The California Independent System Operator (CAISO) is a non-profit Independent System Operator (ISO) serving California. It oversees the operation of California's bulk electric power system, transmission lines, and electricity market generated and transmitted by its member utilities. The primary stated mission of CAISO is to "operate the grid reliably and efficiently, provide fair and open transmission access, promote environmental stewardship, and facilitate effective markets and promote infrastructure development." The CAISO is one of the largest ISOs in the world, delivering 300 million megawatt-hours of electricity each year and managing about 80% of California's electric flow..
The power grid is rapidly evolving, leading to unplanned operating conditions where the distribution system is no longer a passive consumer of electric energy. Most of the bulk system stability analytics assume that the distribution system is a passive consumer of electricity, which needs to be reevaluated with the evolving power grid. Large-scale integration of inverter-based technology, like distributed generation (DG) and flexible loads [(collectively called distributed energy resources (DERs)], in the distribution system is leading to an increase in transmission and distribution (T&D) system interactions. T&D interactions can be defined as the interdependence of system planning, performance, and operational decision making between T&D systems. T&D interactions impact several power grid aspects, including system stability, system planning, protection and controls, system resilience and reliability enhancement, etc. The California Independent System Operator (CAISO) has shed some light on the operational challenges observed in the real world and has highlighted the need to develop mechanisms to utilize T&D interactions for reliable grid operation (e.g., DER-based automatic generation control). For a stable future power grid, modeling, analyzing, and utilizing these T&D interactions effectively will be crucial. Aggregated models like the composite load models (CLMs) and other reduced order models (ROMs) can capture certain aggregated behavior of distribution system aspects, but they do not capture some features, like unbalanced nature and feeder voltage impacts on the distribution loads and DERs. T&D cosimulation can effectively capture the T&D interactions and their impact on power system stability.
The increasing penetration of renewable energy sources, particularly wind power, poses significant challenges to power system operation and control due to their intermittent and weather-dependent nature. This paper investigates the integration of two wind power plants and a Battery Energy Storage System into the IEEE 30-bus system, focusing on enhancing voltage stability and mitigating transmission line congestion. A 24 -hour dynamic load profile, based on real demand patterns and real wind power curves, has been applied to simulate daily operational behavior and evaluate the temporal impacts of renewable integration. The investigation uses MATPOWER for optimal power flow analysis and applies the Power Transfer Distribution Factor and Fast Voltage Stability Index as key metrics for BESS placement. Simulation results show that the combined deployment of wind generation and strategically located BESS significantly improves voltage profiles and reduces congestion along critical transmission paths. These findings provide practical insights for designing resilient and adaptive grid infrastructures in the context of increasing RES integration.
This paper presents a practical application of the Direct Current Optimal Power Flow (DC-OPF) model to the PJM 5-bus test system using the General Algebraic Modeling System (GAMS). The study aims to minimize system generation costs while respecting generator capacity, load balancing, and transmission line constraints through utilizing a linear programming approach for computational efficiency, but also ensuring reliability and operational efficiency. Key operational outcomes such as generator dispatch, power flows, and Locational Marginal Prices (LMP) are analyzed, with observed LMPs ranging from $ 10/MWh to $ 40/Wh depending on system congestion. The results highlight the impact of transmission congestion, notably identifying line E-D as the limiting element affecting market prices. Through comparison of AC power flow, the strengths and limitations of DC-OPF is showcased, particularly its inability to model voltage magnitudes and reactive power. The findings highlight the values of DC-OPF for fast market clearing applications while emphasizing the need for AC analyses in certain scenarios that may be sensitive to voltage and reactive power. The study provides actionable information for system operators and researchers engaged in the design and operational planning of the electricity market.
Much of the electric system is weather dependent; thus, our ability to forecast the weather contributes to its efficient and economical operation. Climatological forecasts of meteorological variables are used for long-term planning, capturing changing frequencies of extreme events, such as cold and hot periods, and identifying suitable locations for deploying new resources. Planning for fuel deliv...
The economic viability of new energy technologies is held as a central tenet to their future deployment; conventional wisdom posits economically rational decision-makers will readily invest in proven low-risk and affordable technologies. But what happens when this is not true. This paper examines the non-financial barriers facing economically viable Combined Heat and Power (CHP) projects. CHP is a mature and lower carbon technology that efficiently uses waste heat from thermal electricity generation; CHP can also provide flexibility services to help integrate variable renewable resources. CHP is low risk and many industrialized countries, particularly those in colder climates in Northern Europe and Russia, generate as much as 50% of their electricity and heat needs from CHP, but United States deployment remains low and investment hurdle rates high. While lower U.S. energy costs make some projects un-economic, many economically-viable CHP projects are stalled or killed by non-financial barriers. To better understand why financially viable CHP projects are not getting built, developers, owners and operators, regulators, and other stakeholders of this technology were interviewed and three major barriers emerged a) the business model of the electrical utility b) negative subjective impressions and c) challenges in allocating the risks and benefits.
