural energizing taps selectively connectible to a tapped graduated direct voltage source 14 in accordance with the potentiometer law required. The respective function potentiometers yield for each unit analogue voltages of the operating cost per hour of the station and of the differen- #Ki tial load/cost factor -, where Ni is the load #Ni and Ki is the station-operating cost (Figs. 1, 2, not shown). The sliders of the potentiometers and autotransformer windings of each unit are ganged together for variation by a rebalancing servomotor M. Bus-bars AS1, AS2; BS1, BS2; CS 1, CS2; are energized in phase opposition from the autotransformer sliders of the respective units, and voltages of preselected phase senses may be connected therefrom to ranks of resistances WAA, WAB, WAC, corresponding to station A; WBA' WBB, WBC corresponding to station B and WCA, WCB, WCC corresponding to station C; each resistance having a conductance representing a coefficient Bik derived from the electrogeographical conditions of distribution of the network connections of the system, the positions of the respective stations, and the individual loads thereon. The currents flowing in the resistances are summed for the ranks corresponding to the respective stations to derive the analogues of the expression #NkBik for the respective stations, together with currents derived from units 16A, 16B, 16C energized from the alternating supply, each comprising (Fig. 4, not shown) a resistance whose conductance represents a loss coefficient Bio for each station in series with a 2: 1 step-down transformer to introduce a current analogue of Bio -, and from series resistances 15A, 15B, 15C 2 introducing constant currents representing ¢; the total currents representing Bio #kNkBik + --- ¢ 2 for respective station, energizing Hall plate multipliers 12A, 12B, 12C also excited in response to a current representing 2#, where # is the load/cost factor of the group of stations as a whole, derived from a rebalancing servomotor driven potentiometer system 13, responsive to the difference between voltages representing the required and the actual output of the whole group. The Hall multiplier outputs are extracted over transformers 12A, 12B, 12C, rectified, and applied to the inputs of the servomotors of the several station simulating units A, B, C, in opposition to the potentiometer outputs representing #Ki/#Ni so that the motors run until the error voltage is zeroized and the equation #Ki Bio - = - 2#[#kBikNk + -- ¢] #Ni 2 (1) is satisfied, the potentiometer slider position represents output for most economical operation, and the remaining potentiometer output represents cost per hour of the station. Other Hall plate multipliers 17A, 17B, 17C energized by the currents #kNkBik corresponding to the respective stations are also energized by currents representing the several power outputs Nk thereof together with currents representing the loss coefficients Bio, and the outputs are summed in series in transformers, rectified and combined with a voltage from potentiometer 18 representing a constant loss coefficient Boo to simulate the expression Nv = #i[#kNkBik+Bio]Ni+Boo (2) representing the total network power loss by a combined direct voltage. An analogue voltage of the total generated output of the power plants is derived by the summation by transformers 20A, 20B, 20C and subsequent rectification of the outputs of the tapped autotransformers of simulating units A, B, C, and may be combined in opposition with a predetermined direct voltage proportional to the required output for actuation of servomotor 13 which operates until the error signal is zero and at the same time adjusts accordingly the # excitation of Hall plate multipliers 12A, 12B, 12C.