Shenzhen Hexing Canada Energy Technology Co., Ltd. Li Xiaoming

[Abstract] This article mainly introduces the application of IPC-PFE elevator energy-saving feedback device in Otis brand elevators. The on-site operation shows that the transformation of returning the regenerative energy generated by the motor in the state of regenerative power generation to the power grid is successful. From the perspective of electric energy feedback technology, it shows that the energy-saving of the elevator is feasible.

[Keywords] PFE series elevator energy-saving feedback device Otis brand elevator electric energy feedback technology

I. Introduction

With the continuous expansion of modern production scale and the continuous improvement of people's living standards, energy prices have also soared, domestic electricity prices have also risen a lot, the contradiction between electricity supply and demand has become increasingly prominent, and the call for electricity saving is increasing. Relevant statistics show that the energy consumption of elevators basically accounts for 5-8% of the overall power consumption of the entire building. If all elevators nationwide carry out energy saving and consumption reduction work, it will save a lot of power resources, which is particularly important. Social significance and economic benefits.

2. Project introduction

A building in Shenzhen, Guangdong, covers an area of 8,549 square meters, with a total construction area of 84,026 square meters, including an office area of 42,499 square meters, a total of 30 floors, 364 units, and 400 parking spaces. It adopts a pure plank structure and uses Otis elevators. . 　

The English name of Otis Elevator is: OTIS, an elevator brand that originated in the United States, and the earliest elevator brand to enter the Chinese market. Otis has developed in China for more than 100 years and has been established in the Chinese market. It has established a number of joint-venture elevator brands headed by Tianjin Otis, Xizi Otis, Express Elevator, Xingma Elevator, etc. The elevator industry in China is in the position of industry leader.

3. Brief introduction of system process and current energy consumption

1. Process introduction

By pressing different function buttons, the car can reach the corresponding floor. After the button is pressed, the indicator light is on, and the corresponding action program starts to run. When the elevator runs to this floor in response to the call, the corresponding indicator light goes out and the elevator door opens. After a period of time, the elevator door closes. In the elevator running process, if the elevator goes up, the up request has priority. After the up request is executed, the down request is executed. Also in the elevator down process, the down request is given priority, and the up request is executed after the down request is executed. When there is no request, the elevator stops at the level where the last action is executed. At this time, press the uplink first, and the uplink request has priority; on the contrary, press the downlink first, and the downlink request has priority.

2. The current technology of elevators has energy consumption problems

After the elevator with variable frequency speed regulation starts and reaches the maximum operating speed, the inertia has the largest mechanical kinetic energy. Before the elevator reaches the target floor, it must gradually decelerate until the elevator stops moving. This process is the elevator traction machine releasing the mechanical energy. process.

In addition, the elevator is also a potential load. In order to evenly drag the load, the load driven by the elevator motor is composed of a passenger car and a counterweight balance block. Only when the load of the car is about 50% (1 ton passenger When the elevator passengers are about 7 people), the car and the counterweight balance weight will balance each other, otherwise, there will be a weight difference between the car and the counterweight balance weight, which will generate mechanical potential energy when the elevator is running. When the weight of the elevator car is less than the weight of the counterweight, the elevator motor generates electricity when the elevator moves up and consumes electricity down; otherwise, it consumes electricity up and down to generate electricity. When the elevator goes down under heavy load and goes up under light load, the excess mechanical energy (including potential energy and kinetic energy) is converted into DC electric energy by the motor and the inverter and stored in the capacitor in the inverter's DC circuit. At this time, the capacitor is like a small reservoir , The more electric energy sent back to the capacitor, the higher the capacitor voltage (for example, the water level of the reservoir is super high). If the electric energy stored in the capacitor is not released in time, an overvoltage fault will occur, which will cause the inverter to stop working and the elevator cannot operate normally. .

