By S.K. Soonee, Former and Founder Chief Executive Officer, Grid Controller of India Limietd (GRID-INDIA); Dr Deb Chattopadhyay, Senior Energy Specialist, World Bank; and Debasis De, Former Executive Director, National Load Despatch Centre, GRID-INDIA
India’s power sector is undergoing rapid transformation. With real-time spot markets, green energy trading and expanding renewable integration, system operations are increasingly guided by market-based optimisation, transparency and competitive procurement.
Ancillary services, too, have evolved from administratively managed technical functions to structured, market-linked products. Frequency regulation, reserves and other balancing services are now progressively integrated into competitive frameworks.
However, it is important to draw a line between ancillary services that can and should be brought under a market regime and those that should not be market-based. There may be a range of reasons, from complexity to insufficient scale, as is the case for a reactive power spot market. There are others like “black start” services that are fundamentally not suited for a market-based service, and one may even argue that the term “ancillary” for such services is a misnomer. Unlike frequency control or reserves, black start is not a routinely deployed service. It is the foundational capability required to restore the grid after a widespread blackout. Invoked rarely, it must perform with certainty and precision. During system collapse, there is no scope for marginal optimisation or competitive substitution, the service is binary; it either works or it does not.
Yet, black start is often grouped under ancillary services. While administratively convenient, these risks conflate market-suitable operating services with functions that exist solely to assure system resilience under extreme conditions.
As the markets mature, drawing a clear boundary between optimisation tools and reliability assurance functions becomes essential. Black start sits squarely at that boundary.
What is black start facility?
Under normal conditions, the grid operates as a synchronised system in which generators supply load and operators maintain balance through reserves and frequency control. But during a widespread collapse, transmission lines are de-energised and most generating stations lose the external power required to start their auxiliary systems.
A black start unit is designed to start independently using dedicated systems such as diesel generators or batteries. Once operational, it provides the initial voltage and frequency reference needed to energise predefined “cranking paths” – the restoration corridors that progressively bring other generators, substations and load centres back online.
System restoration is a pre-planned, sequential process developed by system operators in coordination with generating and transmission utilities. Whether executed through top-down, bottom-up or hybrid strategies, restoration depends on deterministic execution. Switching operations, energisation sequences and synchronisation must occur in a defined order, with careful management of voltage, reactive power and weak-grid conditions. In such circumstances, there is no scope for competitive selection or marginal despatch decisions.
Black start capability is also geographically specific. Its suitability depends not only on technology but also on the location within the network. In many regions, only one or two units may be technically capable of initiating restoration for a large electrical area, leaving little room for economic choice.
Performance requirements are binary. The designated unit must start within defined timelines and operate reliably under stressed conditions. Partial or delayed response can significantly slow restoration and magnify socio-economic impact. Regular mock exercises and testing are therefore essential.
For security reasons, restoration plans, cranking paths and black start locations are treated as sensitive information.
In essence, black start is not a routine balancing service. It is the first spark that re-energises the grid after collapse, a capability embedded in infrastructure, planning and preparedness.
Why does black start not fit the ancillary service model?
As electricity markets expand, more grid-support functions like frequency regulation, operating reserves and other balancing services are being brought under structured procurement frameworks.
Table I: Operational characteristics: Black start vs. market-based ancillary services
| Attribute | Market-based ancillary services (regulation/reserves) | Black start |
| Activation frequency | Continuous or frequent | Extremely rare (major blackout events) |
| Nature of deployment | Incremental and adjustable | Binary – must fully perform |
| Substitutability | Multiple providers available | Highly location-specific; limited providers |
| Despatch mechanism | Real-time market clearing | Pre-designated in restoration plans |
| Performance measurement | Continuous monitoring | Tested periodically; critical during event |
| Role in grid | Maintains stability in normal operations | Enables restoration after collapse |
Black start does not share these characteristics. Its purpose is not to optimise system performance under normal conditions, but to enable restoration after a widespread collapse. It is invoked rarely, constrained by geography and network topology, and intolerant to non-performance. Attempting to treat it as a market-cleared ancillary product creates a structural mismatch between engineering reality and economic design.
Tables I and II clearly demonstrate the difference between these two services.
