Maharashtra State Electricity Distribution Co. Ltd. (Mahavitaran) is one of the largest power distribution companies in India. It has over 6.3 lakhs Distribution Transformers (DTs) with transformation capacity of over 72,500 MVA. Its vision is to be the best power distribution utility in India delivering quality and reliable power at a competitive price.

The key priorities of MSEDCL is to reduce power distribution losses, improve reliability and quality of power supply, and ensure power for all.

In line with this, MSEDCL decided to conduct a pilot project to monitor power quality and reliability of Distribution Transformers under two different substation locations in Mumbai. The pilot project was designed as part a Smart Grid implementation, using an intelligent device with in-built communication module, which relayed real-time parameters to a central monitoring station for processing and analysis. For voltage quality measurements, EN 50160 and IS 17036 – 2018 were used as reference standards.

The pilot project was conceived, designed and implemented by Spectrum Infra Ventures (P) Ltd. (SIVPL), which is one of the leading Infrastructure Development, Construction and Project Management Companies in India.

CHALLENGES FACED BY MSEDCL IN DISTRIBUTION

Growing population and increasing demands is putting a lot of burden on the existing LT network assets and overloading of Distribution Transformers, particularly in congested areas. Overloading, voltage fluctuations and leakage current are some of the key issues which not only cause technical and revenue loss, but also affects the power quality and reliability of the distribution systems.

MSEDCL was keen to try an innovative, IoT (Internet-of-Things)-based solution on its power distribution network, to monitor power and voltage profile in real-time, on a pilot basis. The results of the study were proposed to be used to identify vulnerabilities in the network, and develop proof-of-concept for viable IoT-based solutions in power quality monitoring and analysis. MSEDCL proposes to use the findings in taking decisions to implement projects, under approved central schemes, on network planning and improvements, in compliance with Maharashtra ERC / CEA guidelines.

DETAILS OF PILOT PROJECT

SIVPL proposed and implemented a Smart Distribution PQ Management Solution as pilot project, using Smart MCCB (Molded Case Circuit Breaker), to demonstrate the ability of the device in early detection and restoration of faults in Distribution Transformers (DTs) and power lines. The pilot project was a smart grid implementation, involving intelligent MCCB installed on the LT side of Distribution Transformer. This is a relatively low-cost, cloud-based implementation, using IoT technologies.

The Smart MCCB solution monitors instantaneous line parameters e.g. voltage, current, active/ reactive power and temperature, and detects short circuit, over-current faults, earth leakage current, arcing faults and abrupt temperature rise. The operating limits of these parameters can be remotely configured and monitored on an Intelligent dashboard. Above all, the Smart MCCB solution was also demonstrated to be interoperable with the existing MSEDCL Substation automation and automatic metering system applications.

Two locations were identified by MSEDCL to implement the pilot – Wagle Estate 22/0.433 kV, 630 kVA and Dhokali 11/0.433 kV, 630 kVA Distribution Transformers. The Smart MCCB Distribution Management solution was configured to offer DT protection against overload, short circuit, earth leakage, phase loss, over/ under voltage and high temperature. The system was configured to operate and isolate the faulty section of LT network in case of an emerging fault, prevent cascading of the fault to other sections of the network and operate auto-reclosing of the MCCB when the fault was rectified. Smart auto-reclosing of the LT circuits allowed the system to recover quickly, restore power supply and improve network reliability indices (CAIDI, CAIFI, SAIDI, SAIFI) significantly.

The other benefits of the Smart MCCB based IoT solution was the avoidance of the high cost of failures of the DT and LT distribution system, in repairs and replacements. The table below provides the number of tripping avoided and duration of breakdown reduced, by detecting PQ violations early and timely restoration of LT circuit with auto-reclosing feature.

From the above table, it can be seen that PQ-related tripping was avoided in 7 cases in Jan saving 60 minutes of breakdown, 8 cases in Feb saving 68 minutes of breakdown, and 12 cases in March saving 102 minutes of breakdown. The results of the pilot project implied corresponding improvement in the reliability indices, exceeding the regulatory norms.

The PQ management solution enhanced the safety of the maintenance personnel and LT network assets. Integrated with DT metering system and Substation SCADA, using IEC 61850-compliant communication interfaces, the solution resulted in marked improvement in the operational efficiency of the LT distribution system.  The revenue savings due to breakdown reduction has been computed in the “Cost-Benefit analysis” section.

IMPLEMENTATION SNAPSHOTS OF SMART MCCB SOLUTION

WAGLE ESATE: TRANSFORMER RATING 630 KVA, 22/0.433 KV

After Smart MCCB Installation                                                 Before Smart MCCB Installation

DHOKALI: TRANSFORMER RATING 630 KVA, 11/0.433 kV

              Before Smart MCCB Installation                                                 After Smart MCCB Installation

INFERENCES AND RECOMMENDED ACTIONS

The Smart MCCB Distribution Management solution was able to use its intelligent dashboard effectively to monitor PQ parameters like Earth leakage, Short circuit, arcing, phase imbalance, overloading and undervoltage conditions, in a graphical format, providing real-time information to optimize and improve network performance. The dashboard provided MSEDCL users to identify vulnerabilities in the network, maintain power quality of supply and plan for a balanced LT distribution network upgrades in the future.

