Systems and methods for refrigerant leakage diagnosis

1 . A system for refrigerant leakage detection, the system comprising:

one or more sensors configured to detect one or more parameters of a building system including a refrigerant;

one or more storage devices storing instructions thereon that, when executed by one or more processors, cause the one or more processors to:

receive sensor data from the one or more sensors;

apply the sensor data to a long short-term memory (LSTM) model to generate predicted sensor data corresponding to the one or more sensors;

receive subsequent sensor data from the one or more sensors;

compare the predicted sensor data to the subsequent sensor data, wherein comparing the predicted sensor data to the subsequent sensor data includes determining reconstruction errors for each of the one or more sensors;

determine that the building system has a refrigerant leakage based on at least one reconstruction error exceeding a threshold value, wherein the threshold value is one of a plurality of threshold values corresponding to different refrigerant leakage severities and determining that the building system has the refrigerant leakage includes determining a severity of the refrigerant leakage based on the refrigerant leakage severity corresponding to the exceeded threshold value; and

responsive to determining that the building system has the refrigerant leakage, take an action to address the refrigerant leakage.

2 . The system of claim 1 , wherein the instructions further cause the one or more processors to:

receive a plurality of no-leakage test data samples and a plurality of leakage test data samples from the one or more sensors, the plurality of no-leakage test data samples being collected under a no-leakage condition where the building system has no refrigerant leakage, the plurality of leakage test data samples being collected under at least one leakage condition where the building system has at least one leakage severity, the plurality of no-leakage test data samples and the plurality of leakage test data samples being collected on a rolling and overlapping basis such that consecutive no-leakage test data samples include overlapping no-leakage data elements and consecutive leakage test data samples include overlapping leakage data elements;

apply the plurality of no-leakage test data samples and the plurality of leakage test data samples to the LSTM model;

determine a test reconstruction error for each of the plurality of no-leakage test data samples and each of the plurality of leakage test data samples; and

determine threshold coefficients for the no-leakage condition and the at least one leakage condition based on the test reconstruction errors.

3 . The system of claim 2 , wherein the plurality of threshold values are determined based on a maximum no-leakage threshold value and proportional coefficients generated using the determined threshold coefficients.

4 . The system of claim 2 , wherein the threshold coefficient is determined for the no-leakage condition by averaging the test reconstruction errors of a predetermined number of no-leakage test data samples having the highest values and the threshold coefficient is determined for the at least one leakage condition by averaging the test reconstruction errors of a predetermined number of leakage test data samples having the highest values.

5 . The system of claim 1 , wherein the building system comprises one of a heating, cooling, and/or air conditioning (HVAC) system, a chiller, or an air-conditioning unit.

6 . The system of claim 1 , wherein the action comprises one or more of activating, deactivating, or modifying operation of a device to reduce or stop the refrigerant leakage, raising an alarm indicating the refrigerant leakage, or generating a report indicating the refrigerant leakage.

7 . A system for refrigerant leakage detection, the system comprising:

one or more sensors configured to detect one or more parameters of a building system including a refrigerant;

one or more storage devices storing instructions thereon that, when executed by one or more processors, cause the one or more processors to:

determine reconstruction error enhancement coefficients for each of the one or more sensors;

receive sensor data from the one or more sensors;

apply the sensor data to a long short-term memory (LSTM) model to generate predicted sensor data corresponding to the one or more sensors;

receive subsequent sensor data from the one or more sensors;

compare the predicted sensor data to the subsequent sensor data to generate one or more reconstruction errors;

apply the reconstruction error enhancement coefficients to the one or more reconstruction errors to generate one or more enhanced reconstruction errors;

determine that the building system has a refrigerant leakage based on the one or more enhanced reconstruction errors; and

responsive to determining that the building system has the refrigerant leakage, take an action to address the refrigerant leakage.

8 . The system of claim 7 , wherein the reconstruction error enhancement coefficients are indicative of a given reconstruction error of a given sensor being related to refrigerant leakage.