At present, the most common method is to convert electrical energy into thermal energy and emit it through an external heating resistor. At present, the existing elevators are equipped with an energy-consuming braking resistor box on the top of the elevator control cabinet to consume the electric energy generated during the operation of the elevator. Because of this, a large amount of electric energy generated by the elevator is consumed in the heat-generating resistance box, which not only causes a waste of energy, but also because the heat generated by the resistance is very high during the operation of the elevator, the local temperature of the resistance is usually at Above 100°C, the components of the control system are in a high temperature state for a long time, and will cause the temperature in the elevator machine room to rise, which causes the elevator to malfunction due to the high temperature and reduce the service life. To prevent the equipment from overheating, the computer room must be equipped with air-conditioning for cooling.

If this part of the electric energy generated during the operation of the elevator and wasted on the resistance box can be fed back to the grid for use by other equipment, not only this part of electric energy can be saved, but also due to the drop in the temperature in the elevator machine room. The power consumption of the cooling equipment (air conditioner, fan) in the computer room. After the elevator adopts energy feedback to save energy, because there is no resistance heating source, the temperature of the elevator machine room is significantly reduced, which not only reduces the failure rate of the elevator, but also prolongs the service life of the elevator relatively and achieves the effect of double energy saving.

4. Project transformation plan

After many investigations and comparisons, the user finally decided to adopt the IPC elevator energy-saving feedback device produced by Shenzhen Hexing Canon Technology Co., Ltd. Through the cooperation of the technical personnel of both parties, the elevator feedback energy-saving renovation plan was jointly formulated, and the renovation plan is as follows:

1. Configuration selection

2. Wiring mode with elevator control cabinet

The main circuit wiring of the elevator energy-saving feedback device is very simple. When this series of products are used in conjunction with the inverter, only the DC input terminals "DC (+)" and "DC (-) of the elevator energy-saving feedback device must be correctly connected to the inverter. For the positive and negative terminals of the DC bus, connect the AC feedback output terminals "A", "B", and "C" of the elevator energy-saving feedback device to the AC power supply of the inverter.

Notice

(1) When wiring, pay attention to the polarity of the DC (-) input terminal of the elevator energy-saving feedback device. If the polarity is reversed, it may cause damage to the equipment or even cause a fire hazard.

(2) In order to prevent the leakage of electricity from harming the human body, the ground terminal "PE" of the elevator energy-saving feedback device should be reliably grounded.

(3) The elevator energy-saving feedback device will automatically detect the phase of the grid and automatically work in synchronization with the grid. Therefore, the AC feedback output terminals "A", "B", and "C" of the elevator energy-saving feedback device will be in line with the corresponding grid A, B, The input R, S, T of C or the inverter does not have to correspond to each other. It is strictly prohibited to connect to the motor side and other AC circuits.

3. The installation and operation process of elevator energy-saving feedback device

n Power transmission

(1) If an air switch (QF) is installed at the output of the elevator energy-saving feedback device, first close the air switch (QF) at the output of the elevator's energy-saving feedback device.

(2) The total power supply of the elevator is delivered, and the panel of the elevator energy-saving cabinet is displayed in 5-10 seconds.

n Power off

(1) The main power supply of the elevator is cut off.

(2) The air switch (QF) at the output of the elevator energy-saving feedback device is disconnected.

n Matters needing attention

(1) It is strictly forbidden to continuously send power to the main power switch of the elevator without disconnecting the energy-saving feedback device of the elevator. When the power is transmitted, the internal voltage of the elevator control cabinet must be completely discharged before the elevator is re-powered, so as to avoid the internal energy-saving feedback device of the elevator. The fuse is damaged.

(2) It is strictly forbidden to directly disconnect the air switch (QF) at the output end of the elevator energy-saving feedback device when it is energized.

4. Otis brand elevators have problems in energy-saving renovation

(1) Imported Otis (OTIS) elevator, its control cabinet has a step-up transformer to change the voltage from 380V to 490V to the drive system of the inverter, resulting in the inverter's DC bus terminal voltage being 690V, which is in line with the current standard 380V feedback The operating voltage of the device does not match.

Therefore, it is necessary to modify the operating voltage value parameters of the main control circuit board into four gears of 690V, 700V, 710V, and 720V, and at the same time, the capacitor in the LCL filter circuit should also amplify the withstand voltage capacity.

