Electricity: power supply or regulation systems – For reactive power control
Reexamination Certificate
2000-03-08
2001-02-13
Han, Jessica (Department: 2838)
Electricity: power supply or regulation systems
For reactive power control
C323S207000
Reexamination Certificate
active
06188205
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power system control apparatus and a power system control method in which voltage and reactive power in a power system are adjusted to desired values by operating a control apparatus of the power system.
2. Description of Related Art
As is disclosed in pages 1200-1201 of lectures of a National Conference of Japanese Electrotechnical Committee held in 1987, in a conventional power system control method, a voltage of a first substation corresponding to one power system and a reactive power flow transmitted through a bank are measured, and phase modifying equipment (for example, a transformer tap, a condenser, a reactor and the like) arranged in the first substation is controlled according to measured values.
Accordingly, in cases where the first substation is isolated from another substation, a voltage fluctuation in the first substation can be suppressed according to the conventional power system control method by controlling the phase modifying equipment.
However, in cases where the first substation is connected with a second substation, because a voltage fluctuation of the second substation adjacent to the first substation is not considered, there is a drawback that voltages of the first and second substations adjacent to each other become unstable.
Also, to prevent hunting in a control operation repeatedly performed in the phase modifying equipment by suppressing voltage fluctuations occurring in substations (or power systems) adjacent to each other, a method for controlling all apparatus of the power systems adjacent to each other by collecting all information of the power systems as one package is disclosed in pages 1115-1120, Vol. B117-8, theses in Japanese Electrotechnical Committee. However, in this method, the amount of data included in the information is too large to be processed, so it is difficult to increase control precision of the apparatus because it is required to identify the power systems, and a control time period for the apparatus is undesirably lengthened.
SUMMARY OF THE INVENTION
To solve the above drawbacks, an object of the present invention is to provide a power system control apparatus and a power system control method in which a voltage fluctuation and a reactive power fluctuation in a to-be-controlled power system are immediately suppressed by collecting pieces of information locally existing in the to-be-controlled power system and an adjoining power system adjacent to the to-be-controlled power system so as to perform a cooperation of the to-be-controlled power system with the adjoining power system.
The object is achieved by the provision of a power system control apparatus, comprising:
power flow measuring means for measuring a value of a reactive power flow and a value of an effective power flow, which respectively flow between a to-be-controlled power system and an adjoining power system adjacent to the to-be-controlled power system, for each of one or a plurality of adjoining power systems;
desired value determining means for determining a desired value of the reactive power flow or a desired summed value of the reactive power flows according to the measured values of the reactive power flows and the measured values of the effective power flows obtained by the power flow measuring means, a desired voltage value of the to-be-controlled power system and one or a plurality of desired voltage values of the adjoining power systems;
required value calculating means for calculating a required value of a reactive power of the to-be-controlled power system according to the measured values of the reactive power flows and the measured values of the effective power flows obtained by the power flow measuring means, the desired value of the reactive power flow or the desired summed value of the reactive power flows determined by the desired value determining means, the desired voltage value of the to-be-controlled power system and a measured voltage value of the to-be-controlled power system; and
control means for selecting a control apparatus from a plurality of control apparatuses arranged in the to-be-controlled power system according to the required value of the reactive power calculated by the required value calculating means and controlling an operation of the selected control apparatus to make the selected control apparatus reduce the required value of the reactive power of the to-be-controlled power system.
In the above configuration, pieces of locally-existing information composed of a measured value of a reactive power flow and a measured value of an effective power flow flowing between the to-be-controlled power system and each adjoining power system, the desired voltage value of the to-be-controlled power system, the desired voltage values of the adjoining power systems and a measured voltage value of the to-be-controlled power system are collected, and a required value of a reactive power of the to-be-controlled power system is calculated by the required value calculating means according to the locally-existing information. Thereafter, a control apparatus having an electric capacity near to the required value of the reactive power is selected from a plurality of control apparatuses arranged in the to-be-controlled power system, and the selected control apparatus is controlled by the control means to make the selected control apparatus reduce the required value of the reactive power. Therefore, a voltage of the to-be-controlled power system is increased or decreased by the selected control apparatus, and the required value of the reactive power calculated by the required value calculating means approaches a zero value.
Accordingly, a cooperation of the to-be-controlled power system with the adjoining power systems can be performed by collecting the pieces of locally-existing information, and a voltage fluctuation and a reactive power fluctuation in the to-be-controlled power system can be immediately suppressed.
It is preferable that the required value of the reactive power calculated by the required value calculating means include a term which is obtained by multiplying a deviation value of the measured voltage value of the to-be-controlled power system from the desired voltage value of the to-be-controlled power system by a control constant.
Because a term corresponding to the deviation value between the measured and desired voltage values of the to-be-controlled power system is included in the required value of the reactive power, the voltage fluctuation and the reactive power fluctuation in the to-be-controlled partial power system can be reliably suppressed.
It is preferable that the power system control apparatus further comprise:
constant value changing means for changing a value of the control constant or the desired voltage value of the to-be-controlled power system in cases where a system configuration of the to-be-controlled power system and the adjoining power systems is changed.
Even though a plurality of adjoining power systems exist, because the value of the control constant is changed with the system configuration, the voltage fluctuation and the reactive power fluctuation in the to-be-controlled partial power system can be reliably suppressed even though the system configuration is changed.
It is preferable that the power system control apparatus further comprise:
constant value changing means for changing a value of the control constant in cases where the desired voltage value of the to-be-controlled power system or the desired voltage value of one adjoining power system is changed.
In cases where operation conditions of the to-be-controlled power system or the adjoining power system are changed, the desired voltage value of the to-be-controlled power system or the adjoining power system is changed. Because the value of the control constant is changed with the desired value of the to-be-controlled power system or the adjoining power, the voltage fluctuation and the reactive power fluctuation in the to-be-controlled partial power system ca
Deno Kenichi
Fukuta Naoto
Iba Kenji
Izui Yoshio
Kowada Yasuyuki
Han Jessica
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
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