The Smart MCCB intelligent dashboard integrated seamlessly with Utility GIS and metering application to provide value additions to power distribution management functions, e.g.:

• DT-wise network mapping, energy audit on periodic or on-demand basis
• Real-time visualization of electrical distribution parameters – Energy, Power (Active & Reactive), Current, Voltage, PF, Phase imbalance and Frequency.
• Studying load consumption patterns on hourly, daily, weekly & monthly basis.
• Foreseeing power outages and load violations in each DT.
• Print graphs and capture instantaneous data of PQ parameters.
• Enhance electrical safety of distribution assets and personnel
• Ensure quality and reliable power, as per MERC / CERC guidelines
• Generate distribution analysis report for future network planning

INFERENCES

1. The overloading or undervoltage events recorded by the Smart MCCB-based PQ monitoring system identified the vulnerabilities in the LT distribution system, including phase imbalance, transformer and conductor heating, and arcing fault.
2. The number of overload events showed gradual reduction over the project period – Jan (141), Feb (133) and Mar (103), as recorded by the Smart MCCB-based PQ monitoring system dashboard.
3. This reduction in overloading or undervoltage incidents was seen to have been the result of timely monitoring and acting upon voltage quality index violations.
4. The Smart distribution PQ management system was demonstrated to generate timely alerts for the DISCOM operators to take proactive action to prevent catastrophic failures of the Distribution Transformer.
5. Integrated with Utility GIS, DT metering and outage management system, the Smart distribution PQ management can reduce breakdowns and facilitate early restoration.

RECOMMENDED ACTIONS

Based on the data collected and inferences drawn from the study, the following actions can be recommended for improvements in the LT systems, in the scope of the pilot project:

1. De-stress overloaded LT sections through load rearrangements, balancing of load in each of the 3 phases and/ or re-conductoring
2. Identify the source of leakage current and take necessary remedial actions, on case-to-case basis, as follows:
   1. Check all jumpers and connections at the DTs and LT distribution boxes, and rectify possible causes of arcing faults
   2. Check any damage to LT cabling insulation due to hotspots or overheating, and rectify the same
   3. Reactivate earthing and multiple earthing on LT lines
   4. Check neutral earthing, earth switch contacts and strengthen the same
3. Check rating of shunt capacitors installed on DTs where Smart MCCB dashboard has identified high or abnormal reactive power, and implement PF correction.

COST BENEFIT ANALYSIS

During the first 3 months of the pilot, the continuous LT load profile and the history of DT overloading (undervoltage) incidents, at the two pilot locations, were recorded as follows:

Note: LT voltage variation is as per MSEDCL prescribed regulatory limit of -6% to +6% , in compliance with EN 50160 and IS 17086 standards.

The quarterly revenue savings during 3-month pilot operation (Jan, 2020 to Mar, 2020) of Smart MCCB-based distribution power quality management solution was Rs. 1,68,876/=, with reasonable and realistic assumptions, which corresponds to an annual revenue savings of Rs. 6.75 lakhs in direct costs. Indirect cost savings, other than from tariff, is expected to be much higher. To maximize the gains, it is recommended to perform load flow analysis of the LT network to identify the most vulnerable sections in terms of voltage or load fluctuations to install the smart MCCB-based PQ management solution.

The total investment comprises of the software license cost of the intelligent, real-time monitoring system, cost of MCCB hardware, mounting panel and fixtures, and integration costs. The payback period will depend upon the number of installations based on network study, and vary from case-to-case basis. Typically, the payback period in terms of cost savings has been shown to be 12 months or less, depending upon number and type of consumers connected, applicable tariff, network condition and average restoration time. Also, the estimated savings can be amortized across payback period, under PAYS (Pay-as-you-save) model to pay for the project from the savings on month-to-month basis.

CONCLUSION

The MSEDCL pilot project demonstrated the usefulness of Smart MCCB-based, real-time monitoring system, as a smart grid application in DISCOMs. It has proven to be a cost-effective IoT (Internet-of-Things)-based solution which can be easily integrated with existing LT distribution automation, smart metering and fault management system. Smart Distribution PQ Management Solution offered both tangible and intangible benefits, as explained in the cost-benefit analysis. Apart from measurable revenue gains, the solution provided safety and reliability to the LT distribution systems of MSEDCL, with real-time, remote visualization of LT networks, reduced technical losses, improved network efficiency, lowered maintenance expenditure and improved quality of supply.