Karachi-based K-Electric has engineered a novel solution to a pressing problem: how to meet surging power demand in Pakistan’s largest city without new infrastructure or capital outlays. The utility’s in-house developed Special Protection System, known as the Cross Trip Scheme, has successfully doubled power imports to over 600 MW, providing a blueprint for other utilities grappling with similar challenges.
Karachi’s population has ballooned to 20.3 million, according to the 2023 census, driving up peak demand and testing the limits of K-Electric’s infrastructure. While the utility has made significant investments in generation, transmission, and distribution—reducing losses from 35.9% to 15.99% since 2009—it has also faced increasing system complexity and intermittency. The Cross Trip Scheme, developed entirely in-house, addresses these challenges head-on.
“The project allowed K-Electric to safely enhance the protection and control scheme to enable transformers and lines to be utilized at par, while saving on capital expenditure,” said Abbas Husain, Chief Generation and Transmission Officer. “In a grid environment, where reliability hinges on costly infrastructure and long timelines, KE’s software-driven solution delivered flexibility and resilience with precision—all in a span of nine months.”
The solution emerged from a feasibility study that ruled out conventional infrastructure options due to high costs and extended timelines. Instead, KE explored the technical viability of a special protection system based on “cross trip” logic—a digital control architecture that enables dynamic load rejection in response to real-time grid disturbances. The system KE ultimately designed and implemented consists of three layers: protective relays, communication equipment, and the SCADA system.
“The infrastructure consists of three layers,” explained Faisal Mairaj, head of Network Planning. “Firstly, the protective relays. Secondly, the communication equipment, which consists of Remote Terminal Units (RTUs) and Synchronous Digital Hierarchy (SDH). And lastly, the SCADA—the logics developed on our KE system that alert the operator and guide actions in real time.”
The SPS operates on adaptive trip logic—a customized digital rule set that governs automatic load rejection based on transformer loading, breaker positions, and power flow direction across key interconnections. Relay panels continuously monitor these variables at critical grid nodes. When instability is detected, the system issues transfer trip signals to select substations, initiating staged disconnections of specific 132-kV feeders to maintain system integrity.
One of the project’s most critical design constraints was KE’s lack of access to live SCADA data from the upstream assets it depended on. “This is basically a remote station from which we import power, but it’s maintained and operated by another entity,” Mairaj explained. “If the problem is in our network, we can handle it. But if it’s on the other network and we don’t have the visibility, we cannot manage it.”
To overcome this, KE engineered its system to infer grid conditions from circuit breaker status and transformer loading alone, allowing reliable, real-time action even in the absence of full data or direct control. The project was fully implemented and commissioned by early 2021, unlocking more than 600 MW in additional grid imports—enough to offset increased capex and meet surging demand.
The success of K-Electric’s Cross Trip Scheme offers a compelling case study for other utilities facing similar challenges. By leveraging ingenuity and in-house expertise, KE has demonstrated that it is possible to enhance grid reliability and capacity without massive infrastructure investments. This approach could be particularly relevant for utilities in developing economies, where resources are often limited, and demand is growing rapidly.
Moreover, the project highlights the potential of digital control architectures to enhance grid resilience and flexibility. As utilities around the world grapple with increasing system complexity and intermittency, the lessons learned from KE’s experience could prove invaluable. The Cross Trip Scheme is a testament to the power of innovation and the importance of thinking outside the box to meet the energy challenges of the 21st century.