Load flow analysis is the method of computing the correct amount of steady-state voltage at all the electrical nodes of a load condition. Load flow is mainly used in planning studies, designing a new network or expanding an existing one, and therefore takes place in the planning stages of a new power grid and when making changes to an existing system.
How Important Is It to the Power Grid System?
Modern power grids are the lifeblood of today’s society. The far-reaching impact of any outage can affect economic, political, and social aspects of today’s life. While the power grids have many protective schemes to prevent issues such as outages, sometimes cascading failures that lead to blackouts do happen.
For instance, in Australia the record-breaking heat this summer has caused many providers scramble to keep their systems running continuously, causing power supply shortages and outages in certain parts of the country. “In South Australia, where power capacity has been beefed up with diesel generators and gas-fired plants over the past two years following a state-wide blackout, 30,000 homes lost power on Thursday after transformers on local power lines overheated and switched off,” reports Reuters.
At times, power systems are subjected to unusual conditions, such as rapid load reconnection, a broken generator, a transmission line fault, or any other voltage instability, all of which may cause an overload. For this reason, a load flow analysis is critical to keep the system operational.
With the rapid expansion of power grids throughout the world, it is vital to determine the factors, including government regulations, to keep our systems safe, reliable, and economical.
What Information is Determined in a Load Flow Analysis?
A load flow analysis determines the following information, according to Rose-Hulman Education:
- The voltage magnitude and phase angle at each bus
- Real and reactive power flowing in each element
- Reactive power loading on each generator
In a load flow analysis, the voltage profile of all parts of the system is obtained. If voltages are considerably different throughout the system, large voltage flows could result in power losses and even possibly a voltage collapse.
The Load Flow Analysis Process
To conduct a load flow analysis, the team must develop a model of the system that is in operation or is being designed and obtain the specifics for each component. The next step is to determine the load flow equations. Only then can the team compute the voltage flows. This process requires extensive calculations and takes time because grids are large and complicated.
Types of Load Flow Analyses
There are three methods for calculating the power systems data:
- Gauss-Seidel System (GS)
The Gauss-Seidel System is one of the most common types of analysis. The advantages of this system are its simplicity in operation, limited computational power required, and less time to complete. However, its slow rate of convergence results in many iterations. A greater number of buses increases these iterations.
- Newton–Raphson Method (NR)
The Newton–Raphson method is a more sophisticated method, using the quadratic convergence, and can be used for more complex situations. This method takes fewer iterations to reach convergence, and therefore also takes less computer time. It also is more accurate since it is less sensitive to complicating factors such as slack bus selection or regulation transformers. One disadvantage is that programming can be complicated and requires a large computer memory.
- Fast Decoupled Load Flow System (FDLF)
The main advantage of this method is that it uses less computer memory. The speed of calculation is 5x faster than the Newton–Raphson method, making it a popular choice for real-time management of power grids. However, it can be less accurate since assumptions are used to obtain fast calculations. Since it is more difficult to change this computer program to look for other problems such as power system security or flow, its scope is limited.
Robust Software Programs for Load Flow Analysis
Load flow analysis software run from basic packages to large, complex programs designed for a specific power grid system. The software can be integrated in real-time to control and acquire data with real input from the system. The most frequently used parts of the package are the load flow and fault analysis studies. The load flow calculates the voltage, current, power, and reactive power in the system under regular operating condition while the fault analysis program locates areas of need to rate switchgear and busbar equipment for the maximum current that might flow through them.
When you select an expert firm to run a load flow analysis on your power grid, you can rest assured that the most stringent examination of the components will reveal scenarios to help you provide continuous service to your clients.
To learn more about how we can help you with your load flow analysis, contact us today.