JPH07177660A - Noncutting demand control system - Google Patents

Abstract

PURPOSE:To sustain a control target power level without interrupting the load by connecting a demand controller with a Seebeck commander for commanding reduction of output frequency from a motor inverter or the output voltage from a lighting circuit inverter when the target power level is exceeded. CONSTITUTION:A demand controller 1 receives power pulses from a pulse detector 7 to grasp the working electric energy and operates the demand value, daily electric energy, daily load rate, etc., every time limit. When a contract electrrc energy is reached, a Seebeck commander 2 delivers an (a)-contact switching command to the demand controller 1. Consequently, a motor inverter 4 under control of the demand controller 1 reduces the output frequency and a light circuit inverter 6 reduces the voltage. This constitution allows to sustain the peak power below a control target level without cutting each load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-cut demand control system for managing maximum power demand. Suppresses peak power without cutting the motor or fluorescent light.

[0002]

2. Description of the Related Art Reduction of power consumption, suppression of peak power,
This demand control device, which aims at leveling the load and optimizing the power factor, issues an alarm when there is a risk of exceeding the management target power, and automatically shuts off the load according to a preset control method. In this way, each load is controlled and operated so that the contracted power does not exceed the contracted power within the time limit, the power is reasonably used, the peak power is reduced, and the load factor is improved. Also,
The basic electricity charge is set based on a power factor of 85%. Power factor correction devices that use capacitors for improvement are also popular for specific purposes.

[0003]

[Problems to be Solved by the Invention] Under the basic tariff system that employs the actual amount system (a system in which the contracted electric power for the subsequent year is determined by the actually measured maximum electric power), the contracted electric power is suppressed as much as possible. Therefore, I have a great interest in demand control devices, but the load shedding during peak power is a bottleneck because it hinders business. Moreover, in order to control multiple air conditioners in a cyclic manner, thorough assessment is required in advance. It is the present invention to provide a system for maintaining the management target power value without cutting off the load, which will be described in detail below with reference to the drawings.

[0004]

[Means for solving the problem] Under the control of the demand control device that monitors the power consumption and maintains the management target power, the inverter for the motor such as the blower and the pump, and the inverter for the lighting circuit are arranged to obtain the target power. When the value exceeds the value, a Zebeck commander for instructing the output frequency reduction of the motor inverter or the output voltage reduction of the lighting circuit inverter is connected to the demand control device.

[0005]

[Function] The demand control device grasps the amount of power used by the power pulse from the pulse detector and calculates the demand value for each time period, the total daily power amount, the daily load factor, and the like. When the contracted electric energy is reached, the Zebeck commander issues an a-contact switching command to the demand control device side. The inverter for the motor under the control of this demand control device diminishes the output frequency by this, and the inverter for the lighting circuit diminishes the voltage. Fig. 4 shows the frequency characteristics of an inverter motor with a cubic proportional characteristic such as a fan.
It is understood that it operates smoothly in the range of Hertz to 30 Hertz. Since power consumption by fans is high in factories and buildings, this frequency reduction method that saves energy without cutting off the load is more than expected. Since an inverter ballast is installed in the inverter fluorescent lamp, there is no problem even if the output voltage of the lighting circuit inverter drops. The target power value has a certain range, and the Zebeck commander adjusts the frequency of the motor inverter and the output voltage of the lighting circuit inverter via the demand control device so that the power consumption value falls within this range. In FIG. 3, the peak power value is controlled within the range based on the new contract power value. This difference in basic charges is large.

[0006]

[Embodiment] The demand control device 1 internally calculates a time-consuming power amount, a total daily power amount, a daily load factor, and the like based on a power pulse from a pulse detector 7, and continuously outputs the maximum power for each time period. When there is a possibility that the contract power (management target value) will be exceeded, the fact is transmitted to the Zebeck commander 2. The Zebeck commander 2 sends an optimum control command from a plurality of demand value control options (multiple stages) to this demand
Transfer to the control device 1. Usually, this Zebek commander 2 is incorporated in the demand control device 1. The inverter motor 3 is connected to the inverter motor 3 such as a fan or a pump, and the inverter fluorescent lamp 5 is connected to the lighting circuit inverter 6. The inverter fluorescent lamp 5 requires an inverter ballast. The motor inverter 4 and the lighting circuit inverter 6 are arranged under the control of the demand control device 1. The demand control device 1 causes the motor inverter 4 to reduce the output frequency and the lighting circuit inverter 6 to gradually reduce the output voltage.

FIG. 2 is an item to be examined when this system is implemented. In a building, the importance of the lighting lighting place for each floor is investigated, and the number of target lights (power consumption) is determined. In the case of motors used for fans and pumps, the contracted electric power and demand value are investigated, and then the load factor is investigated. The demand peak cut value is calculated from this load factor and the survey value of the number of target lights. Each inverter is optimally arranged based on this calculated value. Note that the option "load fluctuation" in Fig. 2 is not the demand control of the motor but the motor control that saves energy by the load fluctuation. The load fluctuation is detected as an electric power value to realize high speed by open loop control. A controller (for example, Japanese Patent Laid-Open No. 62-285691).

FIG. 3 is a demand curve for one day in September, which is a typical building power consumption characteristic in which a peak appears after 2:00 pm. After implementing the present invention, it is below the new contract value. Based on the command from the Zebeck commander 2, the demand control device 1 adjusts the frequency or voltage of each inverter to keep the demand value within a predetermined range and cut the peak power.

[0009]

In summary, according to the present invention, an inverter 4 for a motor such as a blower or a pump and an inverter 6 for a lighting circuit are arranged under the control of a demand control device 1 that monitors a power consumption and maintains a management target power. However, when the target power value is exceeded, the Zebeck commander 2 for instructing the output frequency reduction of the motor inverter 4 and the output voltage reduction of the lighting circuit inverter 6 is connected to the demand control device, so that each load is The peak power can be maintained below the management target power without cutting. The present invention that can keep the contracted basic power at a constant value is
It not only saves energy, but also saves electric power users a great deal of money.

[Brief description of drawings]

FIG. 1 is a system block diagram.

FIG. 2 is a flowchart of examination items for enforcement.

FIG. 3 is a daily power consumption curve.

FIG. 4 is a graph showing a relationship between a frequency applied to a motor and power consumption.

[Explanation of symbols]

 1 Demand control device 2 Zebeck commander 3 Inverter motor 4 Inverter for motor 5 Inverter fluorescent lamp 6 Inverter for lighting circuit

Claims (3)

[Claims] 1. The target power value is exceeded by arranging an inverter for a motor such as a blower or a pump or an inverter for a lighting circuit under the control of a demand control device that monitors the power consumption and maintains a management target power. At the same time, a non-cut demand control system that suppresses peak power by connecting a Zebeck commander that directs the output frequency reduction of the motor inverter or the output voltage reduction of the lighting circuit inverter to the demand control device. 2. An inverter fluorescent lamp having an inverter ballast is used as the lighting circuit, in which a group of cubic proportional characteristic motors are managed as the inverter motor.
Non-cut demand control system described. 3. A non-cut demand control system in which an inverter for a motor is arranged under the control of a demand control device, and the output frequency of the inverter for the motor is gradually reduced in order to maintain the used power at a control target power value.