JPH0680344U - Automatic controller for maximum power demand - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] To save energy by intermittently operating a motor that consumes wasted power by soft start. [Structure] The electric power used is reduced by intermittently operating the motor M that is operating when the factory is not operating. In the most demanding period, the demand control manages the electric power, and when the contracted electric power is likely to be exceeded, the load is wirelessly applied. The control and soft start control device S reduce the power consumption at startup and protect the motor and equipment from damage. [Effect] Highly-tech electronic equipment and newly-developed soft-start control device are roughly matched to achieve more effective energy saving and demand control labor saving. Solve.

Description

[Detailed description of the device] [Industrial applications]

 Since the current power situation is such that the supply capacity is insufficient during the maximum demand period in the summer, the power company installs a transaction meter at the customer's private substation and measures and records the maximum power demand in 30-minute units. . In the case of a customer with a contract of 500 KW or less, if the contracted power is exceeded within this 30 minutes, the excess amount of power will be the basic contracted charge from the current month, and even if the maximum power demand falls below that month, it will continue for the next 11 months. Is this charge. In the case of a customer of 500 kW or more, if the contracted power exceeds 4% for 30 minutes, the amount of excess power multiplied by the basic charge will be paid 1,5 times as much. In addition, if the number of contracts is exceeded, the contracted power may be changed. Therefore, it is necessary for each customer to constantly manage the demand power with a demand controller (maximum power monitor) and take measures to suspend the load so as not to exceed the contract power when it is likely to exceed. Become.

[Prior art]

 The transaction instrument on the power receiving side of the substation transmits it to the demand controller with a pulse detector. The demand controller measures for 30 minutes and issues the first alarm in advance when the target power is likely to be exceeded. Therefore, the load stopped by the power manager is stopped. The alarm continues for 30 minutes after the 2nd and 3rd, and if there is enough power, the stopped load is restarted and the following procedure is repeated.

[Problems to be solved by the device]

 (1) Since the load is turned on and off frequently, the shock load at startup causes damage to the motor and drive equipment. (2) When restarting, power consumption is increased because the startup power is consumed. (3) When an ON-OFF command is issued from the control room to a site with a load, it is necessary to wire the circuit concerned, which is very expensive, and in the case of a large factory, it is often physically impossible. Good. (4) Stopping and restarting the load must be done manually by the electric power manager, and it can be too late because the alarm is issued in a short time.

[Means for Solving the Problems]

 (1) For a normal induction motor, the maximum starting current at startup is set to 8 times the rated current. For this reason, if the motor is frequently turned on and off, the motor will start up and burn out due to accumulated heat. This is why motors that operate only intermittently are kept in continuous operation. Even if the motor is not running, the motor consumes power to maintain the specified speed. Such a motor is stopped when it is not operating, and when it is operating, it is operated only during the operating time by soft start. The soft start function limits the current to less than twice the rated current, so the motor temperature becomes lower than during continuous operation. As a result, the power consumption of the entire factory is reduced and the maximum power demand is also reduced. (2) By further reducing the maximum power demand in summer, a greater effect can be achieved. Using a conventional demand controller (commercially available product) that can program a stop command, the stop output signal and restart output signal are transmitted to the load wirelessly. In that method, the output of the demand controller is input to the program sequencer. Program the code number in the sequencer. Input the sequencer output to the transceiver fixed station (master station). A transceiver fixed station is installed on the load side (slave station). The fixed station on the load side specified by the code number stops the load and answers the report. Example: Stop load 01 The first alarm is output from the demand controller → Sequencer 010 signal → Master station transmission → Slave station reception → Load stop → Slave station reply transmission → Master station reply reception (3) Restart the stopped load At this time, a soft start is performed to protect the motor and equipment from damage, and to start up and save power consumption.

Example Effects of the Invention (1) A 450-ton molding machine was operated by a main hydraulic pump motor and a sub hydraulic pump motor. The main motor was operating relatively busy, but the sub motor (200 V, 3 phase, 22 kW) had an operating time of 4,5 seconds for 120 seconds per cycle. Therefore, we extracted the signal from the control panel of the machine, installed a soft start device, and operated the motor only during operating hours. As a result, the power consumption before improvement was 5,5 KWh and after improvement was 1,1 KWh, and energy saving of 4,4 KWh was achieved, resulting in an energy saving rate of 80%. (2) The maximum power demand of consumers with a contract power of 430 kW was 480 kW at the peak of summer. Therefore, we installed a controller for the maximum power demand of the present invention to control three air conditioning equipment. The result was that the maximum power demand was returned to 430 kW at the peak.

[Brief description of drawings]

[Figure 1] Overall system configuration diagram Substation, power management unit,
It is a soft-start of a motor with a long down time, a master station, and a block diagram of a slave station. Each block will be described below.

FIG. 2 is a block diagram of soft start control. The thyristor control device is controlled by a time setting device. The start signal causes the time setter output to rise from 0V to + 10V. Set the rising speed with the time potentiometer. The thyristor control device has AC2 for input voltage change of 0 to + 10V.
The power supply voltage of 00V is controlled to 0 to 200V. 200V
Then, the electromagnetic switch is turned on, bypassing the thyristor and making the current flowing through the thyristor zero. Therefore, a thyristor with a small capacity can be used.

[Fig. 3] System configuration diagram of demand controller The signal of the transaction instrument installed at the electric power company is transmitted to the demand controller by the pulse detector. The demand controller has preset target power, current power, load stop-load restart program.

[Figure 4] Master station load stop-restart system configuration diagram The program sequencer receives stop and restart signals from the demand controller. The identification number of the slave station is programmed in the sequencer. When the ON signal stop command is received from the demand controller, the corresponding slave station identification number is sent to the master station wireless transceiver. The transmitter / receiver transmits the corresponding identification number to the slave station and receives the reply confirmation signal from the slave station. This allows a plurality of slave stations to be controlled freely. Demand controller O also when restarting
Since the same process is performed for the FF signal, the description is omitted.

[Fig. 5] Configuration diagram of slave station load stop / restart system The signal transmitted from the master station is analyzed by a signal analyzer, and if it is its own number, the target load is stopped and a reply confirmation signal is sent to the master station. Send to. The description of the same process will be omitted for restarting.

Claims (3)

[Scope of utility model registration request] 1. The load state of the induction motor is checked, and the motor with a long down time is temporarily stopped, and when operating, the motor is soft-started by current limiting to protect the heat generation of the motor due to the starting current, and after the soft-start is completed, A control device that protects the thyristor by bypassing the internal voltage control thyristor with an electromagnetic switch when the full voltage is reached. 2. A soft start control device for the purpose of protecting damage to a motor and equipment by controlling the maximum demand power in summer and the like by a demand controller and turning the motor on and off. 3. A control device for automatically issuing a stop or start command from a management center to a site where a motor is installed by a wireless system.