Analysis of Nepalese Power System: Issues and Challenges
The history of Nepalese Power System dates back to the first hydro-power developed during the reign of Chandra Shumsher. Constructed with the assistance from British Government in 1911 AD in Pharping; the mere 500 KW pelton wheel generator provided power for the electrification of Singha Durbar, the prime minister residence. By the end of FY 2018/2019 the total installed capacity of Nepal has reached to 1250 MW with a demand of 1320 MW (peak). The excess demand has been fulfilled by power import from India via many inter-border transmission lines.
Although Nepalese power system has gone through myriads of developmental changes, we have yet to reach our true potential. Dr. Hari Man Shrestha, during his Phd thesis, proposed that Nepal has a total generation possibility of 83,000 MW out of which 43,000 MW is economically feasible. Hence, reaching this potential from the present 1250 MW requires immense engineering know-how and major changes in current Nepalese power grid.
The current Nepalese grid has been named as Integrated Nepal Power System (INPS). Most of it basically runs behind the Mahendra highway of Nepal along the flat terai plains. The following figure shows the present transmission and generation plant of Nepal.
The INPS grid is a 132 KV transmission system that runs, as already been said, along the east-west highway. Along the border, there are a number of Nepal-India inter-country transmission tap-lines as shown in the figure. These lines are used for import and export of electricity between two countries. The biggest generation unit within the country is Kaligandaki ‘A’ Hydropower project located in Mirmi, Syangja with a total installation capacity of 144MW. However the biggest hydropower project of Nepal under implementation is Upper Tamakoshi in Lamabagar, Dolakha with a total installed capacity of 456 MW. The project has been of national priority and early commissioning of the project is of utmost importance to end the dependency of Nepalese power demand on India during the dry season. The governing body responsible for all this is “Nepal Electricity Authority (NEA)”. NEA is responsible for generating, transmitting and distributing adequate, reliable and affordable power by planning, constructing, operating and maintaining all the generation, transmission and distribution facilities in Nepal, both inter-connected and isolated.
While transmission of voltage is done via 132 kV lines, distribution of power to domestic and industrial consumers are done in lower voltage levels viz 33 kV and 11 kV. Domestic household consumers are supplied through the 11 Kv feeder network that is stepped down to 230 V single phase supply through distribution transformers located in different locations. The bulky industrial consumers are provided with 33KV feeders directly to meet the high demand of industrial loads.
The quality of Nepalese power system, however, hasn’t been par to the technology and standards of other countries. While majority of the countries have started transmission of power in the range of 765 Kv, Nepal is still struggling to provide the infrastructure for 220 kV transmission system. Besides, frequent tripping of power lines and unreliable power supply along with a poorly regulated voltage in some major cities raise some question about the reliability of Nepalese power systems.
Some of the major issues of Nepalese power system has been discussed below.
1) Unregulated Voltage
If you happen to visit Biratnagar during summer, you will find the hot weather unbearable (if you’re not accustomed to being in hot places) and if somehow you find an AC wall fan, you might have noticed it doesn’t operate in its full capacity even if you max out the speed module. This is mainly because of unregulated voltage supply. According to the national standards Nepalese domestic voltage level must be 230 V with an error of 5–10%. However, due to poor planning and system design voltage can go down to as much as 17–20% which is unacceptable for many electrical equipment. One of the reason of such unregulated voltage is the unprecedented and unscientific length of distribution feeders. The following figure shows a 11kv feeder that was mapped from province 2.
In urban areas feeder length is generally governed by the current carrying capacity of the feeder where as in rural areas feeder length is governed by the voltage drop (that is; the more the length the more will be the voltage drop in the line). As a rule of thumb, 11 kV feeder aren’t supposed to be greater than 12–13 km because of the voltage drop issues. However, the length of above feeder was found to be greater than 30 km which means the end user of the feeder has a poorly regulated voltage supply. This is one of the many issues responsible for the poor voltage regulation in many places of Nepal.
2) High Distribution loss
As per the power utility’s data, Nepal witnessed energy leakage of 11.28% in the FY 2018/19. In the past three years, the power utility has been able to reduce losses to 15.23% from 25.78% in FY 2015/16. In the FY 2017/18 the power utility lost 1156.85 GWh out of total available 7551.23 Gwh.
High system losses has been a major challenge for the power engineers in Nepal. Because of poorly maintained transformers, substations and transmission line, significant energy is lost yearly resulting in loss of revenue amounting to millions of rupees. However, NEA has been working tirelessly to upgrade the transmission system of Nepal. In the previous fiscal year only, Nepal added more than 600 km of power lines and 30 distribution substations. The utility is planning to spend more than 50% of the budget for the current fiscal year in increasing the capacity of transmission lines and power distribution infrastructure. Upgrading the existing substations and building new transmission lines and distribution grids in strategic industrial zones are expected to improve the reliability of electricity transmission throughout the grid.
3) Major dependency in ROR projects
Nepalese generation is highly ROR dependent. As per FY 2018/2019 the generation mix of Nepal is as follows:
ROR: 701 MW (56.08%)
PROR: 335 MW (26.80%)
Storage: 92 MW (7.36%)
Others: 122 MW (9.76%)
More than half of Nepalese generation comes from Run-of-River plants. These plants have an obvious draw back; they can’t be fully operated all around the year. The rivers of Nepal have seasonal variation in flow i.e. they have high discharge rate during rainy season and low discharge during dry season. This unfortunately coincides negatively with the demand of the country as general statistics show that power demand is more during winter and less in summer. Thus, Nepal is highly dependent onto India for meeting the power demand during the winter period. While Peaking Run-of-River (PROR) plants provide greater flexibility in operation and are capable of bridging gap between water availability and power demand, the additional cost of storage facilities required for PROR plants make their energy costlier than energy generated by ROR plants. Besides, no incentives are provided to PROR plants owing to their extra cost. But to meet the morning and evening peak, dry season peak PROR plants are most.
4) Regulated Power System Model
Nepal’s power system had a vertically integrated monopoly before the introduction of “Hydropower Development Policy -1992” and “Nepal Electricity Act-1992”. With the initiation of these policies deregulation of power system in Nepal started to take place. These policies acted as an invitation for private sectors to invest in power sector development. Investor friendly legal arrangements like tax incentives, one window arrangement, Power Purchase Rate (PPR), De-licensing up to 1MW, protection from change in law etc. were some of the initiatives taken in this act.
However, NEA still has upper hand in all forms of policy changes and PPA. Energy pooling and wholesale competition in all stages i.e. generation, transmission and distribution needs to be implemented for a completely free model of power system. And even though, for a developing country like Nepal, a single entity or organization cannot afford the capital and cost of large scale hydropower development, private entities have indeed proven their capabilities for small scale plants as can be seen from the construction of Khimti, Bhotekoshi, Indrawati and Chilime hydropower which are all privately owned and operated.
