app.py

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import streamlit as st

# Define the calculation function
def calculate_relay_curve(tr_kva, tr_volt, ct_pr, ct_sec, fac, tms, i_f_fac, curve):
    tr_curr = round(tr_kva / (tr_volt * np.sqrt(3)), 3)
    pick = round(fac * tr_curr / ct_pr, 3)
    i_f = round(i_f_fac * tr_curr * fac, 3)

    if curve == 'IEC Normal Inverse':
        b_ = 0.14
        a_ = 0.02
    elif curve == 'IEC Very Inverse':
        b_ = 13.5
        a_ = 1
    elif curve == 'IEC Extremely Inverse':
        b_ = 80
        a_ = 2.0
    elif curve == 'IEC Long Time Inverse':
        b_ = 120
        a_ = 1.0
    else:
        st.error("Invalid Curve Selected.")
        return

    trip_t = b_ * tms / (((i_f * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1)

    x_curr = np.linspace(pick * ct_pr + 0.1 * pick * ct_pr, pick * ct_pr * 5, 100)
    y_time = b_ * tms / (((x_curr * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1)

    fault_time = b_ * tms / (((i_f * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1)

    st.write('### Results:')
    st.write('**Rated Current:**', tr_curr, 'A')
    st.write('**Pickup:**', pick, 'x In')
    st.write('**Fault Current:**', round(i_f, 3), 'A')
    st.write('**Trip Time:**', round(fault_time, 3), 'sec')

    # Plot the relay curve
    fig, ax = plt.subplots()
    ax.plot(x_curr, y_time)
    ax.plot(i_f, b_ * tms / (((i_f * (ct_sec / ct_pr) / (pick * ct_sec)) ** a_) - 1), 'o')
    ax.xlabel('Current (Amp)')
    ax.ylabel('Time (sec)')
    ax.title(f"Relay Curve: {curve}")
    ax.set_xlabel('Current (Amp)')
    ax.set_ylabel('Time (sec)')
    ax.set_title(f"Relay Curve: {curve}")
    ax.legend()
    st.pyplot(fig)


# Streamlit app layout
st.title("Relay Curve Calculator")
st.sidebar.header("Input Parameters")

# Input fields
tr_kva = st.sidebar.number_input("Transformer Rating (kVA)", min_value=1.0, value=1000.0, step=1.0)
tr_volt = st.sidebar.number_input("Transformer Voltage (V)", min_value=1.0, value=11000.0, step=1.0)
ct_pr = st.sidebar.number_input("CT Primary (Amp)", min_value=1.0, value=200.0, step=1.0)
ct_sec = st.sidebar.number_input("CT Secondary (Amp)", min_value=1.0, value=5.0, step=1.0)
fac = st.sidebar.number_input("Fault Anticipation Factor", min_value=1.0, value=1.2, step=0.1)
tms = st.sidebar.number_input("Time Multiplier Setting (TMS)", min_value=0.01, value=0.1, step=0.01)
i_f_fac = st.sidebar.number_input("Fault Current Multiplier", min_value=1.0, value=10.0, step=0.1)
curve = st.sidebar.selectbox("Relay Curve Type", ['IEC Normal Inverse', 'IEC Very Inverse', 'IEC Extremely Inverse', 'IEC Long Time Inverse'])

# Run the calculation when the button is clicked
if st.sidebar.button("Calculate"):
    calculate_relay_curve(tr_kva, tr_volt, ct_pr, ct_sec, fac, tms, i_f_fac, curve)