CN-115790020-B - Screw type water chilling unit and control method and device thereof

CN115790020BCN 115790020 BCN115790020 BCN 115790020BCN-115790020-B

Abstract

The invention discloses a screw type water chilling unit and a control method and a control device thereof, wherein the screw type water chilling unit at least comprises a compressor, a frequency converter and an adjustable valve; determining a unit adjusting value according to the target water temperature, the current water temperature and the current water temperature change rate, judging whether the unit adjusting value is in a preset adjusting range, and if not, adjusting the opening of an energy adjusting valve and the frequency of a frequency converter according to the unit adjusting value. According to the technical scheme, the water temperature can be regulated efficiently and accurately, and the energy efficiency is improved.

Inventors

LI JIANZHANG
LI QINGYANG
Zeng Binhao
LI WENLONG
WU HAOHUI

Assignees

广东申菱商用空调设备有限公司

Dates

Publication Date: 20260508
Application Date: 20221209

Claims (8)

1. A control method of a screw water chilling unit is characterized in that the screw water chilling unit at least comprises a compressor, a frequency converter and an adjustable valve, the adjustable valve comprises n-level adjusting openings, the frequency converter comprises m-level adjusting frequencies, opening values of the n-level adjusting openings are gradually increased, frequency values of the m-level adjusting frequencies are sequentially increased, n and m are positive integers which are larger than or equal to 2, and m is larger than n, and the control method of the screw water chilling unit comprises the following steps: Acquiring a target water temperature, a current water temperature and a current water temperature change rate of the screw water chiller; determining a unit adjusting value according to the target water temperature, the current water temperature and the current water temperature change rate; judging whether the unit adjusting value is in a preset adjusting range or not; if not, according to the unit adjusting value, adjusting the opening of the adjustable valve and the frequency of the frequency converter; according to the unit adjusting value, adjusting the opening of the adjustable valve and the frequency of the frequency converter comprises the following steps: When the unit adjusting value is smaller than the lower limit of the preset adjusting range, judging whether the current frequency of the frequency converter is the m-th level adjusting frequency or not; If not, controlling the adjustable valve to keep the current opening, adjusting the current frequency of the frequency converter to the next stage of adjusting frequency of the current frequency, and returning to execute the step of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chilling unit; If yes, controlling the adjustable valve to adjust to the next opening of the current opening, adjusting the current frequency of the frequency converter to the first-stage adjusting frequency, and returning to execute the step of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chilling unit.
2. The control method of a screw chiller according to claim 1 wherein determining a set adjustment value based on the target water temperature, the current water temperature, and the current water temperature rate of change comprises: And determining a unit regulating value based on a PID control algorithm according to the target water temperature, the current water temperature and the current water temperature change rate.
3. The control method of a screw chiller according to claim 1, wherein controlling the adjustable valve to maintain a current opening degree adjusts a current frequency of the frequency converter to a next-stage adjustment frequency of the current frequency, comprising: Controlling the adjustable valve to keep the current opening, and adjusting the current frequency of the frequency converter to the next stage adjusting frequency of the current frequency at a first preset rate; Controlling the adjustable valve to adjust to the opening of the next stage of the current opening, and adjusting the current frequency of the frequency converter to be the first stage adjusting frequency, comprising: controlling the adjustable valve to adjust to the opening of the next stage of the current opening, and adjusting the current frequency of the frequency converter to be the first stage adjusting frequency at a second preset rate; wherein the second preset rate is greater than the first preset rate.
4. The control method of a screw chiller according to claim 1, wherein adjusting the opening of the adjustable valve and the frequency of the frequency converter according to the set adjustment value comprises: when the unit adjusting value is larger than the upper limit of the preset adjusting range, judging whether the current frequency of the frequency converter is the first-stage adjusting frequency or not; If not, controlling the adjustable valve to keep the current opening, adjusting the current frequency of the frequency converter to the upper-stage adjusting frequency of the current frequency, and returning to execute the step of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chilling unit; if yes, controlling the adjustable valve to adjust to the upper-stage opening of the current opening, adjusting the current frequency of the frequency converter to the mth-stage adjusting frequency, and returning to execute the step of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chilling unit.
5. The control method of a screw chiller according to claim 4, wherein controlling the adjustable valve to maintain a current opening degree adjusts a current frequency of the frequency converter to a higher-level adjustment frequency of the current frequency, comprising: controlling the adjustable valve to keep the current opening, and adjusting the current frequency of the frequency converter to be the upper-level adjusting frequency of the current frequency at a third preset rate; controlling the adjustable valve to adjust to the upper-stage opening of the current opening, and adjusting the current frequency of the frequency converter to the mth-stage adjusting frequency, including: controlling the adjustable valve to adjust to the upper-stage opening of the current opening, and adjusting the current frequency of the frequency converter to the mth-stage adjusting frequency at a fourth preset rate; Wherein the fourth preset rate is greater than the third preset rate.
6. The control method of a screw chiller according to claim 1, further comprising: and if the unit regulating value is in the preset regulating range, controlling the adjustable valve to keep the current opening degree and controlling the frequency converter to keep the current frequency.
7. The control device of the screw water chilling unit is characterized by at least comprising a compressor, a frequency converter and an adjustable valve, wherein the adjustable valve comprises n-level adjusting openings, the frequency converter comprises m-level adjusting frequencies, the opening values of the n-level adjusting openings are gradually increased, the frequency values of the m-level adjusting frequencies are sequentially increased, n and m are positive integers which are greater than or equal to 2, and m is greater than n, and the control device of the screw water chilling unit comprises: the temperature acquisition module is used for acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chilling unit; The adjusting value determining module is used for determining a unit adjusting value according to the target water temperature, the current water temperature and the current water temperature change rate; The adjusting value judging module is used for judging whether the unit adjusting value is in a preset adjusting range or not; The opening frequency adjusting module is used for adjusting the opening of the adjustable valve and the frequency of the frequency converter according to the unit adjusting value when the unit adjusting value is not in a preset adjusting range, adjusting the opening of the adjustable valve and the frequency of the frequency converter according to the unit adjusting value, and comprises the steps of judging whether the current frequency of the frequency converter is the m-th adjusting frequency or not when the unit adjusting value is smaller than the lower limit of the preset adjusting range, controlling the adjustable valve to keep the current opening if the current frequency of the frequency converter is not in the m-th adjusting frequency, adjusting the current frequency of the frequency converter to be the next adjusting frequency of the current frequency, and returning to execute the steps of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chiller, and controlling the adjustable valve to adjust to the next opening of the current opening if the unit adjusting value is in the first-stage adjusting frequency, and returning to execute the steps of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chiller.
8. The screw type water chilling unit is characterized by comprising a compressor, a frequency converter, an adjustable valve and a controller; the controller is used for executing the control method of the screw water chilling unit according to any one of claims 1-6.

