Enhanced Reliability of Power Supply in Ho Chi Minh City


The improvement of power grid reliability in 2016 – 2020

Ho Chi Minh City is the economic and cultural center of Vietnam and plays a leading role in the Southern Key Economic Region. With the mindset of “Electricity is always one step ahead”, over the years, the Ho Chi Minh City Power Corporation (EVNHCMC) has been making constant efforts to ensure a stable and uninterrupted power supply, steadily improving its quality of services, significantly contributing to the socio-economic development and social security of the city. Through synchronous and effective implementation of its many solutions, the reliability of power supply in Ho Chi Minh City has been consistently improved.

Statistics of 2016–2020 show that power reliability indicators have been greatly enhanced: SAIFI decreased from 5.11 to 0.59, SAIDI from 514 to just 44 minutes for an average of 37.51% and 41.56% annual decrease respectively. These results marked the Corporation’s contribution to the marvelous achievements of Vietnam and its power sector, recognized in Doing Business 2020 Report with 08/08 technical points for Supply Reliability Indices.

Figure 1: EVNHCMC’s SAIFI and SAIDI from 2016 to 2020[1]

[1] Power supply reliability calculated according to provisions of Ministry of Industry and Trade’s Circular 39/TT-BCT dated November 18, 2015, EVN’s Regulation 717/QD-EVN dated August 28, 2014

1. Coordinated and effective solutions for different types of outages

a. Unplanned outage (average reduction of 38.10%/year) are being addressed by adopting comprehensive, end-to-end construction works quality management encompassing material and equipment procurement, construction, maintenance, supervision and commissioning; execution of CBM-oriented diagnostic testing (PD tests and thermal imaging camera surveillance to prevent faults); focusing on solutions to reduce faults of inherent causes, namely from underground cable and ancillaries damage, equipment bushing partial discharge, animal encroachment; and application of FDIR-based automation (as of 2020, the rate of interruptions successfully tackled with under 5-minute remote load rerouting has reached over 90%).

Figure 2: SAIFI and SAIDI for accidental and planned outages from 2016 to 2020

b. Planned outage (average reduction of 59.22%/year)

The construction of power grids adheres to EVNHCMC’s plans and consolidation criteria.

The 110 kV grid meets N-1 operational criterion (whereas central area power supply stations in particular meet N-2 criterion) with no tolerance for prolonged full load or overload occurred in normal operating mode.

The 22 kV MV lines have 95% of feeder which has a mainline length of less than 8 km; 87% feeder supplying under 6,000 customers; 97% feeder has load factor less than 50%; 97% lines are insulated 24 kV cable; 100% MV lines are constructed in a closed-loop circuit arrangement fed from 2 different 110kV transformers.

The 0.4 kV grid has 86% of distribution substations with cable feeder length under 300 m; 96% feeding under 300 customers; 88% of substations carry loads in the range of 40% – 80% of rated load (average 60 – 65%).

Planned power outages are strictly controlled with the aim of reducing frequency over time:

Closed-loop arrangement implemented for 100% of high and medium voltage grids and portable generators and transformers are utilized in planned maintenance.

 Weekly power outages schedules for high, medium and low voltage systems are designed for maintenance, repair and renovation of the power grid, subject to the review and approval of the Corporation’s leaders.

2. Full statistics and analysis of outage root causes for actionable solutions

As shown in statistics graphs of power failure causes in 2020 (Figure 3), external factors and power cuts for firefighting account for the largest proportions (36% and 29% for SAIFI, 32% and 15% for SAIDI, respectively). Accordingly, the appropriate solutions have been worked out to address the causes of power loss.

To address the external factors violating the grid protected right-of-way (crane trucks, metallic confetti, construction scaffolding, construction excavation breaching underground cables), an active communication channel with local authorities has been maintained to collect information on works in construction and maintenance with proximity to power lines. On-site inspections to houses and works under construction have also been carried out more frequently, up to 3 times per week, to promptly inform contractors and owners about adherence to safety measures. Fireworks, firecrackers, metallic confetti cannon, and kites are discouraged from use near transmission lines through information programs performed twice a year. Coordination has also been established with other relevant parties such as operators of road excavation works, water supply and drainage, telecommunications, and lighting system to provide them with existing underground cable layouts, safety recommendations, GIS drawings, and on-the-spot locating of underground cables with cable detection and color marking, to prevent power cable accidents (digging into power cables).

To accommodate firefighting efforts, portions of the power grid within fire-prone areas are segmented with the help of remote-control devices, thus medium voltage segments can be isolated without setting off upstream circuit breakers. Subsequently, respective sites can be promptly approached, and only low voltage facilities have to be isolated. In alignment with this strategy, a communication campaign on the safe and efficient use of electricity named “Together we use electricity safely and economically” has been carried in 53 local communities across the city.

Figure 3: Power outage causes chart of 2020

3. Rigorous Management of Reliability

Since 2020, EVNHCMC has supplemented its reliability assessment measures with CAIFI and CAIDI indicators and accordingly assigned directive targets to its subsidiaries for implementation. Specific targets include 2-time CAIFI and 120-minute CAIDI in accidental power outages. In other words, each customer will not experience blackouts due to incidents more than two times a year, and each will not exceed 120 minutes. For planned outages, CAIFI is set to two times and CAIDI 300 minutes, meaning power cut plans will not cause more than two blackout events per year to an individual customer (one for grid maintenance and one circumstantial, if any), and each blackout is not to be longer than 300 minutes.