This comparison highlights a fundamental reality: market-based ancillary services such as frequency control are intricately linked to system despatch and should be linked to the associated optimisation tools; black start, on the other hand, is a restoration-enabling capability not suitable for optimisation.
Table II: Economic and institutional characteristics
| Dimension | Market-based ancillary services | Black start |
| Cost structure | Variable, linked to deployment | Predominantly fixed readiness cost |
| Revenue model | Marginal price-based settlement | Availability-based compensation |
| Competition level | Multiple bidders | Often one to three technically suitable units per region |
| Market price discovery | Meaningful and continuous | Impractical due to rare activation |
| Risk of non-performance | Limited operational impact | Severe restoration delays; high socio-economic cost |
| Procurement logic | Efficiency optimisation | Reliability assurance |
Market-compatible ancillary services benefit from price signals and competition because they are deployed regularly and can be substituted across resources. Black start, by contrast, derives its value from continuous readiness and deterministic performance during extreme events.
Importantly, the cost of maintaining black start readiness is typically very small, relative to the total system operating expenditure. Yet, the economic cost of prolonged system collapse is extraordinarily high. This asymmetry further weakens the case for marginal optimisation and strengthens the case for assured procurement.
Reliability assurance service framework
A reliability assurance service is characterised by:
- Infrequent activation but high system impact
- Strong dependence on location and network topology
- Limited or no substitutability during extreme events
- Predominantly fixed, readiness-based cost structure
- Binary or deterministic performance requirement
These features distinguish it from conventional ancillary services that are deployed frequently and priced through competitive mechanisms.
Rather than being optimised in markets, reliability assurance services should be secured through structured, long-term arrangements that emphasise availability, preparedness and accountability.
Table III shows how the two services differ.
Table III: Ancillary services vs. reliability assurance services
| Dimension | Ancillary Services | Reliability Assurance Services |
| Objective | Operational balancing and optimisation | System restoration and resilience |
| Time horizon | Short-term (real-time to day-ahead) | Long-term readiness |
| Procurement logic | Competitive market-based | Structured or regulated contracts |
| Performance nature | Continuous and measurable | Event-driven and deterministic |
| Cost recovery | Marginal price settlement | Availability-based compensation |
| Governance focus | Efficiency | Certainty and accountability |
Procurement implications
Under a Reliability assurance framework, black start capability could be secured through:
- Multi-year availability contracts linked to specific substations and restoration corridors
- Clearly defined technical qualification standards
- Mandatory periodic testing and restoration drills
- Independent technical verification and audit mechanisms
- Transparent cost recovery through regulated system operation charges
Such an approach aligns with international practice and avoids exposing a critical resilience function to market volatility or uncertain revenue streams.
Importantly, this framework is technology-neutral and does not prevent technological innovation. Emerging resources such as battery energy storage systems or fast-start gas turbines can be integrated through structured qualification processes and targeted tenders. What changes is not technology inclusion but the procurement philosophy.
Security and accountability
For a service as strategically critical as black start, confidentiality and controlled coordination remain essential.
A reliability assurance model ensures that:
- System operators retain clear responsibility for restoration planning
- Asset owners understand long-term obligations
- Compensation reflects readiness, not speculative market participation
- Accountability remains unambiguous
Given the relatively modest cost of maintaining black start capability compared to the enormous economic losses associated with prolonged system collapse, prioritising certainty over marginal optimisation is both proportionate and prudent.
Drawing the line between markets and resilience
As systems become more interconnected and renewable penetration increases, the probability of complex disturbances may not necessarily decline. In such an environment, the ability to restore the grid quickly after a widespread disruption becomes even more valuable. Black start is the foundation of that restoration capability.
Black start is invoked rarely, but when required, it must perform without fail. It is location-specific, deterministic and embedded in restoration planning. Its cost is small relative to overall system expenditure, yet its failure carries disproportionate economic and societal consequences. These attributes place it outside the domain of services suited for competitive, short-term market clearing.
As India builds a modern, flexible and market-driven grid, it must also preserve the institutional foundations of resilience. Efficiency mechanisms should enhance system operation, but they should not redefine functions whose primary purpose is to safeguard restoration.