(2) Otis Elevator (OH5100 series) using the Italian SV AVO gearless elevator inverter AVO3130-EBL BR4-0, when the elevator goes up, when the inverter's DC voltage rises from 560V to 610V, the time is only In two or three seconds, the built-in braking unit of the inverter starts to work, discharging the energy dissipation resistor (245V/6A), so that the DC voltage of the inverter drops to 420V. In the later stage of braking, the DC voltage instantly rises to 670V and then drops 567V. (Parking status). The DC voltage from the elevator down to the brake also varies from 552V to 565V.

5. Working principle and characteristics of IPC elevator energy-saving feedback device

1. Working principle of IPC elevator energy-saving feedback device PFE series elevator energy feedback device is a high-performance feedback braking unit for elevators made by Canadian technology. Its working principle: DSP digital central processing unit carries out control logic operation, adopts two-way automatic voltage tracking technology to automatically detect the inverter's DC bus voltage and low-voltage grid voltage in real time, and then uses flexible double PWM pulse width modulation technology to store elevator inverter capacitors The regenerative electric energy is converted into AC power with the same phase, same frequency, same voltage and same phase sequence as the internal local power grid supplying the elevator frequency conversion control system, turning the elevator into a green "power plant" for the internal local power grid Other power-consuming equipment supplies power so that other power-consuming equipment in the internal local power grid does not need to draw power from the power supply grid. If there is no power consumption by other equipment in the internal local power grid, the voltage value of the internal local power grid will be increased. When the voltage value is increased to the no-load voltage value of the transformer, the power will be fed back to the power supply grid. See the figure below for details:
 

2. Features of IPC elevator energy-saving feedback device

(1) Adopt flexible dual PWM technology to greatly reduce machine noise and temperature rise, and the output waveform is more perfect;

(2) The LCL filtering technology effectively suppresses harmonics and electromagnetic interference, so that the returned electric energy fully meets the requirements of the national grid and will not cause pollution to the grid.

(3) The unique "zero-point current" processing technology of the elevator energy-saving feedback device improves the current quality when the feedback current crosses zero, and improves the light-load feedback stability and power factor.

(4) The elevator energy-saving feedback device has a built-in fuse, which will not damage the original elevator system even if the output is short-circuited.

(5). Elevators are special equipment related to personal safety. Safety issues have been fully considered when designing elevator energy-saving feedback devices. When using elevator energy-saving feedback device to transform the elevator, we retained the original control method of the elevator, and "redundant each other" with the original control method. When the elevator energy-saving feedback device fails, it will immediately switch to the original control mode of the elevator and maintain the original control mode operation, so it will not affect the safety of the elevator system.

6. Economic benefits after inverter transformation

1. Data measurement

In order to evaluate the effect of the elevator system's frequency conversion transformation, two watt-hour meters were installed on one of the elevators on the site. The total power consumption meter was mechanical, and the energy-saving meter was tested by Wasion DSS-333 watt-hour meter. , One month after the system was put into normal operation, the actual use and power saving of the equipment were measured and data analyzed. The specific data is as follows:

2. Energy-saving benefits

The above test results show that

According to the analysis of the above figures, after the customer purchases the elevator energy feedback device, each elevator saves 108.2 kWh per week, saving 5,641.54 yuan in electricity bills a year. In addition, the air-conditioning costs saved by the elevator room and other non-calculating costs: reduce the cost of purchasing air-conditioning; because the ambient temperature is reduced, the product life is prolonged, and the air-conditioning maintenance cost is reduced.

Seven, concluding remarks

Elevator power feedback technology is a fully mature energy-saving technology worthy of promotion, and has been recognized by the national elevator quality management department. Office buildings, commercial buildings, hotels, high-rise residential buildings and other buildings can fully consider installing electrical energy feedback devices. It can not only save electricity, but also improve the working environment of the elevator and extend the life of the elevator.

References:

[1] "Technical Guidelines for Frequency Conversion and Speed Regulation of AC Motors"

[2] "PFE Series Elevator Energy Saving Device User Manual" Shenzhen IPC Technology Co., Ltd.