Figure 4: CAIFI, CAIDI of EVNHCMC in 2020

In addition, by leveraging comprehensive power failure statistical data provided by the Outage Management System, EVNHCMC can deliver support to all customers experiencing outages which have occurred more frequently or over longer periods.

Reliability Improvement Strategy for the period 2021-2025

In the pursuit of delivering an ever-improving power supply service to its customers, and contributing to the city’s secure political environment and prosperous socio-economic development, EVNHCM has embarked on the implementation of a 5-year business, investment and development plan for the period 2021-2025. Central to the plan is a roadmap to establish a sustainable power supply with enhanced reliability, attainable by high-performance targets: SAIFI to be reduced to under 0.5 times, with a vision to under 0.3 times, and SAIDI to under 50 minutes with inspirations to go as far as 30 minutes.

Five groups of solutions are proposed by EVNHCMC to achieve the targets.


1. Implement Power Development Plan-based investments and construction to meet time and quality requirements in response to load demand growth.

2. Consolidate the power grid structure to optimize management and operation by adopting standardization, improving power supply stability, with a priority to safety requirements and urban aesthetics. Specifically, this exercise includes reviewing and completing the layout of high/medium/low voltage power grids, formulating and promulgating criteria for building breaker stations, segmenting medium voltage lines, implementing closed-loop circuit arrangements for the underground and overhead low-voltage grid, and considering the design and installation of dry-type transformers in crowded areas and on building rooftops.

3. Implement a program to put the power grid underground in the period of 2021-2025, which focuses on the undergrounding for crowded areas such as hospitals, schools, markets, intersections, gas stations, etc.; exploring solutions to underground low voltage electrical cabinets and distribution substations.

Developing a Comprehensive Smart Grid

1. Grid automation: (i) achieve efficient operation of all 110 kV substations under the unmanned model; (ii) complete construction of the backup remote control center (Site 2), build a modern operation room for all 16 subsidiary Power Companies; (iii) study criteria for the successful construction and deployment of 5 to 10 digital substations of 110 kV; (iv) maintain effective operation of Mini-SCADA for 100% of 22 kV lines, expand and put into operation FDIR (DAS/DMS) for at least 50% of public 22 kV line routes, researching and effectively utilizing DMS functions of grid operation optimization; and (v) monitor and operate 100% of distribution substations remotely (with real-time power failure warning).

2. Continue to deploy the remote metering system for 100% of customers.

3. Implement the Rooftop Solar PV development plan for the period of 2021-2025.

4. Develop a pilot Microgrid project for critical loads in HCMC.

5. Research on the development of a shared information platform connecting applications of smart grids.

Applying Industry 4.0 for Digital Transformation

1. Review and complete information technology applications; digitize the entire technical management and operation of the power grid.

2. Apply Condition-based Maintenance (CBM) while targeting Reliability Centered Maintenance (RCM), and comprehensive Asset Management in the long run.

3. Implement digital transformation through the study of 4.0 core technologies (Big Data, IoT, AI, Data Analytics, etc.) to effectively utilize the Power Sector database; build applications to support decision-making in grid operation and management.

Promoting R&D, Innovation, New Technologies Application

1. Establish and put into operation the Science and Technology Club model to facilitate a professional exchanging and socializing environment, promoting science and technology development.

Prepare annual plans to effectively use science and technology development funding; leverage ASEAN experts and engineers as a core team to implement activities focusing on initiatives and research topics on application of new technologies, Industry 4.0 application, etc.

2. Apply industry international best practices in advanced technologies application by: (i) studying and applying new material technologies (gas-insulated high-voltage transformers, etc.), technologies to monitor in real-time the operation of electrical equipment (applicable for monitoring 110 kV transformers, medium voltage cabinets, power quality, etc.); (ii) studying and deploying specialized and modern means and equipment for electrical construction and maintenance such as 110 kV live-line construction vehicles, compact medium voltage live-line vehicles that can operate narrow alleys, pickup trucks with manlifts, specialized electric maintenance vehicles, electric motorcycles, etc.; (iii) piloting and expanding flexible power supply model (mobile generators with synchronizing function; mobile transformers with integrated RMU cabinet, etc.); and (iv) improving tools, instruments, equipment used by workers in construction, operation and maintenance.

Human Resource Quality Improvement

1. Consider establishing a dedicated Research and Development (R&D) unit.

2. Organize professional examinations on IT and new technology applications for leaders and department/division managers.

3. Build professional capacity for technical workers in (i) using construction machinery, instruments and tools, personal protection equipment (PPE), etc.; (ii) operational and professional skills; (iii) professional work ethics and corporate culture.

4. Organize specialized training courses in key fields such as automation, live-line working, advanced repair and maintenance, Industry 4.0, etc.

5. Strengthen international exchanges and cooperation.


EVNHCMC recognizes power reliability improvement as its top priority to help bring about a prosperous socio-economic development in Ho Chi Minh City, and contribute to the country’s sustainable development. The efforts to modernize the power grid, deploy smart grid, and apply new and digital technologies are extremely important. In a spirit of solidarity and unity, the Ho Chi Minh City Power Corporation maintains strong confidence that it will achieve its aspirations and set goals.

Load Dispatch Center of EVNHCMC

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