9 . The system of claim 7 , wherein the instructions further cause the one or more processors to:

receive a plurality of no-leakage test data samples and a plurality of leakage test data samples from the one or more sensors, the plurality of no-leakage test data samples being collected under a no-leakage condition where the building system has no refrigerant leakage, the plurality of leakage test data samples being collected under at least one leakage condition where the building system has at least one leakage severity, the plurality of no-leakage test data samples and the plurality of leakage test data samples being collected on a rolling and overlapping basis such that consecutive no-leakage test data samples include overlapping no-leakage data elements and consecutive leakage test data samples include overlapping leakage data elements;

apply the plurality of no-leakage test data samples and the plurality of leakage test data samples to the LSTM model; and

determine a test reconstruction error for each of the plurality of no-leakage test data samples and each of the plurality of leakage test data samples.

10 . The system of claim 9 , wherein the reconstruction error enhancement coefficients are determined by performing a multiple linear regression on the plurality of no-leakage test data samples and the plurality of leakage test data samples where a refrigerant charge amount is used as a dependent variable and test sensor data from the plurality of no-leakage test data samples and the plurality of leakage test data samples are used as independent variables.

11 . The system of claim 9 , wherein the instructions further cause the one or more processors to:

apply the reconstruction error enhancement coefficients to the test reconstruction errors to generate enhanced test reconstruction errors; and

determine threshold coefficients for the no-leakage condition and the at least one leakage condition based on the enhanced test reconstruction errors.

12 . The system of claim 11 , wherein the threshold coefficient is determined for the no-leakage condition by averaging the enhanced test reconstruction errors of a predetermined number of no-leakage test data samples having the highest values and the threshold coefficient is determined for the at least one leakage condition by averaging the enhanced test reconstruction errors of a predetermined number of leakage test data samples having the highest values.

13 . A method for refrigerant leakage detection, the method comprising:

receiving, by one or more processors of a system, sensor data from one or more sensors associated with a building system including a refrigerant;

applying, by the one or more processors, the sensor data to a machine learning model to generate predicted sensor data corresponding to the one or more sensors, wherein the machine learning model is a long short-term memory (LSTM) model;

receiving, by the one or more processors, subsequent sensor data from the one or more sensors;

comparing, by the one or more processors, the predicted sensor data to the subsequent sensor data, wherein comparing the predicted sensor data to the subsequent sensor data includes generating one or more reconstruction errors;

determining, by the one or more processors, reconstruction error enhancement coefficients for each of the one or more sensors;

applying, by the one or more processors, the reconstruction error enhancement coefficients to the one or more reconstruction errors to generate one or more enhanced reconstruction errors;

determining, by the one or more processors, that the building system has a refrigerant leakage using the one or more enhanced reconstruction errors; and

responsive to determining that the building system has the refrigerant leakage, taking, by the one or more processors, an action to address the refrigerant leakage.

14 . The method of claim 13 , wherein the reconstruction error enhancement coefficients are indicative of a given reconstruction error of a given sensor being related to refrigerant leakage.

15 . The method of claim 13 , further comprising:

receiving, by the one or more processors, a plurality of no-leakage test data samples and a plurality of leakage test data samples from the one or more sensors, the plurality of no-leakage test data samples being collected under a no-leakage condition where the building system has no refrigerant leakage, the plurality of leakage test data samples being collected under at least one leakage condition where the building system has at least one leakage severity, the plurality of no-leakage test data samples and the plurality of leakage test data samples being collected on a rolling and overlapping basis such that consecutive no-leakage test data samples include overlapping no-leakage data elements and consecutive leakage test data samples include overlapping leakage data elements;

applying, by the one or more processors, the plurality of no-leakage test data samples and the plurality of leakage test data samples to the LSTM model; and

determining, by the one or more processors, a test reconstruction error for each of the plurality of no-leakage test data samples and each of the plurality of leakage test data samples, and

wherein the reconstruction error enhancement coefficients are determined by performing a multiple linear regression on the plurality of no-leakage test data samples and the plurality of leakage test data samples where a refrigerant charge amount is used as a dependent variable and test sensor data from the plurality of no-leakage test data samples and the plurality of leakage test data samples are used as independent variables.