Description

Screw type water chilling unit and control method and device thereof Technical Field The invention relates to a control technology of a water chilling unit, in particular to a screw water chilling unit and a control method and device thereof. Background When the common fixed-frequency screw water chilling unit is started and operated by star-delta, the unit load is regulated by the electromagnetic valve of the compressor, the water temperature is regulated in a step or in a stepless way, but the water temperature is regulated in a step, the specific position of the compressor sliding block cannot be controlled accurately by stepless regulation, and therefore the unit load cannot be controlled accurately, and the accurate control of the water temperature cannot be realized. Disclosure of Invention The invention provides a screw water chilling unit and a control method and device thereof, so as to realize efficient and accurate water temperature regulation. In a first aspect, the present invention provides a control method of a screw water chiller, where the screw water chiller at least includes a compressor, a frequency converter, and an adjustable valve, and the control method of the screw water chiller includes: Acquiring a target water temperature, a current water temperature and a current water temperature change rate of the screw water chiller; determining a unit adjusting value according to the target water temperature, the current water temperature and the current water temperature change rate; judging whether the unit adjusting value is in a preset adjusting range or not; if not, the opening of the adjustable valve and the frequency of the frequency converter are adjusted according to the unit adjusting value. Optionally, determining the unit adjustment value according to the target water temperature, the current water temperature and the current water temperature change rate includes: And determining a unit regulating value based on a PID control algorithm according to the target water temperature, the current water temperature and the current water temperature change rate. Optionally, the adjustable valve comprises n-level adjusting opening degrees, the frequency converter comprises m-level adjusting frequencies, the opening degree value of the n-level adjusting opening degrees is gradually increased, the frequency value of the m-level adjusting frequencies is sequentially increased, wherein n and m are positive integers which are larger than or equal to 2, and m is larger than n. Optionally, according to the unit adjusting value, adjusting the opening of the adjustable valve and the frequency of the frequency converter includes: When the unit adjusting value is smaller than the lower limit of the preset adjusting range, judging whether the current frequency of the frequency converter is the m-th level adjusting frequency or not; If not, controlling the adjustable valve to keep the current opening, adjusting the current frequency of the frequency converter to the next stage of adjusting frequency of the current frequency, and returning to execute the step of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chilling unit; If yes, controlling the adjustable valve to adjust to the next opening of the current opening, adjusting the current frequency of the frequency converter to the first-stage adjusting frequency, and returning to execute the step of acquiring the target water temperature, the current water temperature and the current water temperature change rate of the screw water chilling unit. Optionally, controlling the adjustable valve to maintain a current opening, and adjusting the current frequency of the frequency converter to a next stage of adjusting frequency of the current frequency includes: Controlling the adjustable valve to keep the current opening, and adjusting the current frequency of the frequency converter to the next stage adjusting frequency of the current frequency at a first preset rate; Controlling the adjustable valve to adjust to the opening of the next stage of the current opening, and adjusting the current frequency of the frequency converter to be the first stage adjusting frequency, comprising: controlling the adjustable valve to adjust to the opening of the next stage of the current opening, and adjusting the current frequency of the frequency converter to be the first stage adjusting frequency at a second preset rate; wherein the second preset rate is greater than the first preset rate. Optionally, according to the unit adjusting value, adjusting the opening of the adjustable valve and the frequency of the frequency converter includes: when the unit adjusting value is larger than the upper limit of the preset adjusting range, judging whether the current frequency of the frequency converter is the first-stage adjusting frequency or not; If not, controlling the adjustable valve to ke