This policy aims at establishing a structure on the basis of which large-scale wind-solar hybrid power projects can be promoted.
New Delhi: When it comes to power generation, renewable energy is what’s on everyone’s mind, not only in India but globally. Mostly because it gives us our best chance to battle global endemics such as climate change. But if we consider facts relating to the scale of implementation or rate of adoption, several countries worldwide are still struggling to establish renewable energy as a feasible alternative of conventionally used fossil fuels.
Being a peninsula with tropical climate, India has immense supply of renewable resources which if harnessed to its full potential can help the country reduce its carbon footprint significantly. Some of the most significant factors that limit the generation as well as the adoption of renewable energy is the initial costs associated, uncertainty regarding its viability and scepticism revolving around its applicability in the long run. To address these concerns, the Government of India from time to time has introduced various policies, regulations and subsidies to incentivise the adoption of clean energy, resolve developers’ woes and ameliorate awareness amongst users.
One such policy is the “National Wind-Solar Hybrid Policy” introduced by the Ministry of New and Renewable Energy (MNRE) in 2018. This policy essentially aims at establishing a structure on the basis of which large-scale wind-solar hybrid power projects can be promoted. Further, the objective of the policy is to optimise and improve the efficacy of the usage of transmission infrastructure and land, which in turn will mitigate inconsistencies associated with the generation of renewable power and help in attaining better grid stability. Apart from that, the policy will also stimulate the development of solutions and technological advancements in the field of wind-solar hybrid power generation.
As a part of its contribution to the Paris Agreement on Climate Change, India has set a target of achieving 175 GW installed capacity of renewable energy of which 100 GW would be from solar and 60 GW from wind energy. But, there are some inherent challenges that constrain the productivity of most stand-alone solar or wind power plants. Some of those challenges include the intermittent nature of the availability of these resources, lack of efficient storage devices, etc. In its bid to present an effective solution, MNRE, as a part of the policy, suggests that India not only has major areas where the potential of both wind and solar resources can be harnessed on a high to moderate level but also that in terms of power generation, both the resources complement each other and hybridization will further help in improving grid security and stability.
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Now, let’s take a look at the brief summary and the highlights of the National Wind-Solar Hybrid Policy.
1. The policy is subject to be reviewed as per requirement and shall not cease to exist if not revoked, altered or substituted by the government.
2. A hybrid wind-solar plant requires wind turbine generators (WTGs) and solar PV systems to be configured properly to function at the same point of grid connection. MNRE has prescribed two different approaches for integrating both the systems that vary on the basis of their size and the technology involved.
Fixed speed wind turbines which are directly connected to the utility grid through an induction generator can be integrated with a solar PV system on the AC output bus using an HT (high tension) line. Whereas, variable speed wind turbines which require inverters to connect the generator with the utility grid can be integrated with a solar PV system on the intermediate DC bus of the AC-DC-AC converter.
When it comes to system size, in areas where wind power density is high, the size of the wind power system should be significantly higher than the size of the solar power system installed and vice versa.
According to MNRE, to be recognised as a hybrid power plant, the rated power capacity of one resource should at least be 25% of the rated power capacity of the other resource in a wind-solar plant.
3. Moving forward, MNRE has further suggested two different approaches for implementing hybrid projects based on various configurations and technology being used.
For AC integration of hybrid systems: For this type of integration, AC outputs from both the sources are linked using an LT (low tension) line or HT (high tension) line. If both the systems use different step-up transformers, then the power output from both the systems is connected to the common AC bus. Additionally, appropriate control equipment would also be required to regulate the output power of the system.
For DC integration of hybrid systems: For this type of integration, DC outputs from both the systems are fed to the common DC bus and a compatible inverter is employed to convert the combined DC power output into AC.
4. The government has introduced various policies to aid the development of new wind-solar hybrid projects which are as follows:
The power generated from such hybrid projects can be used for captive usage, can be sold to a third party through open access, can be sold to discoms either at tariff rates stipulated by the related State Electricity Regulatory Commission (SERC) or by following tariff structure determined through a transparent bidding process or can be sold to discoms at average power purchase cost (APPC) to gain renewable energy certificates (RECs).
Power purchased from such hybrid projects is also eligible for the fulfilment of either solar or non-solar renewable purchase obligation (RPO). It would be proportionate to the rated capacity of solar and wind energy in the hybrid system respectively.
Various parameters such as power delivered at grid interface point, effective capacity utilisation factor (CUF) and electricity tariff could be used when power is being purchased through a transparent bidding process.
While inviting to bid for a new hybrid project, government bodies can consider the criteria mentioned in the point above while giving tariff rates the most priority.
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5. The administration has also laid down some conditions for existing standalone wind or solar projects which want to become hybrid power systems to be eligible to avail the benefits provided to hybrid projects which are as follows:
Wind or solar power plants using already granted transmission access would not be charged any additional transmission capacity charges for hybridisation. However, for additional transmission access, charges may be applicable as per existing regulations.
If the transmission substation to which the existing wind or solar project is connected has a capacity margin, allocation of additional transmission access would be subject to its technical feasibility. Moreover, the project developer would be responsible for fulfilling any additional transmission requirements necessary for feeding the substation efficiently.
Solar and wind power fed to the grid by hybrid projects with AC integration would be determined by apportioning the readings of the main meter installed at the receiving station which would refer to the readings of the ABT (availability based tariff) meters installed on LT or HT lines of the hybrid power plant, however applicable.
Solar and wind power fed to the grid by hybrid projects with DC integration would be determined by apportioning the readings of the main meter installed at the receiving station which would refer to the readings of the DC meters installed at the DC output of the hybrid power plant. Only AC integration would be permitted until standards and regulations for DC meters and the procedure for DC metering of hybrid power projects has been developed.
Hybrid project developers may use additional power for captive usage, can be sold to a third party through open access, can be sold to discoms either at tariff rates stipulated by the related SERC or by following tariff structure determined through a transparent bidding process or can be sold to discoms at average power purchase cost (APPC) to gain renewable energy certificates (RECs).
State and central bodies may bid for the hybridization of standalone projects which are connected either to an intra-state transmission system (InSTS) or an inter-state transmission system (ISTS).
Tariff rates would be the main criteria for selection in government invited bids for hybridisation projects.
Power purchased from hybrid projects is also eligible for the fulfilment of either solar or non-solar renewable purchase obligation (RPO).
6. MNRE has defined some purposes for which storage devices might be integrated with a hybrid power project which include:
To improve the consistency with which the hybrid plant delivers output
To enable the delivery of higher output than sanctioned load by increasing the capacity of the hybrid plant
To ensure uninterrupted power supply
7. For a wind-solar hybrid power plant with storage devices, factors such as minimum uninterruptible supply for the whole day or part of the day, level of output inconsistency allowed, electricity tariff, etc. shall affect the bidding process of a project.
8. Essential standards and regulations such as procedure and standards to be followed for metering, norms concerning forecasting and scheduling, process involved with RECs, commissioning connectivity and distribution of transmission lines, etc. associated with wind-solar hybrid systems shall be prescribed by the Central Electricity Authority (CEA) and the Central Electricity Regulatory Commission (CERC).
9. For grid-connected systems, every developer must follow technical guidelines released by MNRE to operate wind turbines, solar panels and balance of system equipment properly.
10. The development of hybrid power projects would be encouraged through various government schemes and plans. Along with that, hybrid system developers can also benefit from all the fiscal as well as financial incentives available for standalone wind or solar power projects.
11. The government will also provide support to aid technological advancements in the field of wind-solar power generation systems and for the development of standards for hybrid systems.